WO2021000545A1 - 正极集流体、正极极片、电化学装置及装置 - Google Patents

正极集流体、正极极片、电化学装置及装置 Download PDF

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WO2021000545A1
WO2021000545A1 PCT/CN2019/129349 CN2019129349W WO2021000545A1 WO 2021000545 A1 WO2021000545 A1 WO 2021000545A1 CN 2019129349 W CN2019129349 W CN 2019129349W WO 2021000545 A1 WO2021000545 A1 WO 2021000545A1
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current collector
positive electrode
layer
electrode current
conductive layer
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PCT/CN2019/129349
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English (en)
French (fr)
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梁成都
黄起森
王铈汶
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宁德时代新能源科技股份有限公司
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Priority to EP19933211.5A priority Critical patent/EP3799170B1/en
Priority to US17/132,173 priority patent/US11621425B2/en
Publication of WO2021000545A1 publication Critical patent/WO2021000545A1/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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H01M4/662—Alloys
    • 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
    • H01M4/664—Ceramic materials
    • 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
    • H01M4/668—Composites of electroconductive material and synthetic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • Lithium-ion secondary 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 secondary batteries are prone to short circuits in the battery when they are subjected to abnormal conditions such as nail penetration. At this time, the battery generates a large current and is accompanied by a large amount of short circuit heat generation, which may easily cause the battery to smoke, catch fire, or even explode. Security risks.
  • a diaphragm with high puncture resistance is used to avoid internal short circuits in the battery, or by means of selecting electrolytes and active materials with high thermal stability, and installing heat dissipation devices to reduce the harm of short circuits in the battery.
  • the existing technology cannot effectively control the internal short circuit and short-circuit heat generation of the battery, and the safety of the battery cannot meet the higher and higher requirements in the market.
  • the embodiments of the present application provide a positive electrode current collector, a positive pole piece, an electrochemical device and a device, aiming to make the positive electrode current collector have high nail penetration safety performance and have good electrical performance, so that the electrochemical device and The device has high safety performance and good electrochemical performance.
  • the first aspect of the embodiments of the present application provides a positive electrode current collector.
  • the positive electrode current collector includes: a support layer having two opposite surfaces in its thickness direction; and a conductive layer provided on at least one of the two surfaces of the support layer
  • the material of the conductive layer is aluminum or aluminum alloy
  • the thickness D 1 of the conductive layer is 300nm ⁇ D 1 ⁇ 2 ⁇ m, preferably 500nm ⁇ D 1 ⁇ 2 ⁇ m, more preferably 600nm ⁇ D 1 ⁇ 1.5 ⁇ m
  • the elongation at break B of the layer satisfies 10000% ⁇ B ⁇ 12%, more preferably 400% ⁇ B ⁇ 15%, more preferably 400% ⁇ B ⁇ 30%
  • the volume resistivity of the support layer is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m
  • the sheet resistance growth rate T 1 of the conductive layer is T 1 ⁇ 10%, preferably T 1 ⁇ 5%, preferably T 1 ⁇ 2%, More preferably, T 1
  • a second aspect of the embodiments of the present application provides a positive pole piece.
  • the positive pole piece includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode current collector is the positive electrode according to the first aspect of the embodiments of the present application Current collector.
  • a third aspect of the embodiments of the present application provides an electrochemical device.
  • the electrochemical device includes 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 second aspect of the embodiments of the present application .
  • the fourth aspect of the embodiments of the present application provides a device, which includes the electrochemical device of the third aspect of the embodiments of the present application.
  • the thickness of the conductive layer is small, and the elongation at break of the support layer is 12% to 10000%, and the volume resistivity of the support layer is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m. Therefore, penetration occurs in the electrochemical device.
  • the burrs generated by the conductive layer are greatly reduced compared with the traditional metal current collectors, but also the burrs generated by the support layer with a larger volume resistivity can wrap the metal burrs generated by the conductive layer, thereby causing the electrochemical device to generate internal It has a larger short-circuit resistance when short-circuited, reducing short-circuit current and reducing short-circuit heat generation.
  • the local conductive network is cut off, which can prevent the electrochemical device from being short-circuited in a large area or even the entire electrochemical device. This can limit the damage to the electrochemical device caused by nail piercing and the like to the piercing site, only forming a "point disconnection" without affecting the normal operation of the electrochemical device within a certain period of time. Therefore, the use of the positive electrode current collector of the embodiment of the present application enables the electrochemical device to have a higher nail penetration safety performance.
  • the sheet resistance growth rate of the conductive layer is 10% or less.
  • the resistance of the conductive layer caused by the tensile deformation can be prevented.
  • the enlargement ensures that the positive electrode current collector has good conductivity and current collection performance, so that the electrochemical device has low impedance and small polarization, so that the electrochemical device has both higher electrochemical performance.
  • the device of the present application includes the electrochemical device described in the third aspect of the present application, and thus has at least the same advantages as the electrochemical device.
  • the sheet resistance growth rate of the conductive layer is more than 50%, which can better ensure that the electrochemical device according to the present application has good nail penetration safety performance.
  • Fig. 1 shows a schematic structural diagram of a positive electrode current collector provided by an embodiment of the present application.
  • Fig. 2 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 3 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 4 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • Fig. 5 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 6 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 7 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 8 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 9 shows a schematic structural diagram of a positive electrode current collector provided by another embodiment of the present application.
  • FIG. 11 shows a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 12 shows a schematic diagram of an embodiment of the battery pack of the present application.
  • Fig. 13 is an exploded view of Fig. 12.
  • FIG. 14 shows a schematic diagram of an embodiment of the electrochemical device of the present application as a power source device.
  • the first aspect of the embodiments of the present application provides a cathode current collector 10. 1 and 2, the positive electrode current collector 10 includes a supporting layer 101 and a conductive layer 102 that are stacked.
  • the supporting layer 101 has a first surface 101 a and a second surface 101 b opposite in its thickness direction, and the conductive layer 102 is disposed on either or both of the first surface 101 a and the second surface 101 b of the supporting layer 101.
  • the material of the conductive layer is aluminum or aluminum alloy
  • the thickness D 1 of the conductive layer is 300 nm ⁇ D 1 ⁇ 2 ⁇ m
  • the breaking elongation B of the support layer is 10000% ⁇ B ⁇ 12 %
  • the volume resistivity of the support layer is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m
  • the sheet resistance growth rate T 1 of the conductive layer is T 1 ⁇ 10%.
  • a conductive layer 102 (aluminum layer or aluminum alloy layer) with a smaller thickness is disposed on at least one surface of the support layer 101.
  • the traditional metal cathode current collector such as aluminum foil
  • the thickness of the conductive layer 102 is small, and the elongation at break B of the support layer 101 is 10000% ⁇ B ⁇ 12%, and the volume resistivity of the support layer 101 is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m, therefore,
  • an abnormal situation such as nail penetration occurs in an electrochemical device
  • the burr generated by the support layer 101 with a larger volume resistivity can wrap the burr generated by the conductive layer 102.
  • Metal burrs which make the electrochemical device have a larger short-circuit resistance when an internal short-circuit occurs, reduce short-circuit current and reduce short-circuit heat generation.
  • the positive current collector 10 is sometimes stretched during the processing and use of the positive pole piece and electrochemical device, such as during rolling or battery expansion, so that the tensile strain of the positive current collector 10 is 2%.
  • sheet resistance of the conductive layer 102 growth rate T 1 of 10% or less can effectively prevent the rapid increase in resistance of the conductive layer 102 caused by the deformation by stretching, the positive electrode collector 10 to ensure good performance and conductivity of the current collector, so that the electrical
  • the chemical device has low impedance and small polarization, so that the electrochemical device has both higher electrochemical performance, and the electrochemical device has both higher rate performance and cycle performance.
  • the thickness D 1 of the conductive layer 102 may be 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, or 2 ⁇ m.
  • the range of the thickness D 1 of the conductive layer 102 can be composed of any two values mentioned above.
  • D 1 is 500 nm ⁇ D 1 ⁇ 2 ⁇ m. More preferably, 600nm ⁇ D 1 ⁇ 1.5 ⁇ m.
  • the thickness of the conductive layer 102 is 2 ⁇ m or less, preferably 1.5 ⁇ m or less, which has a significantly reduced thickness, which is beneficial to improve the nail penetration safety and weight energy density of the electrochemical device.
  • the thickness of the conductive layer 102 is 300 nm or more, preferably 500 nm or more, and more preferably 600 nm or more, which is beneficial to make the positive electrode current collector 10 have good electrical conductivity and current collecting performance, and conduct electricity during the processing and use of the positive electrode current collector 10
  • the layer 102 is not easy to be damaged, so that the positive electrode current collector 10 has good mechanical stability and a long service life.
  • the elongation at break B of the support layer 101 may be 12%, 15%, 20%, 30%, 70%, 100%, 200%, 300%, 400%, 800%, 1000%, 3000%, 5000%, 8000% or 10000%.
  • the range of the breaking elongation B of the support layer 101 can be composed of any two of the aforementioned values. Preferably, 400% ⁇ B ⁇ 15%. More preferably, 400% ⁇ B ⁇ 30%.
  • the breaking elongation B of the support layer 101 is 12% or more, preferably 15% or more, and more preferably 30% or more.
  • the burrs of the support layer 101 can effectively cover Covering the burrs of the conductive layer 102 improves the nail penetration safety performance of the electrochemical device.
  • the ductility of the support layer 101 is significantly greater than the ductility of the conductive layer 102, and the conductive layer 102 can be forced to stretch when an abnormal situation such as nail penetration occurs in the electrochemical device, so as to better cut off the local conductive network. , So as to better limit the damage of the electrochemical device caused by nail piercing to the piercing site, only forming a "point open circuit", without affecting the normal operation of the electrochemical device within a certain period of time.
  • the breaking elongation B of the support layer 101 is 10000% or less, preferably 400% or less, which is beneficial for the support layer 101 to have a good support and protection effect on the conductive layer 102 and to ensure the overall strength of the positive electrode current collector 10.
  • the sheet resistance increase rate T 1 of the conductive layer 102 may be 10%, 9%, 8%, 7%, 6%, 5 %, 4%, 3%, 2%, 1% or 0.
  • T 1 ⁇ 5% More preferably, T 1 ⁇ 2%. More preferably, T 1 ⁇ 1%.
  • the sheet resistance growth rate T 2 of the conductive layer 102 is preferably T 2 ⁇ 50%, which can further improve the nail penetration safety performance of the electrochemical device.
  • the sheet resistance growth rate T 2 of the conductive layer 102 may be 50%, 60%, 70%, 80%, 90%, 100%, 120%, 150%, 200%, 300%, 400%, 500% or 700%.
