WO2020215781A1 - 一种电池及包含电池的装置 - Google Patents

一种电池及包含电池的装置 Download PDF

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WO2020215781A1
WO2020215781A1 PCT/CN2019/129166 CN2019129166W WO2020215781A1 WO 2020215781 A1 WO2020215781 A1 WO 2020215781A1 CN 2019129166 W CN2019129166 W CN 2019129166W WO 2020215781 A1 WO2020215781 A1 WO 2020215781A1
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Prior art keywords
battery
current collector
layer
conductive layer
thickness
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PCT/CN2019/129166
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English (en)
French (fr)
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梁成都
黄华锋
黄起森
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宁德时代新能源科技股份有限公司
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Publication of WO2020215781A1 publication Critical patent/WO2020215781A1/zh

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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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the field of battery technology, in particular to a battery and a device including the battery.
  • 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.
  • lithium-ion batteries are prone to fire and explosion when subjected to abnormal conditions such as crushing, collision or puncture, causing serious harm. Therefore, the safety issues of lithium-ion batteries have greatly restricted the application and popularization of lithium-ion batteries.
  • the present application proposes a battery to improve the safety performance of the battery while having good rate performance.
  • the first aspect of the present application provides a battery including a positive pole piece, a negative pole piece, and an electrolyte.
  • the positive electrode current collector includes an insulating layer and a conductive layer.
  • the insulating layer is used to carry the conductive layer.
  • the conductive layer is located on at least one surface of the insulating layer, the thickness of the conductive layer is D2, and D2 satisfies: 300nm ⁇ D2 ⁇ 2 ⁇ m; at least one of the conductive layers
  • a protective layer is provided on the surface;
  • the negative electrode current collector is a copper foil current collector with a thickness of 1 ⁇ m to 5.9 ⁇ m.
  • a second aspect of the present application provides a device including the battery described in the first aspect of the present application, and the battery is used as a power source for the device.
  • the device includes mobile equipment, electric vehicles, electric trains, satellites, ships, and energy storage systems.
  • the insulating layer of the positive electrode current collector in the battery of the present application is not conductive, so its resistance is relatively large, which can increase the short-circuit resistance of the battery when a short circuit occurs under abnormal conditions, greatly reduce the short-circuit current, and thus greatly reduce the short-circuit Generate heat, thereby improving the safety performance of the battery;
  • the anode current collector of the battery of the present application replaces the traditional pure metal foil current collector with an insulating layer provided with a conductive layer with a smaller thickness, which can also increase the weight energy density of the battery;
  • the positive electrode current collector of the battery of the present application is also provided with a protective layer.
  • the conductive layer can ensure that the current collector can provide electrons for the electrode active material layer, that is, it can conduct electricity and current collection.
  • the mechanical strength of the current collector can be improved as a whole, and the safety performance of the battery can be further improved.
  • it can also effectively prevent the conductive layer from being damaged, or the occurrence of oxidation, corrosion, etc., and significantly improve the working stability and service life of the current collector.
  • the positive electrode current collector of the battery of this application can improve the safety performance of the battery, its conductivity is worse than that of the traditional aluminum foil current collector. Therefore, the negative electrode current collector of the battery of this application uses a copper foil current collector with a thickness of 1 ⁇ m to 5.9 ⁇ m. Thereby, the rate performance of the battery can be ensured, and lithium deposition in the negative electrode can be prevented.
  • the battery of the present application can not only improve the safety performance of the battery, but also has good rate performance, and can also increase the weight energy density of the battery.
  • the device of the present application includes the battery, and therefore has at least the same advantages as the battery, and will not be described in detail here.
  • 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.
  • Figure 7 is a schematic diagram of a nail penetration experiment in this application.
  • Figure 8 is the temperature change curve of battery 1 and battery 4 after a nail penetration experiment
  • Figure 9 is the voltage change curve of battery 1 and battery 4 after a nail penetration experiment
  • FIG. 10 is a schematic diagram of cutting a negative pole piece according to a specific embodiment of this application.
  • FIG. 11 is a schematic structural diagram of a battery according to a specific embodiment of this application.
  • FIG. 12 is a schematic structural diagram of a battery module according to a specific embodiment of this application.
  • FIG. 13 is a schematic diagram of a battery pack according to a specific embodiment of this application.
  • Figure 14 is an exploded view of Figure 13;
  • FIG. 15 is a schematic diagram of a device using a battery as a power source according to a specific embodiment of the application.
  • the first aspect of the embodiments of the present application relates to a battery, which includes a positive electrode, a separator, a negative electrode, and an electrolyte.
  • the positive pole piece includes a positive electrode current collector and a positive electrode active material layer.
  • the cathode current collector in the battery of the embodiment of the present invention is described in detail below.
  • the positive electrode current collector in the battery of the embodiment of the present invention includes an insulating layer and a conductive layer.
  • the insulating layer is used to support the conductive layer
  • the conductive layer is used to support the positive electrode active material layer.
  • the conductive layer is located on at least one surface of the insulating layer.
  • the thickness of the conductive layer is Is D2, and D2 satisfies: 300nm ⁇ D2 ⁇ 2 ⁇ m.
  • the conductive layer in the positive electrode current collector used in the embodiments of the present application can meet the requirements of the current collector to provide electrons for the electrode active material layer, play the role of conduction and current collection, and improve the mechanical strength of the current collector as a whole, on the other hand,
  • the thickness of the conductive layer is D2, and D2 satisfies: 300nm ⁇ D2 ⁇ 2 ⁇ m.
  • the internal resistance of a battery usually includes the ohmic internal resistance of the battery and the polarization internal resistance of the battery.
  • the active material resistance, the current collector resistance, the interface resistance, and the electrolyte composition all have a significant impact on the internal resistance of the battery.
  • the internal resistance of the battery will be greatly reduced due to an internal short circuit. Therefore, increasing the resistance of the current collector can increase the internal resistance of the battery after a short circuit, thereby improving the safety performance of the battery.
  • the above technical problems are solved by using a special current collector with an insulating layer support and a conductive layer with a specific thickness.
  • the insulating layer is not conductive, so its resistance is relatively large, which can increase the short-circuit resistance of the battery when a short circuit occurs under abnormal conditions, greatly reduce the short-circuit current, and thus greatly reduce the short-circuit Generate heat, thereby improving the safety performance of the battery.
  • the specific thickness of the present invention can further ensure that the current collector has a greater resistance.
  • the conductive layer is aluminum, it can also significantly reduce the thermite reaction of the positive electrode current collector, and significantly reduce the battery temperature rise when an internal short circuit occurs. So as to ensure that the battery has good safety performance.
  • the material of the insulating layer is selected from organic polymer insulating materials.
  • Organic polymers are less dense than metals and lighter in weight, which can further ensure that the battery has a higher weight energy density.
  • the conductive layer adopts a metal layer with a smaller thickness, which can further increase the weight energy density of the battery.
  • the insulating layer can play a good bearing and protective effect on the conductive layer on the surface, it is not easy to cause the pole piece fracture phenomenon common in traditional current collectors.
  • the organic polymer insulating material is selected from polyamide (Polyamide, PA for short), Polyethylene terephthalate (PET), Polyimide (PI), Polyethylene (Polyethylene, for short) PE), Polypropylene (PP), Polystyrene (PS), Polyvinyl chloride (PVC), Acrylonitrile butadiene styrene copolymers, Abbreviated as ABS), polybutylene terephthalat (PBT), poly-p-phenylene terephthamide (PPA), epoxy resin (epoxy resin) , Polypropylene (PPE), Polyformaldehyde (POM), Phenol-formaldehyde resin, Polytetrafluoroethylene (PTFE), Silicone rubber, Polyvinylidenefluoride , Referred to as PVDF), at least one of polycarbonate (Polycarbonate, referred to as PC).
  • PC Polycarbonate
  • PC Polycarbonate
  • the insulating layer mainly functions to support and protect the conductive layer, and its thickness is D1, and D1 satisfies 1 ⁇ m ⁇ D1 ⁇ 20 ⁇ m. If the insulating layer is too thin, it is easy to break during the pole piece processing process; if it 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 insulating layer can be 20 ⁇ m, 15 ⁇ m, 12 ⁇ m, 10 ⁇ m, 8 ⁇ m
  • the lower limit of the thickness D1 of the conductive layer can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m
  • the range of the thickness D1 can be composed of any numerical value of the upper limit or the lower limit. It is preferably 2 ⁇ m ⁇ D1 ⁇ 10 ⁇ m, and more preferably 2 ⁇ m ⁇ D1 ⁇ 6 ⁇ m.
  • the conductive layer is too thin, although it is beneficial to increase the normal temperature film resistance RS of the current collector, it is likely to be damaged during the pole piece processing process; if the conductive layer is too thick, it will affect the weight and energy density of the battery, and It is not conducive to increase the normal temperature sheet resistance RS of the conductive layer.
