WO2021000511A1 - 负极集流体、负极极片、电化学装置、电池模块、电池包及设备 - Google Patents

负极集流体、负极极片、电化学装置、电池模块、电池包及设备 Download PDF

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WO2021000511A1
WO2021000511A1 PCT/CN2019/121587 CN2019121587W WO2021000511A1 WO 2021000511 A1 WO2021000511 A1 WO 2021000511A1 CN 2019121587 W CN2019121587 W CN 2019121587W WO 2021000511 A1 WO2021000511 A1 WO 2021000511A1
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layer
current collector
negative electrode
conductive layer
metal conductive
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PCT/CN2019/121587
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English (en)
French (fr)
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刘欣
彭佳
李铭领
黄起森
梁成都
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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 WO2021000511A1 publication Critical patent/WO2021000511A1/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
    • H01M4/661—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
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/06—Electrodes for primary cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or 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
    • 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
    • H01M4/665—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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application belongs to the technical field of electrochemical devices, and in particular relates to a negative electrode current collector, a negative pole piece, an electrochemical device, a battery module, a battery pack, and equipment.
  • 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. However, as the application range of secondary batteries continues to expand, the requirements for the weight and energy density of secondary batteries are also increasing.
  • the weight of each component of the secondary battery can be reduced.
  • the improvement of the current collector is usually to select a lighter weight current collector, for example, a plastic current collector plated with a metal layer can be used.
  • a plastic current collector plated with a metal layer although the weight is reduced, some performance degradations such as electrical performance are caused, which affects the performance of the pole piece and the battery.
  • many improvements are needed.
  • the embodiments of the present application provide a negative electrode current collector, a negative electrode sheet, an electrochemical device, a battery module, a battery pack, and equipment, aiming to enable the negative electrode current collector to have both low weight and high electrical performance at the same time, so that the electrochemical The device takes into account both high weight energy density and electrochemical performance.
  • the first aspect of the embodiments of the present application provides a negative electrode current collector, and the negative electrode current collector includes:
  • the supporting layer includes two opposite surfaces in its thickness direction;
  • the metal conductive layer is disposed on at least one of the two surfaces of the support layer;
  • the ratio of the density of the metal conductive layer to the intrinsic density of the material of the metal conductive layer is greater than or equal to 0.7, and the material of the metal conductive layer is copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the material of the metal conductive layer is copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • a second aspect of the embodiments of the present application provides a negative pole piece.
  • the negative pole piece includes a negative current collector and a negative active material layer disposed on the negative current collector, wherein the negative current collector is the negative electrode of the first aspect of the embodiments of the present application. Current collector.
  • the 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 negative pole piece is the negative pole piece according to the second aspect of the embodiments of the present application .
  • a fourth aspect of the present application provides a battery module, which includes the electrochemical device described in the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack including the battery module described in the fourth aspect of the present application.
  • the sixth aspect of the present application provides a device including the electrochemical device described in the third aspect of the present application, and the electrochemical device is used as a power source for the device.
  • the equipment includes mobile equipment, electric vehicles, electric trains, satellites, ships and energy storage systems.
  • a metal conductive layer with a small thickness is provided on at least one surface of the support layer, which can significantly reduce the weight of the negative electrode current collector, thereby significantly increasing the weight energy density of the electrochemical device.
  • the ratio of the density of the metal conductive layer to the intrinsic density of the material of the metal conductive layer is greater than or equal to 0.7, and the material of the metal conductive layer is copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy
  • the material of the metal conductive layer is copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the battery module, battery pack, and equipment of the present application include the electrochemical device, and thus have at least the same advantages as the electrochemical device.
  • Fig. 1 shows a schematic structural diagram of a negative electrode current collector provided in an embodiment of the present application.
  • FIG. 2 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 3 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 4 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 5 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 6 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 7 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 8 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 9 shows a schematic structural diagram of a negative electrode current collector provided by another embodiment of the present application.
  • FIG. 10 shows a schematic structural diagram of an electrochemical device provided by an embodiment of the present application.
  • FIG. 11 shows a schematic structural diagram of a battery module provided by an embodiment of the present application.
  • Fig. 12 shows a schematic structural diagram of a battery pack provided by an embodiment of the present application.
  • Fig. 13 is an exploded view of Fig. 12.
  • Fig. 14 is a schematic diagram of an embodiment of an apparatus in which an electrochemical device is used as a power source.
  • Support layer 101. Support layer
  • any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range.
  • every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
  • the first aspect of the embodiments of the present application provides a negative electrode current collector 10. Please refer to FIG. 1 and FIG. 2.
  • the negative electrode current collector 10 includes a supporting layer 101 and a metal conductive layer 102 that are stacked.
  • the support layer 101 has a first surface 101a and a second surface 101b opposite to each other in the thickness direction, and the metal conductive layer 102 is disposed on either or both of the first surface 101a and the second surface 101b of the support layer 101 on.
  • the ratio of the density of the metal conductive layer 102 to the intrinsic density of the material of the metal conductive layer 102 is greater than or equal to 0.7, and the material of the metal conductive layer 102 is copper, copper alloy, nickel, nickel alloy, titanium, One or more of titanium alloy, silver and silver alloy.