  • the thickness D 2 of the support layer 101 is preferably 1 ⁇ m ⁇ D 2 ⁇ 20 ⁇ m, such as 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m.
  • the range of the thickness D 2 of the support layer 101 can be composed of any two values mentioned above.
  • D 2 is 2 ⁇ m ⁇ D 2 ⁇ 10 ⁇ m. More preferably, D 2 is 2 ⁇ m ⁇ D 2 ⁇ 6 ⁇ m.
  • the Young's modulus E of the support layer 101 is preferably E ⁇ 1.9 GPa.
  • the supporting layer 101 has appropriate rigidity, which satisfies the supporting function of the supporting layer 101 to the conductive layer 102 and ensures the overall strength of the positive electrode current collector 10.
  • the support layer 101 will not be excessively stretched or deformed, which can prevent the support layer 101 from being broken, and is beneficial to improve the firmness of the bonding between the support layer 101 and the conductive layer 102. It is not easy to detach, which ensures that the positive electrode current collector 10 has high mechanical stability and working stability, so that the electrochemical device has high electrochemical performance, such as a long cycle life.
  • the Young’s modulus E of the support layer 101 is more preferably 4GPa ⁇ E ⁇ 20GPa, so that the support layer 101 has rigidity but also has a certain ability to withstand deformation, and can be wound during the processing and use of the positive electrode current collector 10 The flexibility can better prevent breakage.
  • the Young's modulus E of the support layer 101 may be 1.9GPa, 2.2GPa, 2.5GPa, 4GPa, 5GPa, 6GPa, 7GPa, 8GPa, 9GPa, 10GPa, 11GPa, 12GPa, 13GPa, 14GPa , 15GPa, 16GPa, 17GPa, 18GPa, 19GPa or 20GPa.
  • the range of the Young's modulus E of the support layer 101 can be composed of any two of the aforementioned values.
  • the support layer 101 adopts one or more of polymer materials and polymer-based composite materials. Since the density of the polymer material and the polymer-based composite material is relatively small compared to that of metal, the weight of the positive electrode current collector 10 is significantly reduced compared with the traditional metal current collector, and the weight energy density of the electrochemical device is improved.
  • PA polyamide
  • PI polyimide
  • polyesters polyolefins
  • polyacetylenes polyacetylenes
  • siloxane polymers polyethers
  • polyols polysulfones
  • polysaccharide polymers amino acid polymers
  • polysulfur nitrides polysulfur nitrides
  • aromatic ring polymers aromatic heterocyclic polymers
  • epoxy resins phenolic resins, their derivatives, their cross-linked products and One or more of their copolymers.
  • the polymer material is, for example, polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polyisophthalamide Phenylenediamine (PMIA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycarbonate (PC ), polyethylene (PE), polypropylene (PP), polypropylene (PPE), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyvinyl Tetrafluoroethylene (PTEE), polystyrene sulfonate (PSS), polyacetylene, polypyrrole (PPy), polyaniline (PAN), polythiophene (PT), polypyridine (PPY), silicone rubber (Silicone rubber) ,
  • the above-mentioned polymer-based composite material for example, the above-mentioned polymer material and additives may be included.
  • Additives can adjust the volume resistivity, elongation at break, and Young's modulus of polymer materials.
  • the aforementioned additives may be one or more of metallic materials and inorganic non-metallic materials.
  • the metal material additives are, for example, one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, iron, iron alloy, silver, and silver alloy.
  • the inorganic non-metallic material additives are, for example, one or more of carbon-based materials, alumina, silicon dioxide, silicon nitride, silicon carbide, boron nitride, silicate, and titanium oxide, and for example, glass materials, ceramics One or more of materials and ceramic composite materials.
  • the carbon-based material is, for example, one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the aforementioned additives may also be carbon-based materials coated with metal materials, such as one or more of nickel-coated graphite powder and nickel-coated carbon fibers.
  • the support layer 101 adopts polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polystyrene sulfonate One or more of sodium (PSS) and polyimide (PI).
  • the support layer 101 may have a single-layer structure or a composite layer structure of two or more layers, such as two layers, three layers, or four layers.
  • the supporting layer 101 is a composite layer structure formed by stacking a first sublayer 1011, a second sublayer 1012, and a third sublayer 1013.
  • the supporting layer 101 of the composite layer structure has a first surface 101a and a second surface 101b opposite to each other, and the conductive layer 102 is stacked on the first surface 101a and the second surface 101b of the supporting layer 101.
  • the conductive layer 102 may be provided only on the first surface 101a of the support layer 101, or only on the second surface 101b of the support layer 101.
  • the materials of each sublayer may be the same or different.
  • the conductive layer 102 is made of aluminum or aluminum alloy.
  • the weight percentage of the aluminum element in the aluminum alloy is preferably 90 wt% or more.
  • the above-mentioned aluminum alloy may be an aluminum-zirconium alloy.
  • the density of the conductive layer 102 is preferably 2.5g/cm 3 ⁇ 2.8g/cm 3 , such as 2.5g/cm 3 , 2.52g/cm 3 , 2.55g/cm 3 , 2.57g/cm 3 , 2.6g/cm 3 , 2.63g/cm 3 , 2.65g/cm 3 , 2.67g/cm 3 , 2.7g/cm 3 , 2.75g/cm 3 , 2.8g/cm 3, etc.
  • the density of the conductive layer 102 is preferably 2.5 g/cm 3 to 2.8 g/cm 3 , which can better ensure that the positive electrode current collector has good conductivity and current collection performance, so that the electrochemical device has low impedance and low polarization. , Improve the electrochemical performance of electrochemical devices.
  • the volume resistivity of the conductive layer 102 is preferably 2.5 ⁇ 10 -8 ⁇ m to 7.8 ⁇ 10 -8 ⁇ m, and more preferably 3.2 ⁇ 10 -8 ⁇ m to 7.8 ⁇ 10 -8 ⁇ m.
  • the volume resistivity of the conductive layer 102 is preferably 2.5 ⁇ 10 -8 ⁇ m or more, and more preferably 3.2 ⁇ 10 -8 ⁇ m or more. Under abnormal conditions such as nail penetration, the electrochemical device has a large internal short circuit. The short-circuit resistance is conducive to the high safety performance of electrochemical devices.
  • the volume resistivity of the conductive layer 102 is preferably 7.8 ⁇ 10 -8 ⁇ m or less, which is beneficial for the positive electrode current collector 10 to have good electrical conductivity and current collecting performance, so that the electrochemical device has higher electrochemical performance.
  • FIGS. 4 to 9 schematically show a positive electrode current collector 10 respectively.
  • the positive electrode current collector 10 may optionally include a protective layer 103.
  • the conductive layer 102 includes two opposite surfaces in its thickness direction, and the protective layer 103 is stacked on either or both of the two surfaces of the conductive layer 102 to protect the conductive layer 102 and prevent the conductive layer Damages such as chemical corrosion or mechanical damage occur at 102 to ensure the working stability and service life of the positive electrode current collector 10, which is beneficial to the safety performance and electrochemical performance of the electrochemical device.
  • the protective layer 103 can also enhance the mechanical strength of the positive electrode current collector 10.
  • the material of the protective layer 103 may be one or more of metal, metal oxide, and conductive carbon.
  • the aforementioned metals are, for example, one or more of nickel, chromium, nickel-based alloys, and copper-based alloys.
  • the aforementioned nickel-based alloy is an alloy formed by adding one or more other elements to pure nickel as a matrix, preferably a nickel-chromium alloy.
  • the nickel-chromium alloy is an alloy formed of metallic nickel and metallic chromium.
  • the weight ratio of nickel to chromium in the nickel-chromium alloy is 1:99 to 99:1, such as 9:1.
  • the aforementioned copper-based alloy is an alloy formed by adding one or more other elements to pure copper as a matrix, preferably a nickel-copper alloy.
  • the weight ratio of nickel to copper in the nickel-copper alloy is 1:99-99:1, such as 9:1.
  • the aforementioned metal oxide is, for example, one or more of alumina, cobalt oxide, chromium oxide, and nickel oxide.
  • the conductive carbon is, for example, one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, preferably carbon black, carbon nanotubes , One or more of acetylene black and graphene.
  • the positive electrode current collector 10 includes a supporting layer 101, a conductive layer 102, and a protective layer 103 that are stacked.
  • the support layer 101 has a first surface 101a and a second surface 101b opposite in the thickness direction
  • the conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101 to protect
  • the layer 103 is stacked on the surface of the conductive layer 102 facing away from the support layer 101.
  • a protective layer 103 (referred to as the upper protective layer for short) is provided on the surface of the conductive layer 102 facing away from the support layer 101 to protect the conductive layer 102 from chemical corrosion and mechanical damage, and can also improve the positive electrode current collector 10 and The interface between the positive electrode active material layers improves the binding force between the positive electrode current collector 10 and the positive electrode active material layer, and improves the performance of the electrochemical device.
  • the upper protective layer is preferably a metal oxide protective layer, such as aluminum oxide, cobalt oxide, nickel oxide, chromium oxide, etc.
  • the metal oxide protective layer has high hardness and mechanical strength, a larger specific surface area, and better corrosion resistance. , It can better protect the conductive layer 102, enhance the binding force between the positive electrode current collector 10 and the positive electrode active material layer, and also help increase the overall strength of the positive electrode current collector 10; in addition, it is also beneficial to improve the penetration of electrochemical devices. Nail safety performance.
  • the positive electrode current collector 10 includes a supporting layer 101, a conductive layer 102 and a protective layer 103 that are stacked.
  • the support layer 101 has a first surface 101a and a second surface 101b opposite in the thickness direction
  • the conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101 to protect
  • the layer 103 is stacked on the surface of the conductive layer 102 facing the support layer 101.
  • a protective layer 103 (referred to as a lower protective layer for short) is provided on the surface of the conductive layer 102 facing the support layer 101.
  • the lower protective layer protects the conductive layer 102 from chemical corrosion and mechanical damage, and can also improve the conductivity.
  • the bonding force between the layer 102 and the support layer 101 prevents the conductive layer 102 from being separated from the support layer 101, and improves the support and protection effect of the support layer 101 on the conductive layer 102.
  • the lower protective layer is preferably a metal oxide protective layer, such as aluminum oxide, cobalt oxide, nickel oxide, chromium oxide, etc., which can better play the above-mentioned protective function and further improve the gap between the conductive layer 102 and the support layer 101.
  • the binding force is also beneficial to increase the overall strength of the positive electrode current collector 10.
  • the positive electrode current collector 10 includes a supporting layer 101, a conductive layer 102 and a protective layer 103 that are stacked.