  • the upper limit of the thickness D2 of the conductive layer may be 2 ⁇ m, 1.8 ⁇ m, 1.5 ⁇ m, 1.2 ⁇ m, 1 ⁇ m, 900nm, 800nm, 700nm, 600nm, 500nm, and the lower limit of the thickness D2 of the conductive layer may be 300nm, 350nm, 400nm, 450nm ;
  • the range of the thickness D2 of the conductive layer can be composed of any value of the upper limit or the lower limit. Preferably, it is 500nm ⁇ D2 ⁇ 1.5 ⁇ m.
  • the conductive layer is selected from metal conductive materials, preferably at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy.
  • the conductive layer is preferably metallic aluminum.
  • Conventional positive current collectors have a high aluminum content. When a short circuit occurs under abnormal conditions of the battery, the heat generated at the short circuit point can trigger a violent thermite reaction, thereby generating a lot of heat and causing accidents such as battery explosion. When the battery of the present application is used, since the amount of aluminum in the positive electrode current collector is greatly reduced, the thermite reaction can be avoided, thereby significantly improving the safety performance of the battery.
  • the conductive layer can be formed on the insulating layer by at least one of mechanical rolling, bonding, vapor deposition, and electroless plating.
  • the vapor deposition method is preferably a physical vapor deposition method (Physical Vapor Deposition). , PVD); physical vapor deposition method preferably at least one of evaporation method, sputtering method; evaporation method preferably vacuum evaporation method (vacuum evaporation), thermal evaporation method (Thermal Evaporation Deposition), electron beam evaporation method (electron beam evaporation) At least one of methods, EBEM), and the sputtering method is preferably a magnetron sputtering (Magnetron sputtering).
  • the positive electrode current collector further includes a protective layer provided on at least one surface of the conductive layer.
  • the protective layer can increase the mechanical strength of the conductive layer and further improve the safety performance of the battery. At the same time, it can effectively prevent the conductive layer from being damaged, or oxidation, corrosion, etc., and significantly improve the working stability and service life of the current collector.
  • the protective layer is selected from metal oxides, and the metal oxide is preferably at least one of aluminum oxide, cobalt oxide, chromium oxide, and nickel oxide.
  • the thickness of the protective layer is D3, and D3 satisfies: D3 ⁇ 1/10D2 and 1nm ⁇ D3 ⁇ 200nm, preferably 10nm ⁇ D3 ⁇ 50nm.
  • the upper limit of the thickness D3 of the protective layer can be 200nm, 180nm, 150nm, 120nm, 100nm, 80nm, 60nm, 55nm, 50nm, 45nm, 40nm, 30nm, 20nm
  • the lower limit of the thickness D3 of the protective layer can be 1nm, 2nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm
  • the range of the thickness D3 of the protective layer can be composed of any value of the upper limit or the lower limit. Preferably, 10nm ⁇ D3 ⁇ 50nm. If the protective layer is too thin, it will not be 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.
  • D3 satisfies: 1/2000 D2 ⁇ D3 ⁇ 1/10 D2, that is, the thickness is 1/2000-1/10 of D2, more preferably, D3 satisfies: 1/1000 D2 ⁇ D3 ⁇ 1/10 D2.
  • the protective layer may be provided on the surface of the conductive layer away from the insulating layer.
  • the protective layer when the protective layer is provided on the surface of the conductive layer away from the insulating layer (that is, the upper surface of the conductive layer), it is called the upper protective layer.
  • the thickness of the upper protective layer is D3', and D3' satisfies: D3' ⁇ 1/10D2 and 1nm ⁇ D3' ⁇ 200nm, that is, the thickness satisfies less than or equal to 1/10 of the thickness of D2 and is in the range of 1nm-200nm.
  • the upper protective layer When metal oxide is selected for the upper protective layer, the upper protective layer has a relatively large resistance. Therefore, this type of protective layer can further increase the resistance of the positive electrode current collector to a certain extent, thereby further improving the battery resistance when a short circuit occurs under abnormal conditions. Short-circuit resistance improves the safety performance of the battery. Secondly, since the metal oxide has low ductility and high hardness, the upper surface protective layer can further increase the mechanical strength of the positive electrode current collector. Third, compared with the choice of metal for the protective layer material, the specific surface area of the metal oxide is larger, so the bonding force between the protective layer of the metal oxide material and the conductive layer is stronger, and it can better protect the conductive layer.
  • the binding force between the protective layer with an increased specific area and the positive electrode active material layer has also been further increased. Therefore, compared with the positive electrode current collector without a protective layer or the material of the upper protective layer, the present application is implemented
  • the current collector of Example can further increase the binding force with the positive electrode active material layer, thereby improving the overall strength of the battery.
  • the protective layer may also be provided on the surface of the conductive layer facing the insulating layer.
  • the protective layer is provided on the surface of the conductive layer facing the insulating layer (ie, the lower surface of the conductive layer), it is called a lower protective layer.
  • the lower protective layer can constitute a complete support structure to protect the conductive layer, thereby better protecting the conductive layer, thereby preventing the conductive layer from being oxidized, corroded or damaged; in addition, it further enhances the mechanical strength of the current collector.
  • the lower protective layer of the metal oxide material has a relatively large resistance, so this type of protective layer can further increase the resistance of the positive electrode current collector to a certain extent, thereby further increasing the short-circuit resistance when the battery is short-circuited under abnormal conditions, and improving the battery The safety performance.
  • the bonding force between the protective layer of the metal oxide material and the insulating layer is enhanced.
  • the protective layer can increase the surface area of the insulating layer.
  • the roughness plays a role in enhancing the bonding force between the conductive layer and the insulating layer, thereby improving the overall strength of the current collector.
  • the thickness of the lower protective layer is D3", D3" satisfies: D3" ⁇ 1/10D2 and 1nm ⁇ D3" ⁇ 200nm, that is, the thickness satisfies less than or equal to 1/10 of the thickness of D2 and is in the range of 1nm-200nm.
  • the protective layer may be provided on two opposite surfaces of the conductive layer, that is, an upper protective layer and a lower protective layer are provided at the same time.
  • 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'. That is, the thickness of the upper protective layer is greater than the thickness of the lower protective layer. If the thickness of the lower protective layer is increased, the improvement effect on the mechanical strength and safety of the current collector will be limited, but it will affect the weight energy density of the battery.
  • the material of the conductive layer is aluminum
  • the thickness of the conductive layer is 500nm ⁇ D2 ⁇ 1.5 ⁇ m
  • the material of the protective layer is nickel oxide or aluminum oxide, and is arranged on the conductive layer. On two opposite surfaces.
  • 1 to 4 are schematic diagrams of the structure of a positive electrode current collector according to an embodiment of the application.
  • the positive electrode current collector 10 includes a positive electrode insulating layer 101 and a positive electrode conductive layer 102 disposed on two opposite surfaces of the positive electrode insulating layer 101.
  • the positive electrode conductive layer 102 includes a positive electrode conductive layer 102 and a positive electrode conductive layer 102.
  • the positive protective layer 103 (that is, the upper protective layer) on the upper surface (that is, the surface away from the positive insulating layer 101).
  • the positive electrode current collector 10 includes a positive electrode insulating layer 101 and a positive electrode conductive layer 102 disposed on two opposite surfaces of the positive electrode insulating layer 101.
  • the positive electrode conductive layer 102 includes a positive electrode conductive layer 102 and a positive electrode conductive layer 102. Opposite the positive electrode protective layer 103 on the two surfaces.
  • the positive electrode current collector 10 includes a positive electrode insulating layer 101 and a positive electrode conductive layer 102 disposed on one surface of the positive electrode insulating layer 101.
  • the positive electrode conductive layer 102 includes a positive electrode conductive layer 102 and a positive electrode insulating layer disposed on the positive electrode conductive layer 102.
  • the positive electrode protective layer 103 (ie, the upper protective layer) on the face of the layer 101.
  • the positive electrode current collector 10 includes a positive electrode insulating layer 101 and a positive electrode conductive layer 102 disposed on one surface of the positive electrode insulating layer.
  • the positive electrode conductive layer 102 includes a positive electrode conductive layer 102 and two opposite surfaces of the positive electrode conductive layer 102.
  • FIGs 5 and 6 are schematic diagrams of the structure of the positive pole piece according to the embodiment of the application.
  • the positive pole piece 1 includes a positive electrode current collector 10 and a positive electrode active material layer 11 formed on the surface of the positive electrode current collector 10, wherein
  • the positive electrode current collector 10 includes a positive electrode insulating layer 101 and a positive electrode conductive layer 102 arranged in sequence, wherein the positive electrode conductive layer 102 includes a positive electrode conductive layer 102 and a positive electrode protective layer 103 arranged on one or both sides of the positive electrode conductive layer 102 (in the figure Not shown).
  • the positive active material layer includes a positive active material, a binder, and a conductive additive. Since the conductive performance of the positive electrode current collector is worse than that of the traditional aluminum foil current collector, it is preferable that the mass percentage of the conductive additive is not less than 0.8 wt% based on the total weight of the positive electrode active material layer. This can ensure that the polarization of the positive pole piece is small, so that the impact on the high-rate performance of the battery is small. The higher the content of conductive additives, the smaller the polarization, and the better the rate performance of the battery. However, if the content of the conductive additive is too high, the charge and discharge capacity of the battery will be reduced.