  • the density of the metal conductive layer 102 can be measured by methods known in the art. As an example, cut the negative electrode current collector 10 (where the metal conductive layer 102 is metallic copper) with an area of 10 cm 2 and weigh it with a balance accurate to 0.0001 g. Measure its mass and count it as m 1 in g. Measure the thickness at 20 locations with a micrometer, and take the average value and count as d 1 in ⁇ m. Soak the weighed negative current collector 10 with a 1mol/L FeCl 3 aqueous solution for 12 hours. After the metal conductive layer 102 is completely dissolved, take out the support layer 101, rinse it with deionized water for 5 times, and bake it at 100°C for 20 minutes.
  • the density of the metal conductive layer 102 is calculated according to the following formula 1 in g/cm 3 .
  • five negative current collectors 10 of the same size can be used to test the density of the metal conductive layer 102 respectively, and the results are averaged.
  • the intrinsic density of copper is 8.96g/cm 3
  • the intrinsic density of copper alloy is 6.5g/cm 3 ⁇ 9g/cm 3
  • the intrinsic density of nickel is 8.9g/cm 3
  • the intrinsic density of nickel alloy 6.0g/cm 3 ⁇ 9.0g/cm 3
  • the intrinsic density of titanium is 4.51g/cm 3
  • the intrinsic density of titanium alloy is 4.0g/cm 3 ⁇ 5.0g/cm 3
  • the intrinsic density of silver is 10.49g / cm 3
  • an intrinsic density of a silver alloy is 9.0g / cm 3 ⁇ 12.0g / cm 3.
  • the metal conductive layer 102 with a small thickness is disposed on at least one surface of the support layer 101.
  • the negative electrode current collector can be significantly reduced. 10 weight, thereby significantly improving the weight energy density of the electrochemical device.
  • the negative electrode current collector 10 will inevitably be stretched during the preparation, processing and use of the negative electrode pieces and electrochemical devices, such as the rolling of the electrode pieces or the expansion of the battery.
  • the ratio of the density of the metal conductive layer 102 to the intrinsic density of the material of the metal conductive layer 102 is greater than or equal to 0.7, and the material of the metal conductive layer 102 is copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and One or more of the silver alloys can prevent the metal conductive layer 102 with a small thickness from being damaged due to stretching, and prevent the conductive metal layer 102 with a small thickness from being unevenly distributed and caused by tensile deformation.
  • the sharp increase in resistance ensures that the negative electrode current collector 10 has good and uniform conductivity and current collection performance, so that the electrochemical device has low impedance and small polarization, so that the electrochemical device has both high electrochemical performance. Among them, the electrochemical device has both high rate performance and cycle performance.
  • the use of the negative electrode current collector 10 of the embodiment of the present application enables the electrochemical device to have both high weight energy density and electrochemical performance.
  • the thickness D 2 of the support layer 101 is preferably 1 ⁇ m ⁇ D 2 ⁇ 20 ⁇ m, for example, 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.
  • the thickness D 2 of the support layer 101 is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more, which is conducive to making the support layer 101 have sufficient mechanical strength, and it is not easy to break during the processing and use of the negative electrode current collector 10, and the metal conductive layer 102 Play a good support and protection role, and ensure good mechanical stability and a long service life of the negative electrode current collector 10.
  • the thickness D 2 of the support layer 101 is preferably 20 ⁇ m or less, more preferably 10 ⁇ m or less, and more preferably 6 ⁇ m or less, which is beneficial for making the electrochemical device have a smaller volume and weight, thereby increasing the energy density of the electrochemical device.
  • the Young's modulus E of the support layer 101 is preferably E ⁇ 1.9 GPa.
  • the support layer 101 has appropriate rigidity, which satisfies the support and protection function of the support layer 101 on the metal conductive layer 102 and ensures the overall strength of the negative electrode current collector 10.
  • the support layer 101 will not be excessively stretched or deformed, which can prevent the support layer 101 from breaking and is beneficial to improve the bonding fastness between the support layer 101 and the metal conductive layer 102 , It is not easy to detach, so that the negative electrode current collector 10 has higher mechanical stability and working stability, so that the electrochemical device has higher electrochemical performance, such as a longer cycle life.
  • the Young's modulus E of the support layer 101 is 1.9 GPa ⁇ E ⁇ 20 GPa, so that the support layer 101 has rigidity while also having a certain ability to withstand deformation, which can be used during the processing and use of the negative current collector 10 The flexibility of the winding can better prevent breakage.
  • the Young's modulus E of the support layer 101 may be 1.9GPa, 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 volume resistivity of the support layer 101 is greater than or equal to 1.0 ⁇ 10 -5 ⁇ m. Due to the relatively large volume resistivity of the support layer 101, in the case of an abnormal situation such as nail penetration of the electrochemical device, the short-circuit resistance of the electrochemical device when an internal short circuit occurs can be increased, thereby improving the safety performance of the electrochemical device.
  • the breaking elongation of the support layer 101 is greater than or equal to the breaking elongation of the metal conductive layer 102, so as to better prevent the negative electrode current collector 10 from breaking.
  • the elongation at break of the support layer 101 is greater than or equal to 5%, preferably, the elongation at break of the support layer 101 is greater than or equal to 10%.
  • the support layer 101 uses one or more of a polymer material and a polymer-based composite material. Since the density of polymer materials and polymer-based composite materials is significantly lower than that of metals, compared with traditional metal current collectors, the weight of the negative electrode current collector 10 is significantly reduced and the energy density of the electrochemical device is increased.
