WO2020211454A1 - 正极极片、电化学装置及装置 - Google Patents

正极极片、电化学装置及装置 Download PDF

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Publication number
WO2020211454A1
WO2020211454A1 PCT/CN2019/129357 CN2019129357W WO2020211454A1 WO 2020211454 A1 WO2020211454 A1 WO 2020211454A1 CN 2019129357 W CN2019129357 W CN 2019129357W WO 2020211454 A1 WO2020211454 A1 WO 2020211454A1
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Prior art keywords
conductive
layer
current collector
active material
pole piece
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PCT/CN2019/129357
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English (en)
French (fr)
Inventor
李静
李伟
薛庆瑞
张子格
张扬
王鹏翔
陆阳
Original Assignee
宁德时代新能源科技股份有限公司
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Priority to EP19925225.5A priority Critical patent/EP3930056B1/en
Priority to ES19925225T priority patent/ES2950771T3/es
Publication of WO2020211454A1 publication Critical patent/WO2020211454A1/zh
Priority to US17/501,905 priority patent/US11923547B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—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
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
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    • H01M4/364—Composites as mixtures
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/48—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
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
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    • 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
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/626—Metals
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/661—Metal or alloys, e.g. alloy coatings
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    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H01M4/662—Alloys
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/668—Composites of electroconductive material and synthetic resins
    • H—ELECTRICITY
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    • 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
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    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to the field of batteries, and in particular to a positive pole piece, electrochemical device and device.
  • Lithium-ion batteries are widely used in electric vehicles and consumer electronic products due to their advantages of high energy density, high output power, long cycle life and low environmental pollution. With the continuous expansion of the application range of lithium-ion batteries, the requirements for the weight energy density and volume energy density of lithium-ion batteries are getting higher and higher.
  • lithium-ion batteries with higher mass energy density and volumetric energy density
  • improvements are usually made to lithium-ion batteries: (1) Choose a positive electrode material or negative electrode material with a high specific discharge capacity; (2) Optimize the mechanical design of lithium-ion batteries , To minimize its volume; (3) Choose a positive pole piece or negative pole piece with high compaction density; (4) Reduce the weight of each component of the lithium ion battery.
  • the improvement of the current collector is usually to select a lighter or thinner current collector.
  • a perforated current collector or a metal-plated plastic current collector can be used.
  • this application proposes a positive pole piece, electrochemical device and device.
  • the present application relates to a positive pole piece, which includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein the current collector includes a support layer and at least A conductive layer on one surface, the single-sided thickness D2 of the conductive layer satisfies: 30nm ⁇ D2 ⁇ 3 ⁇ m, the thickness D1 of the support layer satisfies: 1 ⁇ m ⁇ D1 ⁇ 30 ⁇ m, and the support layer is made of polymer material or high Molecular composite material; the electrode active material layer includes an electrode active material, a binder, and a conductive agent, and the electrode active material includes a small particle active material with an average particle size D50 of 1.0 ⁇ m to 7.0 ⁇ m and an average particle size D50 of 7.1 ⁇ m ⁇ 20.0 ⁇ m large particle active material.
  • the present application relates to an electrochemical device, including a positive pole piece, a negative pole piece, a separator and an electrolyte, wherein the positive pole piece is the positive pole piece described in the first aspect of the application.
  • the present application relates to a device, including the electrochemical device described in the second aspect of the present application.
  • the positive pole piece of the present application uses a composite current collector, which can significantly improve the energy density of the electrochemical device, such as the weight energy density;
  • the positive pole piece of the present application and the electrochemical device (such as a lithium ion battery) containing the positive pole piece also have both good electrochemical performance and safety performance. Because the conductive layer in the positive electrode current collector of the present application is relatively thin (the metal burrs generated in abnormal situations such as nail penetration are also small) and have a high short-circuit internal resistance, the safety performance of nail penetration is improved. On the other hand, the conductive layer in the positive electrode current collector is relatively thin, and is easily damaged during the preparation process of the pole piece (such as the rolling process).
  • the electrode active material layer of the present application includes two active materials with different particle sizes, namely The particles are mixed, so that the damage to the conductive layer can be reduced during the rolling process, and a current collector with good conductivity and a positive electrode sheet with small internal resistance and polarization and good electrochemical performance can be obtained.
  • the surface of the conductive layer of the composite current collector is also provided with a protective layer to further reduce the damage to the conductive layer during the pole piece processing, and to improve the conductivity of the composite current collector and the positive pole piece.
  • a protective layer to further reduce the damage to the conductive layer during the pole piece processing, and to improve the conductivity of the composite current collector and the positive pole piece. The electrochemical performance.
  • the positive pole piece is additionally provided with a conductive primer layer containing a conductive material and a binder between the current collector and the electrode active material layer, and the conductive primer layer may be further Reduce the damage to the conductive layer during the pole piece processing, and can effectively repair and construct the conductive network between the current collector, the conductive primer layer and the active material, improve the electron transmission efficiency, and reduce the gap between the current collector and the electrode active material layer.
  • the binder content in the electrode active material layer of the positive pole piece is not less than 1 wt%, preferably not less than 1.5 wt%, and more preferably not less than 2 wt%, so that the active material layer and The binding force between the composite current collectors is good, so that in abnormal situations such as nail penetration, the active material layer can effectively wrap the metal burrs generated in the conductive layer to improve the safety performance of the battery.
  • the device of the present application includes the electrochemical device described in the second aspect of the present application, and therefore has at least the same advantages as the electrochemical device.
  • the positive pole piece and electrochemical device of the present application have good and balanced electrochemical performance, safety performance, processing performance, and higher energy density.
  • Fig. 1 is a schematic structural diagram of a positive electrode current collector according to a specific embodiment of the application
  • FIG. 2 is a schematic structural diagram of a positive electrode current collector according to another specific embodiment of this application.
  • FIG. 3 is a schematic structural diagram of a positive electrode current collector according to another specific embodiment of the application.
  • FIG. 4 is a schematic structural diagram of a positive electrode current collector according to another specific embodiment of this application.
  • FIG. 5 is a schematic diagram of the structure of a positive pole piece according to a specific embodiment of this application.
  • FIG. 6 is a schematic structural diagram of a positive pole piece according to another specific embodiment of this application.
  • FIG. 7 is a schematic structural diagram of a positive pole piece according to another specific embodiment of this application.
  • FIG. 8 is a surface microscopic observation diagram of a positive electrode current collector according to a specific embodiment of this application.
  • FIG. 9 is a schematic diagram of an embodiment of the electrochemical device of this application.
  • FIG. 10 is a schematic diagram of an embodiment of the battery module of this application.
  • FIG. 11 is a schematic diagram of an embodiment of the battery pack of this application.
  • Figure 12 is an exploded view of Figure 11;
  • FIG. 13 is a schematic diagram of an embodiment of the electrochemical device of the application as a power source device
  • the first aspect of the present application relates to a positive pole piece, which includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein the current collector includes a support layer and at least one surface of the support layer
  • the conductive layer on the upper side, the single-sided thickness D2 of the conductive layer satisfies: 30nm ⁇ D2 ⁇ 3 ⁇ m, the thickness D1 of the support layer satisfies: 1 ⁇ m ⁇ D1 ⁇ 30 ⁇ m, and the support layer is a polymer material or a polymer composite material;
  • the electrode active material layer includes an electrode active material, a binder, and a conductive agent, and the electrode active material includes a small particle active material having an average particle diameter D50 of 1.0 ⁇ m to 7.0 ⁇ m and an average particle diameter D50 of 7.1 ⁇ m to 20.0 ⁇ m large particle active material.
  • the positive current collector used for the positive pole piece of the first aspect of the present application is a composite current collector, which is a composite of at least two materials.
  • the current collector includes a support layer and a conductive layer disposed on at least one surface of the support layer, the single-sided thickness D2 of the conductive layer satisfies: 30nm ⁇ D2 ⁇ 3 ⁇ m, and the thickness D1 of the support layer satisfies: 1 ⁇ m ⁇ D1 ⁇ 30 ⁇ m. Therefore, the conductive layer is the conductive layer in the current collector.
  • the thickness D2 of the conductive layer is much smaller than the thickness of the commonly used Al foil metal current collector in the prior art (the thickness of the commonly used Al foil metal current collector is usually 12 ⁇ m), and the support layer is made of polymer material or polymer composite material, so The weight energy density of an electrochemical device (such as a lithium battery) using the pole piece can be improved.
  • the composite current collector when the composite current collector is applied to the positive electrode current collector, it can also greatly improve the nail penetration safety performance of the positive electrode sheet, because the conductive layer in the positive electrode current collector is thin, and the metal burr generated when the nail penetration occurs is also Smaller, and due to the existence of the support layer, its short-circuit internal resistance is larger, so it is less likely to cause a short circuit.
  • the composite current collector has poor conductivity, and the conductive layer is easy to be used in the pole piece processing process (such as pole piece).
  • the sheet rolling is damaged, which affects the conductivity of the conductive layer and the electrochemical performance of the electrochemical device.
  • the support layer (polymer material or polymer composite material) of the composite current collector has a greater rebound degree than traditional metal current collectors during pole piece rolling and other processes, so the bonding force between the support layer and the conductive layer ,
  • the binding force between the composite current collector and the electrode active material layer preferably needs to be enhanced by improving the interface. Therefore, in the process of applying the above-mentioned composite current collector to an electrochemical device, some technical improvements are required.
  • the electrode active material layer is specially designed, so that the positive pole piece containing the composite current collector of the present application and the electrochemical device containing the positive pole piece (such as lithium ion battery ) It has good energy density, electrochemical performance and safety performance.
  • the electrode active material layer of the present application includes a combination of two active materials with different particle diameters, namely, a small particle active material with an average particle diameter D50 of 1.0 ⁇ m to 7.0 ⁇ m and an average particle diameter D50 of 7.1 ⁇ m to 20.0 ⁇ m
  • the combination of large-particle active materials can reduce the damage to the conductive layer during the rolling process, and can obtain a positive electrode sheet with small internal resistance, small polarization and good electrochemical performance.
  • an additional layer of conductive primer layer containing a conductive material and a binder is provided between the current collector and the electrode active material layer.
  • the conductive primer layer is provided on the surface of the current collector. Between the conductive layer and the electrode active material layer.
  • the conductive primer layer can further reduce the damage to the conductive layer during the processing of the pole piece, and can improve the interface between the composite current collector and the electrode active material layer, improve the binding force between the current collector and the electrode active material layer, and ensure The electrode active material layer is more firmly arranged on the surface of the composite current collector; in addition, the conductive network between the current collector, the conductive undercoat layer and the active material can be effectively repaired and constructed to improve the electron transmission efficiency and reduce the electrode containing the composite current collector.
  • Sheet resistance overcomes the shortcomings of poor conductivity of the composite current collector and easy damage to the conductive layer in the composite current collector, which can effectively reduce the DC internal resistance (DCR) of the electrode assembly, improve the power performance of the electrode assembly, and ensure the electrode assembly In the long-term cycling process, it is not easy to cause large polarization and lithium evolution, which effectively improves the long-term reliability of the electrode assembly.
  • DCR DC internal resistance
  • the conductive layer plays a role of conduction and current collection, and is used to provide electrons to the electrode active material layer.
  • the material of the conductive layer is selected from at least one of metal conductive materials and carbon-based conductive materials.
  • the metal conductive material is preferably at least one of aluminum, nickel, titanium, silver, and aluminum-zirconium alloy;
  • the carbon-based conductive material is preferably at least one of graphite, acetylene black, graphene, and carbon nanotubes;
  • the material of the conductive layer is preferably a metal conductive material, that is, the conductive layer is preferably a metal conductive layer.
  • the current collector is the positive electrode current collector
  • aluminum is usually used as the material of the conductive layer.
  • the conductivity of the conductive layer When the conductivity of the conductive layer is poor or the thickness is too small, the internal resistance of the battery will be large, and the polarization will be large. When the thickness of the conductive layer is too large, it is not enough to improve the weight energy density and volume energy density of the battery. Effect.
  • the single-sided thickness of the conductive layer is D2, and D2 preferably satisfies: 30nm ⁇ D2 ⁇ 3 ⁇ m, more preferably 300nm ⁇ D2 ⁇ 2 ⁇ m, most preferably 500nm ⁇ D2 ⁇ 1.5 ⁇ m; in order to better ensure the lightweight performance of the current collector It also has good electrical conductivity.
  • the upper limit of the single-sided thickness D2 of the conductive layer may be 3 ⁇ m, 2.5 ⁇ m, 2 ⁇ m, 1.8 ⁇ m, 1.5 ⁇ m, 1.2 ⁇ m, 1 ⁇ m, 900 nm
  • the lower limit of the single-sided thickness D2 of the conductive layer may be It is 800nm, 700nm, 600nm, 500nm, 450nm, 400nm, 350nm, 300nm, 100nm, 50nm, 30nm
  • the range of the single-sided thickness D2 of the conductive layer can be composed of any upper limit or lower limit.
  • cracks exist in the conductive layer of the positive pole piece described in this application.
  • the cracks in the conductive layer usually exist irregularly in the conductive layer. They can be elongated cracks, cross-shaped cracks, divergent cracks, etc.; they can be cracks that penetrate the entire conductive layer, or they can be in the conductive layer. Cracks formed on the surface layer. Cracks in the conductive layer are usually caused by the rolling during the pole piece processing, the excessive amplitude of the welding tab, and the excessive tension of the substrate winding.
  • the conductive layer can be formed on the support layer by at least one of mechanical rolling, bonding, vapor deposition, and electroless plating.
  • the vapor deposition method is preferably Physical Vapor Deposition (PVD). ); the physical vapor deposition method is preferably at least one of evaporation and sputtering; the evaporation method is preferably vacuum evaporation, thermal evaporation (thermal evaporation), electron beam evaporation (electron beam evaporation), At least one of EBEM), the sputtering method is preferably magnetron sputtering (Magnetron sputtering).
  • At least one of vapor deposition or electroless plating is preferred to make the bonding between the support layer and the conductive layer stronger.