  • the mass percentage content of the conductive additive is 0.8 wt% to 2 wt%.
  • the upper limit of the conductive additive can be 2wt%, 1.8wt%, 1.5wt%, 1.3wt%, 1.2wt%, and the lower limit of the conductive additive can be 0.8wt%, 0.9wt%, 0.95wt%. , 1.0wt%, 1.1wt%.
  • the conductive additive may be selected from conductive carbon black, graphene, carbon nanotubes, Ketjen black, flake graphite and other commonly used conductive agents for pole pieces.
  • the negative pole piece of the battery of the embodiment of the present application includes a negative current collector and a negative active material layer.
  • the negative electrode current collector in the battery of the embodiment of the present invention is described in detail below.
  • the negative electrode current collector of the battery of the embodiment of the application adopts a copper foil current collector with a thickness of 6 ⁇ m-12 ⁇ m.
  • a copper foil current collector with a thickness of 1.0 ⁇ m to 5.9 ⁇ m is preferably used. This is because, although the positive electrode current collector of the battery of the present application can improve the safety performance of the battery, its conductivity is worse than that of the traditional aluminum foil current collector. Therefore, the embodiment of the application uses the copper foil current collector with a specific thickness to be used in conjunction with the positive electrode current collector.
  • the negative electrode current collector of the embodiment of the application has good electrical conductivity, and the polarization of the pole pieces is small, thereby ensuring the rate performance of the battery , And can prevent the negative electrode lithium precipitation.
  • the negative electrode current collector is a copper foil current collector with a thickness of 2.0 ⁇ m to 5.9 ⁇ m, more preferably a copper foil current collector with a thickness of 3.0 ⁇ m to 5.9 ⁇ m. More preferably, it is a copper foil current collector with a thickness of 4.5 ⁇ m to 5.9 ⁇ m.
  • a copper foil collection with a breaking elongation greater than or equal to 1%. fluid If the elongation at break is less than 1%, the copper foil current collector is likely to crack or break during processing and battery operation, thereby affecting the cost and long-term reliability of the battery.
  • a copper foil current collector with an elongation at break greater than or equal to 2% is used. More preferably, a copper foil current collector with a breaking elongation of 3% or more is used.
  • the elongation at break in the MD direction and TD direction of the copper foil current collector are both greater than or equal to 1%, so as to improve the weight energy density of the battery and better ensure that the copper foil current collector has a certain mechanical strength to ensure that the The copper foil has good processing performance during the battery manufacturing process, and after being applied to the battery, the battery has good electrochemical and long-term reliability.
  • a copper foil current collector with an elongation at break in the MD and TD directions is greater than or equal to 2%. More preferably, a copper foil current collector with the elongation at break in the MD and TD directions is greater than or equal to 3%.
  • the "length direction (MD direction)” and “width direction (TD direction)” of the copper foil current collector respectively refer to the two dimensions of the surface, and the length direction refers to the main dimension direction (that is, the larger dimension). Direction), and the width direction refers to the secondary dimension direction (that is, the direction of the smaller size).
  • the length direction is consistent with the coating direction of each material layer (such as electrode active material layer) during the processing of the pole piece, and is also consistent with the winding direction of the pole piece during the manufacturing process of an electrochemical device (such as a battery) ;
  • the width direction is perpendicular to the length direction.
  • the copper foil current collector can be a current collector made of metallic copper, or a copper alloy current collector, such as copper-nickel alloy, copper-chromium alloy, copper-zinc alloy, red copper, bronze, and the like.
  • the weight percentage of the copper element in the copper alloy is 90 wt% or more.
  • the battery of the present application preferably adopts a negative pole piece with the following overcurrent capability: a negative pole piece with a single piece width of 50 mm, and a fusing time of greater than or equal to 10 seconds at a current of 10 A.
  • a negative pole piece with a single piece width of 50 mm preferably adopts a negative pole piece with the following overcurrent capability.
  • test method for the over-current capability of the negative pole piece is as follows: cut the negative pole piece to the size shown in Figure 10, apply a current of 10A, and observe the fusing time. The shorter the fusing time, the worse its overcurrent capability.
  • the elongation at break of the copper foil current collector is related to the defects in the current collector, which in turn is related to the processing and material composition of the current collector.
  • the thinner the thickness of the copper foil current collector the more difficult the processing and the more defects. This will also directly affect the flow capacity of the negative pole piece containing the copper foil current collector. Therefore, in order to make the battery have both high weight energy density and excellent electrochemical performance, it is necessary to use a copper foil current collector with a thinner thickness, a large elongation at break, and a good flow capacity of the negative electrode.
  • the battery further includes electrolyte.
  • the normal temperature conductivity of the electrolyte is 6.0 mS/cm to 9.0 mS/cm, so as to further ensure that the negative electrode does not deposit lithium.
  • the higher the room temperature conductivity of the electrolyte the better the rate performance of the battery.
  • the content of a certain type of organic solvent is simply increased to improve the conductivity at room temperature, it will increase the side reactions due to the excessive addition of a certain type of organic solvent, which will affect the cycle life and other performance of the battery to a certain extent. If the room temperature conductivity of the electrolyte is too high,
  • the room temperature conductivity of the electrolyte can be adjusted by adjusting the ratio of cyclic carbonate and chain carbonate. If the conductivity at room temperature is too high, the addition of cyclic carbonate is required. Large, but increase side reactions. In addition, the conductivity at room temperature can be improved by adding carboxylic acid ester, and it is not limited to this.
  • the battery of the embodiment of the present application may be a winding type or a laminated type.
  • the battery type it can also be one of lithium ion secondary batteries, lithium primary batteries, sodium ion batteries, and magnesium ion batteries. But it is not limited to this.
  • FIG. 7 is a schematic diagram of a nail penetration experiment of this application.
  • the figure only shows that the nail 4 penetrates a layer of positive pole piece 1, a layer of separator 3 and a layer of negative pole piece 2 of the battery.
  • the actual nail penetration experiment is that the nail 4 penetrates
  • the entire battery usually includes a multilayer positive pole piece 1, a multilayer separator 3 and a multilayer negative pole piece 2.
  • the heat generated at the site of the internal short-circuit can be completely absorbed by the battery, which will cause damage to the battery.
  • the temperature rise is also very small, so that the impact of short-circuit damage on the battery can be limited to the nail-piercing point, only forming a "point open circuit", without affecting the normal operation of the battery in a short time.
  • the battery 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 battery can be one or several, which can be adjusted according to requirements.
  • the outer packaging of the battery may be a soft bag, such as a pouch 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 battery can also be a hard shell, such as an aluminum shell.
  • FIG. 11 shows a lithium ion secondary battery 9 having a square structure as an example.
  • the lithium ion secondary battery can be assembled into a battery module, and the number of lithium ion secondary batteries 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. 12 is a battery module 8 as an example. 12, in the battery module 8, a plurality of lithium ion secondary batteries 9 may be arranged in order along the length direction of the battery module 8. Of course, it can also be arranged in any other manner. Furthermore, the plurality of lithium ion secondary batteries 9 can be fixed by fasteners.
  • the battery module 8 may further include a housing having an accommodation space, and a plurality of lithium ion secondary batteries 9 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.
  • the battery pack 5 may include a battery box and a plurality of battery modules 8 provided in the battery box.
  • the battery box includes an upper box body 6 and a lower box body 7.
  • the upper box body 6 can be covered on the lower box body 7 and forms a closed space for accommodating the battery module 8.
  • a plurality of battery modules 8 can be arranged in the battery box in any manner.
  • a device in the second aspect of the present application, includes the battery of the first aspect of the present application.
  • the battery can be used as a power source of the device or as an energy storage unit of 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.
  • the device can select a lithium ion secondary battery, battery module, or battery pack according to its usage requirements.
  • Figure 15 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 is usually thin and light, and batteries can be used as a power source.
  • An insulating layer of a certain thickness is selected, and a conductive layer of a certain thickness is formed on its surface by vacuum evaporation, mechanical rolling or bonding, and the protective layer is by vapor deposition, in-situ formation or coating.
  • the formation conditions of the conductive layer vacuum evaporation method are as follows: The insulating 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 metal passes through the cooling system in the vacuum plating chamber and is finally deposited on the surface of the insulating layer to form a conductive layer.
  • the formation conditions of the conductive layer 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 on the passing surface The surface of the insulating layer is cleaned, and finally the two are placed in a mechanical roller, and the two are tightly combined by applying a pressure of 30t to 50t.
  • the formation conditions of the conductive layer 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; The surface of the layer is coated with a mixed solution of PVDF and NMP; finally, the conductive layer with the predetermined thickness is bonded to the surface of the insulating layer and dried at 100°C.
  • a protective layer is provided on the surface of the insulating layer by vapor deposition or coating, and then a conductive layer with a certain thickness is formed on the surface of the insulating layer with a protective layer by vacuum evaporation, mechanical rolling or bonding.
  • the surface of the conductive layer away from the insulating layer can be vapor-deposited, in-situ Forming method or coating method to form the upper protective layer to prepare a current collector having an upper protective layer and a lower 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 insulating layer by mechanical rolling or bonding.