  • polystyrene resin for example, polyamide (PA), polyimide (PI), polyesters, polyolefins, polyacetylenes, siloxane polymers, polyethers, polyols, polysulfones Types, polysaccharide polymers, amino acid polymers, polysulfur nitrides, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenolic resins, their derivatives, their cross-linked products and their One or more of copolymers.
  • PA polyamide
  • PI polyimide
  • polyesters for example, polyamide (PA), polyimide (PI), polyesters, polyolefins, polyacetylenes, siloxane polymers, polyethers, polyols, polysulfones Types, polysaccharide polymers, amino acid polymers, polysulfur nitrides, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenolic resins, their derivatives, their cross-
  • 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.
  • Inorganic non-metallic materials are one or more of carbon-based materials, alumina, silicon dioxide, silicon nitride, silicon carbide, boron nitride, silicate, and titanium oxide, such as 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 be carbon-based materials coated with metal materials, such as one or more of nickel-coated graphite powder and nickel-coated carbon fibers.
  • the supporting layer 101 adopts one or more of insulating polymer materials and insulating polymer-based composite materials.
  • the support layer 101 has a high volume resistivity, which can improve the safety performance of the electrochemical device.
  • 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 supporting layer 101 may be a single-layer structure or a composite layer structure of two or more layers, such as two layers, three layers, four layers, and so on.
  • 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 metal conductive layer 102 is stacked on the first surface 101a and the second surface 101b of the supporting layer 101.
  • the metal 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 material of the metal conductive layer 102 is preferably copper or copper alloy.
  • the weight percentage of the copper element in the copper alloy is preferably 90% or more.
  • the aforementioned copper alloy may be, for example, a copper-nickel alloy.
  • the density of the metal conductive layer 102 is preferably 6.5 g/cm 3 to 8.96 g/cm 3 , such as 6.5 g/cm 3 , 6.8 g/cm 3 , and 7.0 g/cm 3 , 7.2g/cm 3 , 7.5g/cm 3 , 7.8g/cm 3 , 8.0g/cm 3 , 8.1g/cm 3 , 8.2g/cm 3 , 8.3g/cm 3 , 8.4g/cm 3 , 8.5g/cm 3 , 8.6g/cm 3 , 8.7g/cm 3 , 8.8g/cm 3 , 8.9g/cm 3 , 8.96g/cm 3 and so on. More preferably, when the material of the metal conductive layer 102 is copper or copper alloy, the density of the metal conductive layer 102 is 8.0 g/cm 3 to 8.96 g
  • the density of the metal conductive layer 102 is preferably 6.5 g/cm 3 to 8.96 g/cm 3 , more preferably 8.0 g/cm 3 to 8.96 g/cm 3 , and can be more It is well ensured that the negative electrode current collector 10 has good processing performance, electrical conductivity and current collection performance, and the electrochemical performance of the electrochemical device is improved.
  • the volume resistivity of the metal conductive layer 102 is preferably 1.3 ⁇ 10 -8 ⁇ m to 1.3 ⁇ 10 -7 ⁇ m, more preferably 1.3 ⁇ 10 -8 ⁇ m to 3.3 ⁇ 10 ⁇ 8 ⁇ m is beneficial to make the negative electrode current collector 10 have better conductivity and current collection performance, thereby improving the performance of the electrochemical device.
  • the sheet resistance growth rate T of the metal conductive layer 102 is T ⁇ 10%, such as T being 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.
  • T ⁇ 5% More preferably, T ⁇ 2%. More preferably, T ⁇ 1%.
  • the negative electrode current collector 10 is sometimes stretched during the processing and use of the negative electrode pieces and electrochemical devices, such as the rolling of the electrode pieces or the expansion of the battery.
  • the sheet resistance growth rate T of the metal conductive layer 102 is 10% or less, which can effectively prevent the metal conductive layer 102 from increasing the resistance caused by the tensile deformation and ensure the negative electrode
  • the current collector 10 has good electrical conductivity and current collecting performance, so that the electrochemical device has low impedance and small polarization, so that the electrochemical device has higher electrochemical performance, including higher rate performance and cycle performance. .
  • the increase rate T of the sheet resistance of the metal conductive layer 102 can be affected by the selection, performance, and thickness of the support layer 101 and the metal conductive layer 102 of the negative current collector 10, and the bonding force between the support layer 101 and the metal conductive layer 102. Change and change.
  • the thickness D 1 of the metal conductive layer 102 is preferably 300 nm ⁇ D 1 ⁇ 2 ⁇ m, such as 2 ⁇ m, 1.8 ⁇ m, 1.5 ⁇ m, 1.2 ⁇ m, 1 ⁇ m, 900 nm, 800 nm, 700 nm, 600 nm, 500 nm, 450 nm, 400 nm , 350nm or 300nm.
  • the range of the thickness D 1 of the metal conductive layer 102 can be composed of any two values mentioned above.
  • D 1 is 500 nm ⁇ D 1 ⁇ 1.5 ⁇ m. More preferably, D 1 is 800nm ⁇ D 1 ⁇ 1.2 ⁇ m.
  • the thickness of the metal conductive layer 102 is preferably 2 ⁇ m or less, more preferably 1.5 ⁇ m or less, and more preferably 1.2 ⁇ m or less.