  • the supporting layer plays a role of supporting and protecting the conductive layer. Since the support layer generally uses organic polymer materials or polymer composite materials, the density of the support layer is usually lower than that of the conductive layer, so that the weight energy density of the battery can be significantly increased compared with traditional metal current collectors.
  • the conductive layer adopts a metal layer with a smaller thickness, which can further increase the weight energy density of the battery.
  • the support layer can play a good bearing and protection effect on the conductive layer on its surface, it is not easy to produce the common pole piece fracture phenomenon in traditional current collectors.
  • the material of the support layer can be specifically selected from at least one of insulating polymer materials, insulating polymer composite materials, conductive polymer materials, and conductive polymer composite materials.
  • the insulating polymer material is for example selected from polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polyphenylene diamide, acrylonitrile -Butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, poly Phenyl sulfide, polyvinylidene fluoride, silicone rubber, polycarbonate, cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked products, polyethylene glycol and its At least one of cross-linked products.
  • the insulating polymer composite material is, for example, selected from composite materials formed by insulating polymer materials and inorganic materials, and the inorganic material is preferably at least one of ceramic materials, glass materials, and ceramic composite materials.
  • the conductive polymer material is, for example, selected from polysulfur nitride polymer materials or doped conjugated polymer materials, such as at least one of polypyrrole, polyacetylene, polyaniline, and polythiophene.
  • the conductive polymer composite material is, for example, selected from composite materials formed by insulating polymer materials and conductive materials, where the conductive material is selected from at least one of conductive carbon materials, metal materials, and composite conductive materials, and the conductive carbon materials are selected from carbon black, At least one of carbon nanotubes, graphite, acetylene black, and graphene, the metal material is selected from at least one of nickel, iron, copper, aluminum or alloys of the foregoing metals, and the composite conductive material is selected from nickel-coated graphite powder , At least one of nickel-coated carbon fibers.
  • the material of the support layer in this application is preferably an insulating polymer material or an insulating polymer composite material, especially when the current collector is a positive electrode current collector.
  • the safety performance of the battery can be significantly improved by using a special current collector supported by an insulating layer and a conductive layer with a specific thickness.
  • the insulating layer is non-conductive, its resistance is relatively large, which can increase the short-circuit resistance of the battery when a short circuit occurs under abnormal conditions, and greatly reduce the short-circuit current. Therefore, it can greatly reduce the short-circuit heat generation and improve the safety performance of the battery;
  • the conductive layer is relatively thin. Therefore, under abnormal circumstances such as nail penetration, the local conductive network is cut off, preventing a large area of the electrochemical device or even the entire electrochemical device from short-circuiting, which can reduce the damage of the electrochemical device caused by nail penetration. The damage is limited to the puncture site, only forming a "point disconnection", and does not affect the normal operation of the electrochemical device within a certain period of time.
  • the thickness of the support layer is D1, and D1 preferably satisfies: 1 ⁇ m ⁇ D1 ⁇ 30 ⁇ m; more preferably 1 ⁇ m ⁇ D1 ⁇ 15 ⁇ m.
  • the support layer is too thin, the mechanical strength of the support layer is insufficient, and it is easy to break during the pole piece processing process; if the support layer is too thick, the volumetric energy density of the battery using the current collector will be reduced.
  • the upper limit of the thickness D1 of the support layer can be 30 ⁇ m, 25 ⁇ m, 20 ⁇ m, 15 ⁇ m, 12 ⁇ m, 10 ⁇ m, 8 ⁇ m, and the lower limit can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m; the thickness of the support layer D1
  • the range of can be composed of any number of upper or lower limit.
  • the specific thickness of the present application can further ensure that the current collector has a larger resistance, and significantly reduce the battery heating when an internal short circuit occurs.
  • the conductive layer is aluminum, it can also significantly reduce or prevent the aluminum heat of the positive electrode current collector. Response to ensure that the battery has good safety performance.
  • the conductive layer is a metal conductive layer
  • the normal temperature Young's modulus of the support layer satisfies: 20GPa ⁇ E ⁇ 4GPa.
  • the testing method of the normal temperature Young's modulus of the support layer described in this application is as follows:
  • metal Since metal is relatively rigid relative to polymers or polymer composites, that is, it deforms less during the rolling process of pole piece processing, so in order to ensure that the deformation difference between the support layer and the conductive layer is not too large, so
  • the conductive layer is torn, and the normal temperature Young's modulus of the support layer should preferably meet: 20GPa ⁇ E ⁇ 4Gpa, so that the support layer can have a certain rigidity, and the rigidity matching between the support layer and the conductive layer can be further improved Therefore, during the processing of the current collector and the pole piece, it is ensured that the deformation of the support layer and the conductive layer will not be too different.
  • the current collector Since the support layer has a certain rigidity (20GPa ⁇ E ⁇ 4GPa), the current collector is not easy to deform or stretch too much during the processing of the current collector and the pole piece, so that the support layer and the conductive layer can be firmly bonded. It is not easy to detach, and can prevent the conductive layer from being "forced" to expand and causing damage to the conductive layer.
  • the current collector according to the present application has a certain degree of toughness, so that the current collector and the pole piece have a certain ability to withstand deformation and are not easy to break.
  • the Young's modulus of the support layer should not be too large, otherwise the rigidity will be too strong, which will cause difficulty in winding and winding, and poor workability.
  • the support layer can be guaranteed to have a certain degree of flexibility, and the pole piece can also have a certain ability to withstand deformation.
  • the thermal shrinkage rate of the support layer at 90° C. is not greater than 1.5%, so that the thermal stability of the current collector can be better ensured during the pole piece processing.
  • the current collector is further provided with a protective layer, and the protective layer is provided on one surface of the conductive layer of the current collector or on two of the conductive layers of the current collector. On the surface, that is, on the surface of the conductive layer away from the support layer and on the surface facing the support layer.
  • the protective layer can be a metal protective layer or a metal oxide protective layer.
  • the protective layer can prevent the conductive layer of the current collector from being damaged by chemical corrosion or mechanical damage, and can also enhance the mechanical strength of the current collector.
  • the protective layer is provided on both surfaces of the conductive layer of the current collector.
  • the lower protective layer of the conductive layer that is, the protective layer provided on the surface of the conductive layer facing the support layer
  • the technical effect of the upper protective layer of the conductive layer is mainly to prevent the conductive layer from being damaged and corroded during processing (such as electrolyte immersion, rolling, etc.)
  • the surface of the conductive layer affects).
  • the metal protective layer can not only further improve the mechanical strength and corrosion resistance of the conductive layer, but also reduce the polarization of the pole piece.
  • the material of the metal protective layer is, for example, selected from at least one of nickel, chromium, nickel-based alloys, and copper-based alloys, preferably nickel or nickel-based alloys.
  • the nickel-based alloy is an alloy formed by adding one or more other elements to pure nickel as the matrix.
  • it is a nickel-chromium alloy.
  • the nickel-chromium alloy is an alloy formed of metallic nickel and metallic chromium.
  • the molar ratio of nickel element to chromium element is 1:99-99:1.
  • Copper-based alloy is an alloy formed by adding one or more other elements to pure copper as the matrix. Preferably, it is a copper-nickel alloy. Optionally, in the copper-nickel alloy, the molar ratio of nickel to copper is 1:99-99:1.
  • metal oxide When metal oxide is selected for the protective layer, due to its low ductility, large specific surface area, and high hardness, it can also form effective support and protection for the conductive layer, and improve the bonding force between the support layer and the conductive layer. Has a good technical effect.
  • the material of the metal oxide protective layer is, for example, at least one selected from aluminum oxide, cobalt oxide, chromium oxide, and nickel oxide.
  • the protective layer of the composite current collector preferably adopts metal oxides, so as to achieve good technical effects of support and protection, while further improving the safety performance of the positive pole piece and the battery.
  • the thickness of the protective layer is D3, and D3 preferably satisfies: D3 ⁇ 1/10D2 and 1nm ⁇ D3 ⁇ 200nm. If the protective layer is too thin, it is not enough to protect the conductive layer; if the protective layer is too thick, it will reduce the weight energy density and volume energy density of the battery. More preferably, 5nm ⁇ D3 ⁇ 500nm, further preferably 10nm ⁇ D3 ⁇ 200nm, most preferably 10nm ⁇ D3 ⁇ 50nm.
  • the materials of the protective layers on the two surfaces of the conductive layer can be the same or different, and the thickness can be the same or different.
  • the thickness of the lower protective layer is smaller than the thickness of the upper protective layer to help improve the weight energy density of the battery.
  • the ratio of the thickness D3" of the lower protective layer to the thickness D3' of the upper protective layer is: 1/2D3' ⁇ D3" ⁇ 4/5D3'.
  • the current collector is the positive electrode current collector
  • aluminum is usually used as the material of the conductive layer
  • the lower protective layer is preferably a metal oxide material.
  • the metal oxide material has a larger resistance. Therefore, this type of lower protective layer can further increase the resistance of the positive electrode current collector to a certain extent, thereby further improving the abnormality of the battery.
  • the short circuit resistance in the event of a short circuit improves the safety performance of the battery.
  • the lower protective layer is preferably a metal oxide material
  • the upper protective layer is a metal material or a metal oxide material
  • the upper protective layer is preferably also a metal oxide material.
  • FIG. 1 to 4 show schematic structural diagrams of current collectors used in positive pole pieces according to certain embodiments of the present application.
  • the positive current collector 10 includes a positive current collector support layer 101 and a positive current collector conductive layer 102 disposed on two opposite surfaces of the positive current collector support layer 101, and also includes a positive current collector conductive layer 102
  • the positive current collector protective layer 103 on the lower surface is the lower protective layer.
  • the positive electrode current collector 10 includes a positive electrode current collector support layer 101 and a positive electrode current collector conductive layer 102 provided on two opposite surfaces of the positive electrode current collector support layer 101, and also includes a positive electrode current collector conductive layer 102 The positive current collector protective layer 103 on the opposite two surfaces, namely the lower protective layer and the upper protective layer.
  • the positive current collector 10 includes a positive current collector support layer 101 and a positive current collector conductive layer 102 disposed on one surface of the positive current collector support layer 101, and also includes a positive current collector disposed on the positive current collector conductive layer 102.
  • the positive current collector protective layer 103 on the surface of the fluid supporting layer 101 is the lower protective layer.
  • the positive electrode current collector current collector 10 includes a positive electrode current collector support layer 101 and a positive electrode current collector conductive layer 102 arranged on one surface of the positive electrode current collector support layer 101, and also includes an opposite electrode arranged on the positive electrode current collector conductive layer 102.
  • the positive current collector protective layer 103 on both surfaces, namely the lower protective layer and the upper protective layer.
  • the material of the protective layer on the two opposite surfaces of the conductive layer can be the same or different, and the thickness can be the same or different.
  • a conductive layer may be provided on two opposite surfaces of the support layer, or as shown in FIG. 3 and FIG. As shown in 4, a conductive layer may be provided on only one side of the support layer.
  • the composite current collector used in the positive pole piece of the present application preferably contains a current collector protective layer as shown in FIGS. 1 to 4, it should be understood that the current collector protective layer is not a necessary structure of the current collector. In some embodiments, The current collector used in may not contain a current collector protective layer.
  • the electrode active material layer generally includes an electrode active material, a binder, and a conductive agent. According to needs, the electrode active material layer may further include optional other additives or auxiliary agents.
  • the electrode active material in the electrode active material layer is composed of particles of two sizes, and specifically the electrode active material includes an average particle size D50 of 1.0 ⁇ m to 7.0 ⁇ m small particle active material and large particle active material with an average particle size D50 of 7.1 ⁇ m-20.0 ⁇ m.
  • D50 refers to the particle size when the cumulative volume percentage of the active material reaches 50%, that is, the median particle size of the volume distribution. D50 can be measured using, for example, a laser diffraction particle size distribution measuring instrument (such as Malvern Mastersizer 3000).
  • the mass ratio of the small particle active material to the large particle active material is 1:9-9:1.
  • the positive electrode active material can be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, transition Metal phosphate, lithium iron phosphate, etc., but the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials of lithium ion batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • the positive electrode active material may be selected from LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 ( NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 O 2 , LiFePO 4 (LFP), LiMnPO 4 Kind.
  • the small particle active material and the large particle active material are different active materials; more preferably, it is a combination of an active material with higher thermal stability and an active material with higher electrochemical capacity.
  • Active materials with higher thermal stability such as NCM333, NCM523, LFP; active materials with higher electrochemical capacity, such as NCM811, NCM622.
  • the conductive agent in the electrode active material layer is at least one of conductive carbon material and metal material; wherein the conductive carbon material is selected from zero-dimensional conductive carbon, such as acetylene black, conductive carbon black; one-dimensional conductive carbon, such as carbon nanotube ; Two-dimensional conductive carbon, such as conductive graphite, graphene; three-dimensional conductive carbon, such as at least one of reduced graphene oxide; metal materials selected from at least one of aluminum powder, iron powder and silver powder;
  • the binder in the electrode active material layer is selected from styrene butadiene rubber, oily polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer (such as PVDF-HFP copolymer, PVDF-TFE copolymer), carboxymethyl cellulose Sodium, polystyrene, polyacrylic acid, polytetrafluoroethylene, polyacrylonitrile, polyimide, water-based PVDF, polyurethane, polyvinyl alcohol, polyacrylate, polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-poly At least one of acrylonitrile copolymers.
  • PVDF oily polyvinylidene fluoride
  • PVDF-HFP copolymer such as PVDF-HFP copolymer, PVDF-TFE copolymer
  • carboxymethyl cellulose Sodium carboxymethyl cellulose Sodium
  • PVDF oily polyvinylidene fluoride
  • the binder content in the electrode active material layer is not less than 1wt%, preferably not less than 1.5wt%, more preferably not Less than 2wt%.
  • the bonding force between the active material layer and the current collector is better, so that under abnormal conditions such as nail penetration, the active material layer can effectively wrap the metal burrs generated in the conductive layer to improve Improve the safety performance of battery nail penetration.