  • Layer surface, and the protective layer is arranged between the insulating layer and the conductive layer to prepare a current collector with a lower protective layer (the protective layer is located between the insulating layer and the conductive layer); in addition, on the basis of the above, the conductive layer
  • the upper protective layer is formed on the surface of the layer away from the insulating layer by vapor deposition, in-situ formation or coating to prepare a current collector with an upper protective layer and a lower protective layer (the protective layer is located on two opposite sides of the conductive layer surface);
  • 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 insulating layer by mechanical rolling or bonding. Layer surface, and the protective layer is arranged on the surface of the conductive layer away from the insulating layer to prepare a current collector with an upper protective layer (the protective layer is located on the surface of the conductive layer away from the insulating 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 insulating layer to prepare a current collector with an upper protective layer and a lower protective layer (the protective layer is located on two opposite surfaces of the conductive layer);
  • a conductive layer is formed on the surface of the insulating layer, and then an upper protective layer is formed on the surface of the conductive layer in the direction away from the insulating layer by vapor deposition, in-situ formation, or coating to prepare a set with an upper protective layer. Fluid (the protective layer is located on the surface of the conductive layer away from the insulating layer).
  • the vapor deposition method adopts the vacuum evaporation method
  • the in-situ formation method adopts the in-situ passivation method
  • the coating method adopts the knife 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 20-75%) is coated on the surface of the sample, and then the coating is controlled with a gravure roll The thickness is finally dried at 100-130°C.
  • a copper foil with a thickness of 8 ⁇ m is selected as the negative electrode current collector (ie, negative pole piece 1#).
  • the positive electrode slurry or the negative electrode slurry is coated on the surface of the current collector and dried at 100° C. to obtain a positive electrode or negative electrode.
  • the mass percentage content of the conductive additive conductive carbon black
  • the specific parameters of the prepared positive pole piece are shown in Table 1 and Table 2.
  • the positive pole piece 1-1 indicates the pole piece obtained by preparing the corresponding protective layer on the positive pole piece 1, and so on.
  • the current collector of the conventional positive pole piece is an Al foil with a thickness of 12 ⁇ m
  • the positive active material layer is a ternary (NCM) material layer with a thickness of 55 ⁇ m
  • the mass percentage of the conductive additive is 1.5 wt%.
  • Negative pole piece The negative electrode current collector is a Cu foil with a certain thickness, and the negative electrode active material layer is a 55 ⁇ m thick graphite material layer.
  • Ethylene carbonate (EC) and methyl vinyl carbonate (EMC) are used as organic solvents (the volume ratio of EC to EMC is 1:10-10:1); the electrolyte is LiPF 6 with a concentration of 1 mol/L.
  • electrolytes with room temperature conductivity of 6.5mS/cm, 7.0mS/cm, 7.3mS/cm, 8.0mS/cm, 8.5mS/cm, and 9.0mS/cm were prepared respectively.
  • room temperature conductivity of 6.5mS/cm, 7.0mS/cm, 7.3mS/cm, 8.0mS/cm, 8.5mS/cm, and 9.0mS/cm were prepared respectively.
  • room temperature conductivity of 6.5mS/cm, 7.0mS/cm, 7.3mS/cm, 8.0mS/cm, 8.5mS/cm, and 9.0mS/cm were prepared respectively.
  • the positive pole piece, the PP/PE/PP separator and the negative pole piece are wound together into a bare cell, and then placed in the battery case, electrolyte is injected, and then the process of sealing and forming is performed. , And finally get a lithium ion battery, the standard battery capacity (25°C, 1C/1C) is 3.2Ah.
  • the cycle life test of lithium-ion batteries is carried out.
  • the specific test methods are as follows:
  • a nail-piercing experiment After the battery is fully charged, fix it, insert a steel needle with a diameter of 8mm through the battery at a speed of 25mm/s at room temperature, keep the steel needle in the battery, and observe and test.
  • Battery temperature test Use a multi-channel thermometer to attach temperature sensing wires to the geometric center of the acupuncture surface and the back of the battery to be nailed. After the nailing is completed, perform a five-minute battery temperature tracking Test, and then record the battery temperature at five minutes.
  • Battery voltage test Connect the positive and negative electrodes of the battery to be nailed to the measuring terminal of the internal resistance meter. After nailing is completed, perform a five-minute battery voltage tracking test, and then record the battery at five minutes The voltage.
  • N/A means that a steel needle penetrates into the battery and causes thermal runaway and destruction instantly.
  • the battery temperature variation curve with time of battery 1# and battery 4# is shown in Fig. 8, and the voltage variation curve with time is shown in Fig. 9.
  • the batteries of the embodiments of the present application may have good safety performance. From the results in Table 6 and Figures 8 and 9, battery 1# (conventional battery), at the moment of nail penetration, the battery temperature rises several hundred degrees and the voltage drops to zero, which shows that at the moment of nail penetration, The battery has an internal short circuit, which generates a lot of heat, and the battery is thermally out of control and destroyed in an instant, and it cannot continue to work; and because the battery is thermally out of control and destroyed immediately after the first steel needle penetrates the battery, it cannot be The six steel needles are continuously pierced through the test of the similar battery.
  • the temperature rise of the battery can be basically controlled below 6°C, the voltage is basically stable, and the battery cell can work normally.
  • the safety performance of the battery with the metal oxide protective layer is better. It can be seen that in the case of an internal short circuit in the battery, the battery of the embodiment of the present application can greatly reduce the short-circuit heat generation, thereby improving the safety performance of the battery; in addition, The impact of short-circuit damage on the battery can also be limited to the "point" range, only forming a "point open circuit” without affecting the normal operation of the battery in a short time.
  • the battery of the embodiment of the application has a good rate performance comparable to that of a conventional battery.
  • Example 1 The difference from Example 1 is that the negative electrode current collector is a copper foil with a thickness of 1-12 ⁇ m as the negative electrode current collector.
  • Table 7 shows the data recording the elongation at break of the negative electrode current collector.
  • the positive pole piece 2-9, PP/PE/PP separator and negative pole piece 1# ⁇ negative pole piece 9# in Example 1 are respectively wound into bare cells, and then placed in the battery Into the casing, electrolyte is injected, followed by sealing, chemical formation and other processes, and finally a lithium-ion battery is obtained.
  • the standard battery capacity (25°C, 1C/1C) is 3.2Ah.
  • the composition of the copper alloy used in the negative pole piece 5# is: 95 wt% of copper and 5 wt% of nickel.
  • the copper foil current collector of negative pole piece 2#-8# is thinner than negative pole piece 1# in thickness, and the thickness is 1 ⁇ m ⁇
  • the 5.9 ⁇ m copper foil current collector can meet the requirements of breaking elongation (elongation at break ⁇ 1%), ensuring that the copper foil current collector has a certain mechanical strength to ensure that the copper foil has good processing performance during the battery production process .
  • the copper foil current collector of the negative pole piece 2# ⁇ 8# In the copper foil current collector of the negative pole piece 2# ⁇ 8#, the fusing time of the negative pole piece 2# and the negative pole piece 3# is shorter, and its overcurrent capability is also poor. Therefore, the copper foil current collector with a thickness of 2.0 ⁇ m to 5.9 ⁇ m has a thinner thickness, a larger elongation at break, a long fusing time, and a better flow capacity.