  • the negative electrode current collector 10 has a significantly reduced weight, which is beneficial to improve the weight energy density of the electrochemical device.
  • the thickness of the metal conductive layer 102 is preferably 300 nm or more, more preferably 500 nm or more, and more preferably 800 nm or more, which is conducive to making the negative electrode current collector 10 have good electrical conductivity and current collecting performance, and is used during the processing and use of the negative electrode current collector 10
  • the medium is not easily damaged, so that the negative electrode current collector 10 has good mechanical stability and a long service life.
  • the negative electrode current collector 10 may further include a protective layer 103.
  • the metal 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 metal conductive layer 102 to protect the metal conductive layer 102. Prevent the metal conductive layer 102 from chemical corrosion or mechanical damage, and ensure that the negative electrode current collector 10 has high working stability and service life.
  • the protective layer 103 can also enhance the mechanical strength of the negative electrode current collector 10.
  • the material of the protective layer 103 may be one or more of metal, metal oxide, and conductive carbon.
  • the protective layer 103 using a metal material is a metal protective layer; the protective layer 103 using a metal oxide material is a metal oxide protective layer.
  • 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 negative electrode current collector 10 includes a supporting layer 101, a metal 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 metal conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101
  • the protective layer 103 is stacked on the surface of the metal 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 metal conductive layer 102 facing away from the support layer 101, which protects the metal conductive layer 102 from chemical corrosion and mechanical damage, and can also improve the negative electrode current collector
  • the interface between 10 and the anode active material layer improves the binding force between the anode current collector 10 and the anode active material layer.
  • the upper protective layer of the negative current collector 10 may be 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, and has a specific surface area. Larger, better corrosion resistance, can better protect the metal conductive layer 102.
  • the upper protective layer of the negative electrode current collector 10 is preferably a metal protective layer, which can improve the conductivity of the negative electrode current collector 10, can reduce battery polarization, reduce the risk of lithium evolution in the negative electrode, and improve the cycle of electrochemical devices. Performance and safety performance.
  • the upper protective layer of the negative current collector 10 is more preferably a double protective layer, that is, a composite layer formed by a metal protective layer and a metal oxide protective layer, wherein preferably, the metal protective layer is disposed on the metal conductive layer 102 is facing away from the surface of the support layer 101, and the metal oxide protective layer is arranged on the surface of the metal protective layer facing away from the support layer 101, which can simultaneously improve the conductivity and corrosion resistance of the negative electrode current collector 10, as well as the metal conductive layer 102 and the negative electrode.
  • the interface between the active material layers, etc., can obtain a negative electrode current collector 10 with better overall performance.
  • the negative electrode current collector 10 includes a supporting layer 101, a metal 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 metal conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101
  • the protective layer 103 is stacked on the surface of the metal conductive layer 102 facing the support layer 101.
  • a protective layer 103 (referred to as the lower protective layer for short) is provided on the surface of the metal conductive layer 102 facing the support layer 101.
  • the lower protective layer protects the metal conductive layer 102 from chemical corrosion and mechanical damage. Improve the bonding force between the metal conductive layer 102 and the support layer 101, prevent the metal conductive layer 102 from separating from the support layer 101, and improve the support and protection effect of the support layer 101 on the metal conductive layer 102.
  • the lower protection layer is a metal oxide or a metal protection layer.
  • the metal oxide protective layer has high corrosion resistance, and its specific surface area is large, which can further improve the interface bonding force between the metal conductive layer 102 and the support layer 101, so that the lower protective layer can better protect the metal conductive layer.
  • the protective effect of 102 improves the performance of the electrochemical device, and the metal oxide protective layer has higher hardness and better mechanical strength, which is more conducive to improving the strength of the negative electrode current collector 10.
  • the metal protective layer can protect the metal conductive layer 102 from chemical corrosion and mechanical damage, and can also improve the conductivity of the negative electrode current collector 10, reduce battery polarization, and reduce the risk of lithium precipitation in the negative electrode. Improve the cycle performance and safety performance of electrochemical devices. Therefore, the lower protective layer of the anode current collector 10 is preferably a metal protective layer.
  • the negative electrode current collector 10 includes a supporting layer 101, a metal 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 metal conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the support layer 101
  • the protective layer 103 is stacked on the surface of the metal conductive layer 102 facing away from the support layer 101 and on the surface facing the support layer 101.
  • the protective layer 103 is provided on both surfaces of the metal conductive layer 102 to more fully protect the metal conductive layer 102, so that the negative electrode current collector 10 has a higher comprehensive performance.
  • the material of the protective layer 103 on the two surfaces of the metal conductive layer 102 may be the same or different, and the thickness 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 protection layer 103 is within the above range, which can effectively protect the metal 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. , 5nm, 2nm, 1nm the like, the scope of the layer thickness D 103 3 may consist of any of the previous two values. Preferably, 5nm ⁇ D 3 ⁇ 200nm. More preferably, 10nm ⁇ D 3 ⁇ 200nm.
  • both surfaces of the metal conductive layer 102 are provided with protective layers 103, that is, an upper protective layer and a lower protective layer are respectively provided on both surfaces of the metal conductive layer 102, and the thickness of the upper protective layer D a is 1nm ⁇ D a ⁇ 200nm, and D a ⁇ 0.1D 1, the thickness of the lower protective layer, D b B to ⁇ 200 nm 1nm ⁇ D, and D b ⁇ 0.1D 1.