  • a slurry composed of electrode active materials, conductive agents, and binders is coated on the positive electrode current collector (or pre-coated on the undercoat layer of the positive electrode current collector), and then dried and other post-processing
  • the desired positive electrode active material layer can be obtained.
  • the positive pole piece is further provided with a conductive primer layer between the current collector and the electrode active material layer, and the conductive primer layer includes a conductive material and a binder.
  • the conductive primer layer can not only further reduce the damage to the conductive layer during the pole piece processing, but also improve the composite current collector interface, increase the adhesion between the current collector and the electrode active material layer, and ensure that the electrode active material layer is better. It is firmly arranged on the surface of the composite current collector; in addition, the conductive network between the current collector and the active material in the electrode active material layer can be effectively repaired and constructed to improve the electron transmission efficiency and reduce the gap between the current collector and the electrode active material layer.
  • Electrical resistance overcomes the shortcomings of poor conductivity of the composite current collector and easy damage to the conductive layer in the composite current collector, which can effectively reduce the DC internal resistance of the electrode assembly, improve the power performance of the electrode assembly, and ensure the electrode assembly in the long-term cycle process It is not prone to phenomena such as large polarization and lithium evolution, which effectively improves the long-term reliability of the electrode assembly.
  • the weight percentage of the conductive material is 10% to 99%, preferably 20% to 80%, more preferably 50% to 80%; the weight percentage of the binder The content is 1% to 90%, preferably 20% to 80%, more preferably 20% to 50%. This ratio can help to improve the conductivity of the positive pole piece and the binding force between the current collector and the electrode active material layer.
  • the conductive undercoat layer may further contain an electrode active material.
  • the electrode active material is included, the electrochemical capacity of the positive pole piece can be increased.
  • the balance other than the conductive material and the binder may be the electrode active material.
  • the content of the conductive material is preferably 10 wt% to 98 wt%
  • the content of the binder is preferably 1 wt% to 89 wt%
  • the electrode (positive electrode) The content of the active material is preferably 1 wt% to 89 wt%.
  • the conductive material may be at least one of a conductive carbon material and a metal material; the conductive material in the conductive primer layer and the conductive agent in the active material layer may be the same or different.
  • the conductive carbon material is selected from zero-dimensional conductive carbon (such as acetylene black, conductive carbon black), one-dimensional conductive carbon (such as carbon nanotubes), two-dimensional conductive carbon (such as conductive graphite, graphene), three-dimensional conductive carbon (such as Reduced graphene oxide);
  • the metal material is selected from at least one of aluminum powder, iron powder and silver powder.
  • the preferred conductive material contains one-dimensional conductive carbon material or two-dimensional conductive carbon material. Because after adding the two-dimensional conductive carbon material, during the compaction of the pole piece, the two-dimensional conductive carbon material in the conductive undercoat can produce "horizontal sliding", which acts as a buffer and reduces the impact on the current collector during the compaction process. Destruction of the conductive layer, thereby reducing cracks.
  • the particle size D50 of the preferred two-dimensional conductive carbon material is 0.01 to 0.1 ⁇ m.
  • the two-dimensional conductive carbon material accounts for 1 wt% to 50 wt% of the conductive material.
  • the one-dimensional conductive carbon material due to the special morphology of the one-dimensional conductive carbon material, it can improve the conductivity of the conductive undercoat after adding, especially when the amount of conductive material added is certain, the one-dimensional conductive carbon material is compared with other types of conductive materials.
  • the material can better improve the conductivity of the conductive primer.
  • carbon nanotubes Preferably, carbon nanotubes have an aspect ratio of 1,000 to 5,000.
  • the preferred conductive material is a mixed material of a zero-dimensional conductive carbon material and a one-dimensional conductive carbon material or a mixed material of a zero-dimensional conductive carbon material and a two-dimensional conductive carbon material.
  • the binder in the conductive primer layer and the binder in the active material layer may be the same or different.
  • the binder in the conductive primer layer is selected from styrene butadiene rubber, oily polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer (such as PVDF-HFP copolymer, PVDF-TFE copolymer), carboxymethyl cellulose Sodium, polystyrene, polyacrylic acid, polytetrafluoroethylene, polyacrylonitrile, polyimide, water-based PVDF, polyurethane, polyvinyl alcohol, polyacrylate, polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-poly At least one of acrylonitrile copolymers.
  • PVDF oily polyvinylidene fluoride
  • PVDF-HFP copolymer such as PVDF-HFP copolymer, PVDF-TFE copolymer
  • carboxymethyl cellulose Sodium carboxymethyl cellulose Sodium
  • PVDF oily polyvinylidene fluoride
  • the binder in the conductive primer layer is preferably an aqueous binder, such as aqueous PVDF, polyacrylic acid, polyurethane, polyvinyl alcohol, polyacrylate, polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer At least one of them, so that the DCR growth of the electrochemical device is small.
  • aqueous polymer material means that the polymer molecular chain is fully extended and dispersed in water
  • “oily” polymer material means that the polymer molecular chain is fully extended and dispersed in an oily solvent.
  • the same type of polymer material can be dispersed in water and oil respectively, that is, by using a suitable surfactant, the same type of polymer material can be made into water-based Polymer materials and oily polymer materials.
  • those skilled in the art can modify PVDF into aqueous PVDF or oily PVDF as needed.
  • the electrode active material in the conductive primer layer and the electrode active material in the active material layer may be the same or different.
  • the electrode active material in the conductive primer layer can be selected from various electrode active materials commonly used in the art (ie, positive electrode active materials).
  • the thickness H of one side of the conductive primer layer is preferably 0.1 ⁇ m to 5 ⁇ m.
  • H/D2 is 0.5:1 to 5:1. If the ratio is too small, it cannot effectively improve the cracks of the conductive layer and improve the conductivity of the pole piece; if the ratio is too large, it will not only reduce the weight and energy density of the battery, but also increase the battery DCR, which is not conducive to the dynamic performance of the battery. Improvement.
  • 5 to 7 show schematic structural diagrams of positive pole pieces according to some embodiments of the present application.
  • the positive pole piece PP includes a positive current collector 10 and a positive active material layer 12 disposed on two opposite surfaces of the positive current collector 10, and the positive current collector 10 includes a positive current collector support layer 101 and a positive The positive current collector conductive layer 102 on the two opposite surfaces of the current collector support layer 101.
  • the positive pole piece PP includes a positive current collector 10 and a conductive primer layer 11 and a positive active material layer 12 disposed on two opposite surfaces of the positive current collector 10.
  • the positive current collector 10 includes a positive current collector support The layer 101 and the positive electrode current collector conductive layer 102 provided on two opposite surfaces of the positive electrode current collector support layer 101.
  • the positive electrode sheet PP includes a positive electrode current collector 10 and a conductive undercoat layer 11 and a positive electrode active material layer 12 disposed on one surface of the positive electrode current collector 10.
  • the positive electrode current collector 10 includes a positive electrode current collector support layer 101 and The positive electrode current collector conductive layer 102 provided on one surface of the positive electrode current collector support layer 101.
  • the electrode active material layer can be provided on one surface of the current collector, or can be provided on both surfaces of the current collector.
  • the positive pole piece when a current collector provided with a double-sided conductive layer is used, the positive pole piece can be coated on both sides (that is, the electrode active material layer is provided on both surfaces of the current collector), or only on one side. Coating (that is, the electrode active material layer is only provided on one surface of the current collector); and when the current collector provided with only a single-sided conductive layer is used, the positive pole piece can only be coated on one side, and the electrode active material layer (And the conductive primer layer) can only be coated on the side of the current collector provided with the conductive layer.
  • the second aspect of the present application relates to an electrochemical device, including a positive pole piece, a negative pole piece, a separator and an electrolyte, wherein the positive pole piece is the positive pole piece according to the first aspect of the present application.
  • the electrochemical device may be a capacitor, a primary battery, or a secondary battery.
  • it may be a lithium ion capacitor, a lithium ion primary battery, or a lithium ion secondary battery.
  • the structure and preparation method of these electrochemical devices are well known per se. Due to the use of the positive pole piece of the present application, the electrochemical device can have high energy density, improved safety (such as nail penetration safety) and electrochemical performance.
  • the positive pole piece of the present application is easy to process, so the manufacturing cost of an electrochemical device using the positive pole piece of the present application can be reduced.
  • the specific types and compositions of the negative pole piece, separator, and electrolyte are not specifically limited, and can be selected according to actual needs.
  • the isolation film can be selected from polyethylene film, polypropylene film, polyvinylidene fluoride film and their multilayer composite film.
  • a non-aqueous electrolyte is generally used as the electrolyte.
  • a lithium salt solution dissolved in an organic solvent is generally used as the non-aqueous electrolyte.
  • the lithium salt is, for example, LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts, or LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC n F 2n+1 SO 3 (n ⁇ 2) and other organic lithium salts.
  • the organic solvent used in the non-aqueous electrolyte is, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, etc.
  • the negative electrode piece a negative electrode piece formed of various negative electrode active materials commonly used in the art can be selected.
  • the negative electrode active material can be selected from carbonaceous materials such as graphite (artificial graphite or natural graphite), conductive carbon black, carbon fiber, etc., such as metals or semi-metals such as Si, Sn, Ge, Bi, Sn, and In. Metal material or its alloy, lithium-containing nitride or lithium-containing oxide, lithium metal or lithium aluminum alloy, etc.
  • the electrochemical device may include an outer package for packaging the positive pole piece, the negative pole piece, and the electrolyte.
  • the positive pole piece, the negative pole piece and the separator can be laminated or wound to form a laminated structure electrode assembly or a wound structure electrode assembly, the electrode assembly is encapsulated in an outer package; the electrolyte can be an electrolyte, which is infiltrated In the electrode assembly.
  • the number of electrode assemblies in the electrochemical device can be one or several, which can be adjusted according to requirements.
  • the outer packaging of the electrochemical device may be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag can be plastic, for example, it can include one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • the outer packaging of the electrochemical device can also be a hard shell, such as an aluminum shell.
  • Fig. 9 is an electrochemical device 5 with a square structure as an example.
  • the electrochemical device can be assembled into a battery module, and the number of electrochemical devices contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 10 shows the battery module 4 as an example.
  • a plurality of electrochemical devices 5 may be arranged in order along the length direction of the battery module 4. Of course, it can also be arranged in any other manner. Furthermore, the plurality of electrochemical devices 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space, and a plurality of electrochemical devices 5 are accommodated in the accommodation space.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • FIG. 11 and FIG. 12 are the battery pack 1 as an example. 11 and 12, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3.
  • the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4.
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the third aspect of the application relates to a device, including the electrochemical device described in the second aspect of the application.
  • the electrochemical device provides power to the device.
  • the device can be, but is not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf Vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • electric trains, ships, and satellites are all vehicles and belong to vehicles in a broad sense.
  • the device can select an electrochemical device, a battery module or a battery pack according to its usage requirements.
  • Figure 13 is a device as an example.
  • the device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • battery packs or battery modules can be used.
  • the device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • the device usually requires lightness and thinness, and an electrochemical device can be used as a power source.
  • the formation conditions of the vacuum evaporation method are as follows: the support layer with the surface cleaning treatment is placed in the vacuum coating chamber, and the high-purity metal wire in the metal evaporation chamber is melted and evaporated at a high temperature of 1600°C to 2000°C. The evaporated metal After the cooling system in the vacuum coating chamber, it is finally deposited on the surface of the support layer to form a conductive layer.
  • the forming conditions of the mechanical rolling method are as follows: the foil of the conductive layer material is placed in a mechanical roller, and it is rolled to a predetermined thickness by applying a pressure of 20t to 40t, and then it is placed and subjected to surface cleaning treatment The surface of the support layer is finally placed in a mechanical roller, and the two are tightly combined by applying a pressure of 30t to 50t.
  • the formation conditions of the bonding method are as follows: the foil of the conductive layer material is placed in a mechanical roller, and it is rolled to a predetermined thickness by applying a pressure of 20t to 40t; and then the surface cleaning treatment of the support layer The surface is coated with a mixed solution of PVDF and NMP; finally, the conductive layer with the predetermined thickness is adhered to the surface of the support layer and dried at 100°C.
  • a protective layer is provided on the surface of the support layer by vapor deposition or coating, and then a conductive layer with a certain thickness is formed on the surface of the support layer with the protective layer by vacuum evaporation, mechanical rolling or bonding.
  • the protective layer is located between the support layer and the conductive layer
  • the surface of the conductive layer away from the support layer can be vapor-deposited in situ Forming method or coating method to form another protective layer to prepare a current collector with protective layer (the protective layer is located on two opposite surfaces of the conductive layer);
  • a protective layer is formed on one surface of the conductive layer by vapor deposition, in-situ formation or coating, and then the conductive layer with the protective layer is placed on the support by mechanical rolling or bonding.
  • Layer surface, and the protective layer is arranged between the support layer and the conductive layer to prepare a current collector with a protective layer (the protective layer is located between the support layer and the conductive layer); in addition, on the basis of the above, the conductive layer
  • another protective layer is formed by vapor deposition, in-situ formation or coating to prepare a current collector with a protective layer (the protective layer is located on two opposite surfaces of the conductive layer);
  • a protective layer is formed on one surface of the conductive layer by vapor deposition, in-situ formation or coating, and then the conductive layer with the protective layer is placed on the support by mechanical rolling or bonding. Layer surface, and the protective layer is arranged on the surface of the conductive layer away from the support layer to prepare a current collector with a protective layer (the protective layer is located on the surface of the conductive layer away from the support layer);
  • a protective layer is formed on the two surfaces of the conductive layer by vapor deposition, in-situ formation or coating, and then the conductive layer with the protective layer is placed on the conductive layer by mechanical rolling or bonding.
  • the surface of the support layer to prepare a current collector with a protective layer (the protective layer is located on two opposite surfaces of the conductive layer);
  • the vapor deposition method uses a vacuum evaporation method
  • the in-situ formation method uses an in-situ passivation method
  • the coating method uses a doctor blade coating method.