  • the support layer 101 has a first surface 101a and a second surface 101b opposite in the thickness direction
  • the conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101 to protect
  • the layer 103 is stacked on the surface of the conductive layer 102 facing away from the support layer 101 and the surface facing the support layer 101.
  • the protective layer 103 is provided on both surfaces of the conductive layer 102, that is, an upper protective layer and a lower protective layer are respectively provided on the two surfaces of the conductive layer 102 to more fully protect the conductive layer 102. Further, the upper protective layer and the lower protective layer are both metal oxide protective layers.
  • the materials of the protective layers 103 on the two surfaces of the conductive layer 102 may be the same or different, and the thicknesses may be the same or different.
  • the thickness D 3 of the protective layer 103 is 1 nm ⁇ D 3 ⁇ 200 nm, and D 3 ⁇ 0.1D 1 .
  • the thickness D 3 of the protective layer 103 is within the above range, which can effectively protect the conductive layer 102 and at the same time enable the electrochemical device to have a higher energy density.
  • the thickness D 3 of the protective layer 103 may be 200 nm, 180 nm, 150 nm, 120 nm, 100 nm, 80 nm, 60 nm, 55 nm, 50 nm, 45 nm, 40 nm, 30 nm, 20 nm, 18 nm, 15 nm, 12 nm, 10 nm, 8 nm, 5 nm, 2 nm, 1 nm, etc.
  • the range of the thickness D 3 of the protective layer 103 can be composed of any two values mentioned above.
  • the protective layer has a thickness D a of 1nm ⁇ D a ⁇ 200nm, and D a ⁇ 0.1D 1
  • the lower protective layer thickness D b is 1nm ⁇ D b ⁇ 200nm
  • D b ⁇ 0.1D 1
  • 103 pairs facilitate the conductive protective layer 102 functions as a good protective effect, while the electrochemical device having high energy density. More preferably, 0.5D a ⁇ D b ⁇ 0.8D a .
  • the bonding force between the support layer 101 and the conductive layer 102 is F ⁇ 100 N/m, more preferably F ⁇ 400 N/m.
  • the conductive layer 102 is formed on the support layer 101 by vapor deposition, and the vapor deposition process conditions, such as the deposition temperature, the deposition rate, and the atmosphere conditions of the deposition chamber, can be adjusted reasonably, so that when the cathode current collector 10 is stretched, The increase rate of the sheet resistance of the conductive layer 102 meets the aforementioned requirements to improve the safety performance and electrochemical performance of the positive electrode current collector 10.
  • the above-mentioned vapor deposition method is preferably a physical vapor deposition method (Physical Vapor Deposition, PVD).
  • the physical vapor deposition method is preferably at least one of an evaporation method and a sputtering method; the evaporation method is preferably at least one of a vacuum evaporation method, a thermal evaporation method, and an electron beam evaporation method, and the sputtering method is preferably a magnetron sputtering method.
  • forming the conductive layer 102 by a vacuum evaporation method includes: placing the support layer 101 with a surface cleaning treatment in a vacuum coating chamber, and melting and evaporating the high-purity metal wire in the metal evaporation chamber at a high temperature of 1300°C to 2000°C , The evaporated metal passes through the cooling system in the vacuum coating chamber, and is finally deposited on the support layer 101 to form the conductive layer 102.
  • the process of forming the conductive layer 102 by mechanical rolling may include: placing an aluminum sheet or aluminum alloy sheet in a mechanical roller, rolling it to a predetermined thickness by applying a pressure of 20t to 40t, and then placing it after surface cleaning. After treating the surface of the support layer 101, the two are placed in a mechanical roller, and the two are tightly combined by applying a pressure of 30t-50t.
  • the process of forming the conductive layer 102 by bonding may include: placing an aluminum sheet or aluminum alloy sheet in a mechanical roller, and rolling it to a predetermined thickness by applying a pressure of 20t to 40t; and then applying a surface cleaning treatment to the support layer
  • the surface of 101 is coated with a mixed solution of polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP); finally, the conductive layer 102 with the predetermined thickness is bonded to the surface of the support layer 101 and dried to make both Closely integrated.
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the protective layer 103 may be formed on the conductive layer 102 by at least one of a vapor deposition method, an in-situ formation method, and a coating method.
  • the vapor deposition method may be the vapor deposition method as described above.
  • the in-situ formation method is preferably an in-situ passivation method, such as a method of forming a metal oxide passivation layer in situ on the metal surface.
  • the coating method is preferably at least one of roll coating, extrusion coating, knife coating, and gravure coating.
  • the protective layer 103 is formed on the conductive layer 102 by at least one of a vapor deposition method and an in-situ formation method, which is conducive to making the conductive layer 102 and the protective layer 103 have a higher bonding force, which is better.
  • the protective layer 102 protects the positive electrode current collector 10 and ensures that the positive electrode current collector 10 has high working performance.
  • the method of using the four-probe method to test the sheet resistance of the conductive layer is as follows: Using the RTS-9 double-electric four-probe tester, the test environment is: normal temperature 23 ⁇ 2°C, 0.1MPa, relative humidity ⁇ 65%. During the test, clean the surface of the sample to be tested, then place it horizontally on the test bench, put down the four probes to make good contact with the surface of the conductive layer, and then adjust the automatic test mode to calibrate the current range of the sample to a suitable current Measure the sheet resistance under the range, and collect 8 to 10 data points of the same sample as the data measurement accuracy and error analysis. Finally, the average value is recorded as the sheet resistance value of the conductive layer.
  • the breaking elongation B of the support layer can be measured by a method known in the art.
  • the test method is as follows: Place the wafer sample between two electrodes, and apply a potential difference between the two electrodes, the current generated will be distributed in the body of the wafer sample and measured by a picoammeter or electrometer , In order to avoid the measurement error caused by including the surface leakage current in the measurement.
  • the reading is the volume resistivity in ⁇ m.
  • the Young's modulus E of the support layer can be measured using methods known in the art. As an example, take the support layer and cut it into a sample of 15mm ⁇ 200mm, measure the thickness of the sample l ( ⁇ m) with a micrometer, and use a high-speed rail tensile machine to perform a tensile test under normal temperature and pressure (25°C, 0.1MPa).
  • the bonding force F between the support layer and the conductive layer can be tested by methods known in the art.
  • the positive current collector sample to be tested with the conductive layer arranged on one side of the support layer is selected, and the width h is 0.02m, and it is at room temperature and pressure ( At 25°C, 0.1MPa), use 3M double-sided tape to evenly paste on the stainless steel plate, then evenly paste the sample to be tested on the double-sided tape, and use a high-speed rail tension machine to peel off the conductive layer and support layer of the sample to be tested.
  • a second aspect of the embodiments of the present application provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode active material layer that are stacked, wherein the positive electrode current collector is the positive electrode current collector 10 of the first aspect of the embodiments of the present application.
  • the positive electrode active material used in lithium ion secondary batteries can be lithium transition metal composite oxides, where the transition metals can be Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg One or more of.
  • the lithium transition metal composite oxide can also be doped with elements with high electronegativity, such as one or more of S, F, Cl and I, which can make the positive electrode active material have higher structural stability and electrochemical performance .
  • the lithium transition metal composite oxide is, for example, LiMn 2 O 4 , LiNiO 2 , LiCoO 2 , LiNi 1-y Co y O 2 (0 ⁇ y ⁇ 1), LiNi a Co b Al 1-ab O 2 (0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ a+b ⁇ 1), LiMn 1-mn Ni m Co n O 2 (0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇ m+n ⁇ 1 ), LiMPO 4 (M can be one or more of Fe, Mn, and Co), and Li 3 V 2 (PO 4 ) 3 at one or more.
  • LiMn 2 O 4 LiNiO 2 , LiCoO 2 , LiNi 1-y Co y O 2 (0 ⁇ y ⁇ 1), LiNi a Co b Al 1-ab O 2 (0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ a+b ⁇ 1), LiMn 1-mn Ni m Co n O 2 (0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇
  • the positive electrode active material layer may further include a conductive agent.
  • the conductive agent is one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive active material layer may further include a binder.
  • the binder is styrene butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE)
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the positive pole piece can be prepared according to conventional methods in the art. Usually, the positive electrode active material, optional conductive agent, and binder are dispersed in a solvent (such as N-methylpyrrolidone, referred to as NMP) to form a uniform positive electrode slurry, and the positive electrode slurry is coated on the positive electrode current collector After drying and other processes, the positive pole piece is obtained.
  • a solvent such as N-methylpyrrolidone, referred to as NMP
  • a third aspect of the embodiments of the present application provides an electrochemical device.
  • the electrochemical device includes a positive pole piece, a negative pole piece, a separator and an electrolyte, wherein the positive pole piece is the positive pole piece of the second aspect of the embodiments of the present invention.
  • the electrochemical device described above may be a lithium ion secondary battery, a lithium primary battery, a sodium ion battery, a magnesium ion battery, etc., but is not limited thereto.
  • the electrochemical device adopts the positive pole piece provided according to the second aspect of the embodiment of the present application
  • the electrochemical device of the embodiment of the present application has a higher weight energy density and good nail penetration safety performance and electrochemical performance.
  • the aforementioned negative pole piece may include a negative current collector and a negative active material layer.
  • the negative electrode active material layer may use a negative electrode active material known in the art, which can perform reversible intercalation/deintercalation of ions.
  • the negative electrode active material used in lithium ion secondary batteries can be metallic lithium, natural graphite, artificial graphite, mesophase micro-carbon spheres (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO One or more of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithium titanate and Li-Al alloy.
  • MCMB mesophase micro-carbon spheres
  • the negative active material layer may further include a binder.
  • the binder is styrene butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE)
  • SBR styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PVA polyvinyl alcohol
  • PVB polyvinyl butyral
  • the negative active material layer may further include a conductive agent.
  • the conductive agent is one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative pole piece can be prepared according to conventional methods in the art. Generally, the negative electrode active material and optional conductive agent and binder are dispersed in a solvent.
  • the solvent can be NMP or deionized water to form a uniform negative electrode slurry.
  • the negative electrode slurry is coated on the negative electrode current collector and dried After the drying process, the negative pole piece is obtained.
  • isolation membrane there is no particular limitation on the above-mentioned isolation membrane, and any well-known porous structure isolation membrane with electrochemical and chemical stability can be selected, for example, glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride One or more of the single-layer or multi-layer films.
  • the above-mentioned electrolyte includes an organic solvent and an electrolyte salt.
  • organic solvent as a medium for transporting ions in an electrochemical reaction, organic solvents known in the art for electrochemical device electrolytes can be used.
  • the electrolyte salt may be an electrolyte salt used in the electrolyte of an electrochemical device known in the art.