  • D a> D b help to protect layer 103 functions as a good protection of metallic conductive layer 102, and the electrochemical device has a high weight energy density. More preferably, 0.5D a ⁇ D b ⁇ 0.8D a .
  • the metal conductive layer 102 may be formed on the support layer 101 by at least one of mechanical rolling, bonding, vapor deposition, electroless plating, and electroplating, and vapor deposition is preferred.
  • Method or electroplating method that is, the metal conductive layer 102 is preferably a vapor deposition layer or an electroplated layer, which can better realize the tight bonding between the metal conductive layer 102 and the support layer 101, and effectively play the role of the support layer 101 on the metal conductive layer 102.
  • the support and protection function is preferred.
  • the bonding force between the support layer 101 and the metal conductive layer 102 is F ⁇ 100 N/m, more preferably F ⁇ 400 N/m.
  • the metal conductive layer 102 is formed on the support layer 101 by vapor deposition.
  • the vapor deposition process conditions such as deposition temperature, deposition rate, and atmosphere conditions of the deposition chamber
  • the density of the metal conductive layer 102 can be adjusted to the same level as the metal.
  • the ratio of the intrinsic density of the materials of the conductive layer 102 meets the aforementioned requirements; further, when the negative electrode current collector 10 is stretched, the sheet resistance growth rate of the metal conductive layer 102 can meet the aforementioned requirements.
  • 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 metal 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 the high-purity metal wire in the metal evaporation chamber at a high temperature of 1300°C to 2000°C After evaporation, 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 metal conductive layer 102.
  • the process of forming the metal conductive layer 102 by mechanical rolling may include: placing a metal sheet in a mechanical roller, rolling it to a predetermined thickness by applying a pressure of 20t-40t, and then placing it on a support that has undergone surface cleaning treatment. The surface of layer 101 is then placed in a mechanical roller, and the two are tightly combined by applying a pressure of 30t to 50t.
  • the process of forming the metal conductive layer 102 by bonding may include: placing a metal sheet in a mechanical roller, rolling it to a predetermined thickness by applying a pressure of 20t to 40t; and then applying a surface cleaning treatment to the surface of the support layer 101 Coat a mixed solution of polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP); finally, bond the metal conductive layer 102 with the predetermined thickness to the surface of the support layer 101 and dry it to make the two tightly bonded .
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the protective layer 103 may be formed on the metal 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, that is, 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 metal conductive layer 102 by at least one of a vapor deposition method and an in-situ formation method, which is beneficial to make the metal conductive layer 102 and the protective layer 103 have a higher bonding force, thereby The protective effect of the protective layer 102 on the negative electrode current collector 10 can be better exerted, and the negative electrode current collector 10 can be guaranteed to have higher working performance.
  • the sheet resistance growth rate T of the metal conductive layer can be measured by a method known in the art.
  • the negative electrode current collector is cut into a sample of 20mm ⁇ 200mm, and four probes are used.
  • the method of using the four-probe method to test the sheet resistance of the metal 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, then place it horizontally on the test bench, put down the four probes to make good contact with the surface of the metal conductive layer, and then adjust the automatic test mode to calibrate the current range of the sample to the appropriate current range Measure the sheet resistance in the next step, and collect 8 to 10 data points of the same sample as data measurement accuracy and error analysis. Finally, the average value is recorded as the sheet resistance value of the metal conductive layer.
  • the sheet resistance R S of the metal conductive layer can be tested with reference to the four-probe method described above, which will not be repeated here.
  • 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 volume resistivity of the support layer is the volume resistivity at 20°C, which can be measured by methods known in the art. As an example, the test is carried out in a constant temperature, normal pressure and low humidity room (20°C, 0.1MPa, RH ⁇ 20%), and a wafer support layer sample with a diameter of 20mm is prepared (the sample size can be adjusted according to the actual size of the test instrument). The three-electrode surface resistivity method (GB T1410-2006) was used to measure the surface resistivity, and the insulation resistance tester (precision 10 ⁇ ) was used.
  • 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 elongation at break of the support layer can be measured by a method known in the art.
  • the support layer is cut into a sample of 15mm ⁇ 200mm, and it is stretched using a high-speed rail tensile machine at normal temperature and pressure (25°C, 0.1MPa).
  • a high-speed rail tensile machine at normal temperature and pressure (25°C, 0.1MPa).
  • For tensile test set the initial position so that the length of the sample between the clamps is 50mm long, and the tensile speed is 50mm/min. Record the device displacement y (mm) at tensile fracture, and finally calculate the elongation at break (y/50) ⁇ 100%.
  • the elongation at break of the metal conductive layer can be conveniently measured using the same method.
  • the binding force F between the support layer and the metal conductive layer can be tested by methods known in the art.
  • the negative electrode current collector with the metal conductive layer provided on one side of the support layer is selected as the sample to be tested, and the width h is 0.02m.
  • Under normal pressure (25°C, 0.1MPa) use 3M double-sided tape to evenly paste on the stainless steel plate, and then evenly paste the sample to be tested on the double-sided tape.
  • a second aspect of the embodiments of the present application provides a negative electrode sheet, which includes a stacked negative current collector and a negative active material layer, wherein the negative current collector is the negative current collector 10 of the first aspect of the embodiments of the present application.