  • the formation conditions of the vacuum evaporation method are as follows: put the sample with surface cleaning treatment in the vacuum plating chamber, melt and evaporate the protective layer material in the evaporation chamber at a high temperature of 1600°C to 2000°C, and the evaporated protective layer material passes through the vacuum coating chamber The cooling system is finally deposited on the surface of the sample to form a protective layer.
  • the formation conditions of the in-situ passivation method are as follows: the conductive layer is placed in a high-temperature oxidizing environment, the temperature is controlled at 160°C to 250°C, while the oxygen supply is maintained in the high-temperature environment, and the treatment time is 30 minutes, thereby forming metal oxides.
  • the protective layer is controlled at 160°C to 250°C, while the oxygen supply is maintained in the high-temperature environment, and the treatment time is 30 minutes, thereby forming metal oxides.
  • the formation conditions of the gravure coating method are as follows: the protective layer material and NMP are stirred and mixed, and then the slurry of the protective layer material (solid content of 20% to 75%) is coated on the surface of the sample, and then the gravure roll is used to control the coating The thickness is finally dried at 100°C to 130°C.
  • conductive materials such as conductive carbon black
  • binders such as PVDF or polyacrylic acid, etc.
  • an appropriate solvent such as NMP or water
  • NCM333 is used by default if no specific material is specified
  • SP 5wt% conductive agent Super-P
  • 3wt% PVDF 3wt% PVDF
  • the preparation method is similar to the preparation method of the positive electrode sheet (with conductive undercoat layer) in the above embodiment, but wherein the positive electrode active material layer slurry is directly coated on the surface of the composite current collector without the undercoat layer.
  • the current collector is an Al foil with a thickness of 12 ⁇ m, which is similar to the preparation method of the positive electrode (without conductive undercoating) above.
  • the positive electrode active material layer slurry is directly coated on the surface of the Al foil current collector. After post-processing, the conventional positive pole piece is obtained.
  • the positive pole piece (compact density: 3.4g/cm 3 ), PP/PE/PP separator and negative pole piece (compact density: 1.6g/cm 3 ) are wound together to form an electrode assembly , Then put into the battery case, inject electrolyte (EC:EMC volume ratio is 3:7, LiPF 6 is 1mol/L), followed by sealing, chemical conversion and other processes, and finally get a lithium ion secondary battery (hereinafter referred to as battery).
  • electrolyte ECC volume ratio is 3:7, LiPF 6 is 1mol/L
  • Adjust the secondary battery to 50% SOC with 1C current at 25°C, and record the voltage U1. Then discharge with 4C current for 30 seconds, and record the voltage U2. DCR (U1-U2)/4C. Then the battery is subjected to a 1C/1C charge-discharge cycle for 500 weeks, and the DCR of the 500th week is recorded. The DCR of the 500th week is divided by the DCR of the first week and subtracted by 1 to obtain the DCR growth rate of the 500th week.
  • the secondary batteries (10 samples) were fully charged to the charge cut-off voltage with a current of 1C, and then charged at a constant voltage until the current dropped to 0.05C, and the charging was stopped.
  • the secondary battery After the secondary battery is fully discharged, it is fully charged at 0.33C, and the 4.2V constant voltage is used to 0.05C, and then 0.33C is used to fully discharge, and the 0.33C full discharge capacity C 0 is recorded, and then fully charged at 0.33C, 4.2V constant voltage to 0.05C, then use 4C full discharge, record the 4C full discharge capacity C 1 , then the discharge rate capacity retention rate is C 1 /C 0 .
  • the current collector weight percentage refers to the percentage of the weight of the positive current collector per unit area divided by the weight of the conventional positive current collector per unit area.
  • Lithium-ion batteries using composite current collectors have a thinner conductive layer than traditional metal current collectors, resulting in smaller metal burrs under abnormal conditions such as nail penetration, and the support layer of the composite current collector has a larger short-circuit resistance. Conducive to improving the safety performance of battery nail penetration. As can be seen from the above table, conventional batteries will suffer thermal runaway and destruction under nail penetration and cannot pass the nail penetration safety test. All lithium-ion batteries using composite current collectors can pass the nail penetration safety test.
  • Table 3 shows the cycle performance data measured after the pole pieces listed in Table 2 are assembled into a battery.
  • the cycle life of the battery using the composite current collector is good, which is equivalent to the cycle performance of the conventional battery.
  • the battery capacity retention rate of a battery made of a current collector containing a protective layer can be further improved compared to a battery made of a current collector without a protective layer, indicating that the battery is more reliable.
  • Table 4 shows the specific composition and related parameters of the batteries of the respective examples and comparative examples, as well as the positive pole pieces and current collectors used therein.
  • Table 5 shows the performance measurement results of each battery.
  • the composite current collector has poorer conductivity than traditional metal current collectors, and the conductive layer in the composite current collector Shortcomings such as easy to break, the DCR of the battery is large, and the cycle capacity retention rate is low.
  • the conductive primer layer effectively repairs and constructs a conductive network between the current collector, the conductive primer layer and the active material, which improves the efficiency of electron transmission and reduces the resistance of the current collector and the electrode active material layer. Can effectively reduce DCR.
  • the DCR of the battery can be improved to a greater extent.
  • flake graphite Since the flake graphite can produce "horizontal sliding", it plays a buffering role, reducing the damage to the conductive layer of the current collector during the compaction process, thereby reducing cracks, so the introduction of flake graphite can further reduce the battery DCR (positive electrode) Pole piece 24 vs. positive pole piece 29).
  • the DCR of the battery can also be more significantly improved.
  • the thickness of the conductive primer layer is too large, it is not conducive to the improvement of the energy density of the battery.
  • Electrode active materials with different particle sizes in the electrode active material layer to improve the electrochemical performance of the battery.
  • Table 6 shows the specific composition and related parameters of the positive pole piece and current collector used in the battery of each embodiment.
  • Table 7 shows the performance measurement results of each battery.