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Abstract

一种电池及包含电池的装置，涉及电池领域。该电池包括正极极片（1）、负极极片（2）和电解液，正极集流体（10）包括绝缘层（101）和导电层（102），绝缘层（101）用于承载导电层（102），导电层（102）用于承载正极活性材料层（11），导电层（102）位于绝缘层（101）的至少一个表面上，导电层（102）的厚度为D2，D2满足：300nm≤D2≤2μm；导电层（102）的至少一个表面上设置有保护层（103）；负极集流体（20）为厚度为1μm～5.9μm的铜箔集流体。该电池不仅可提高电池的安全性能，同时兼具良好的倍率性能，还可以提高电池的重量能量密度。

Description

一种电池及包含电池的装置
本申请要求于2019年04月26日提交中国专利局、申请号为201910345708.3、发明名称为“一种电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，具体地讲，涉及一种电池及包含电池的装置。
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。然而锂离子电池在受到挤压、碰撞或穿刺等异常情况时很容易发生着火、***，从而引起严重危害。因此锂离子电池的安全问题很大程度地限制了锂离子电池的应用和普及。
大量实验结果表明，电池内短路是造成锂离子电池安全隐患的根本所在。为了避免发生电池内短路，研究者们试图改进隔膜结构、电池机械结构等。其中有些研究是从改善集流体的设计方面来提升锂离子电池的安全性能。
当由于发生碰撞、挤压、穿刺等异常情况而导致电池发生内短路时，电池温度会上升；已有技术中有采用在金属集流体的材料中加入低熔点合金的技术方案，随着电池温度的上升，该集流体中的低熔点合金发生熔融，从而造成极片断路，由此切断电流，从而改善了电池的安全性；或采用具有树脂层两面复合有金属层的多层结构的集流体，随着电池温度的上升，当达到树脂层的材料的熔点时，该集流体的树脂层熔融而使极片破损，由此切断电流，从而改善电池的安全问题。
然而已有技术中的这些方法都无法有效地阻止锂离子电池内短路的发生，而且也无法保证在异常情况发生后电池还可以继续工作。在上述这些改进方法中，电池发生内短路后，电池温度依然会急剧升高，当电池温度骤升 时，若安全构件不能快速响应的话，则依然会发生不同程度的危险；而且在上述这些改进方法中，在安全构件响应后，虽然电池的安全隐患得以解决，然而电池却无法继续工作。
因此，有必要提供一种能在碰撞、挤压、穿刺等异常情况发生后，有效地防止电池由于内短路的发生而引起的着火、***等事故且不影响电池正常工作的电池设计。
申请内容
鉴于此，本申请提出一种电池，以提高电池的安全性能，同时兼具良好的倍率性能。
本申请的第一方面提供一种电池包括正极极片、负极极片和电解液，所述正极集流体包括绝缘层和导电层，所述绝缘层用于承载所述导电层，所述导电层用于承载所述正极活性材料层，所述导电层位于所述绝缘层的至少一个表面上，所述导电层的厚度为D2，D2满足：300nm≤D2≤2μm；所述导电层的至少一个表面上设置有保护层；所述负极集流体为厚度为1μm～5.9μm的铜箔集流体。
本申请的第二方面提供一种装置，其包括本申请的第一方面所述的电池，所述电池用作所述装置的电源。
优选地，所述装置包括移动设备、电动车辆、电气列车、卫星、船舶及储能***。
本申请的技术方案至少具有以下有益的效果：
首先，本申请电池中的正极集流体的绝缘层不导电，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；同时本申请电池的正极集流体通过采用设置有较小厚度的导电层的绝缘层代替传统的纯金属箔集流体，还可以提高电池的重量能量密度；
其次，本申请电池的正极集流体上还设置有保护层，该导电层一方面可以保证集流体能够为电极活性材料层提供电子，即起到导电和集流的作用，另一方面保护层还可以整体提高集流体的机械强度，进一步提高电池的安全 性能，同时还有效防止导电层被破坏，或者发生氧化、腐蚀等现象，显著改善集流体的工作稳定性和使用寿命。
最后，本申请电池的正极集流体虽然可以改善电池的安全性能，但其导电性能较传统铝箔集流体差，因此本申请的电池的负极集流体采用厚度为1μm～5.9μm的铜箔集流体，从而可以保证电池的倍率性能，且可以防止负极析锂。
本申请的电池不仅可提高电池的安全性能，同时兼具良好的倍率性能，还可以提高电池的重量能量密度。
本申请的装置包括所述的电池，因而至少具有与所述电池相同的优势，在此不再一一详细描述。
附图说明
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为本申请一次穿钉实验的示意图；
图8为电池1和电池4在一次穿钉实验后的温度变化曲线；
图9为电池1和电池4在一次穿钉实验后的电压变化曲线；
图10为本申请某一具体实施方式的负极极片的裁切示意图；
图11为本申请某一具体实施方式的电池的结构示意图；
图12为本申请某一具体实施方式的电池模块的结构示意图；
图13为本申请某一具体实施方式的电池包示意图；
图14为图13的分解图；
图15为本申请某一具体实施方式的电池用作电源的装置的示意图。
其中：
1-正极极片；
10-正极集流体；
101-正极绝缘层；
102-正极导电层；
103-正极保护层；
11-正极活性材料层；
2-负极极片；
20-负极集流体；
21-负极活性材料层；
3-隔膜；
4-钉子；
5-电池包；
6-上箱体；
7-下箱体；
8-电池模块；
9-锂离子二次电池。
具体实施方式
下面结合具体实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
下面对本申请实施例提出的电池的结构和性能，以及装置进行详细描述。
本申请实施例第一方面涉及一种电池，包括正极、隔离膜、负极和电解液。
在正极极片中，正极极片包括正极集流体和正极活性材料层。下面详细描述本发明实施例电池中的正极集流体。
本发明实施例电池中的正极集流体包括绝缘层和导电层，绝缘层用于承载导电层，导电层用于承载正极活性材料层，导电层位于绝缘层的至少一个表面上，导电层的厚度为D2，D2满足：300nm≤D2≤2μm。
本申请实施例采用的正极集流体中的导电层一方面可以满足集流体为电极活性材料层提供电子，起到导电和集流的作用的要求，整体提高集流体的机械强度，另一方面，导电层的厚度为D2，D2满足：300nm≤D2≤2μm。
电池的内阻通常包括电池欧姆内阻和电池极化内阻，其中活性物质电阻、 集流体电阻、界面电阻、电解液组成等均会对电池内阻产生较明显的影响。在异常情况下发生短路时，由于发生内短路，电池的内阻会大大降低。因此增大集流体的电阻，可增大电池短路后的内阻，由此改善电池的安全性能。在现有的锂离子电池中，当在异常情况下发生电池内短路时，瞬间产生大电流，并伴随着大量的短路产热，这些热量通常还会引发正极铝箔集流体处的铝热反应，进而使电池发生着火、***等。
在本申请实施例中，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从而解决了上述技术问题。在本发明实施例的正极集流体中，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。同时，本发明特定的厚度可以进一步保证该集流体具有较大的电阻，当导电层为铝时，还可显著降低正极集流体的铝热反应，显著降低电池在发生内短路时的电池升温，从而保证电池具有良好的安全性能。
可选的，绝缘层的材料选自有机聚合物绝缘材料。有机聚合物比金属的密度小，重量轻，从而可以进一步保证电池具有较高的重量能量密度。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。并且由于绝缘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。
其中，有机聚合物绝缘材料选自聚酰胺(Polyamide，简称PA)、聚对苯二甲酸酯(Polyethylene terephthalate，简称PET)、聚酰亚胺(Polyimide，简称PI)、聚乙烯(Polyethylene，简称PE)、聚丙烯(Polypropylene，简称PP)、聚苯乙烯(Polystyrene，简称PS)、聚氯乙烯(Polyvinyl chloride，简称PVC)、丙烯腈-丁二烯-苯乙烯共聚物(Acrylonitrile butadiene styrene copolymers，简称ABS)、聚对苯二甲酸丁二醇酯(Polybutylene terephthalat，简称PBT)、聚对苯二甲酰对苯二胺(Poly-p-phenylene terephthamide，简称PPA)、环氧树脂(epoxy resin)、聚丙乙烯(简称PPE)、聚甲醛(Polyformaldehyde，简称POM)、酚醛树脂(Phenol-formaldehyde resin)、聚四氟乙烯(Polytetrafluoroethylene，简称PTFE)、硅橡胶(Silicone rubber)、聚偏氟乙烯(Polyvinylidenefluoride，简称PVDF)、聚碳酸酯(Polycarbonate，简称PC)中的至少一种。
在本申请实施例的集流体中，绝缘层主要起到支撑和保护导电层的作用，其厚度为D1，D1满足1μm≤D1≤20μm。若绝缘层太薄的话，很容易在极片加工工艺等过程中发生断裂；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，绝缘层的厚度D1的上限可为20μm、15μm、12μm、10μm、8μm，导电层的厚度D1的下限可为1μm、1.5μm、2μm、3μm、4μm、5μm、6μm、7μm；绝缘层的厚度D1的范围可由上限或下限的任意数值组成。优选为2μm≤D1≤10μm，更优选为2μm≤D1≤6μm。
如果导电层太薄的话，虽然有益于增大集流体的常温薄膜电阻RS，却易在极片加工工艺等过程中发生破损；如果导电层太厚的话，则会影响电池的重量能量密度，且会不利于增大导电层的常温薄膜电阻RS。