  • the negative pole piece of the embodiment of the present application adopts the negative current collector 10 of the first aspect of the embodiment of the present application, and has a higher weight energy density and good electrochemical performance compared with the traditional negative pole piece.
  • the negative pole piece includes a support layer 101, a metal conductive layer 102, and a negative active material layer that are stacked.
  • the support layer 101 includes a first surface 101a and a second surface 101b opposed to each other.
  • the metal conductive layer 102 is stacked on the support layer 101.
  • the negative electrode active material layer is disposed on the surface of the metal conductive layer 102 facing away from the support layer 101.
  • the negative electrode active material layer may be a negative electrode active material known in the art.
  • 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 , Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel structure lithium titanate and one or more of Li-Al alloy.
  • 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 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 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 N-methylpyrrolidone (NMP) or deionized water to form a uniform negative electrode slurry.
  • NMP N-methylpyrrolidone
  • the negative electrode slurry is coated on After drying and other processes on the negative current collector, a negative pole piece is obtained.
  • 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 negative pole piece is the negative pole piece of the second aspect of the embodiments of this application. In some embodiments, refer to FIG. 10.
  • 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 negative 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 electrochemical performance.
  • the above-mentioned positive electrode piece may include a positive electrode current collector and a positive electrode active material layer provided on the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or porous metal foil including one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
  • the positive electrode active material layer may use positive electrode active materials known in the art.
  • 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. Generally, the positive electrode active material and optional conductive agent and binder are dispersed in a solvent (such as NMP) to form a uniform positive electrode slurry. The positive electrode slurry is coated on the positive electrode current collector, and after drying and other processes, Obtain the positive pole piece.
  • a solvent such as NMP
  • 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 electric core is placed in the packaging shell, electrolyte is injected and sealed to prepare an electrochemical device.
  • the fourth aspect of the embodiments of the present application provides a battery module, which includes any one or several electrochemical devices described in the third aspect of the present application.
  • the number of electrochemical devices included in the battery module can be adjusted according to the application and capacity of the battery module.
  • a plurality of electrochemical devices 5 may be arranged in sequence 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 fifth aspect of the embodiments of the present application provides a battery pack, which includes any one or more of the battery modules described in the fourth aspect of the present application. That is, the battery pack includes any one or several electrochemical devices described in the third aspect of the present application.
  • the number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed 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 sixth aspect of the present application provides a device, which includes any one or several electrochemical devices described in the third aspect of the present application.
  • the electrochemical device can be used as a power source for the device.
  • the device may be, but 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 carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • 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 carts, electric trucks, etc.
  • electric trains ships and satellites, energy storage systems, etc.
  • FIG. 14 shows a device containing the electrochemical device of the present application
  • the device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • the electrochemical device of the present application is the device powered by.
  • the above-mentioned battery module, battery pack and equipment include the electrochemical device provided in the present application, and therefore have at least the same advantages as the electrochemical device, and will not be described in detail here.
  • a support layer of predetermined thickness Place the support layer after surface cleaning treatment in a vacuum coating chamber, and melt and evaporate the high-purity copper 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 metal conductive layer.
  • the material and thickness of the metal conductive layer, the preparation process conditions (such as vacuum, atmosphere, humidity, temperature, etc.), and the material and thickness of the support layer can be adjusted to make the density of the metal conductive layer and the material of the metal conductive layer different.
  • the intrinsic density ratio has different values, and the negative electrode current collector has different T values.
  • 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.
  • Copper foil with a thickness of 8 ⁇ m.
  • the difference from the negative pole piece of the embodiment of the present application is that a conventional negative current collector is used.
  • Aluminum foil with a thickness of 12 ⁇ m.
  • 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.
  • 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 a battery core and packed into the package shell.
  • the above electrolyte is injected into the battery core and then sealed , Standing, hot-cold pressing, forming and other processes to obtain lithium ion secondary batteries.
  • the over-current test of the negative electrode current collector includes: cutting the negative electrode current collector into a width of 100mm, coating the negative electrode active material layer with a width of 80mm in the middle of the width direction and rolling it into a negative electrode piece, and then pressing the rolled
  • the pole pieces are cut into strips of 100mm ⁇ 30mm along the width direction, and 10 pieces of each pole piece are cut.
  • the lithium ion secondary battery is charged to 4.2V at a constant current rate of 1C, then charged at a constant voltage until the current is less than or equal to 0.05C, and then discharged at a constant current rate of 1C to 2.8V, which is a charge and discharge Cycle, the discharge capacity this time is the discharge capacity of the first cycle.
  • the battery was subjected to 1000 charge and discharge cycles according to the above method, and the discharge capacity of the 1000th cycle was recorded.
  • 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%
  • the lithium ion secondary battery is charged to 4.2V at a constant current rate of 1C, then charged at a constant voltage until the current is less than or equal to 0.05C, and then discharged to 3.0V at a rate of 1C at a constant current rate, and the lithium ion secondary battery is tested. 1C rate discharge capacity of the battery.
  • the lithium ion secondary battery is charged to 4.2V at a constant current rate of 1C, then charged at a constant voltage until the current is less than or equal to 0.05C, and then discharged to 3.0V at a rate of 4C at a constant current rate, and the test obtains the lithium ion secondary
  • the battery has a 4C rate discharge capacity.