  • the electrode active material layer containing electrode active materials of different particle diameters can be directly formed on the surface of the composite current collector, that is, no conductive primer layer is provided, but in a preferred embodiment of the present application, On the basis of the conductive primer layer, the use of electrode active materials with different particle diameters to improve the electrochemical performance of the battery and other aspects are studied to better study its technical effects.
  • the binding force between the active material layer and the current collector is better.
  • the entire membrane layer ie, the active material layer and the conductive
  • the binding force between the undercoat layer and the composite current collector is also good, so that under abnormal conditions such as nail penetration, the active material layer (or membrane layer) can effectively wrap the metal burrs generated in the conductive layer to Improve the safety performance of battery nail penetration.
  • the positive electrode pieces are prepared according to the method described in the previous embodiment, but the composition of the positive electrode active material layer slurry is adjusted to prepare multiple positive electrode pieces with different binder content in the positive electrode active material layer.
  • the specific pole piece composition is shown in the table below. For simplicity, a single particle size active material is used here.
  • Table 10 shows the nail penetration test results when the above-mentioned different positive pole pieces are assembled into a battery. The results show that the higher the content of the binder in the positive electrode active material layer, the better the nail penetration safety performance of the corresponding battery.
  • the binder content in the positive electrode active material layer is not less than 1 wt%, more preferably not less than 1.5 wt%, and most preferably not less than 2 wt%.
  • the surface of the conductive layer of the composite current collector is different from that of the traditional metal aluminum foil current collector, that is, the surface is prone to cracks.
  • the positive pole piece 24 after cold pressing, take a small sample, and wipe the surface of the positive pole piece 24 with a dust-free paper soaked in DMC solvent to expose the surface of the composite current collector.
  • a CCD microscope to observe the surface topography.
  • the observation diagram is shown in Figure 8. From Figure 8 you can see obvious cracks. This kind of crack is unique to the surface of the conductive layer of the composite current collector, and it is not observed on the surface of the traditional metal current collector.
  • the conductive layer of the composite current collector is thin, cracks are likely to occur under pressure during the cold pressing of the pole pieces.
  • the electrode active material layer of the present application includes two kinds of active materials with different particle sizes, that is, a mixture of small and large particles, so that during the rolling process, the damage to the conductive layer can be reduced, thereby improving the conductivity of the composite current collector and the battery The internal resistance, polarization and other properties of the battery, so as to finally obtain a positive pole piece with small internal resistance and good electrochemical performance.
  • the conductive primer layer can not only further reduce the damage to the conductive layer, but also can effectively repair and construct the conductive network between the current collector and the active material, improve the electron transmission efficiency, and reduce the current collector and the electrode active material layer.
  • This can effectively reduce the DC internal resistance of the electrode assembly, improve the power performance of the electrode assembly, and ensure that the electrode assembly is not prone to large polarization and lithium evolution during long-term cycling, which effectively improves The long-term reliability of the electrode assembly; the specific manifestation is that the DCR growth is significantly reduced, thereby improving the battery performance.

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Abstract

一种正极极片、电化学装置及装置，涉及电池领域。所述正极极片包括集流体（10）和设置于所述集流体（10）至少一个表面上的电极活性材料层（12），其中，所述集流体（10）包括支撑层（101）和设置于支撑层（101）至少一个表面上的导电层（102），所述导电层（102）的单面厚度D2满足：30nm≤D2≤3μm，所述支撑层（101）的厚度D1满足：1μm≤D1≤30μm，且支撑层（101）为高分子材料或高分子复合材料；所述电极活性材料层（12）包括电极活性材料、粘结剂和导电剂，且所述电极活性材料包括平均粒径D50为1.0μm～7.0μm的小颗粒活性材料以及平均粒径D50为7.1μm～20.0μm的大颗粒活性材料。包含该正极极片的电化学装置具有高的能量密度和良好的安全性能（尤其是穿钉安全性能）及电化学性能。

Description

正极极片、电化学装置及装置 技术领域
本申请涉及电池领域，具体地讲，涉及一种正极极片、电化学装置及装置。
背景技术
锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。随着锂离子电池的应用范围不断扩大，大家对锂离子电池的重量能量密度和体积能量密度的要求也越来越高。
为了得到质量能量密度和体积能量密度较高的锂离子电池，通常对锂离子电池进行如下改进：(1)选择放电比容量高的正极材料或负极材料；(2)优化锂离子电池的机械设计，使其体积最小化；(3)选择高压实密度的正极极片或负极极片；(4)对锂离子电池的各部件进行减重。
其中，对集流体的改进通常是选择重量较轻或厚度较小的集流体，例如可以采用打孔集流体或镀有金属层的塑料集流体等。
对于采用镀有金属层的塑料集流体的极片和电池来说，虽然能量密度得以提高，但是有可能带来加工性能和电化学性能等方面的一些性能劣化。要得到电化学性能好的极片和集流体，还需要很多方面的改进。
为了克服现有技术之不足，特提出本申请。
发明内容
鉴于此，本申请提出一种正极极片、电化学装置及装置。
第一方面，本申请涉及一种正极极片，包括集流体和设置于所述集流体至少一个表面上的电极活性材料层，其中，所述集流体包括支撑层和设置于所述支撑层至少一个表面上的导电层，所述导电层的单面厚度D2满足：30nm≤D2≤3μm，所述支撑层的厚度D1满足：1μm≤D1≤30μm，且所述支撑层为高分子材料或高分子复合材料；所述电极活性材料层包括电极活性材料、粘结剂和导电剂，且所述电极活性材料包括平均粒径D50为1.0μm～7.0μm的小颗粒活性材料以及平均粒径D50为7.1μm～20.0μm的大颗粒活性材料。
第二方面，本申请涉及一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，其中所述正极极片为本申请第一方面所述的正极极片。
第三方面，本申请涉及一种装置，包括本申请第二方面所述的电化学装置。
本申请的技术方案至少具有以下有益的效果：
第一，本申请的正极极片采用复合集流体，可以显著改善电化学装置的能量密度，例如重量能量密度；
第二，本申请的正极极片和含有该正极极片的电化学装置(例如锂离子电池)还兼具良好的电化学性能和安全性能。因为本申请的正极集流体中的导电层较薄(在发生穿钉等异常情况时产生的金属毛刺也较小)且具有较高的短路内阻，因此改善了穿钉安全性能。另一方面，正极集流体中的导电层较薄，在极片制备过程中(例如辊压工艺)容易被破坏，而本申请的电极活性材料层包括两种粒径不同的活性材料，即大小颗粒混合，从而在辊压的过程中，可以减少对导电层的破坏，得到导电性能良好的集流体以及内阻和极化较小、电化学性能良好的正极极片。
另外，根据本申请某些优选实施方式的复合集流体的导电层表面还设置有保护层，以进一步地减少极片加工过程中对导电层的破坏，改善复合集流体的导电性和正极极片的电化学性能。
此外，根据本申请某些优选实施方式的正极极片在所述集流体与电极活性材料层之间还额外设置有包含导电材料和粘结剂的导电底涂层，导电底涂层可以进一步地减少极片加工过程中对导电层的破坏，且可以通过有效修补并构筑集流体、导电底涂层与活性物质间的导电网络，提高电子传输效率，降低集流体与电极活性材料层之间的电阻，很好地克服复合集流体导电能力较差、且复合集流体中的导电层易于破损等缺点，从而可以有效降低电极组件的直流内阻，提高电极组件的功率性能，并保证电极组件在长期循环过程中不易于发生较大的极化及析锂等现象，即有效改善了电极组件的长期可靠性。
此外，根据本申请某些优选实施方式的正极极片的电极活性材料层中的粘结剂含量不小于1wt％，优选不小于1.5wt％，更优选不小于2wt％，从而使得活性材料层与复合集流体间的结合力较好，以使得在穿钉等异常情况下，活性材料层可有效地包裹导电层中产生的金属毛刺，以改善电池的穿钉安全性能。
本申请的装置包括本申请第二方面所述的电化学装置，因而至少具有与所述电化学装置相同的优势。
因此，本申请的正极极片和电化学装置具有良好且均衡的电化学性能、安全性能和加工性能以及较高的能量密度。
附图说明
下面结合附图和具体实施方式，对本申请的正极极片、电化学装置及其有益效果进行详细说明。
图1为本申请某一具体实施方式的正极集流体的结构示意图；
图2为本申请又一具体实施方式的正极集流体的结构示意图；
图3为本申请又一具体实施方式的正极集流体的结构示意图；
图4为本申请又一具体实施方式的正极集流体的结构示意图；
图5为本申请某一具体实施方式的正极极片的结构示意图；
图6为本申请又一具体实施方式的正极极片的结构示意图；
图7为本申请又一具体实施方式的正极极片的结构示意图；
图8为本申请某一具体实施方式的正极集流体的表面显微观测图；
图9为本申请的电化学装置的一实施方式的示意图；
图10为本申请的电池模块的一实施方式的示意图；
图11为本申请的电池包的一实施方式的示意图；
图12是图11的分解图；
图13为本申请的电化学装置作为电源的装置的一实施方式的示意图；
其中：
PP-正极极片；
10-正极集流体；
101-正极支撑层；
102-正极导电层；
103-正极保护层；
11-导电底涂层；
12-正极活性材料层
1-电池包；
2-上箱体；
3-下箱体；
4-电池模块；
5-电化学装置。
具体实施方式
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
本申请的第一方面涉及一种正极极片，包括集流体和设置于所述集流体至少一个表面上的电极活性材料层，其中，所述集流体包括支撑层和设置于支撑层至少一个表面上的导电层，所述导电层的单面厚度D2满足：30nm≤D2≤3μm，所述支撑层的厚度D1满足：1μm≤D1≤30μm，且支撑层为高分子材料或高分子复合材料；所述电极活性材料层包括电极活性材料、粘结剂和导电剂，且所述电极活性材料包括平均粒径D50为1.0μm～7.0μm的小颗粒活性材料以及平均粒径D50为7.1μm～20.0μm的大颗粒活性材料。
用于本申请第一方面所述正极极片的正极集流体是一种复合集流体，其由至少两种材料复合而成。在结构上，所述集流体包括支撑层和设置于支撑层至少一个表面上的导电层，所述导电层的单面厚度D2满足：30nm≤D2≤3μm，所述支撑层的厚度D1满足：1μm≤D1≤30μm。因此，所述集流体中起导电作用的是导电层。该导电层厚度D2远小于现有技术中常用的诸如Al箔金属集流体的厚度(常用的Al箔金属集流体的厚度通常为12μm)，且支撑层为高分子材料或高分子复合材料，因此可以提高使用该极片的电化学装置(例如锂电池)的重量能量密度。此外，该复合集流体应用于正极集流体时，还可以大大改善正极极片的穿钉安全性能，因为正极集流体中的导电层较薄，在发生穿钉等异常情况时产生的金属毛刺也较小，且由于支撑层的存在，其短路内阻较大，因此更不容易引起短路。