其中，导电层的厚度D2的上限可为2μm、1.8μm、1.5μm、1.2μm、1μm、900nm、800nm、700nm、600nm、500nm，导电层的厚度D2的下限可为300nm、350nm、400nm、450nm；导电层的厚度D2的范围可由上限或下限的任意数值组成。优选为500nm≤D2≤1.5μm。
可选的，导电层选自金属导电材料，优选铝、铜、镍、钛、银、镍铜合金和铝锆合金中的至少一种。
进一步的，导电层优选为金属铝。常规正极集流体中的铝含量高，在电池异常情况下发生短路时，短路点处产生的热量可以引发剧烈的铝热反应，从而产生大量的热并引起电池发生***等事故。当采用本申请的电池时，由于正极集流体中铝的量大大减少，因此可以避免产生铝热反应，从而显著改善电池的安全性能。
其中，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绝缘层上，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)。
在本申请实施例中，正极集流体还包括设置于导电层的至少一个表面上 的保护层。保护层可以提高导电层的机械强度，进一步提高电池的安全性能，同时还有效防止导电层被破坏，或者发生氧化、腐蚀等现象，显著改善集流体的工作稳定性和使用寿命。
在本申请实施例中，保护层选自金属氧化物，金属氧化物优选氧化铝、氧化钴、氧化铬和氧化镍中的至少一种。
其中，保护层的厚度为D3，D3满足：D3≤1/10D2且1nm≤D3≤200nm，优选10nm≤D3≤50nm。
其中，保护层的厚度D3的上限可为200nm、180nm、150nm、120nm、100nm、80nm、60nm、55nm、50nm、45nm、40nm、30nm、20nm，保护层的厚度D3的下限可为1nm、2nm、5nm、8nm、10nm、12nm、15nm、18nm；保护层的厚度D3的范围可由上限或下限的任意数值组成。优选的，10nm≤D3≤50nm。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。
从保护层占整个导电层的厚度来看，D3满足：1/2000 D2≤D3≤1/10 D2，即厚度是D2的1/2000～1/10，更优选的，D3满足：1/1000 D2≤D3≤1/10 D2。
可选的，保护层可以设置于导电层的背离绝缘层的面上。在申请实施例中为了描述方便，当保护层设置于导电层的背离绝缘层的面(即导电层的上表面)上时，称为上保护层。
其中，上保护层的厚度为D3′，D3′满足：D3′≤1/10D2且1nm≤D3′≤200nm，即厚度满足小于等于D2厚度的1/10且在1nm～200nm范围内。
当上保护层选用金属氧化物时，上保护层具有较大电阻，因此该类型的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。其次，由于金属氧化物的延展性小、硬度大，因此该上表面保护层可进一步增大正极集流体的机械强度。第三，相对于保护层材料选用金属来讲，金属氧化物的比表面积更大，所以金属氧化物材料的保护层与导电层之间的结合力更强，更能起到保护导电层的作用，并且，比面积增大的保护层与正极活性物质层之间的结合力也进一步增大，因此，相对于不设置保护层、或上保护层材料选用金属的正极集流体来讲，本申请实施例的集流体可以进一步增加与正极活 性物质层之间的结合力，从而可提高电池的整体强度。
进一步可选的，保护层也可以设置于导电层的朝向绝缘层的面上。当保护层设置于导电层的朝向绝缘层的面(即导电层的下表面)上时，称为下保护层。
下保护层可构成完整的支撑结构来保护导电层，从而更好的对导电层形成保护作用，从而防止导电层被氧化、腐蚀或破坏；此外，进一步增强集流体的机械强度。金属氧化物材料的下保护层具有较大电阻，因此该类型的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保护层与绝缘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，因此保护层可以增加绝缘层表面的粗糙度，起到增强导电层与绝缘层之间的结合力的作用，从而提高了集流体整体的强度。
其中，下保护层的厚度为D3″，D3″满足：D3″≤1/10D2且1nm≤D3″≤200nm，即厚度满足小于等于D2厚度的1/10且在1nm～200nm范围内。
进一步可选的，保护层可以设置于导电层的相对的两个表面上，即同时设置有上保护层和下保护层。
进一步可选的，同时设置有上保护层和下保护层时，下保护层的厚度D3″与上保护层的厚度D3′的比例关系为：1/2D3′≤D3″≤4/5D3′。即上保护层的厚度大于下保护层的厚度。如果下保护层的厚度增加，对集流体的机械强度、安全作用等改善作用有限，反而会影响电池的重量能量密度。
在本申请实施例电池的一种具体实施方式中，导电层的材料为铝，导电层的厚度为500nm≤D2≤1.5μm，保护层的材料为氧化镍或氧化铝，并设置在导电层的相对的两个表面上。
图1至图4为本申请实施例正极集流体的结构示意图。
在图1中，正极集流体10包括正极绝缘层101和设置于正极绝缘层101相对的两个表面上的正极导电层102，正极导电层102包括正极导电层102以及设置于正极导电层102的上表面(即背离正极绝缘层101的面)上的正极保护层103(即上保护层)。
在图2中，正极集流体10包括正极绝缘层101和设置于正极绝缘层101相对的两个表面上的正极导电层102，正极导电层102包括正极导电层102以及设置于正极导电层102的相对两个表面上的正极保护层103。
在图3中，正极集流体10包括正极绝缘层101和设置于正极绝缘层101一个表面上的正极导电层102，正极导电层102包括正极导电层102以及设置于正极导电层102的背离正极绝缘层101的面上的正极保护层103(即上保护层)。
在图4中，正极集流体10包括正极绝缘层101和设置于正极绝缘层一个表面上的正极导电层102，正极导电层102包括正极导电层102以及设置于正极导电层102的相对两个表面上的正极保护层103。
图5和图6为本申请实施例正极极片结构示意图，如图5和图6所示，正极极片1包括正极集流体10和形成于正极集流体10表面的正极活性材料层11，其中，正极集流体10包括依次设置的正极绝缘层101、正极导电层102，其中，正极导电层102包括正极导电层102以及设置于正极导电层102一侧或两侧的正极保护层103(图中未示出)。
在正极极片中，正极活性材料层包括正极活性材料、粘结剂和导电添加剂。由于正极集流体的导电性能较传统的铝箔集流体差，因此优选地，基于正极活性材料层的总重量，导电添加剂的质量百分含量不低于0.8wt％。这样可以保证正极极片的极化较小，从而对电池的高倍率性能的影响较小。导电添加剂的含量越高，极化越小，电池的倍率性能越好。然而，如果导电添加剂的含量过高，则会降低电池的充放电容量。因此，优选导电添加剂的质量百分含量为0.8wt％～2wt％。在该优选范围内，导电添加剂添加的上限可为2wt％、1.8wt％、1.5wt％、1.3wt％、1.2wt％，导电添加剂添加的下限可为0.8wt％、0.9wt％、0.95wt％、1.0wt％、1.1wt％。
进一步可选的，导电添加剂可选自导电碳黑、石墨烯、碳纳米管、科琴黑、鳞片石墨等常用的极片用导电剂。
在本申请实施例电池的负极极片中，包括负极集流体和负极活性材料层。下面详细描述本发明实施例电池中的负极集流体。
本申请实施例电池的负极集流体采用厚度为6μm～12μm的铜箔集流体。 为了进一步地提高整个电池的重量能量密度，优选采用厚度为1.0μm～5.9μm的铜箔集流体。这是由于，本申请电池的正极集流体虽然可以改善电池的安全性能，但其导电性能较传统铝箔集流体差。所以本申请实施例采用该特定厚度的铜箔集流体与该正极集流体配合使用，本申请实施例的负极集流体具有良好的导电性能，极片的极化小，从而可以保证电池的倍率性能，且可以防止负极析锂。
虽然选择较小厚度的铜箔集流体，有利于改善电池的重量能量密度。但是为了同时使得电池具有较为优异的电化学性能和加工性能，优选的，负极集流体为厚度2.0μm～5.9μm的铜箔集流体，更优选为厚度3.0μm～5.9μm的铜箔集流体，更优选为厚度4.5μm～5.9μm的铜箔集流体。
在将铜箔集流体应用于电池产品的生产过程中，尤其是当将厚度较薄的铜箔集流体应用于电池产品的生产过程中，优选采用断裂伸长率大于等于1％的铜箔集流体。若断裂伸长率小于1％，则铜箔集流体易于在加工以及电池工作等过程中发生裂纹或者断裂，从而影响电池的成本和长期可靠性。优选地，采用断裂伸长率大于等于2％的铜箔集流体。进一步优选的，采用断裂伸长率大于等于3％的铜箔集流体。
进一步的，铜箔集流体的MD方向和TD方向的断裂伸长率均大于等于1％，以在改善电池重量能量密度的同时更好地保证铜箔集流体具有一定的机械强度，以保证在电池制作过程中铜箔具有良好的加工性能，以及应用于电池后，电池具有良好的电化学和长期可靠性能。优选地，采用MD方向和TD方向的断裂伸长率大于等于2％的铜箔集流体。进一步优选的，采用MD方向和TD方向的断裂伸长率大于等于3％的铜箔集流体。
在本申请中，铜箔集流体的“长度方向(MD方向)”和“宽度方向(TD方向)”分别是指表面的两个维度，其中长度方向是指主要维度方向(即尺寸较大的方向)，而宽度方向是指次要维度方向(即尺寸较小的方向)。通常，长度方向与极片加工过程中的各个材料层(例如电极活性材料层)的涂覆方向是一致的，也与电化学装置(例如电池)制造过程中极片的卷绕方向是一致的；而宽度方向是与长度方向垂直的。
在本申请中，铜箔集流体可以为金属铜制成的集流体，也可以为铜合金集流体，例如铜镍合金、铜铬合金、铜锌合金、紫铜、青铜等。优选铜合金 中铜元素的重量百分含量为90wt％以上。
进一步的，本申请的电池优选采用具有下述过流能力的负极极片：单片宽度为50mm的负极极片，10A电流下，熔断时间大于等于10s。这是因为当采用厚度较薄的铜箔集流体作为集流体时，负极极片也需要具有一定的过流能力，否则在电池工作过程中，易于“烧断”，从而影响电池的电化学性能以及正常工作。