  • Lithium ion secondary battery 4C rate capacity retention rate (%) 4C rate discharge capacity/1C rate discharge capacity ⁇ 100%
  • the ratio is the ratio of the density ⁇ 1 of the metal conductive layer to the intrinsic density ⁇ 2 of the material of the metal conductive layer;
  • the composition of the copper alloy is: 95wt% copper and 5wt% nickel;
  • the volume resistivity of the support layer is 2.1 ⁇ 10 14 ⁇ m, and the thickness D 2 of the support layer is 8 ⁇ m.
  • the electrical performance test of the negative electrode current collector in Table 1 is performed, and the test results are shown in Table 2.
  • the electrical performance of the negative electrode current collector is better, and the pass rate in the overcurrent test is higher.
  • T ⁇ 5% Preferably, T ⁇ 2%. More preferably, T ⁇ 1%.
  • the use of the anode current collector of the embodiments of the present application can improve the electrochemical performance of the battery.
  • the weight percentage of the negative electrode current collector is the weight of the negative electrode current collector per unit area divided by the weight of the conventional negative electrode current collector per unit area.
  • the weight of the negative electrode current collector of the present application can be reduced to varying degrees, thereby increasing the weight energy density of the battery.
  • the negative electrode current collector is a protective layer provided on the basis of the negative electrode current collector 20 in Table 3;
  • the nickel-based alloy contains: 90wt% nickel and 10wt% chromium;
  • the double-layer protective layer includes a nickel protective layer disposed on the surface of the metal conductive layer facing away from the support layer, with a thickness of 25nm; and a nickel oxide protective layer disposed on the surface of the nickel protective layer facing away from the support layer, with a thickness of 25nm.

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Abstract

本申请公开了一种负极集流体、负极极片、电化学装置、电池模块、电池包及设备，负极集流体包括支撑层及设置于支撑层上的金属导电层，其中，金属导电层的密度与金属导电层的材料的本征密度之比大于或等于0.7，金属导电层的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。本申请提供的负极集流体能够同时兼顾较低的重量及较高的电性能，从而能够使电化学装置同时兼顾较高的重量能量密度及电化学性能。

Description

负极集流体、负极极片、电化学装置、电池模块、电池包及设备
本申请要求于2019年07月01日提交中国专利局、申请号为201910586055.8、发明名称为“负极集流体、负极极片及电化学装置”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
本申请属于电化学装置技术领域，尤其涉及一种负极集流体、负极极片、电化学装置、电池模块、电池包及设备。
背景技术
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，随着二次电池的应用范围不断扩大，大家对二次电池的重量能量密度的要求也越来越高。
为了得到重量能量密度较高的二次电池，可以对二次电池的各部件进行减重。其中，对集流体的改进通常是选择重量较轻的集流体，例如可以采用镀有金属层的塑料集流体等。然而，对于镀有金属层的塑料集流体来说，虽然重量得以减轻，但是带来电性能等方面的一些性能劣化，影响极片及电池的性能。要得到性能良好的集流体，还需要很多方面的改进。
基于此，提出本申请。
申请内容
本申请实施例提供一种负极集流体、负极极片、电化学装置、电池模块、电池包及设备，旨在使负极集流体同时兼顾较低的重量及较高的电性能，以使电化学装置同时兼顾较高的重量能量密度及电化学性能。
本申请实施例的第一方面提供一种负极集流体，负极集流体包括：
支撑层，在自身厚度方向上包括相对的两个表面；
金属导电层，设置于支撑层的两个所述表面中的至少一者上；
其中，金属导电层的密度与金属导电层的材料的本征密度之比大于或等于0.7，金属导电层的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。
本申请实施例的第二方面提供一种负极极片，负极极片包括负极集流体以及设置于负极集流体上的负极活性材料层，其中负极集流体为如本申请实施例第一方面的负极集流体。
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，其中负极极片为如本申请实施例第二方面的负极极片。
本申请的第四方面提供了一种电池模块，其包括本申请的第三方面所述的电化学装置。
本申请的第五方面提供了一种电池包，其包括本申请的第四方面所述的电池模块。
本申请的第六方面提供了一种设备，其包括本申请的第三方面所述的电化学装置，所述电化学装置用作所述设备的电源。
优选地，所述设备包括移动设备、电动车辆、电气列车、卫星、船舶及储能系统。
本申请实施例提供的负极集流体，将厚度较小的金属导电层设置于支撑层的至少一个表面，能够显著降低负极集流体的重量，从而显著提高电化学装置的重量能量密度。另外，金属导电层的密度与金属导电层的材料的本征密度之比大于或等于0.7，且金属导电层的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种，在负极集流体的加工及使用等过程中，可以防止厚度较小的金属导电层因拉伸而被破坏、或者因拉伸形变而导致的电阻急剧增大，保证负极集流体具有较高的结构稳定性以及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。
本申请的电池模块、电池包和设备包括所述的电化学装置，因而至少具有与所述电化学装置相同的优势。
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负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负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负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负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负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负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负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负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负极集流体的结构示意图。