但是，由于这种复合集流体的导电层较薄，所以相对于传统的金属集流体(Al箔)而言，复合集流体的导电能力较差，且导电层容易在极片加工过程(如极片辊压)中产生破损，进而影响导电层的导电性能和电化学装置的电化学性能。此外，该复合集流体的支撑层(高分子材料或高分子复合材料)在极片辊压等工艺过程中，其反弹程度较传统金属集流体大，因此支撑层与导电层之间的结合力、复合集流体与电极活性材料层之间的结合力均优选地需要通过改善界面进行增强。因此，在将上述复合集流体应用于电化学装置的过程中，需要进行一些技术改进。
在根据本申请的正极极片中，对于电极活性材料层进行了特殊设计，从而可以使得本申请的包含该复合集流体的正极极片和含有该正极极片的电化学装置(例如锂离子电池)兼具良好的能量密度、电化学性能和安全性能。
具体而言，本申请的电极活性材料层包括两种粒径不同的活性材料的组合，即平均粒径D50为1.0μm～7.0μm的小颗粒活性材料和平均粒径D50为7.1μm～20.0μm的大颗粒活性材料的组合，从而在辊压的过程中可以减少对导电层的破坏，可以得到内阻较小、极化较小、电化学性能良好的正极极片。
根据本申请的某些优选实施方式，在集流体与电极活性材料层之间额外设置一层包含导电材料和粘结剂的导电底涂层，具体的说，导电底涂层设置于集流体的导电层与电极活性材料层之间。因此导电底涂层可以进一步减少极片加工过程中对导电层的破坏，且可以改善复合集流体与电极活性材料层之间的界面，提高集流体和电极活性材料层之间的结合力，保证电极活性材料层更牢固地设置于复合集流体的表面；此外，可以通过有效修补并构筑集流体、导电底涂层与活性物质间的导电网络，提高电子传输效率，降低含有复合集流体的极片电阻，克服复合集流体导电能力较差、且复合集流体中的导电层易于破损等缺点，从而可以有效降低电极组件的直流内阻(DCR)，提高电极组件的功率性能，并保证电极组件在长期循环过程中不易于发生较大的极化及析锂等现象，即有效改善了电极组件的长期可靠性。
下面对本申请实施方式涉及的正极极片(以及其中的集流体)的结构、材料和性能等进行详细描述。
[集流体导电层]
相对于传统的金属集流体来说，在本申请实施方式的集流体中，导电层起到导电和集流的作用，用于为电极活性材料层提供电子。
导电层的材料选自金属导电材料、碳基导电材料中的至少一种。
所述金属导电材料优选铝、镍、钛、银、铝锆合金中的至少一种；
所述碳基导电材料优选石墨、乙炔黑、石墨烯、碳纳米管中的至少一种；
导电层的材料优选为金属导电材料，即导电层优选为金属导电层。其中，当集流体为正极集流体时，通常采用铝为导电层的材料。
当导电层的导电性较差或厚度太小时，会造成电池的内阻较大、极化较大，当导电层的厚度太大时，则不足以起到改善电池重量能量密度和体积能量密度的效果。
所述导电层的单面厚度为D2，D2优选满足：30nm≤D2≤3μm，更优选300nm≤D2≤2μm，最优选为500nm≤D2≤1.5μm；以便更好的保证集流体的轻质性能并兼 具良好的导电性能。
在本申请优选实施方式中，导电层的单面厚度D2的上限可为3μm、、2.5μm、2μm、1.8μm、1.5μm、1.2μm、1μm、900nm，导电层的单面厚度D2的下限可为800nm、700nm、600nm、500nm、450nm、400nm、350nm、300nm、100nm、50nm、30nm；导电层的单面厚度D2的范围可由上限或下限的任意数值组成。优选地，300nm≤D2≤2μm；更优选为500nm≤D2≤1.5μm。
由于本申请中导电层的厚度较小，因此在极片制作等过程中，易产生裂纹等破损。通常，在本申请所述正极极片的导电层中有裂纹存在。导电层中的裂纹通常不规则地存在于导电层中，可以是长条形裂纹、可以为交叉型裂纹、可以为发散状裂纹等；可以是贯穿整个导电层的裂纹，也可以是在导电层的表层形成的裂纹。导电层中的裂纹通常是由于在极片加工过程中的辊压、焊接极耳振幅过大、基材收卷张力过大，等情况造成的。
导电层可通过机械辊轧、粘结、气相沉积法(vapor deposition)、化学镀(Electroless plating)中的至少一种形成于支撑层上，气相沉积法优选物理气相沉积法(Physical Vapor Deposition，PVD)；物理气相沉积法优选蒸发法、溅射法中的至少一种；蒸发法优选真空蒸镀法(vacuum evaporating)、热蒸发法(Thermal Evaporation Deposition)、电子束蒸发法(electron beam evaporation method，EBEM)中的至少一种，溅射法优选磁控溅射法(Magnetron sputtering)。
优选气相沉积法或化学镀中的至少一种，以使得支撑层与导电层之间的结合更牢固。
[集流体支撑层]
在本申请实施方式的集流体中，支撑层对导电层起到支撑和保护的作用。由于支撑层一般采用有机高分子材料或高分子复合材料，因此支撑层的密度通常小于导电层的密度，从而较传统的金属集流体可显著提升电池的重量能量密度。
并且，导电层采用厚度较小的金属层，可进一步提高电池的重量能量密度。并且由于支撑层可以对位于其表面的导电层起到良好的承载和保护作用，因而不易产生传统集流体中常见的极片断裂现象。
所述支撑层的材料具体可选自绝缘高分子材料、绝缘高分子复合材料、导电高分子材料、导电高分子复合材料中的至少一种。
绝缘高分子材料例如选自聚酰胺、聚对苯二甲酸酯、聚酰亚胺、聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、芳纶、聚二甲酰苯二胺、丙烯腈-丁二烯-苯乙烯共聚物、聚对苯二甲酸丁二醇酯、聚对苯二甲酰对苯二胺、聚丙乙烯、聚甲醛、环氧树脂、酚醛树脂、聚四氟乙烯、聚苯硫醚、聚偏氟乙烯、硅橡胶、聚碳酸酯、纤维素及其衍生物、淀粉及其衍生物、蛋白质及其衍生物、聚乙烯醇及其交联物、聚乙二醇及其交联物中的至少一种。
绝缘高分子复合材料例如选自绝缘高分子材料与无机材料形成的复合材料，其中无机材料优选陶瓷材料、玻璃材料、陶瓷复合材料中的至少一种。
导电高分子材料例如选自聚氮化硫类高分子材料或经掺杂的共轭类高分子材料， 比如聚吡咯、聚乙炔、聚苯胺、聚噻吩等中的至少一种。
导电高分子复合材料例如选自绝缘高分子材料与导电材料形成的复合材料，其中导电材料选自导电碳材料、金属材料、复合导电材料中的至少一种，其中导电碳材料选自碳黑、碳纳米管、石墨、乙炔黑、石墨烯中的至少一种，金属材料选自镍、铁、铜、铝或上述金属的合金中的至少一种，复合导电材料选自镍包覆的石墨粉、镍包覆的碳纤维中的至少一种。
根据应用环境的实际需要和成本等因素，本领域技术人员可以合理地选择和确定支撑层的材料。本申请中所述支撑层的材料优选为绝缘高分子材料或绝缘高分子复合材料，尤其是当集流体为正极集流体时。
当集流体为正极集流体时，通过采用具有绝缘层支撑、且具有特定厚度的导电层的特殊集流体，可以明显改善电池的安全性能。由于绝缘层不导电，因此其电阻较大，可以提高电池在异常情况下发生短路时的短路电阻，使短路电流大幅度减小，因此可极大地降低短路产热量，从而改善电池的安全性能；且导电层较薄，因此在穿钉等异常情况下，局部的导电网络被切断，防止电化学装置大面积甚至整个电化学装置发生内短路，这就可以将穿钉等造成的电化学装置的损坏局限于刺穿位点，仅形成“点断路”，而不影响电化学装置在一定时间内的正常工作。
支撑层的厚度为D1，D1优选满足：1μm≤D1≤30μm；更优选1μm≤D1≤15μm。
若支撑层太薄的话，则支撑层的机械强度不够，很容易在极片加工工艺等过程中发生断裂；支撑层太厚的话，则会降低使用该集流体的电池的体积能量密度。
其中，支撑层的厚度D1的上限可为30μm、25μm、20μm、15μm、12μm、10μm、8μm，下限可为1μm、1.5μm、2μm、3μm、4μm、5μm、6μm、7μm；支撑层的厚度D1的范围可由上限或下限的任意数值组成。优选的，1μm≤D1≤15μm；更优选2μm≤D1≤10μm；最优选3μm≤D1≤8μm。
同时，本申请特定的厚度可以进一步保证该集流体具有较大的电阻，显著降低电池在发生内短路时的电池升温，当导电层为铝时，还可显著减少或防止正极集流体的铝热反应，从而保证电池具有良好的安全性能。
此外，当导电层为金属导电层时，优选支撑层的常温杨氏模量满足：20GPa≥E≥4GPa。
本申请中所述支撑层的常温杨氏模量的测试方法如下：
取支撑层样品裁剪成15mm×200mm，用万分尺量取样品的厚度h(μm)，常温常压下使用高铁拉力机进行拉伸测试，设置初始位置，并使夹具之间样品为50mm长，拉伸以50mm/min速度进行，记录拉伸至断裂的载荷L(N)，设备位移y(mm)，则应力ε＝L/(15*h)*1000，应变η＝y/50*100，绘制应力应变曲线，取初始线性区曲线，该曲线的斜率既为杨氏模量E。
由于金属相对于高分子或高分子复合材料刚性较强，即在极片加工的辊压等过程中变形较小，因此为了确保支撑层和导电层之间的形变差别不至于过大，以至于将导电层撕裂，所述支撑层的常温杨氏模量最好满足：20GPa≥E≥4Gpa，从而可以使得支撑层具有一定的刚性，且可进一步提高支撑层与导电层之间的刚性匹配性，从而在集流体、极片的加工过程中，保证支撑层与导电层的形变量不会差别太大。
由于支撑层具有一定的刚性(20GPa≥E≥4GPa)，因此在集流体、极片的加工过程中，集流体不易变形或不易延展太大，从而可使得支撑层与导电层之间结合牢固，不易脱离，且可防止导电层“被迫”延展而导致的导电层破损。且根据本申请的集流体具有一定的韧性，从而可使得集流体和极片具有一定的承受变形的能力，不易于断带。
但是支撑层的杨氏模量不能过大，否则刚性过强，会造成收卷及卷绕困难、可加工性变差。当20GPa≥E，可以保证支撑层具有一定的柔性，还可使得极片具有一定的承受变形的能力。
此外，优选支撑层在90℃的热收缩率不大于1.5％，从而在极片加工过程中，可以更好的保证集流体的热稳定性。
[集流体的保护层]
在本申请的一些优选实施方式中，所述集流体还设置有保护层，所述保护层设置于所述集流体的导电层的一个表面上或设置于所述集流体的导电层的两个表面上，即导电层的远离支撑层的表面上和面对支撑层的表面上。
保护层可为金属保护层或金属氧化物保护层。保护层可以防止集流体的导电层受到化学腐蚀或机械损坏而导致的破损，此外还可以增强集流体的机械强度。
优选保护层设置于集流体的导电层的两个表面上。导电层的下保护层(即设置于导电层的面对支撑层的表面上的保护层)不仅可以防止导电层受到损坏、增强集流体的机械强度，还可以增强支撑层与导电层之间的结合力，防止脱膜(即支撑层与导电层分离)。
导电层的上保护层(即设置于导电层的远离支撑层的表面上的保护层)的技术效果主要是防止加工过程中导电层被破坏、腐蚀等(例如电解液浸泡、辊压等都会对导电层表面造成影响)。
由于良好的导电性，金属保护层不仅可以进一步改进导电层的机械强度和耐蚀性，还能降低极片的极化。所述金属保护层的材料例如选自镍、铬、镍基合金、铜基合金中的至少一种，优选镍或镍基合金。
其中，镍基合金是以纯镍为基体加入一种或几种其他元素所构成的合金。优选为镍铬合金，镍铬合金是金属镍和金属铬形成的合金，可选的，镍元素与铬元素的摩尔比为1：99～99：1。
铜基合金是以纯铜为基体加入一种或几种其他元素所构成的合金。优选为铜镍合金，可选的，在铜镍合金中，镍元素与铜元素的摩尔比为1：99～99：1。
保护层选用金属氧化物时，由于金属氧化物的延展性小、比表面积大、硬度大，同样也可形成对导电层的有效支撑和保护，并对于改善支撑层与导电层之间的结合力具有良好的技术效果。金属氧化物保护层的材料例如选自氧化铝、氧化钴、氧化铬、氧化镍中的至少一种。
根据本申请的复合集流体的保护层优选采用金属氧化物，以在达到良好的支撑和保护的技术效果的同时，进一步改善正极极片和电池的安全性能。
所述保护层的厚度为D3，D3优选满足：D3≤1/10D2且1nm≤D3≤200nm。如果 保护层太薄，则不足以起到保护导电层的作用；保护层太厚，则会降低电池的重量能量密度和体积能量密度。更优选的，5nm≤D3≤500nm，进一步优选10nm≤D3≤200nm，最优选10nm≤D3≤50nm。
位于导电层的两个表面上的保护层的材料可相同或不同，厚度可相同或不同。
优选，下保护层的厚度小于上保护层的厚度，以有利于改善电池的重量能量密度。
进一步可选的，下保护层厚度D3”与上保护层厚度D3'的比例关系为：1/2D3'≤D3”≤4/5D3'。
当集流体为正极集流体时，通常采用铝为导电层的材料，下保护层优选选用金属氧化物材料。相对于下保护层的材料选用金属来讲，金属氧化物材料具有较大电阻，因此该类型的下保护层可以在一定程度上进一步增大正极集流体的电阻，从而进一步的提高电池异常情况下发生短路时的短路电阻，改善电池的安全性能。此外，由于金属氧化物的比表面积更大，所以金属氧化物材料的下保护层与支撑层之间的结合力增强；同时由于金属氧化物的比表面积更大，因此下保护层可以增加支撑层表面的粗糙度，起到增强导电层与支撑层之间的结合力的作用，从而提高了集流体整体的强度。因此，当集流体为正极集流体时，下保护层优选为金属氧化物材料，上保护层为金属材料或金属氧化物材料，优选上保护层也为金属氧化物材料。
[集流体]
图1至图4示出了根据本申请某些实施方式的正极极片中所采用的集流体的结构示意图。
正极集流体的示意图如图1至图4所示。
在图1中，正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101相对的两个表面上的正极集流体导电层102，还包括设置于正极集流体导电层102的下表面(即朝向正极集流体支撑层101的面)上的正极集流体保护层103，即下保护层。
在图2中，正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101相对的两个表面上的正极集流体导电层102，还包括设置于正极集流体导电层102的相对两个表面上的正极集流体保护层103，即下保护层和上保护层。
在图3中，正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101一个表面上的正极集流体导电层102，还包括设置于正极集流体导电层102的朝向正极集流体支撑层101的面上的正极集流体保护层103，即下保护层。
在图4中，正极集流体集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101一个表面上的正极集流体导电层102，还包括设置于正极集流体导电层102的相对两个表面上的正极集流体保护层103，即下保护层和上保护层。
位于导电层的两个相对的表面上的保护层的材料可相同或不同，厚度可相同或不同。
其中，对于用于根据本申请的正极极片的集流体而言，如图1、图2所示，可在支撑层的相对的两个表面上均设置有导电层，或者如图3、图4所示，也可在仅支撑层的一面上设置有导电层。
另外，虽然本申请的正极极片所采用的复合集流体优选地如图1至4所示含有集流体保护层，但是应该理解：集流体保护层并非集流体的必须结构，在某些实施方式中所用的集流体可以不含集流体保护层。
[正极极片的电极活性材料层]
电极活性材料层通常包括电极活性材料、粘结剂和导电剂。根据需要，电极活性材料层还可以包括可选的其它添加剂或助剂。
作为本申请的正极极片的一个重要特征，其电极活性材料层中的电极活性材料是由大小两种颗粒组合而成的，具体地所述电极活性材料包括平均粒径D50为1.0μm～7.0μm的小颗粒活性材料以及平均粒径D50为7.1μm～20.0μm的大颗粒活性材料。
D50指活性材料累计体积百分数达到50％时所对应的粒径，即体积分布中位粒径。D50例如可以使用激光衍射粒度分布测量仪(例如Malvern Mastersizer 3000)进行测量。
优选地，所述小颗粒活性材料与大颗粒活性材料的质量比为1:9～9:1。
对于本申请的正极极片而言，可以选用本领域常用的各种电极活性材料(即正极活性材料)。例如，对于锂电池来说，正极活性材料可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、过渡金属磷酸盐、磷酸铁锂等，但本申请并不限定于这些材料，还可以使用其他可被用作锂离子电池正极活性物质的传统公知的材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。优选地，正极活性材料可选自LiCoO 2、LiNiO 2、LiMnO 2、LiMn 2O 4、LiNi 1/3Co 1/3Mn 1/3O 2(NCM333)、LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)、LiNi 0.6Co 0.2Mn 0.2O 2(NCM622)、LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)、LiNi 0.85Co 0.15Al 0.05O 2、LiFePO 4(LFP)、LiMnPO 4中的一种或几种。
在本申请的一些优选实施方式中，小颗粒活性材料与大颗粒活性材料是不同的活性材料；更优选地为热稳定性较高的活性材料与电化学容量较高的活性材料的组合。热稳定性较高的活性材料例如NCM333、NCM523、LFP；电化学容量较高的活性材料例如NCM811、NCM622。