负极极片过流能力的测试方法如下：将负极极片裁切为如附图10的尺寸，施加10A的电流，观测熔断时间。熔断时间越短则其过流能力越差。
这里需要说明的是，铜箔集流体的断裂伸长率与集流体中的缺陷有关，这又与集流体的加工制成工艺以及材料组成等有关。通常来说，铜箔集流体的厚度越薄，则加工越困难，缺陷越多。这也会直接影响包含了铜箔集流体的负极极片的过流能力。因此，为了使得电池兼具较高的重量能量密度以及优良的电化学性能，需要采用厚度较薄、且断裂伸长率较大且能使负极极片过流能力较好的铜箔集流体。
在本申请实施例电池中，还包括电解液。作为在本申请实施例的一种改进，为了进一步提高电池的高倍率性能，电解液的常温电导率为6.0mS/cm～9.0mS/cm，从而可以进一步确保负极不析锂。电解液的常温导电率越高，则电池的倍率性能越好。但如果单纯为提高常温电导率而增加某一类有机溶剂的含量，反而会因为某类有机溶剂的添加比例过大而增加副反应，反而在一定程度上影响电池的循环寿命等性能。如果电解液的常温导电率过高，
在电解液的具体实施方式中，例如，可通过调节环状碳酸酯和链状碳酸酯的比例来调节电解液的常温电导率，如果常温电导率过高，则要求环状碳酸酯的添加较大，反而增加副反应。除此之外，还可通过加入羧酸酯来改善常温电导率，并不限于此。
按照卷绕方式来看，本申请实施例的电池可为卷绕式，也可为叠片式。按电池类型来看，也可以为锂离子二次电池、锂一次电池、钠离子电池、镁离子电池中的一种。但并不局限于此。
在本申请实施例中采用穿钉实验来模拟电池的异常情况，并观察穿钉后电池的变化。图7为本申请一次穿钉实验示意图。为了简单起见，图中仅仅 示出了钉子4穿透电池的一层正极极片1、一层隔膜3和一层负极极片2，需要说明的是，实际的穿钉实验是钉子4穿透整个电池，通常包括多层正极极片1、多层隔膜3和多层负极极片2。当电池因穿钉发生短路后，短路电流大幅减小，将短路产热量控制在电池可以完全吸收的范围，因此在发生内短路的位点处产生的热量可以被电池完全吸收，对电池造成的温升也很小，从而可以将短路损坏对电池的影响局限于穿钉位点，仅形成“点断路”，而不影响电池在短时间内的正常工作。
在一些实施例中，电池可以包括外包装，用于封装正极极片、负极极片和电解质。作为一个示例，正极极片、负极极片和隔离膜可经叠片或卷绕形成叠片结构电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。电池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，电池的外包装可以是软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。电池的外包装也可以是硬壳，例如铝壳等。
本申请对电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图11是作为一个示例的方形结构的锂离子二次电池9。
在一些实施例中，锂离子二次电池可以组装成电池模块，电池模块所含锂离子二次电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图12是作为一个示例的电池模块8。参照图12，在电池模块8中，多个锂离子二次电池9可以是沿电池模块8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锂离子二次电池9进行固定。
可选地，电池模块8还可以包括具有容纳空间的壳体，多个锂离子二次电池9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13和图14是作为一个示例的电池包5。参照图13和图14，在电池包 5中可以包括电池箱和设置于电池箱中的多个电池模块8。电池箱包括上箱体6和下箱体7，上箱体6能够盖设于下箱体7，并形成用于容纳电池模块8的封闭空间。多个电池模块8可以按照任意的方式排布于电池箱中。
接下来说明本申请第二方面的装置。
在本申请的第二方面提供一种装置，所述装置包括本申请第一方面的电池，所述电池可以用作所述装置的电源，也可以用作所述装置的能量储存单元。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***等。
所述装置可以根据其使用需求来选择锂离子二次电池、电池模块或电池包。
图15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。为了满足该装置对锂离子二次电池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，可以采用电池作为电源。
实施例1
1、正极集流体的制备：
选取一定厚度的绝缘层，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，保护层则通过气相沉积法、原位形成法或涂布法的方式。
1.1导电层的形成
导电层的形成有如下几种方式：
(1)导电层真空蒸镀方式的形成条件如下：将经过表面清洁处理的绝缘层置于真空镀室内，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***，最后沉积于绝缘层的表面，形成导电层。
(2)导电层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绝缘层的表面，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)导电层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绝缘层的表面涂布PVDF与NMP的混合溶液；最后将上述预定厚度的导电层粘结于绝缘层的表面，并于100℃下烘干。
1.2保护层的形成
保护层的形成有如下几种方式：
(1)先通过气相沉积法或涂布法在绝缘层表面设置保护层，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绝缘层表面形成一定厚度的导电层，以制备具有下保护层的集流体(保护层位于绝缘层与导电层之间)；此外，也可在上述基础上，再在导电层的背离绝缘层的面上通过气相沉积法、原位形成法或涂布法形成上保护层，以制备具有上保护层与下保护层的集流体(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绝缘层表面，且保护层设置于绝缘层与导电层之间，以制备具有下保护层的集流体(保护层位于绝缘层与导电层之间)；此外，也可在上述基础上，再在导电层的背离绝缘层的面上通过气相沉积法、原位形成法或涂布法形成上保护层，以制备具有上保护层和下保护层的集流体(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绝缘层表面，且保护层设置于导电层的背离绝缘层的面上，以制备具有上保护层的集流体(保护层位于导电层的背离绝缘层的表面)；
(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绝缘层表面，以制备具有上保护层和下保护层的集流体(保护层位于导 电层的两个相对的表面)；
(5)在绝缘层的表面形成导电层，然后在导电层的背离绝缘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上保护层，以制备具有上保护层的集流体(保护层位于导电层的背离绝缘层的表面)。
在制备实施例中，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***，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20～75％)，其次用凹版辊控制涂布的厚度，最后在100～130℃下进行干燥。
2、负极集流体
选用厚度为8μm的铜箔作为负极集流体(即负极极片1#)。
3、极片的制备：
通过常规的电池涂布工艺，在集流体的表面涂布正极浆料或负极浆料，100℃干燥后得到正极极片或负极极片。其中，基于正极活性材料层的总重量，导电添加剂(导电炭黑)的质量百分含量不低于0.8wt％。
制备得到的正极极片的具体参数由表1和表2所示。在表2中，正极极片1-1表示采用正极极片1上制备相应保护层所得到的极片，依次类推。
其中，常规正极极片的集流体是厚度为12μm的Al箔片，正极活性材料层是55μm的三元(NCM)材料层，导电添加剂的质量百分含量为1.5wt％。
负极极片：负极集流体是一定厚度的Cu箔片，负极活性材料层是55μm厚的石墨材料层。
4、电解液的制备
采用碳酸乙烯酯(EC)和碳酸甲乙烯酯(EMC)为有机溶剂(EC与EMC 体积比为1:10～10:1)；电解质为LiPF 6，浓度为1mol/L。
通过调整EC和EMC的体积比，分别制备得到常温导电率为6.5mS/cm、7.0mS/cm、7.3mS/cm、8.0mS/cm、8.5mS/cm、9.0mS/cm的电解液，用于电池的制备。
5、电池的制备：
通过常规的电池制作工艺，将正极极片、PP/PE/PP隔膜和负极极片一起卷绕成裸电芯，然后置入电池壳体中，注入电解液，随之进行密封、化成等工序，最终得到锂离子电池，标准电池容量(25℃，1C/1C)均为3.2Ah。
本申请的实施例制作的锂离子电池以及对比例锂离子电池的具体组成如表3所示。
表1
Figure PCTCN2019129166-appb-000001
表2
Figure PCTCN2019129166-appb-000002
Figure PCTCN2019129166-appb-000003
其中，“/”代表没有设置该保护层。
表3
Figure PCTCN2019129166-appb-000004
实验例2：
1、电池测试方法：
对锂离子电池进行循环寿命测试，具体测试方法如下：
将锂离子电池分别于25℃和45℃两种温度下进行充放电，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。
实验结果如表4所示。
2、一次穿钉实验和六次连续穿钉实验的实验方法和测试方法：