  • the organic solvent used in lithium ion secondary batteries can be ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC) ), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), Methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate ( MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulf
  • the electrolyte salt used in lithium ion secondary batteries can be LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI ( Lithium bisfluorosulfonimide), LiTFSI (lithium bis(trifluoromethanesulfonimide)), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate), LiBOB (lithium bisoxalate), LiPO 2 F 2 (lithium difluorophosphate), LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate) one or more.
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • the electrode assembly is placed in a packaging shell, electrolyte is injected and sealed to prepare an electrochemical device.
  • 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. 10 shows 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. 11 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.
  • Figures 12 and 13 show the battery pack 1 as an example.
  • 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 fourth aspect of the embodiments of the present application provides a device, and the device includes the electrochemical device of the third aspect of the embodiments of the present application.
  • the electrochemical device can be used as a power source of the device, and can also be used as an energy storage unit of the device.
  • the device includes, 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 an electrochemical device, a battery module or a battery pack according to its usage requirements.
  • Figure 14 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.
  • a support layer of a predetermined thickness Place the support layer after surface cleaning treatment in a vacuum coating chamber, and melt and evaporate the high-purity aluminum wire in the metal evaporation chamber at a high temperature of 1300°C ⁇ 2000°C. After the cooling system in the vacuum coating chamber, it is finally deposited on the two surfaces of the support layer to form a conductive layer.
  • the cathode current collector By adjusting material, thickness, density, preparation conditions of the conductive layer (e.g., the degree of vacuum, atmosphere, humidity, temperature, etc.), and adjusting the support layer material, thickness, etc., so that the cathode current collector having a different T 1 of the value and the T 2 value.
  • material, thickness, density, preparation conditions of the conductive layer e.g., the degree of vacuum, atmosphere, humidity, temperature, etc.
  • preparation conditions of the conductive layer e.g., the degree of vacuum, atmosphere, humidity, temperature, etc.
  • the positive electrode active material LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), conductive carbon black, and binder polyvinylidene fluoride (PVDF) are added to an appropriate amount of N in a weight ratio of 93:2:5.
  • -Methylpyrrolidone (NMP) solvent is fully stirred and mixed to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and the positive electrode pieces are obtained after drying and other processes.
  • Aluminum foil with a thickness of 12 ⁇ m.
  • the negative active material graphite, conductive carbon black, thickener sodium carboxymethyl cellulose (CMC), and binder styrene butadiene rubber emulsion (SBR) are placed in an appropriate amount of deionized water at a weight ratio of 96.5:1.0:1.0:1.5 Stir and mix thoroughly to form a uniform negative electrode slurry; coat the negative electrode slurry on the negative electrode current collector, and after drying and other processes, a negative electrode piece is obtained.
  • Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7 are uniformly mixed to obtain an organic solvent, and then 1 mol/L LiPF 6 is uniformly dissolved in the above organic solvent.
  • the positive pole piece, the separator (PP/PE/PP composite film), and the negative pole piece are stacked in sequence, and then wound into an electrode assembly and packed into a packaging shell.
  • the above-mentioned electrolyte is injected into the electrode assembly, after sealing, Steps such as standing, hot and cold pressing, and chemical conversion to obtain a lithium ion secondary battery.
  • Capacity retention rate of lithium ion secondary battery after 1000 cycles at 45°C and 1C/1C (%) discharge capacity at the 1000th cycle/discharge capacity at the first cycle ⁇ 100%
  • 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 nailing is completed, perform a five-minute battery temperature tracking test, and then Record the battery temperature at five minutes to get the battery temperature rise.
  • 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 voltage at five minutes.
  • the positive electrode current collector of the embodiment of the present application can greatly improve the nail penetration safety performance of the battery. From the data in Table 2, we can see that for batteries using conventional positive current collectors, or the support layer of the positive current collector, the elongation at break is less than 12%. At the moment of nail penetration, the battery temperature rises by 500°C and the voltage drops sharply. Zero, which means that at the moment of nail penetration, the battery has an internal short circuit, which generates a lot of heat, and the battery loses its effect due to thermal runaway and destruction in an instant. In the cathode current collector of the embodiment of the application, the thickness D 1 of the conductive layer, the elongation at break B and the volume resistivity of the support layer are all within a specific range. In the nail penetration test, the battery temperature rise can be controlled within Below 35°C, further below 25°C, even further below 10°C, and the battery voltage remains basically stable, the battery can work normally.
  • the positive current collector 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 the short circuit damage on the battery can also be limited to "points" The range only forms a "point open circuit” without affecting the normal operation of the battery for a period of time.