电极活性材料层中的导电剂为导电碳材料、金属材料中的至少一种；其中，导电碳材料选自零维导电碳，如乙炔黑、导电炭黑；一维导电碳，如碳纳米管；二维导电碳，如导电石墨、石墨烯；三维导电碳，如还原后的氧化石墨烯中的至少一种；金属材料选自铝粉，铁粉以及银粉中的至少一种；
电极活性材料层中的粘结剂选自丁苯橡胶，油性聚偏氟乙烯(PVDF)，聚偏氟乙烯共聚物(如PVDF-HFP共聚物、PVDF-TFE共聚物)、羧甲基纤维素钠，聚苯乙烯，聚丙烯酸，聚四氟乙烯，聚丙烯腈、聚酰亚胺、水性PVDF、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种。
此外，对于本申请的正极极片来说，当电极活性材料层中的粘结剂的含量较高时，则活性材料层与复合集流体间的结合力也较好，从而使得在穿钉等异常情况下，活性材料层可有效地包裹导电层中产生的金属毛刺，以改善电池的穿钉安全性能。因此，就进一步改善电池安全性而言，优选的基于所述电极活性材料层的总重量，电极活性 材料层中的粘结剂含量不小于1wt％，优选的不小于1.5wt％，更优选不小于2wt％。粘结剂含量保持在一定量，则活性材料层与集流体间间的结合力较好，从而使得在穿钉等异常情况下，活性材料层可有效地包裹导电层中产生的金属毛刺，以改善电池的穿钉安全性能。
本领域技术人员熟知，将电极活性材料、导电剂和粘结剂等组成的浆料涂覆到正极集流体(或预先涂覆到正极集流体的底涂层)上，再经干燥等后处理即可得所需的正极活性材料层。
[正极极片的导电底涂层]
根据本申请的某些优选实施方式，正极极片在其集流体与电极活性材料层之间还设置有导电底涂层，导电底涂层包含导电材料和粘结剂。导电底涂层不仅可以进一步地减少在极片加工过程中对导电层的破坏，还可以改善复合集流体界面，提高集流体和电极活性材料层之间的粘结力，保证电极活性材料层更牢固地设置于复合集流体的表面；此外，还可以通过有效修补并构筑集流体与电极活性材料层中活性物质间的导电网络，提高电子传输效率，降低集流体与电极活性材料层之间的电阻，克服复合集流体导电能力较差、且复合集流体中的导电层易于破损等缺点，从而可以有效降低电极组件的直流内阻，提高电极组件的功率性能，并保证电极组件在长期循环过程中不易于发生较大的极化及析锂等现象，即有效改善了电极组件的长期可靠性。
基于所述导电底涂层的总重量，导电材料的重量百分含量为10％～99％，优选20％～80％，更优选为50％～80％；所述粘结剂的重量百分含量为1％～90％，优选20％～80％，更优选为20％～50％。该比例可以有助于改善正极极片的导电性以及集流体与电极活性材料层之间的结合力。
优选地导电底涂层还可以包含电极活性材料。当包含电极活性材料时，可以增加正极极片的电化学容量。
在导电材料和粘结剂之外的余量可以为电极活性材料。在本申请的一个优选实施方式中，基于所述导电底涂层的总重量，导电材料的含量优选为10wt％～98wt％，粘结剂的含量优选为1wt％～89wt％，电极(正极)活性材料的含量优选为1wt％～89wt％。
导电材料可以为导电碳材料、金属材料中的至少一种；导电底涂层中的导电材料与活性材料层中的导电剂可以相同或不同。
其中，导电碳材料选自零维导电碳(如乙炔黑、导电炭黑)，一维导电碳(如碳纳米管)，二维导电碳(如导电石墨、石墨烯)，三维导电碳(如还原后的氧化石墨烯)中的至少一种；金属材料选自铝粉，铁粉以及银粉中的至少一种。
优选的导电材料含有一维导电碳材料或二维导电碳材料。因为加入二维导电碳材料后，在极片压实过程中，导电底涂层中的二维导电碳材料可以产生“水平滑动”，从而起到缓冲作用，减少压实过程中对集流体的导电层的破坏，从而减少裂纹。优选的二维导电碳材料的粒径D50为0.01～0.1μm。优选地，二维导电碳材料占所述导电材料的1wt％～50wt％。另外由于一维导电碳材料的形貌特殊，因此添加后可以改善导电底涂层的导电性，尤其是在导电材料的添加量一定的情况下，一维导电碳材料相较于其 他类型的导电材料可以更好的改善导电底涂层的导电性。优选碳纳米管，其长径比优选为1000～5000。
优选的导电材料为零维导电碳材料与一维导电碳材料的混合材料或者为零维导电碳材料与二维导电碳材料的混合材料。
导电底涂层中的粘结剂与活性材料层中的粘结剂可以相同或不同。
导电底涂层中的粘结剂选自丁苯橡胶，油性聚偏氟乙烯(PVDF)，聚偏氟乙烯共聚物(如PVDF-HFP共聚物、PVDF-TFE共聚物)、羧甲基纤维素钠，聚苯乙烯，聚丙烯酸，聚四氟乙烯，聚丙烯腈、聚酰亚胺、水性PVDF、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种。
导电底涂层中的粘结剂优选水性粘结剂，如水性PVDF、聚丙烯酸、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种，这样电化学装置的DCR增长较小。在本申请中，“水性”高分子材料是指高分子分子链完全伸展开分散在水中，“油性”高分子材料是指高分子分子链完全伸展开分散在油性溶剂中。本领域技术人员理解，通过采用合适的表面活性剂可以将同一类的高分子材料分别分散在水中和油中，即通过采用合适的表面活性剂，同一类的高分子材料可以被分别做成水性高分子材料和油性高分子材料。例如，本领域技术人员可以根据需要，将PVDF改性为水性PVDF或油性PVDF。
导电底涂层中的电极活性材料与活性材料层中的电极活性材料可以相同或不同。导电底涂层中的电极活性材料可以选用本领域常用的各种电极活性材料(即正极活性材料)。
导电底涂层的单面厚度H优选为：0.1μm至5μm。优选H/D2为0.5：1至5：1。比例过小，则不能有效地起到改善导电层裂纹、改善极片导电性能的作用；比例过大，则不仅会降低电池的重量能量密度，还会增大电池DCR，不利于电池动力学性能的改善。
[正极极片]
图5至图7示出了根据本申请某些实施方式的正极极片的结构示意图。
在图5中，正极极片PP包括正极集流体10和设置于正极集流体10相对的两个表面上的正极活性材料层12，而正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101相对的两个表面上的正极集流体导电层102。
在图6中，正极极片PP包括正极集流体10和设置于正极集流体10相对的两个表面上的导电底涂层11和正极活性材料层12，而正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101相对的两个表面上的正极集流体导电层102。
在图7中，正极极片PP包括正极集流体10和设置于正极集流体10一个表面上的导电底涂层11和正极活性材料层12，而正极集流体10包括正极集流体支撑层101和设置于正极集流体支撑层101一个表面上的正极集流体导电层102。
如图5至图7所示，电极活性材料层可以设置于集流体的一个表面上，也可以设置于集流体的两个表面。
本领域技术人员可以理解：当采用设置有双面导电层的集流体时，正极极片既可 以双面涂布(即电极活性材料层设置于集流体的两个表面)，也可以仅单面涂布(即电极活性材料层仅设置于集流体的一个表面上)；而当采用仅设置有单面导电层的集流体时，正极极片也仅能单面涂布，且电极活性材料层(以及导电底涂层)仅能涂布在集流体设置有导电层的一面。
[电化学装置]
本申请的第二方面涉及一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，其中所述正极极片为根据本申请的第一方面所述的正极极片。
所述电化学装置可以为电容器、一次电池或二次电池。例如可以为锂离子电容器、锂离子一次电池或锂离子二次电池。除了使用了本申请的正极极片外，这些电化学装置的构造和制备方法本身是公知的。由于使用了本申请的正极极片，所述电化学装置可以具有高的能量密度、改善的安全性(如穿钉安全性)和电化学性能。并且本申请的正极极片容易加工，因此可以降低使用了本申请的正极极片的电化学装置的制造成本。
在本申请的电化学装置中，负极极片、隔离膜以及电解液的具体种类及组成均不受具体的限制，可根据实际需求进行选择。具体地，所述隔离膜可选自聚乙烯膜、聚丙烯膜、聚偏氟乙烯膜以及它们的多层复合膜。当电池为锂离子电池时，通常使用非水电解液作为电解质。作为非水电解液，通常使用在有机溶剂中溶解的锂盐溶液。锂盐例如是LiClO 4、LiPF 6、LiBF 4、LiAsF 6、LiSbF 6等无机锂盐、或者LiCF 3SO 3、LiCF 3CO 2、Li 2C 2F 4(SO 3) 2、LiN(CF 3SO 2) 2、LiC(CF 3SO 2) 3、LiC nF 2n+1SO 3(n≥2)等有机锂盐。非水电解液中使用的有机溶剂例如是碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、碳酸亚乙烯酯等环状碳酸酯，碳酸二甲酯、碳酸二乙酯、碳酸甲基乙酯等链状碳酸酯，丙酸甲酯等链状酯，γ-丁内酯等环状酯，二甲氧基乙烷、二乙醚、二甘醇二甲醚、三甘醇二甲醚等链状醚，四氢呋喃、2-甲基四氢呋喃等环状醚，乙腈、丙腈等腈类，或者这些溶剂的混合物。对于负极极片而言，可以选用本领域常用的各种负极活性材料形成的负极极片。例如，对于锂电池来说，负极活性材料可选自例如石墨(人造石墨或天然石墨)、导电炭黑、碳纤维等碳质材料，例如Si、Sn、Ge、Bi、Sn、In等金属或半金属材料或其合金，含锂氮化物或含锂氧化物，锂金属或锂铝合金等。
在一些实施例中，电化学装置可以包括外包装，用于封装正极极片、负极极片和电解质。作为一个示例，正极极片、负极极片和隔离膜可经叠片或卷绕形成叠片结构电极组件或卷绕结构电极组件，电极组件封装在外包装内；电解质可采用电解液，电解液浸润于电极组件中。电化学装置中电极组件的数量可以为一个或几个，可以根据需求来调节。
在一些实施例中，电化学装置的外包装可以是软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。电化学装置的外包装也可以是硬壳，例如铝壳等。
本申请对电化学装置的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图9是作为一个示例的方形结构的电化学装置5。
在一些实施例中，电化学装置可以组装成电池模块，电池模块所含电化学装置的 数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图10是作为一个示例的电池模块4。参照图10，在电池模块4中，多个电化学装置5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电化学装置5进行固定。
可选地，电池模块4还可以包括具有容纳空间的壳体，多个电化学装置5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图11和图12是作为一个示例的电池包1。参照图11和图12，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
[装置]
本申请的第三方面涉及一种装置，包括本申请第二方面所述的电化学装置。所述电化学装置为所述装置提供电源。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。此外，电气列车、船舶及卫星均是运载工具，属于广义上的车辆(vehicle)。
所述装置可以根据其使用需求来选择电化学装置、电池模块或电池包。
图13是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对电化学装置的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用电化学装置作为电源。
本领域技术人员可以理解：以上提到的本申请的不同实施方式中对于极片、电极活性材料层等的组分选择、组分含量和材料理化性能参数的各种限定或优选范围可以任意组合，其组合而得到的各种实施方式仍然在本申请范围内，且视为本说明书公开内容的一部分。
除非特别规定，本说明书中涉及的各种参数具有本领域公知的通用含义，可以按本领域公知的方法进行测量。例如，可以按照在本申请的实施例中给出的方法进行测试。另外，各种优选实施方式中给出的各种不同参数的优选范围和选项可以进行任意组合，由此得到的各种组合都视为在本申请的公开范围之内。
以下结合实施例进一步说明本申请的有益效果。
实施例
1、不具有保护层的集流体的制备：
选取一定厚度的支撑层，在其表面通过真空蒸镀、机械辊轧或粘结的方式形成 一定厚度的导电层。
其中，
(1)真空蒸镀方式的形成条件如下：将经过表面清洁处理的支撑层置于真空镀室内，以1600℃至2000℃的高温将金属蒸发室内的高纯金属丝熔化蒸发，蒸发后的金属经过真空镀室内的冷却系统，最后沉积于支撑层的表面，形成导电层。
(2)机械辊轧方式的形成条件如下：将导电层材料的箔片置于机械辊中，通过施加20t至40t的压力将其碾压为预定的厚度，然后将其置于经过表面清洁处理的支撑层的表面，最后将两者置于机械辊中，通过施加30t至50t的压力使两者紧密结合。
(3)粘结方式的形成条件如下：将导电层材料的箔片置于机械辊中，通过施加20t至40t的压力将其碾压为预定的厚度；然后在经过表面清洁处理的支撑层的表面涂布PVDF与NMP的混合溶液；最后将上述预定厚度的导电层粘结于支撑层的表面，并于100℃下烘干。
2、具有保护层的集流体的制备：
制备具有保护层的集流体有如下几种方式：
(1)先通过气相沉积法或涂布法在支撑层表面设置保护层，然后通过真空蒸镀、机械辊轧或粘结的方式，在上述具有保护层的支撑层表面形成一定厚度的导电层，以制备具有保护层的集流体(保护层位于支撑层与导电层之间)；此外，也可在上述基础上，再在导电层的远离支撑层方向的表面上通过气相沉积法、原位形成法或涂布法形成另外一层保护层，以制备具有保护层的集流体(保护层位于导电层的两个相对的表面)；
(2)先通过气相沉积法、原位形成法或涂布法在导电层的一个表面上形成保护层，然后通过机械辊轧或粘结的方式，将上述具有保护层的导电层设置于支撑层表面，且保护层设置于支撑层与导电层之间，以制备具有保护层的集流体(保护层位于支撑层与导电层之间)；此外，也可在上述基础上，再在导电层的远离支撑层方向的表面上通过气相沉积法、原位形成法或涂布法形成另外一层保护层，以制备具有保护层的集流体(保护层位于导电层的两个相对的表面)；
(3)先通过气相沉积法、原位形成法或涂布法在导电层的一个表面上形成保护层，然后通过机械辊轧或粘结的方式，将上述具有保护层的导电层设置于支撑层表面，且保护层设置于导电层的远离支撑层的表面上，以制备具有保护层的集流体(保护层位于导电层的远离支撑层的表面)；
(4)先通过气相沉积法、原位形成法或涂布法在导电层的两个表面上形成保护层，然后通过机械辊轧或粘结的方式，将上述具有保护层的导电层设置于支撑层表面，以制备具有保护层的集流体(保护层位于导电层的两个相对的表面)；
(5)在上述“不具有保护层的集流体的制备”的基础上，再在导电层的远离支撑层方向的表面上通过气相沉积法、原位形成法或涂布法形成另外一层保护层，以制备具有保护层的集流体(保护层位于导电层的远离支撑层的表面)。
在制备实例中，气相沉积法采用真空蒸镀方式，原位形成法采用原位钝化方式，涂布法采用刮刀涂布方式。
真空蒸镀方式的形成条件如下：将经过表面清洁处理的样品置于真空镀室内，以 1600℃至2000℃的高温将蒸发室内的保护层材料熔化蒸发，蒸发后的保护层材料经过真空镀室内的冷却系统，最后沉积于样品的表面，形成保护层。
原位钝化法的形成条件如下：将导电层置于高温氧化环境中，温度控制在160℃至250℃，同时在高温环境中维持氧气供应，处理时间为30min，从而形成金属氧化物类的保护层。
凹版涂布方式的形成条件如下：将保护层材料与NMP进行搅拌混合，然后在样品表面涂布上述保护层材料的浆料(固含量为20％至75％)，其次用凹版辊控制涂布的厚度，最后在100℃至130℃下进行干燥。
3、极片的制备：
1)实施例的正极极片(带导电底涂层)：
采用一定配比的导电材料(如导电炭黑)和粘结剂(如PVDF或聚丙烯酸等)溶于适当的溶剂中(例如NMP或水中)，搅拌均匀配成底涂浆料。
将底涂浆料均匀双面涂覆于按照上述方法制备的复合集流体上，涂布速度20m/min，并对底涂层进行干燥，烘箱温度为70～100℃，烘干时间为5min。
待底涂层完全干燥后，再将92wt％正极活性材料(未指明具体材料的情况下，缺省使用NCM333)、5wt％导电剂Super-P(简称“SP”)和3wt％PVDF，以NMP为溶剂，搅拌均匀配成正极活性材料层浆料(某些实施例的活性材料层浆料组成可能有所变化，此时以该实施例中特别注明的为准)，采用挤压涂布将正极活性材料层浆料涂布于底涂层表面；在85℃下烘干后得到正极活性材料层。
然后对带有各涂层的集流体进行冷压，然后切割，再在85℃真空条件下烘干4小时，焊接极耳，得到正极极片。
2)实施例的正极极片(不带导电底涂层)：
类似于上面实施例的正极极片(带导电底涂层)的制备方法进行制备，但是其中将正极活性材料层浆料直接涂布到复合集流体的表面上，而不设置底涂层。
3)常规正极极片：
集流体是厚度为12μm的Al箔片，类似于上面正极极片(不带导电底涂层)的制备方法，将正极活性材料层浆料直接涂布到Al箔片集流体的表面上，再经后处理得到常规正极极片。