(1)一次穿钉实验：电池满充后，固定，在常温下将直径为8mm的钢针，以25mm/s的速度贯穿电池，将钢针保留于电池中，穿钉完毕，然后观察和测试。
(2)六次穿钉实验：电池满充后，固定，在常温下将六根直径为8mm的钢针，以25mm/s的速度先后迅速地贯穿电池，将钢针保留于电池中，穿钉完毕，然后进行观察和测试。
(3)电池温度的测试：使用多路测温仪，分别于待穿钉的电池的针刺面和背面的几何中心附上感温线，待穿钉完毕后，进行五分钟的电池温度跟踪测试，然后记录下五分钟时的电池的温度。
(4)电池电压的测试：将待穿钉的电池的正极和负极连接至内阻仪的测量端，待穿钉完毕后，进行五分钟的电池电压跟踪测试，然后记录下五分钟时的电池的电压。
记录的电池的温度和电压的数据如表5所示。
3、倍率实验：
对锂离子电池进行倍率测试，具体测试方法如下：
将锂离子电池于25℃进行大倍率充放电，即先以1C的电流充电至4.2V，然后再以4C的电流放电至2.8V，记录下第一周的放电容量，将该放电容量除以25℃1C/1C充放电的第一周放电容量，得到电池的4C倍率性能。
实验结果如表6所示。
表4
Figure PCTCN2019129166-appb-000005
Figure PCTCN2019129166-appb-000006
表5
Figure PCTCN2019129166-appb-000007
注：“N/A”表示一根钢针贯穿入电池瞬间发生热失控和毁坏。
表6
电池编号 4C倍率性能
电池1# 46.0％
电池2# 43.4％
电池4# 43.3％
其中，电池1#和电池4#的电池温度随时间的变化曲线如图8所示，电压随时间的变化曲线如图9所示。
根据表5中的结果来看，与采用常规的正极极片和常规的负极极片的电池1#相比，本申请实施例的电池的循环寿命良好，与常规的电池的循环性能相当。这说明本申请实施例的集流体并不会对制得的极片和电池有任何明显的不利影响。与不具有保护层的集流体相比，本申请实施例的含有保护层的集流体制成的电池，容量保有率进一步获得提升，说明电池的可靠性更好。
此外，本申请实施例的电池可以具有良好的安全性能。从表6以及图8和图9中的结果来看，电池1#(常规电池)，在穿钉的瞬间，电池温度骤升几百度，电压骤降至零，这说明在穿钉的瞬间，电池发生内短路，产生大量的热，电池瞬间发生热失控和毁坏，无法继续工作；而且由于在第一根钢针穿入电池之后的瞬间，电池就发生了热失控和毁坏，因此无法对这类电池进行六根钢针连续穿钉实验。
而本申请实施例的电池，无论对其进行一次穿钉实验还是六次连续穿钉实验，电池温升基本都可以被控制在6℃以下，电压基本保持稳定，电芯可以正常工作。且具有金属氧化物类的保护层的电池的安全性能更好可见，在电池发生内短路的情况下，本申请实施例的电池可极大地降低短路产热量，从而改善电池的安全性能；此外，还可将短路损坏对电池的影响局限于“点”范围，仅形成“点断路”，而不影响电池在短时间内的正常工作。
根据表6中的结果来看，采用本申请厚度范围内的负极集流体、本申请含量范围内的导电添加剂和本申请参数范围内的电解液，可获得良好的倍率性能。本申请实施例的电池具有与常规电池相当的、良好的倍率性能。
实施例3
与实施例1不同的是，负极集流体选用厚度为1～12μm的铜箔作为负极集 流体。
1、负极集流体的断裂伸长率测试：
选取厚度为1～12μm范围内的9种规格的负极集流体，在负极集流体上取2个长度为200mm，宽度为15mm的负极集流体样片。然后将负极集流体样片固定于拉力机(型号AI7000)上，记录初始长度L0，启动拉力机测试，直至负极集流体样片断裂，从拉力机上读取断裂时负极集流体样片的位移距离L1。2次测试所得数值的平均值为测试结果。断裂伸长率＝(L1-L0)/L0*100％。
记录负极集流体的断裂伸长率的数据如表7所示。
2、负极集流体的过流能力测试：
选取厚度为1～12μm范围内的9种规格的负极极片裁切为如附图10的尺寸，分别施加10A电流，观测熔断时间。记录负极集流体的熔断时间数据如表7所示。(需要说明的是，极片过流能力与裁切后极片的宽度有关，至于极耳的宽度、极片长度、活性物质的种类等对过流能力的影响可忽略。图10仅是示例)
3、电池的制备：
通过常规的电池制作工艺，用实施例1中的正极极片2-9、PP/PE/PP隔膜分别和负极极片1#～负极极片9#卷绕成裸电芯，然后置入电池壳体中，注入电解液，随之进行密封、化成等工序，最终得到锂离子电池，标准电池容量(25℃，1C/1C)均为3.2Ah。
本申请的实施例制作的锂离子电池以及对比例锂离子电池的具体组成如表8所示。
4、对锂离子电池进行循环寿命测试，具体测试方法如下：
将锂离子电池在温度为25℃±2℃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。
实验结果如表9所示。
表7
Figure PCTCN2019129166-appb-000008
Figure PCTCN2019129166-appb-000009
其中，负极极片5#采用的铜合金的成分为：铜95wt％，镍5wt％。
表8
Figure PCTCN2019129166-appb-000010
表9
电池编号 重量能量密度(wh/kg) 25℃循环1000周容量保有率(％)
电池12# 248 88.9
电池22# 264 21.2
电池23# 261 29.7
电池24# 258 48.3
电池25# 257 69.9
电池26# 257 75.4
电池27# 252 90.2
电池28# 252 89.7
电池9# 240 89.9
根据表7～表9中的结果来看，相对于负极极片1#，负极极片2#～8#的铜箔集流体在厚度上相对负极极片1#更薄，并且厚度为1μm～5.9μm的铜箔集流体能够满足断裂伸长率的要求(断裂伸长率≥1％)，保证铜箔集流体具有一定的机械强度，以保证在电池制作过程中铜箔具有良好的加工性能。
负极极片2#～8#的铜箔集流体中，负极极片2#及负极极片3#的熔断时间较短，其过流能力也较差。因此，厚度为2.0μm～5.9μm的铜箔集流体厚度较薄、断裂伸长率较大、熔断时间长、过流能力较好。
此外，由表9的结果可见，负极极片2#～8#制成的锂离子电池的重量能量密度保持在250wh/kg以上，相比于由负极极片1#或负极极片9#制成的锂离子电池，能够有效提高重量能量密度，并且随着铜箔集流体的厚度的增大，电池的循环稳定性也逐步提高。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (13)

  1. 一种电池，包括正极极片、负极极片和电解液，所述正极极片包括正极集流体和正极活性材料层，所述负极极片包括负极集流体和负极活性材料层，其中，
    所述正极集流体包括绝缘层和导电层，所述绝缘层用于承载所述导电层，所述导电层用于承载所述正极活性材料层，所述导电层位于所述绝缘层的至少一个表面上，所述导电层的厚度为D2，D2满足：300nm≤D2≤2μm；
    所述导电层的至少一个表面上设置有保护层；
    所述负极集流体为厚度为1μm～5.9μm的铜箔集流体。
  2. 根据权利要求1所述的电池，其中，所述导电层选自金属导电材料，所述金属导电材料优选铝、铜、镍、钛、银、镍铜合金和铝锆合金中的至少一种；和/或，
    所述保护层的材料选自金属氧化物，所述金属氧化物优选氧化铝、氧化钴、氧化铬和氧化镍中的至少一种。
  3. 根据权利要求1所述的电池，其中，所述保护层设置于所述导电层的背离所述绝缘层的一面上。
  4. 根据权利要求1或3所述的电池，其中，所述保护层设置于所述导电层的朝向所述绝缘层的一面上。
  5. 根据权利要求1-4任一项所述的电池，其中，所述保护层的厚度为D3，D3满足：D3≤1/10D2且1nm≤D3≤200nm，优选10nm≤D3≤50nm。
  6. 根据权利要求1-5任一项所述的电池，其中，所述正极活性材料层包括正极活性材料、粘结剂和导电添加剂，所述导电添加剂在所述正极活性材料层中的质量百分含量不低于0.8wt％。
  7. 根据权利要求1-6任一项所述的电池，其中，所述电解液的常温电导率为6.0mS/cm～9.0mS/cm。
  8. 根据权利要求1-7任一项所述的电池，其中，所述导电层的材料为铝，所述导电层的厚度为500nm≤D2≤1.5μm；和/或，
    所述保护层的材料为氧化镍或氧化铝，并设置在所述导电层的相对的两个表面上。
  9. 根据权利要求8所述的电池，其中，设置于所述导电层的背离所述绝缘层的一面上的保护层的厚度大于设置于所述导电层的朝向所述绝缘层的一面上的保护层。
  10. 根据权利要求1-9任一项所述的电池，其中，所述绝缘层的厚度为D1，D1满足：1μm≤D1≤20μm，优选为2μm≤D1≤10μm，更优选为2μm≤D1≤6μm；
    优选的，所述绝缘层为有机聚合物绝缘材料，优选聚酰胺、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、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、聚偏氟乙烯、硅橡胶、聚碳酸酯中的至少一种。
  11. 根据权利要求1-10任一项所述的电池，其中，所述负极集流体优选为厚度2.0μm～5.9μm的铜箔集流体，优选为厚度3.0μm～5.9μm的铜箔集流体，更优选为厚度4.5μm～5.9μm的铜箔集流体，和/或，
    所述铜箔集流体的断裂伸长率大于等于1％，进一步地所述铜箔集流体的断裂伸长率大于等于2％，更进一步地所述铜箔集流体的断裂伸长率大于等于3％，优选的，所述铜箔集流体的MD方向和TD方向的断裂伸长率大于等于1％，进一步地大于等于2％，更进一步地大于等于3％。
  12. 根据权利要求1-11任一项所述的电池，其中，所述负极极片过流能力为：单片宽度为50mm的所述负极极片，10A熔断时间大于等于10秒。
  13. 一种装置，其特征在于，包括权利要求1-12任一项所述的电池，所述电池用作所述装置的电源；
    优选的，所述装置包括移动设备、电动车辆、电气列车、卫星、船舶及储能***。
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