  • the aluminum alloy is aluminum alloy 7049 (aluminum-zinc alloy, Fincola, USA).
  • the positive electrode current collector in Table 3 was subjected to an overcurrent test.
  • the positive electrode current collector was cut into a width of 100mm, and a positive electrode active material layer of 80mm width was coated at the center of the width direction and rolled into a positive pole piece.
  • the latter pole piece is cut into strips of 100mm ⁇ 30mm along the width direction, and 10 pieces of each pole piece are cut.
  • connect the non-coated conductive areas on both sides of the pole piece sample to the positive and negative terminals of the charging and discharging machine, and then set up the charging and discharging machine to pass 1A current through the pole pieces, and keep the pole pieces without fuse for 10 seconds. , Otherwise it is regarded as not passed.
  • Table 4 Each set of samples tested 10, and the overcurrent test results are shown in Table 4 below.
  • the sheet resistance growth rate T 1 of the conductive layer is not more than 10%.
  • the positive electrode sheet using the positive electrode current collector can have better conductivity after rolling. . Otherwise, the electrical conductivity is poor, and it is of little practical value in battery products.
  • the sheet resistance growth rate T 2 of the conductive layer is more than 50%, especially more than 100%, and more particularly more than 150%, which may cause internal short circuit in the battery. In this case, it can greatly reduce the short-circuit heat generation and improve the safety performance of the battery; in addition, the impact of short-circuit damage on the battery can be limited to the "point" range, only forming a "point open circuit” without affecting the battery in a certain period of time Works normally.
  • the battery using the positive electrode current collector of the present application has good cycle life, especially the battery made of the positive electrode current collector provided with a protective layer, the capacity retention rate after 1000 cycles at 45°C and 1C/1C is further improved, indicating that the battery The reliability is better.
  • the weight percentage of the positive electrode current collector refers to the percentage of the weight of the positive electrode current collector per unit area divided by the weight of the conventional positive electrode current collector per unit area.
  • the weight of the anode current collector of the present application can be reduced to varying degrees, thereby increasing the weight energy density of the battery.

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Abstract

一种正极集流体（10）、正极极片、电化学装置（5）及装置，正极集流体（10）包括支撑层（101）及设置于支撑层（101）上的导电层（102），其中，导电层（102）的材质为铝或铝合金，导电层（102）的厚度D1为300nm≤D1≤2μm；支撑层（101）的断裂伸长率B为10000％≥B≥12％；支撑层（101）的体积电阻率大于或等于1.0×10 -5Ω•m；正极集流体（10）的拉伸应变为2％时，导电层（102）的方块电阻增长率T1为T1≤10％。正极集流体（10）能够同时兼顾较高的安全性能及电性能，从而能够使采用其的正极极片、电化学装置（5）及装置同时兼顾较高的安全性能及电化学性能。

Description

正极集流体、正极极片、电化学装置及装置 技术领域
本申请属于电化学装置技术领域，尤其涉及一种正极集流体、正极极片、电化学装置及装置。
背景技术
锂离子二次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，锂离子二次电池受到穿钉等异常情况时容易造成电池内短路，此时电池产生大电流并伴随着大量的短路产热，容易引起电池冒烟、着火、甚至爆炸，具有较大的安全隐患。
现有技术中采用抗穿刺强度高的隔膜来避免电池发生内短路，或者通过选择热稳定性高的电解液和活性材料、设置散热装置等手段来降低电池内短路的危害性。但是现有技术不能有效控制电池的内短路及短路产热，电池的安全性不能满足市场上越来越高的要求。
基于此，提出本申请。
发明内容
本申请实施例提供一种正极集流体、正极极片、电化学装置及装置，旨在使正极集流体具有较高的穿钉安全性能，且兼具良好的电性能，以使得电化学装置及装置具有较高的安全性能以及良好的电化学性能。
本申请实施例的第一方面提供一种正极集流体，正极集流体包括：支撑层，在自身厚度方向上具有相对的两个表面；导电层，设置于支撑层的两个表面中的至少一者上；其中，导电层的材质为铝或铝合金，导电层的厚度D 1为300nm≤D 1≤2μm，优选为500nm≤D 1≤2μm，更优选为600nm≤D 1≤1.5μm；支撑层的断裂伸长率B满足10000％≥B≥12％，进一步优选为400％≥B≥15％，更优选为400％≥B≥30％；支撑层的体积电阻率大于或等于1.0×10 -5Ω·m；正极集流体的拉伸应变为2％时，导电层的方块电阻增长率T 1为T 1≤10％，优选为T 1≤5％，优选为T 1≤2％，更优选为T 1≤1％。
本申请实施例的第二方面提供一种正极极片，正极极片包括正极集流体以及设置于正极集流体上的正极活性材料层，其中正极集流体为如本申请实施例第一方面的正极集流体。
本申请实施例的第三方面提供一种电化学装置，电化学装置包括正极极片、负极极片、隔离膜和电解液，其中正极极片为如本申请实施例第二方面的正极极片。
本申请实施例的第四方面提供一种装置，所述装置包括本申请实施例第三方面的 电化学装置。
本申请实施例提供的正极集流体，将厚度较小的导电层(铝层或铝合金层)设置于支撑层的至少一个表面，相对于传统金属正极集流体(如铝箔)而言，有利于降低集流体的重量，提高电化学装置的重量能量密度。
其次，导电层的厚度较小，且支撑层的断裂伸长率为12％～10000％，且支撑层的体积电阻率大于或等于1.0×10 -5Ω·m，因此在电化学装置发生穿钉等异常情况时，不仅导电层产生的毛刺较传统的金属集流体大幅减小，而且体积电阻率较大的支撑层产生的毛刺可以包裹导电层产生的金属毛刺，从而使得电化学装置发生内短路时具有较大的短路电阻，减小短路电流及减少短路产热。并且在穿钉发生时，局部的导电网络被切断，可以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对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。因此，采用本申请实施例的正极集流体，使得电化学装置具有较高的穿钉安全性能。
此外，正极集流体的拉伸应变为2％时，导电层的方块电阻增长率为10％以下，在极片加工、电池膨胀等过程中，可以防止导电层因拉伸形变而导致的电阻急剧增大，保证正极集流体具有良好的导电和集流的性能，使得电化学装置具有低阻抗、且极化较小，从而使电化学装置兼具较高的电化学性能。
本申请的装置包括本申请第三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。
进一步地，正极集流体的拉伸应变大于等于4％时，导电层的方块电阻增长率为50％以上，能够更好地保证根据本申请的电化学装置具有良好的穿钉安全性能。
进一步的，导电层的密度为2.5g/cm 3～2.8g/cm 3，能够更好地保证正极集流体具有良好的导电和集流的性能，提高电化学装置的电化学性能。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1示出了本申请一个实施例提供的正极集流体的结构示意图。
图2示出了本申请另一个实施例提供的正极集流体的结构示意图。
图3示出了本申请另一个实施例提供的正极集流体的结构示意图。
图4示出了本申请另一个实施例提供的正极集流体的结构示意图。
图5示出了本申请另一个实施例提供的正极集流体的结构示意图。
图6示出了本申请另一个实施例提供的正极集流体的结构示意图。
图7示出了本申请另一个实施例提供的正极集流体的结构示意图。
图8示出了本申请另一个实施例提供的正极集流体的结构示意图。
图9示出了本申请另一个实施例提供的正极集流体的结构示意图。
图10示出了本申请的电化学装置的一实施方式的示意图。
图11示出了本申请的电池模块的一实施方式的示意图。
图12示出了本申请的电池包的一实施方式的示意图。
图13是图12的分解图。
图14示出了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。
标号说明：
10、正极集流体；
101、支撑层；
101a、第一表面；101b、第二表面；
1011、第一子层；1012、第二子层；1013、第三子层；
102、导电层；
103、保护层；
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
为了使本申请的目的、技术方案和有益技术效果更加清晰，以下结合实施例对本申请进行进一步详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或多种”中“多种”的含义是两个以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
正极集流体
本申请实施例的第一方面提供一种正极集流体10。请参照图1和图2，正极集流体10包括层叠设置的支撑层101及导电层102。支撑层101在自身厚度方向上具有相对的第一表面101a和第二表面101b，导电层102设置于支撑层101的第一表面101a 及第二表面101b中的任意一者或者两者上。
本申请实施例的正极集流体10中，导电层的材质为铝或铝合金，导电层的厚度D 1为300nm≤D 1≤2μm；支撑层的断裂伸长率B为10000％≥B≥12％；支撑层的体积电阻率大于或等于1.0×10 -5Ω·m；正极集流体的拉伸应变为2％时，导电层的方块电阻增长率T 1为T 1≤10％。
本申请实施例的正极集流体10，将厚度较小的导电层102(铝层或铝合金层)设置于支撑层101的至少一个表面，相对于传统金属正极集流体(如铝箔)而言，有利于降低正极集流体10的重量，提高电化学装置的重量能量密度。