4)常规负极极片：
将负极活性物质人造石墨、导电剂Super-P、增稠剂CMC、粘接剂SBR按质量比96.5:1.0:1.0:1.5加入到溶剂去离子水中混合均匀制成负极活性材料层浆料；采用挤压涂布将负极活性材料层浆料涂布于厚度为8μm的Cu箔片(负极集流体)两面；在85℃下烘干后得到负极活性材料层，再经后处理得到常规负极极片。
4、电池的制备：
通过常规的电池制作工艺，将正极极片(压实密度：3.4g/cm 3)、PP/PE/PP隔膜和负极极片(压实密度：1.6g/cm 3)一起卷绕成电极组件，然后置入电池壳体中，注入电解液(EC:EMC体积比为3:7，LiPF 6为1mol/L)，随之进行密封、化成等工序，最终得到锂离子二次电池(以下简称电池)。
5、电池测试方法：
1)锂离子电池循环寿命测试方法：
将锂离子电池于45℃下进行充放电，即先以1C的电流充电至4.2V，然后再以1C的电流放电至2.8V，记录下第一周的放电容量；然后使电池进行1C/1C充放电循环1000周，记录第1000周的电池放电容量，将第1000周的放电容量除以第一周的放电容量，得到第1000周的容量保有率。
2)DCR增长率的测试方法：
在25℃下，以1C电流将二次电池调整至50％SOC，记录电压U1。然后以4C电流放电30秒，记录电压U2。DCR＝(U1-U2)/4C。然后使电池进行1C/1C充放电循环500周，记录第500周的DCR，将第500周的DCR除以第一周的DCR并减1，得到第500周的DCR增长率。
3)针刺测试：
将二次电池(10个样品)以1C电流满充至充电截止电压，再恒压充电至电流降至0.05C，停止充电。用φ8mm的耐高温钢针，以25mm/s的速度，从垂直于电池极板的方向贯穿，贯穿位置宜靠近所刺面的几何中心，钢针停留在电池中，观察电池是否有燃烧、爆炸现象。
4)倍率性能(4C放电容量保持率)：
二次电池满放后，0.33C满充，并采用4.2V恒压至0.05C，后采用0.33C满放，记录0.33C满放容量C 0，再以0.33C满充，4.2V恒压至0.05C，后采用4C满放，记录4C满放容量C 1，则放电倍率容量保持率为C 1/C 0。
6、测试结果和讨论：
6.1复合集流体在改善电池重量能量密度方面的作用
各实施例的集流体及其极片具体参数如表1所示(表1中所列各实施例的集流体均未设置保护层)。在表1中，集流体重量百分数是指单位面积正极集流体重量除以单位面积常规正极集流体重量的百分数。
表1
Figure PCTCN2019129357-appb-000001
根据表1可知，本申请采用的正极集流体的重量相对于传统的集流体(Al，12μm)都得到了不同程度的减轻，从而可提升电池的重量能量密度。不过当导电层的厚度大于1.5μm以后，对于集流体的减重改善程度变小。
另外，还考察了复合集流体对于改善电池穿钉安全的作用。测试的正极极片组成见下表1-1(其中各极片均未设置导电底涂层)，穿钉实验结果见表1-2。
表1-1
Figure PCTCN2019129357-appb-000002
表1-2
电池编号 正极极片 负极极片 穿钉实验结果
电池60 常规正极极片 常规负极极片 全部不通过
电池61 正极极片11 常规负极极片 全部通过
电池62 正极极片12 常规负极极片 全部通过
电池63 正极极片13 常规负极极片 全部通过
电池64 正极极片14 常规负极极片 全部通过
电池65 正极极片15 常规负极极片 全部通过
电池66 正极极片16 常规负极极片 全部通过
采用复合集流体的锂离子电池，由于导电层较传统的金属集流体薄，在穿钉等异常情况下产生的金属毛刺较小，且复合集流体的支撑层具有较大的短路电阻，因此有利于改善电池的穿钉安全性能。从上表中可以看出，常规电池在穿钉情况下会发生热失控和毁坏，不能通过穿钉安全测试。而采用了复合集流体的锂离子电池，均可以通过穿钉安全测试。
6.2保护层在改善复合集流体的电化学性能方面的作用
在表1中所列各实施例的集流体基础上，进一步形成保护层，以便研究保护层对于改善复合集流体的电化学性能方面的作用。表2中“正极集流体2-1”表示在表1中“正极集流体2”的基础上形成保护层所得集流体，其它集流体的编号含义类似。
表2
Figure PCTCN2019129357-appb-000003
表3示出了以表2中所列极片组装成电池后测得的循环性能数据。
表3
Figure PCTCN2019129357-appb-000004
如表3所示，与采用常规的正极极片和常规的负极极片的电池1相比，采用复合集流体的电池的循环寿命良好，与常规的电池的循环性能相当。尤其是含有保护层的集流体制成的电池，相对于不含保护层的集流体制成的电池，其电池的容量保有率可进一步获得提升，说明电池的可靠性更好。
6.3导电底涂层在改善电池的电化学性能方面的作用
下面说明导电底涂层、以及导电底涂层的组成等因素对于改善电池的电化学性能方面的作用。表4示出了各个实施例和对比例的电池以及其中采用的正极极片和集流体的具体组成和相关参数。表5示出了各电池的性能测量结果。
表4
Figure PCTCN2019129357-appb-000005
Figure PCTCN2019129357-appb-000006
表5
Figure PCTCN2019129357-appb-000007
Figure PCTCN2019129357-appb-000008
从以上测试数据可以看出：
1.采用导电层较薄的复合集流体时(即不含导电底涂层的对比正极极片20)，由于复合集流体导电能力较传统的金属集流体差、且复合集流体中的导电层易于破损等缺点，电池的DCR较大、循环容量保持率较低。而在引入了导电底涂层后，导电底涂层通过有效修补并构筑集流体、导电底涂层与活性物质间的导电网络，提高电子传输效率，降低集流体与电极活性材料层电阻，从而可以有效降低DCR。
2.随着导电底涂层中的导电剂含量的提高(正极极片21至26)，电池的DCR可得到较大程度的改善。
3.在相同的组成下，水性粘结剂的引入较油性粘结剂可使得DCR的改善程度更明显(正极极片24vs.正极极片27以及正极极片25vs.正极极片28)。
4.由于片状石墨可产生“水平滑动”，从而起到缓冲作用，减少压实过程中对集流体的导电层的破坏，从而减少裂纹，因此片状石墨的引入可进一步降低电池DCR(正极极片24vs.正极极片29)。
5.随着导电底涂层的厚度的增大(正极极片30至正极极片32)，电池的DCR也可得到更明显的改善。但是若导电底涂层的厚度过大，则不利于电池的能量密度的改进。
6.5大小颗粒混合在改善电池的电化学性能方面的作用
下面研究电极活性材料层中不同粒径的电极活性材料的使用对于改善电池的电化学性能等方面的作用。表6示出了各个实施例电池中采用的正极极片和集流体的具体组成和相关参数。表7示出了各电池的性能测量结果。虽然在本申请中，含有不同粒径的电极活性材料的电极活性材料层可以直接形成于复合集流体的表面，即不设置 导电底涂层，但是在本申请的优选实施例中，在设置有导电底涂层的基础上，研究不同粒径的电极活性材料的使用对于改善电池的电化学性能等方面的作用，以更好地研究其技术效果。
表6
Figure PCTCN2019129357-appb-000009
表7
Figure PCTCN2019129357-appb-000010
从表7的电池倍率性能测试结果可知：当电极活性材料采用小颗粒活性材料(平均粒径D50为1.0μm～7.0μm)和大颗粒活性材料(平均粒径D50为7.1μm～20.0μm)混合时，电池的倍率性能要好于单独采用小颗粒活性材料的电池(电池41)或单独采用大颗粒活性材料的电池(电池47)。而且，如以上数据所示，小颗粒活性材料与大颗粒活性材料的质量比在1:9～9:1的范围内时，都能获得良好的倍率性能改善。
6.6电极活性材料层中的粘结剂的含量在改善电池的电化学性能方面的作用
当电极活性材料层中的粘结剂的含量较高时，则活性材料层与集流体之间的结合力较好，当有导电底涂层时，整个膜片层(即活性材料层和导电底涂层的统称)与复合集流体之间的结合力也较好，从而使得在穿钉等异常情况下，活性材料层(或膜片层)可有效地包裹导电层中产生的金属毛刺，以改善电池的穿钉安全性能。
下面从电池穿钉安全的角度来说明电极活性材料层中的粘结剂的含量在改善电池的电化学性能方面的作用。
按照前面实施例所述方法制备正极极片，但是调整正极活性材料层浆料的组成，制得正极活性材料层中粘结剂含量不同的多个正极极片。具体极片组成见下表。为了简便起见，这里采用的是单一粒径的活性材料。
表9
Figure PCTCN2019129357-appb-000011
Figure PCTCN2019129357-appb-000012
表10示出了上述不同正极极片组装成电池时的穿钉测试结果。结果表明正极活性材料层中的粘结剂的含量越高时，相应电池的穿钉安全性能越好。优选地，正极活性材料层中的粘结剂含量不小于1wt％，更优选不小于1.5wt％，最优选不小于2wt％。
表10
Figure PCTCN2019129357-appb-000013
6.7复合集流体的表面形貌
申请人发现，在含有复合集流体的极片中，复合集流体的导电层的表面与传统的金属铝箔集流体不同，即其表面易产生裂纹。例如正极极片24，在冷压之后取一小块样片，用无尘纸沾取DMC溶剂擦拭正极极片24的表面，可暴露出复合集流体表面，采用CCD显微镜仪器观测表面形貌，其观测图见图8。从图8可以看到明显的裂纹。这种裂纹是复合集流体的导电层表面特有的，在传统的金属集流体的表面上是观察不到这种裂纹的。复合集流体的导电层较薄时，在极片加工冷压过程中受压力容易出现裂纹。
而本申请的电极活性材料层包括两种粒径不同的活性材料，即大小颗粒混合，从而在辊压的过程中，可以减少对导电层的破坏，以此改善复合集流体的导电性和电池的内阻、极化等性能，从而最终获得内阻较小、电化学性能良好的正极极片。
另外，如果导电底涂层存在的话，不仅可以进一步减少对导电层的破坏，还可以通过有效修补并构筑集流体与活性物质间的导电网络，提高电子传输效率，降低集流体与电极活性材料层之间的电阻，从而可以有效降低电极组件的直流内阻，提高电极 组件的功率性能，并保证电极组件在长期循环过程中不易于发生较大的极化及析锂等现象，即有效改善了电极组件的长期可靠性；具体表现为DCR增长被显著降低，从而改善了电池性能。
以上观测结果对于导电底涂层的作用机理给出一种可能的理论解释，但是应该理解本申请并不受限于这种特定的理论解释。
本领域技术人员可以理解：以上仅以锂电池为例示出了本申请的极片的应用实例，但是本申请的极片同样可以应用于其它类型的电化学装置，而仍然可以获得本申请的良好技术效果。
根据上述说明书的揭示和教导，本申请所属领域的技术人员还可以对上述实施方式进行适当的变更和修改。因此，本申请并不局限于上面揭示和描述的具体实施方式，对本申请的一些修改和变更也应当落入本申请的权利要求的保护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本申请构成任何限制。

Claims (11)

  1. 一种正极极片，包括集流体和设置于所述集流体至少一个表面上的电极活性材料层，其中，
    所述集流体包括支撑层和设置于所述支撑层至少一个表面上的导电层，所述导电层的单面厚度D2满足：30nm≤D2≤3μm，所述支撑层的厚度D1满足：1μm≤D1≤30μm，且所述支撑层为高分子材料或高分子复合材料；
    所述电极活性材料层包括电极活性材料、粘结剂和导电剂，且所述电极活性材料包括平均粒径D50为1.0μm～7.0μm的小颗粒活性材料以及平均粒径D50为7.1μm～20.0μm的大颗粒活性材料。
  2. 根据权利要求1所述的正极极片，其中，所述小颗粒活性材料与所述大颗粒活性材料的质量比为1:9～9:1，和/或，
    所述小颗粒活性材料与所述大颗粒活性材料是不同的活性材料。
  3. 根据权利要求1或2所述的正极极片，其中，所述电极活性材料层中的粘结剂含量不小于1wt％，优选不小于1.5wt％，更优选不小于2wt％。
  4. 根据权利要求1或2所述的正极极片，其中，所述集流体的导电层表面还设置有保护层，所述保护层仅设置于所述集流体的导电层的一个表面上或设置于所述集流体的导电层的两个表面上；
    优选地，所述保护层的厚度D3满足：D3≤1/10D2且1nm≤D3≤200nm，优选10nm≤D3≤50nm。
  5. 根据权利要求1至4任一项所述的正极极片，其中，所述导电层为金属导电层，所述金属导电层的材料优选铝、镍、钛、银、铝锆合金中的至少一种；和/或，
    所述支撑层的材料选自绝缘高分子材料、绝缘高分子复合材料、导电高分子材料、导电高分子复合材料中的至少一种，
    优选地，所述绝缘高分子材料选自聚酰胺、聚对苯二甲酸酯、聚酰亚胺、聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、芳纶、聚二甲酰苯二胺、丙烯腈-丁二烯-苯乙烯共聚物、聚对苯二甲酸丁二醇酯、聚对苯二甲酰对苯二胺、聚丙乙烯、聚甲醛、环氧树脂、酚醛树脂、聚四氟乙烯、聚苯硫醚、聚偏氟乙烯、硅橡胶、聚碳酸酯、纤维素及其衍生物、淀粉及其衍生物、蛋白质及其衍生物、聚乙烯醇及其交联物、聚乙二醇及其交联物中的至少一种；
    优选地，所述绝缘高分子复合材料选自绝缘高分子材料与无机材料形成的复合材料，其中所述无机材料优选陶瓷材料、玻璃材料、陶瓷复合材料中的至少一种，
    优选地，所述导电高分子材料选自聚氮化硫类高分子材料或经掺杂的共轭类高分子材料，更优选地，所述导电高分子材料选自聚吡咯、聚乙炔、聚苯胺、聚噻吩等中的至少一种；
    优选地，所述导电高分子复合材料选自绝缘高分子材料与导电材料形成的复合材料，更优选地，所述导电材料选自导电碳材料、金属材料、复合导电材料中的至少一种，所述导电碳材料选自碳黑、碳纳米管、石墨、乙炔黑、石墨烯中的至少一种，所 述金属材料选自镍、铁、铜、铝或上述金属的合金中的至少一种，所述复合导电材料选自镍包覆的石墨粉、镍包覆的碳纤维中的至少一种；
    所述支撑层的材料优选为绝缘高分子材料或绝缘高分子复合材料。
  6. 根据权利要求1至5任一项所述的正极极片，其中，所述支撑层的厚度D1满足：1μm≤D1≤15μm；和/或，
    所述支撑层的常温杨氏模量E满足：20GPa≥E≥4GPa；和/或，
    所述导电层中有裂纹；和/或，
    所述导电层的单面厚度D2满足300nm≤D2≤2μm，优选地，500nm≤D2≤1.5μm。
  7. 根据权利要求1至6任一项所述的正极极片，其中，所述导电剂为导电碳材料、金属材料中的至少一种；其中，所述导电碳材料选自零维导电碳，优选为乙炔黑、导电炭黑；一维导电碳，优选为碳纳米管；二维导电碳，优选为导电石墨、石墨烯；三维导电碳，优选为还原后的氧化石墨烯中的至少一种；所述金属材料选自铝粉，铁粉以及银粉中的至少一种；和/或，
    所述粘结剂选自丁苯橡胶，油性聚偏氟乙烯(PVDF)，聚偏氟乙烯共聚物(如PVDF-HFP共聚物、PVDF-TFE共聚物)、羧甲基纤维素钠，聚苯乙烯，聚丙烯酸，聚四氟乙烯，聚丙烯腈、聚酰亚胺、水性PVDF、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种。
  8. 根据权利要求1至7任一项所述的正极极片，其中，在所述集流体与所述电极活性材料层之间还设置有导电底涂层，所述导电底涂层包含导电材料和粘结剂，优选地还包含电极活性材料，优选地所述导电底涂层的单面厚度H为0.1μm至5μm，更优选H与D2的比例为0.5：1至5：1。
  9. 根据权利要求8所述的正极极片，其中，
    所述导电底涂层中的粘结剂与所述活性材料层中的粘结剂相同或不同，且所述导电底涂层中的粘结剂选自丁苯橡胶，油性聚偏氟乙烯(PVDF)，聚偏氟乙烯共聚物(如PVDF-HFP共聚物、PVDF-TFE共聚物)、羧甲基纤维素钠，聚苯乙烯，聚丙烯酸，聚四氟乙烯，聚丙烯腈、聚酰亚胺、水性PVDF、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种，优选水性粘结剂，更优选为水性PVDF、聚丙烯酸、聚氨酯、聚乙烯醇、聚丙烯酸酯、聚丙烯酸-聚丙烯腈共聚物、聚丙烯酸酯-聚丙烯腈共聚物中的至少一种；
    所述导电底涂层中的导电材料与所述活性材料层中的导电剂相同或不同，且所述导电底涂层中的导电材料为导电碳材料、金属材料中的至少一种；其中，所述导电碳材料选自零维导电碳，优选为乙炔黑、导电炭黑；一维导电碳，优选为碳纳米管；二维导电碳，优选为导电石墨、石墨烯；三维导电碳，优选为还原后的氧化石墨烯中的至少一种；所述金属材料选自铝粉，铁粉以及银粉中的至少一种；所述导电底涂层中的导电材料优选含有二维导电碳材料或一维导电碳材料。
  10. 一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，其中，所述正极极片为权利要求1至9任一项所述的正极极片。
  11. 一种装置，其中，包括权利要求10所述的电化学装置。
PCT/CN2019/129357 2019-04-15 2019-12-27 正极极片、电化学装置及装置 WO2020211454A1 (zh)

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