其次，导电层102的厚度较小，且支撑层101的断裂伸长率B为10000％≥B≥12％，支撑层101的体积电阻率大于或等于1.0×10 -5Ω·m，因此，在电化学装置发生穿钉等异常情况时，不仅导电层102产生的毛刺较传统的金属集流体大幅度减小，而且体积电阻率较大的支撑层101产生的毛刺可以包裹导电层102产生的金属毛刺，从而使得电化学装置发生内短路时具有较大的短路电阻，减小短路电流及减少短路产热。并且在穿钉发生时，局部的导电网络被切断，可以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对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。因此，采用本申请实施例的正极集流体10，使得电化学装置具有较高的穿钉安全性能。
此外，正极集流体10在正极极片及电化学装置的加工及使用过程中，例如辊压或电池膨胀过程中，有时会被拉伸，使正极集流体10的拉伸应变为2％时，导电层102的方块电阻增长率T 1为10％以下，能够有效防止导电层102因拉伸形变而导致的电阻急剧增大，保证正极集流体10具有良好的导电和集流的性能，使得电化学装置具有低阻抗、且极化较小，从而使电化学装置兼具较高的电化学性能，其中电化学装置兼具较高的倍率性能及循环性能。
在一些可选的实施方式中，导电层102的厚度D 1可以为300nm、350nm、400nm、450nm、500nm、600nm、700nm、800nm、900nm、1μm、1.2μm、1.5μm、1.8μm或2μm。导电层102的厚度D 1的范围可由前述任意两个数值组成。优选地，D 1为500nm≤D 1≤2μm。更优选地，600nm≤D 1≤1.5μm。
导电层102的厚度为2μm以下，优选1.5μm以下，其具有显著降低的厚度，有利于改善电化学装置的穿钉安全性能及重量能量密度。导电层102的厚度为300nm以上，优选为500nm以上，更优选为600nm以上，有利于使正极集流体10具有良好的导电和集流的性能，并且在正极集流体10加工及使用过程中，导电层102不易发生破损，使正极集流体10具有良好的机械稳定性及较高的使用寿命。
在一些可选的实施方式中，支撑层101的断裂伸长率B可以为12％、15％、20％、30％、70％、100％、200％、300％、400％、800％、1000％、3000％、5000％、8000％或10000％。支撑层101的断裂伸长率B的范围可由前述任意两个数值组成。优选地，400％≥B≥15％。更优选地，400％≥B≥30％。
进一步地，支撑层101的断裂伸长率B为12％以上，优选为15％以上，更优选为 30％以上，在电化学装置发生穿钉等异常情况时，支撑层101的毛刺能够有效包覆住导电层102的毛刺，提高电化学装置的穿钉安全性能。特别地，此时支撑层101的延展性显著大于导电层102的延展性，可以在电化学装置发生穿钉等异常情况时，导电层102被迫延展，更好地使局部的导电网络被切断，从而更好地将穿钉等造成的电化学装置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101的断裂伸长率B为10000％以下，优选为400％以下，有利于使支撑层101对导电层102具有良好的支撑保护作用，确保正极集流体10的整体强度。
在一些可选的实施方式中，正极集流体10的拉伸应变为2％时，导电层102的方块电阻增长率T 1可以为10％、9％、8％、7％、6％、5％、4％、3％、2％、1％或0。优选地，T 1≤5％。更优选地，T 1≤2％。更优选地，T 1≤1％。
进一步地，正极集流体10的拉伸应变大于等于4％时，导电层102的方块电阻增长率T 2优选为T 2≥50％，能够进一步提高电化学装置的穿钉安全性能。
在一些可选的实施方式中，正极集流体10的拉伸应变大于等于4％时，导电层102的方块电阻增长率T 2可以为50％、60％、70％、80％、90％、100％、120％、150％、200％、300％、400％、500％或700％。优选地，T 2≥100％。更优选地，T 2≥150％。
本申请实施例的正极集流体10，支撑层101的厚度D 2优选为1μm≤D 2≤20μm，例如1μm、1.5μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、10μm、12μm、15μm、18μm、20μm。支撑层101的厚度D 2的范围可由前述任意两个数值组成。优选地，D 2为2μm≤D 2≤10μm。更优选地，D 2为2μm≤D 2≤6μm。
支撑层101的厚度D 2优选为1μm以上，更优选为2μm以上，有利于使支撑层101具有足够的机械强度，在正极集流体10的加工及使用过程中不易发生断裂，对导电层102起到良好的支撑和保护作用，保证正极集流体10良好的机械稳定性及较高的使用寿命。支撑层101的厚度D 2优选为20μm以下，更优选为10μm以下，更优选为6μm以下，有利于使电化学装置具有较小的体积及重量，提高电化学装置的能量密度。
支撑层101的杨氏模量E优选为E≥1.9GPa。支撑层101具有适当的刚性，满足支撑层101对导电层102的支撑作用，确保正极集流体10的整体强度。在正极集流体10的加工过程中，支撑层101不会发生过大的延展或变形，能够防止支撑层101发生断带，并有利于提高支撑层101和导电层102之间结合的牢固度，不易发生脱离，保证正极集流体10具有较高的机械稳定性和工作稳定性，从而使电化学装置具有较高的电化学性能，如较长的循环寿命。
支撑层101的杨氏模量E更优选为4GPa≤E≤20GPa，使得支撑层101具有刚性的同时还具有一定的承受变形的能力，能够在正极集流体10加工及使用过程中具有进行卷绕的柔性，更好地防止发生断带。
在一些可选的实施方式中，支撑层101的杨氏模量E可以为1.9GPa、2.2GPa、2.5GPa、4GPa、5GPa、6GPa、7GPa、8GPa、9GPa、10GPa、11GPa、12GPa、13GPa、14GPa、15GPa、16GPa、17GPa、18GPa、19GPa或20GPa。支撑层101的杨氏模量E的范围可由前述任意两个数值组成。
优选地，支撑层101采用高分子材料及高分子基复合材料中的一种或多种。由于高分子材料和高分子基复合材料的密度相对金属较小，从而较传统的金属集流体明显减轻正极集流体10的重量，提高电化学装置的重量能量密度。
作为上述高分子材料，例如可以是聚酰胺(PA)、聚酰亚胺(PI)、聚酯类、聚烯烃类、聚炔烃类、硅氧烷聚合物、聚醚类、聚醇类、聚砜类、多糖类聚合物、氨基酸类聚合物、聚氮化硫类、芳环聚合物、芳杂环聚合物、环氧树脂、酚醛树脂、它们的衍生物、它们的交联物及它们的共聚物中的一种或多种。
进一步地，高分子材料例如是聚己内酰胺(俗称尼龙6)、聚己二酰己二胺(俗称尼龙66)、聚对苯二甲酰对苯二胺(PPTA)、聚间苯二甲酰间苯二胺(PMIA)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚萘二甲酸乙二醇酯(PEN)、聚碳酸酯(PC)、聚乙烯(PE)、聚丙烯(PP)、聚丙乙烯(PPE)、聚乙烯醇(PVA)、聚苯乙烯(PS)、聚氯乙烯(PVC)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTEE)、聚苯乙烯磺酸钠(PSS)、聚乙炔、聚吡咯(PPy)、聚苯胺(PAN)、聚噻吩(PT)、聚吡啶(PPY)、硅橡胶(Silicone rubber)、聚甲醛(POM)、聚苯、聚苯醚(PPO)、聚苯硫醚(PPS)、聚乙二醇(PEG)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)、纤维素、淀粉、蛋白质、它们的衍生物、它们的交联物及它们的共聚物中的一种或多种。
作为上述高分子基复合材料，例如可以是包括上述的高分子材料和添加剂。通过添加剂能够调整高分子材料的体积电阻率、断裂伸长率及杨氏模量等。前述添加剂可以是金属材料及无机非金属材料中的一种或多种。
金属材料添加剂例如是铝、铝合金、铜、铜合金、镍、镍合金、钛、钛合金、铁、铁合金、银及银合金中的一种或多种。
无机非金属材料添加剂例如是碳基材料、氧化铝、二氧化硅、氮化硅、碳化硅、氮化硼、硅酸盐及氧化钛中的一种或多种，再例如是玻璃材料、陶瓷材料及陶瓷复合材料中的一种或多种。其中碳基材料例如是石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。
在一些实施例中，上述添加剂还可以是金属材料包覆的碳基材料，例如镍包覆的石墨粉及镍包覆的碳纤维中的一种或多种。
优选地，支撑层101采用绝缘高分子材料及绝缘高分子基复合材料中的一种或多种。该支撑层101的体积电阻率较高，能够更好地提高电化学装置的安全性能。
进一步优选地，支撑层101采用聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚萘二甲酸乙二醇酯(PEN)、聚苯乙烯磺酸钠(PSS)及聚酰亚胺(PI)中的一种或多种。
本申请实施例的正极集流体10，支撑层101可以是单层结构，也可以是两层以上的复合层结构，如两层、三层、四层等。
作为复合层结构的支撑层101的一个示例，请参照图3，支撑层101是由第一子层1011、第二子层1012及第三子层1013层叠设置形成的复合层结构。复合层结构的支撑层101具有相对的第一表面101a和第二表面101b，导电层102层叠设置在支撑层 101的第一表面101a和第二表面101b上。当然，导电层102可以是仅设置于支撑层101的第一表面101a上，也可以是仅设置于支撑层101的第二表面101b上。
当支撑层101为两层以上的复合层结构时，各子层的材料可以相同，也可以不同。
本申请实施例的正极集流体10，导电层102的材质为铝或铝合金。上述铝合金中铝元素的重量百分含量优选为90wt％以上。上述铝合金可以为铝锆合金。
导电层102的密度优选为2.5g/cm 3～2.8g/cm 3，如2.5g/cm 3、2.52g/cm 3、2.55g/cm 3、2.57g/cm 3、2.6g/cm 3、2.63g/cm 3、2.65g/cm 3、2.67g/cm 3、2.7g/cm 3、2.75g/cm 3、2.8g/cm 3等。
导电层102的密度优选为2.5g/cm 3～2.8g/cm 3，能够更好地保证正极集流体具有良好的导电和集流的性能，使电化学装置具有低阻抗、且极化较小，提高电化学装置的电化学性能。
导电层102的体积电阻率优选为2.5×10 -8Ω·m～7.8×10 -8Ω·m，更优选为3.2×10 -8Ω·m～7.8×10 -8Ω·m。
导电层102的体积电阻率优选为2.5×10 -8Ω·m以上，更优选为3.2×10 -8Ω·m以上，在穿钉等异常情况下，电化学装置发生内短路时具有较大的短路电阻，有利于使电化学装置具有较高的安全性能。导电层102的体积电阻率优选为7.8×10 -8Ω·m以下，有利于使正极集流体10具有良好的导电和集流的性能，使得电化学装置具有较高的电化学性能。
图4至图9分别示意性地示出了一种正极集流体10，请参照图3至图8，正极集流体10还可选地包括保护层103。具体地，导电层102在自身厚度方向上包括相对的两个表面，保护层103层叠设置于导电层102的两个表面中的任意一者或两者上，以保护导电层102，防止导电层102发生化学腐蚀或机械破坏等损害，保证正极集流体10的工作稳定性及使用寿命，从而有利于电化学装置的安全性能及电化学性能。此外，保护层103还能够增强正极集流体10的机械强度。
保护层103的材料可以为金属、金属氧化物及导电碳中的一种或多种。
上述金属例如是镍、铬、镍基合金及铜基合金中的一种或多种。前述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，镍铬合金中镍与铬的重量比为1:99～99:1，如9:1。前述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，优选为镍铜合金。可选的，镍铜合金中镍与铜的重量比为1:99～99:1，如9:1。
上述金属氧化物例如是氧化铝、氧化钴、氧化铬及氧化镍中的一种或多种。
上述导电碳例如是石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯、碳纳米纤维中的一种或多种，优选为炭黑、碳纳米管、乙炔黑及石墨烯中的一种或多种。
作为一些示例，请参照图4和图5，正极集流体10包括层叠设置的支撑层101、导电层102和保护层103。其中，在支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，导电层102层叠设置于支撑层101的第一表面101a及第二表面 101b中的至少一者上，保护层103层叠设置于导电层102的背向支撑层101的表面。
在导电层102的背向支撑层101的表面上设置保护层103(简称为上保护层)，对导电层102起到防化学腐蚀、防机械破坏的保护作用，还可以改善正极集流体10与正极活性材料层之间的界面，提高正极集流体10与正极活性材料层之间的结合力，提高电化学装置的性能。
进一步地，上保护层优选为金属氧化物保护层，例如氧化铝、氧化钴、氧化镍、氧化铬等，金属氧化物保护层的硬度及机械强度高，比表面积更大，抗腐蚀性能更好，可以更好地保护导电层102、以及增强正极集流体10与正极活性材料层之间的结合力，还有利于提高正极集流体10的整体强度；此外，还有利于改善电化学装置的穿钉安全性能。
作为另一些示例，请参照图6和图7，正极集流体10包括层叠设置的支撑层101、导电层102和保护层103。其中，在支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，导电层102层叠设置于支撑层101的第一表面101a及第二表面101b中的至少一者上，保护层103层叠设置于导电层102的朝向支撑层101的表面。
在导电层102的朝向支撑层101的表面上设置保护层103(简称为下保护层)，下保护层对导电层102起到防化学腐蚀、防机械损害的保护作用的同时，还能够提高导电层102和支撑层101之间的结合力，防止导电层102与支撑层101分离，提高支撑层101对导电层102的支撑保护作用。
进一步地，下保护层优选为金属氧化物保护层，例如氧化铝、氧化钴、氧化镍、氧化铬等，可以更好地起到上述保护作用、以及进一步提高导电层102和支撑层101之间的结合力，还有利于提高正极集流体10的整体强度。
作为又一些示例，请参照图8和图9，正极集流体10包括层叠设置的支撑层101、导电层102和保护层103。其中，在支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，导电层102层叠设置于支撑层101的第一表面101a及第二表面101b中的至少一者上，保护层103层叠设置于导电层102的背向支撑层101的表面及朝向支撑层101的表面上。
在导电层102的两个表面上均设置保护层103，即在导电层102的两个表面上分别设置有上保护层及下保护层，更加充分地保护导电层102。进一步地，上保护层及下保护层均为金属氧化物保护层。
可以理解的是，导电层102的两个表面上的保护层103，其材料可以相同、也可以不同，其厚度可以相同、也可以不同。
优选地，保护层103的厚度D 3为1nm≤D 3≤200nm、且D 3≤0.1D 1。保护层103的厚度D 3在上述范围内，能够对导电层102起到有效的保护作用，同时使电化学装置具有较高的能量密度。
在一些可选的实施例中，保护层103的厚度D 3可以为200nm、180nm、150nm、120nm、100nm、80nm、60nm、55nm、50nm、45nm、40nm、30nm、20nm、18nm、15nm、12nm、10nm、8nm、5nm、2nm、1nm等，保护层103的厚度D 3的范围可由前 述任意两个数值组成。优选地，5nm≤D 3≤200nm。更优选地，10nm≤D 3≤200nm。
进一步地，当导电层102的两个表面均设置有保护层103时，上保护层的厚度D a为1nm≤D a≤200nm、且D a≤0.1D 1，下保护层的厚度D b为1nm≤D b≤200nm、且D b≤0.1D 1。优选地，D a与D b之间满足D a＞D b，有利于保护层103对导电层102起到良好的保护作用，同时使电化学装置具有较高的能量密度。更优选地，0.5D a≤D b≤0.8D a。
导电层102可以是通过机械辊轧、粘结、气相沉积法(vapor deposition)、化学镀(Electroless plating)、电镀(Electroplating)中的至少一种手段形成于支撑层101上，其中优选气相沉积法或电镀，即导电层102为气相沉积层或电镀层，可以提高导电层102与支撑层101之间的结合力，有效地发挥支撑层101对导电层102的支撑作用，还能够使支撑层101的毛刺更好地包覆住导电层102的毛刺，提高电化学装置的穿钉安全性能。
优选地，支撑层101与导电层102之间的结合力F≥100N/m，更优选为F≥400N/m。
例如，通过气相沉积法将导电层102形成于支撑层101上，通过合理调控气相沉积工艺条件，如沉积温度、沉积速率、沉积室的气氛条件等，可以使正极集流体10被拉伸时，导电层102的方块电阻增长率满足前文所述的要求，以改善正极集流体10的安全性能及电化学性能。
上述气相沉积法优选为物理气相沉积法(Physical Vapor Deposition，PVD)。物理气相沉积法优选蒸发法及溅射法中的至少一种；蒸发法优选真空蒸镀法、热蒸发法及电子束蒸发法中的至少一种，溅射法优选磁控溅射法。
作为一个示例，通过真空蒸镀法形成导电层102，包括：将经过表面清洁处理的支撑层101置于真空镀室内，以1300℃～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101上，形成导电层102。
通过机械辊轧形成导电层102的工艺可以包括：将铝片或铝合金片置于机械辊中，通过施加20t～40t的压力将其碾压为预定的厚度，之后将其置于经过表面清洁处理的支撑层101的表面，然后将两者置于机械辊中，通过施加30t～50t的压力使两者紧密结合。
通过粘结形成导电层102的工艺可以包括：将铝片或铝合金片置于机械辊中，通过施加20t～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101的表面涂布聚偏氟乙烯(PVDF)与N-甲基吡咯烷酮(NMP)的混合溶液；最后将上述预定厚度的导电层102粘结于支撑层101的表面，并烘干，使两者紧密结合。
当正极集流体10具有保护层103时，保护层103可以是通过气相沉积法、原位形成法及涂布法中的至少一种手段形成于导电层102上。气相沉积法可以是如前文所述的气相沉积法。原位形成法优选原位钝化法，如在金属表面原位形成金属氧化物钝化层的方法。涂布法优选辊压涂布、挤压涂布、刮刀涂布及凹版涂布中的至少一种。
优选地，保护层103通过气相沉积法及原位形成法中的至少一种手段形成于导电 层102上，有利于使导电层102与保护层103之间具有较高的结合力，从而更好地发挥保护层102对正极集流体10的保护作用，并保证正极集流体10具有较高的工作性能。
本申请实施例中，正极集流体的拉伸应变为2％时导电层的方块电阻增长率T 1、及正极集流体的拉伸应变大于等于4％时导电层的方块电阻增长率T 2均可以按照如下方法进行测试。
正极集流体的拉伸应变设为ε，则ε＝ΔL/L×100％，其中，ΔL是正极集流体被拉伸产生的伸长量，L是正极集流体的原长，即被拉伸之前的长度。
正极集流体的拉伸应变为ε时，导电层的方块电阻增长率设为T，T值可以采用本领域已知的方法测定，作为示例，取正极集流体裁剪成20mm×200mm的样品，采用四探针法测试样品的中心区域的方块电阻，记录为R 1，然后使用高铁拉力机对样品的中心区域进行拉伸，设置初始位置，并使夹具之间的样品长度为50mm，以50mm/min速度进行拉伸，拉伸距离为样品原长L(50mm)与ε的乘积，即拉伸距离为ΔL，取下拉伸后的样品，测试夹具之间导电层的方块电阻，记录为R 2，根据公式T＝(R 2-R 1)/R 1×100％，计算得到正极集流体的拉伸应变为ε时导电层的方块电阻增长率T。
其中采用四探针法测试导电层的方块电阻的方法如下：使用RTS-9型双电测四探针测试仪，测试环境为：常温23±2℃，0.1MPa，相对湿度≤65％。测试时，将待测样品进行表面清洁，然后水平置于测试台上，将四探针放下，使探针与导电层表面良好接触，然后调节自动测试模式标定样品的电流量程，在合适的电流量程下进行方块电阻的测量，并采集相同样品的8至10个数据点作为数据测量准确性和误差分析。最后取平均值记录为导电层的方块电阻值。
支撑层的断裂伸长率B可以采用本领域已知的方法测定，作为一个示例，取支撑层裁剪成15mm×200mm的样品，在常温常压(25℃、0.1MPa)下使用高铁拉力机进行拉伸测试，设置初始位置使夹具之间样品长度为50mm长，拉伸速度为50mm/min，记录拉伸断裂时的设备位移y(mm)，最后计算断裂伸长率B＝(y/50)×100％。
支撑层的体积电阻率是在20℃时的体积电阻率，可以采用本领域已知的方法测定。作为示例，测试在恒温常压低湿度房下进行(20℃，0.1MPa，RH≤20％)，制备直径为20mm的圆片支撑层样品(样品尺寸可根据测试仪器的实际尺寸调整)，测试采用三电极测表面电阻率法(GB T 1410-2006)，使用绝缘电阻测试仪(精度10Ω)进行。测试方法如下：将圆片样品放置在两个电极之间，并在两个电极之间施加一个电位差，产生的电流将分布在圆片样品的体内，并由皮安计或静电计来测量，以避免因在测量中计入表面泄露电流而产生测量误差。读数即为体积电阻率，单位为Ω·m。
支撑层的杨氏模量E可以采用本领域已知的方法测定。作为示例，取支撑层裁剪成15mm×200mm的样品，用万分尺量取样品的厚度l(μm)，在常温常压(25℃、0.1MPa)下使用高铁拉力机进行拉伸测试，设置初始位置使夹具之间样品为50mm长，拉伸速度为50mm/min，记录拉伸至断裂的载荷Q(N)，设备位移z(mm)，则应力ξ(GPa)＝Q/(15×l)，应变η＝z/50，绘制应力应变曲线，取初始线性区曲线，该曲线的斜率即为杨氏模量E。
导电层的密度可以采用本领域已知的方法测定，作为一个示例，裁取面积为10cm 2的正极集流体，用精确到0.0001g的天平称量其质量，计为m 1，单位g，用万分尺测量20个位置的厚度，并取其平均值，计为d 1，单位μm。将称量完的正极集流体用1mol/L的NaOH水溶液浸泡1min，待导电层完全溶解，取出支撑层，去离子水漂洗5次后，在100℃下烘烤20min，之后用同一个天平称量其质量，记为m 2，单位g，用同一把万分尺测量20个位置的厚度，并取其平均值，记为d 2，单位μm。根据如下公式计算导电层的密度，单位g/cm 3。
Figure PCTCN2019129349-appb-000001
取5片同样大小的正极集流体分别测试导电层的密度，结果取平均值。
导电层的体积电阻率设为ρ，则ρ＝R S×d，其中，ρ的单位为Ω·m；R S为导电层的方块电阻，单位为Ω；d为导电层以m为单位的厚度。可以参照前文所述的四探针法测试导电层的方块电阻R S，在此不再赘述。
可以采用本领域已知的方法测试支撑层与导电层之间的结合力F，例如选用导电层设置于支撑层一面上的正极集流体待测样品，宽度h为0.02m，在常温常压(25℃、0.1MPa)下，使用3M双面胶，均匀贴于不锈钢板上，再将待测样品均匀贴于双面胶上，使用高铁拉力机将待测样品的导电层与支撑层剥离，根据拉力和位移的数据图，读取最大拉力x(N)，根据F＝x/h计算得到导电层与支撑层之间的结合力F(N/m)。
正极极片
本申请实施例第二方面提供一种正极极片，包括层叠设置的正极集流体及正极活性材料层，其中正极集流体为本申请实施例第一方面的正极集流体10。
本申请实施例的正极极片，由于采用了本申请实施例第一方面的正极集流体10，与传统的正极极片相比，具有较高的重量能量密度和良好的穿钉安全性能及电化学性能。
作为示例，正极极片包括层叠设置的支撑层101、导电层102及正极活性材料层，支撑层101包括相对的第一表面101a和第二表面101b，导电层102设置于支撑层101的第一表面101a和/或第二表面101b上，正极活性材料层设置于导电层102的背向支撑层101的表面上。
本申请实施例的正极极片，正极活性材料层可以采用本领域已知的正极活性材料，能够进行离子的可逆嵌入/脱嵌。
例如用于锂离子二次电池的正极活性材料，可以为锂过渡金属复合氧化物，其中过渡金属可以是Mn、Fe、Ni、Co、Cr、Ti、Zn、V、Al、Zr、Ce及Mg中的一种或多种。锂过渡金属复合氧化物中还可以掺杂电负性大的元素，如S、F、Cl及I中的一种或多种，能够使正极活性材料具有较高的结构稳定性和电化学性能。作为示例，锂过渡金属复合氧化物例如为LiMn 2O 4、LiNiO 2、LiCoO 2、LiNi 1-yCo yO 2(0<y<1)、LiNi aCo bAl 1-a-bO 2(0<a<1，0<b<1，0<a+b<1)、LiMn 1-m-nNi mCo nO 2(0<m<1，0<n<1， 0<m+n<1)、LiMPO 4(M可以为Fe、Mn、Co中的一种或多种)及Li 3V 2(PO 4) 3中的一种或多种。
可选地，正极活性材料层还可以包括导电剂。作为示例，导电剂为石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
可选地，正极活性材料层还可以包括粘结剂。作为示例，粘结剂为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
正极极片可以按照本领域常规方法制备。通常将正极活性材料及可选的导电剂、粘结剂分散于溶剂(例如N-甲基吡咯烷酮，简称为NMP)中，形成均匀的正极浆料，将正极浆料涂覆在正极集流体上，经烘干等工序后，得到正极极片。
电化学装置
本申请实施例的第三方面提供一种电化学装置，电化学装置包括正极极片、负极极片、隔离膜和电解液，其中正极极片为本发明实施例第二方面的正极极片。
上述电化学装置可以是锂离子二次电池、锂一次电池、钠离子电池、镁离子电池等，但并不限于此。
由于电化学装置采用根据本申请实施例的第二方面提供的正极极片，使得本申请实施例的电化学装置具有较高的重量能量密度和良好的穿钉安全性能及电化学性能。
上述负极极片可以是包括负极集流体及负极活性材料层。
负极集流体可以为包括铜、铜合金、镍、镍合金、铁、铁合金、钛、钛合金、银及银合金中的一种或多种的金属箔或多孔金属箔。
负极活性材料层可以采用本领域已知的负极活性材料，能够进行离子的可逆嵌入/脱嵌。
例如用于锂离子二次电池的负极活性材料，可以为金属锂、天然石墨、人造石墨、中间相微碳球(简写为MCMB)、硬碳、软碳、硅、硅-碳复合物、SiO、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的钛酸锂及Li-Al合金中的一种或多种。
可选地，负极活性材料层还可以包括粘结剂。作为示例，粘结剂为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
可选地，负极活性材料层还可以包括导电剂。作为示例，导电剂为石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
负极极片可以按照本领域常规方法制备。通常将负极活性材料及可选的导电剂和粘结剂分散于溶剂中，溶剂可以是NMP或去离子水，形成均匀的负极浆料，将负极浆料涂覆在负极集流体上，经烘干等工序后，得到负极极片。
对上述隔离膜没有特别的限制，可以选用任意公知的具有电化学稳定性和化学稳 定性的多孔结构隔离膜，例如可以是玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或多种的单层或多层薄膜。
上述电解液包括有机溶剂和电解质盐。有机溶剂作为在电化学反应中传输离子的介质，可以采用本领域已知的用于电化学装置电解液的有机溶剂。电解质盐作为离子的供源，可以是本领域已知的用于电化学装置电解液的电解质盐。
例如用于锂离子二次电池的有机溶剂，可以为碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸丁烯酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)、二乙砜(ESE)中的一种或多种。
例如用于锂离子二次电池的电解质盐，可以为LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或多种。
将正极极片、隔离膜、负极极片按顺序堆叠好，使隔离膜处于正极极片、负极极片之间起到隔离的作用，得到电极组件，也可以是经卷绕后得到电极组件；将电极组件置于包装外壳中，注入电解液并封口，制备电化学装置。
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10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11是作为一个示例的电池模块4。参照图11，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12和图13是作为一个示例的电池包1。参照图12和图13，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
本申请实施例的第四方面提供一种装置，所述装置包括本申请实施例第三方面的电化学装置。所述电化学装置可以用作所述装置的电源，也可以作为所述装置的能量存储单元。所述装置包括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。
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14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。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于重量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
制备方法
正极集流体的制备
选取预定厚度的支撑层并进行表面清洁处理，将经过表面清洁处理的支撑层置于真空镀室内，以1300℃～2000℃的高温将金属蒸发室内的高纯铝丝熔化蒸发，蒸发后的铝经过真空镀室内的冷却系统，最后沉积于支撑层的两个表面，形成导电层。
可以通过调整导电层的材料、厚度、密度、制备工艺条件(例如真空度、气氛、湿度、温度等)、以及调整支撑层的材料、厚度等，使得正极集流体具有不同的T 1值及T 2值。
正极极片的制备
将正极活性材料LiNi 1/3Co 1/3Mn 1/3O 2(NCM333)、导电炭黑、粘结剂聚偏二氟乙 烯(PVDF)按93:2:5的重量比在适量的N-甲基吡咯烷酮(NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将正极浆料涂覆于正极集流体上，经烘干等工序后，得到正极极片。
常规正极集流体
厚度为12μm的铝箔。
常规正极极片
与上述本申请实施例的正极极片不同的是，采用常规正极集流体。
负极集流体
厚度为8μm的铜箔。
负极极片的制备
将负极活性材料石墨、导电炭黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶乳液(SBR)按96.5:1.0:1.0:1.5的重量比在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料；将负极浆料涂覆于负极集流体上，经烘干等工序后，得到负极极片。
电解液的制备
将体积比为3:7的碳酸乙烯酯(EC)和碳酸甲乙酯(EMC)混合均匀，得到有机溶剂，然后将1mol/L的LiPF 6均匀溶解在上述有机溶剂中。
锂离子二次电池的制备
将正极极片、隔离膜(PP/PE/PP复合薄膜)、负极极片依次层叠设置，然后卷绕成电极组件并装入包装外壳中，将上述电解液注入到电极组件中，经过密封、静置、热冷压、化成等工序，得到锂离子二次电池。
测试部分
1.按照前文所述的测试方法对正极集流体进行测试。
2.电池的性能测试
(1)循环性能测试
在45℃下，将锂离子二次电池以1C的倍率恒流充电至4.2V，再恒压充电至电流小于等于0.05C，再以1C的倍率恒流放电至2.8V，此为一个充放电循环，此次的放电容量即为第1次循环的放电容量。将电池按照上述方法进行1000次充放电循环，记录第1000次循环的放电容量。
锂离子二次电池45℃、1C/1C循环1000次后的容量保持率(％)＝第1000次循环的放电容量/第1次循环的放电容量×100％
(2)穿钉测试
在25℃下，将锂离子二次电池以1C的倍率恒流充电至4.2V，再恒压充电至电流小于等于0.05C。之后将直径为8mm的钢针以25mm/s的速度刺透整个锂离子二次电池，并将钢针保留于锂离子二次电池中，监测锂离子二次电池在温度和电压方面的变化。
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，得到电池温升。
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。
测试结果
1.导电层的厚度D 1、支撑层的断裂伸长率B及体积电阻率的影响
表1
Figure PCTCN2019129349-appb-000002
表2
Figure PCTCN2019129349-appb-000003
Figure PCTCN2019129349-appb-000004
采用本申请实施例的正极集流体可以大大改善电池的穿钉安全性能。从表2中的数据可以看到，采用常规正极集流体的电池，或者正极集流体的支撑层断裂伸长率小于12％，在穿钉的瞬间，电池温度骤升500℃，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而导致失效。而本申请实施例的正极集流体，导电层的厚度D 1、以及支撑层的断裂伸长率B和体积电阻率均在特定范围内，在穿钉测试中，电池温升都可以被控制在35℃以下，进一步地25℃以下，更进一步地10℃以下，且电池电压基本保持稳定，电池可以正常工作。
可见，在电池发生内短路的情况下，本申请实施例的正极集流体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”，而不影响电池在一段时间内的正常工作。
2.正极集流体的T 1值对电化学装置的影响
表3
Figure PCTCN2019129349-appb-000005
表3中，铝合金采用铝合金7049(铝锌合金，美国芬可乐公司)。
对表3中的正极集流体进行过流测试，将正极集流体剪裁成100mm幅宽，在幅宽方向正中的位置涂布80mm宽的正极活性材料层并辊压制作成正极极片，将辊压后的 极片沿幅宽方向剪裁成100mm×30mm的长条，每种极片剪裁10条。测试时，将极片样品两侧无涂膜的导电区分别连接到充放电机的正负极端，随后设置充放电机，使1A电流通过极片，保持10s极片不发生熔断即为通过测试，否则视为不通过。每组样品测试10个，过流测试结果示于下面的表4。
表4
正极极片编号 正极集流体编号 过流测试通过率(％)
正极极片3 正极集流体3 80
正极极片31 正极集流体31 60
正极极片32 正极集流体32 70
正极极片33 正极集流体33 100
正极极片34 正极集流体34 100
正极极片35 正极集流体35 100
正极极片36 正极集流体36 100
对比正极极片2 对比集流体2 0
对比正极极片3 对比集流体3 0
正极集流体的拉伸应变为2％时，导电层的方块电阻增长率T 1不大于10％，此时，采用该正极集流体的正极极片在辊压之后，可以具有较好的导电性能。否则导电性能较差，在电池产品中实用价值不大。优选地，T 1≤5％。优选地，T 1≤2％。更优选地，T 1≤1％。
3.正极集流体的T 2值对于电化学装置的穿钉安全性能的作用
表5
Figure PCTCN2019129349-appb-000006
表6
Figure PCTCN2019129349-appb-000007
从表6中的数据可以看到，当正极集流体的拉伸应变大于等于4％，导电层的方块电阻增长率T 2小于50％时，电池穿钉安全性能较差，例如对比电池4，在穿钉的瞬间，电池温度骤升500℃，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而导致失效。而正极集流体的拉伸应变大于等于4％，导电层的方块电阻增长率T 2为50％以上时，电池穿钉安全性能较好，在穿钉测试中，电池温升基本都可以被控制在30℃以下，进一步地在20℃以下，更进一步地在10℃以下，且电池电压基本保持稳定，电池可以正常工作。
可见，正极集流体的拉伸应变大于等于4％时，导电层的方块电阻增长率T 2为50％以上，尤其是为100％以上，更尤其是为150％以上，在电池发生内短路的情况下，可极大地降低短路产热量，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”，而不影响电池在一定时间内的正常工作。
4.保护层的影响
表7
Figure PCTCN2019129349-appb-000008
Figure PCTCN2019129349-appb-000009
表7中，正极集流体3-1至3-13均是基于正极集流体3设置保护层。
表8
Figure PCTCN2019129349-appb-000010
采用本申请实施例正极集流体的电池的循环寿命良好，尤其是设置有保护层的正极集流体制成的电池，45℃、1C/1C循环1000次后的容量保持率进一步获得提升，说明电池的可靠性更好。
5.本申请正极集流体在改善电化学装置的重量能量密度方面的作用
表9
Figure PCTCN2019129349-appb-000011
Figure PCTCN2019129349-appb-000012
表9中，正极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。
相较于传统的铝箔正极集流体，采用本申请的正极集流体的重量都得到不同程度的减轻，从而可提升电池的重量能量密度。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (11)

  1. 一种正极集流体，其特征在于，包括：
    支撑层，在自身厚度方向上具有相对的两个表面；
    导电层，设置于所述支撑层的两个所述表面中的至少一者上；
    其中，
    所述导电层的材质为铝或铝合金，所述导电层的厚度D 1为300nm≤D 1≤2μm，优选为500nm≤D 1≤2μm，更优选为600nm≤D 1≤1.5μm；
    所述支撑层的断裂伸长率B为10000％≥B≥12％，优选为400％≥B≥15％，更优选为400％≥B≥30％；
    所述支撑层的体积电阻率大于或等于1.0×10 -5Ω·m；
    所述正极集流体的拉伸应变为2％时，所述导电层的方块电阻增长率T 1为T 1≤10％，优选为T 1≤5％，优选为T 1≤2％，更优选为T 1≤1％。
  2. 根据权利要求1所述的正极集流体，其特征在于，所述正极集流体的拉伸应变大于等于4％时，所述导电层的方块电阻增长率T 2为T 2≥50％，优选为T 2≥100％，更优选为T 2≥150％。
  3. 根据权利要求1至2任一项所述的正极集流体，其特征在于，所述导电层的密度为2.5g/cm 3～2.8g/cm 3。
  4. 根据权利要求1至3任一项所述的正极集流体，其特征在于，所述支撑层包括高分子材料及高分子基复合材料中的一种或多种；
    优选地，所述高分子材料为聚酰胺、聚酰亚胺、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚碳酸酯、聚乙烯、聚丙烯、聚丙乙烯、丙烯腈-丁二烯-苯乙烯共聚物、聚乙烯醇、聚苯乙烯、聚氯乙烯、聚偏氟乙烯、聚四氟乙烯、聚苯乙烯磺酸钠、聚乙炔、硅橡胶、聚甲醛、聚苯醚、聚苯硫醚、聚乙二醇、聚氮化硫类高分子材料、聚苯、聚吡咯、聚苯胺、聚噻吩、聚吡啶、纤维素、淀粉、蛋白质、环氧树脂、酚醛树脂、它们的衍生物、它们的交联物及它们的共聚物中的一种或多种；
    优选地，所述高分子基复合材料包括所述高分子材料和添加剂，所述添加剂包括金属材料及无机非金属材料中的一种或多种。
  5. 根据权利要求1至4任一项所述的正极集流体，其特征在于，
    所述支撑层的厚度D 2为1μm≤D 2≤20μm，优选为2μm≤D 2≤10μm，更优选为2μm≤D 2≤6μm；和/或，
    所述支撑层的杨氏模量E为E≥1.9GPa，优选为4GPa≤E≤20GPa。
  6. 根据权利要求1至5任一项所述的正极集流体，其特征在于，所述导电层为气相沉积层或电镀层。
  7. 根据权利要求1至6任一项所述的正极集流体，其特征在于，进一步包括保护层，所述保护层设置于所述导电层自身厚度方向上相对的两个表面中的至少一者上；
    优选地，所述保护层包括金属、金属氧化物及导电碳中的一种或多种，更优选地，所述保护层包括镍、铬、镍基合金、铜基合金、氧化铝、氧化钴、氧化铬、氧化镍、石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种；
    优选地，所述保护层的厚度D 3为1nm≤D 3≤200nm、且D 3≤0.1D 1。
  8. 根据权利要求7所述的正极集流体，其特征在于，所述保护层包括设置于所述导电层背向所述支撑层的表面的上保护层、以及设置于所述导电层朝向所述支撑层的表面的下保护层；
    优选地，所述上保护层的厚度D a为1nm≤D a≤200nm、且D a≤0.1D 1，所述下保护层的厚度D b为1nm≤D b≤200nm、且D b≤0.1D 1，所述D a与D b之间满足D a＞D b，更优选地，0.5D a≤D b≤0.8D a；
    优选地，所述上保护层和所述下保护层均为金属氧化物保护层。
  9. 一种正极极片，其特征在于，所述正极极片包括正极集流体以及设置于所述正极集流体上的正极活性材料层，其中所述正极集流体为如权利要求1至8任一项所述的正极集流体。
  10. 一种电化学装置，其特征在于，所述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如权利要求9所述的正极极片。
  11. 一种装置，其特征在于，所述装置包括权利要求10所述的电化学装置。
PCT/CN2019/129349 2019-07-01 2019-12-27 正极集流体、正极极片、电化学装置及装置 WO2021000545A1 (zh)

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