图10示出了本申请一个实施例提供的电化学装置的结构示意图。
图11示出了本申请一个实施例提供的电池模块的结构示意图。
图12示出了本申请一个实施例提供的电池包的结构示意图。
图13是图12的分解图。
图14是电化学装置用作电源的设备的一实施方式的示意图。
标号说明：
10、负极集流体；
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、金属导电层；
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
为了使本申请的发明目的、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”的含义是两种以上。
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。
负极集流体
本申请实施例的第一方面提供一种负极集流体10，请参照图1和图2，负极集流体10包括层叠设置的支撑层101及金属导电层102。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，金属导电层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。
负极集流体10中，金属导电层102的密度与金属导电层102的材料的本征密度之比大于或等于0.7，且金属导电层102的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。
金属导电层102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的负极集流体10(其中金属导电层102为金属铜)，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。将称量完的负极集流体10用1mol/L的FeCl 3水溶液浸泡12h，待金属导电层102完全溶解，取出支撑层101，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。根据如下式1计算金属导电层102的密度，单位g/cm 3。
Figure PCTCN2019121587-appb-000001
为了进一步提高测量精确度，可以取5片同样大小的负极集流体10分别测试金属导电层102的密度，结果取平均值。
其中，铜的本征密度为8.96g/cm 3，铜合金的本征密度为6.5g/cm 3～9g/cm 3，镍的本征密度为8.9g/cm 3，镍合金的本征密度为6.0g/cm 3～9.0g/cm 3，钛的本征密度为4.51g/cm 3，钛合金的本征密度为4.0g/cm 3～5.0g/cm 3，银的本征密度为10.49g/cm 3，银合金的本征密度为9.0g/cm 3～12.0g/cm 3。
本申请实施例的负极集流体10，将厚度较小的金属导电层102设置于支撑层101的至少一个表面，相对于传统金属负极集流体(如铜箔)而言，能够显著降低负极集流体10的重量，从而显著提高电化学装置的重量能量密度。
另外，负极集流体10在制备、以及负极极片和电化学装置的加工及使用过程中，例如极片辊压或电池膨胀过程中，难免会被拉伸。使金属导电层102的密度与金属导电层102的材料的本征密度之比大于或等于0.7，且金属导电层102的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种，能够防止厚度较小的金属导电层102因拉伸而被 破坏，以及防止厚度较小的金属导电层102因拉伸形变而导致的导电性分布不均和电阻急剧增大，保证负极集流体10具有良好且均匀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。
因此，采用本申请实施例的负极集流体10，使得电化学装置同时兼顾较高的重量能量密度及电化学性能。
本申请实施例的负极集流体10，支撑层101的厚度D 2优选为1μm≤D 2≤20μm，例如可以为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，2μm≤D 2≤10μm。更优选地，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，在负极集流体10的加工及使用过程中不易发生断裂，对金属导电层102起到良好的支撑和保护作用，保证负极集流体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，从而提高电化学装置的能量密度。
在一些实施例中，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对金属导电层102的支撑与保护作用，确保负极集流体10的整体强度。在负极集流体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和金属导电层102之间地结合牢度，不易发生脱离，使负极集流体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。
进一步地，支撑层101的杨氏模量E为1.9GPa≤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，能够在负极集流体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、2.5GPa、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。
在一些实施例中，优选地，支撑层101的体积电阻率大于或等于1.0×10 -5Ω·m。由于支撑层101的体积电阻率较大，在电化学装置发生穿钉等异常情况下，能够增大电化学装置发生内短路时的短路电阻，从而提高电化学装置的安全性能。
在一些实施例中，优选地，支撑层101的断裂伸长率大于或等于金属导电层102的断裂伸长率，从而更好地防止负极集流体10发生断带。
可选地，支撑层101的断裂伸长率大于或等于5％，优选地，支撑层101的断裂伸长率大于或等于10％。
在一些实施例中，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明显较金属的密度小，从而较传统的金属集流体来说，明显减轻负极集流体10的重量，提高电化学装置的能量密度。
上述高分子材料，例如是聚酰胺(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。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。
无机非金属材料例如添加剂是碳基材料、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。支撑层101的体积电阻率较高，能够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。
本申请实施例的负极集流体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，金属导电层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，金属导电层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。
在一些实施例中，金属导电层102的材料优选为铜或铜合金。上述铜合金中铜元素的重量百分含量优选为90％以上。上述铜合金例如可以为铜 镍合金。
金属导电层102的材料为铜或铜合金时，金属导电层102的密度优选为6.5g/cm 3～8.96g/cm 3，如6.5g/cm 3、6.8g/cm 3、7.0g/cm 3、7.2g/cm 3、7.5g/cm 3、7.8g/cm 3、8.0g/cm 3、8.1g/cm 3、8.2g/cm 3、8.3g/cm 3、8.4g/cm 3、8.5g/cm 3、8.6g/cm 3、8.7g/cm 3、8.8g/cm 3、8.9g/cm 3、8.96g/cm 3等。更优选地，金属导电层102的材料为铜或铜合金时，金属导电层102的密度为8.0g/cm 3～8.96g/cm 3。
金属导电层102的材料为铜或铜合金时，金属导电层102的密度优选为6.5g/cm 3～8.96g/cm 3，更优选为8.0g/cm 3～8.96g/cm 3，能够更好地保证负极集流体10具有良好的加工性能及导电和集流的性能，提高电化学装置的电化学性能。
在一些实施例中，金属导电层102的体积电阻率优选为1.3×10 -8Ω·m～1.3×10 -7Ω·m，更优选为1.3×10 -8Ω·m～3.3×10 -8Ω·m，有利于使负极集流体10具有更好的导电和集流的性能，从而改善电化学装置的性能。
在一些实施例中，负极集流体10的拉伸应变为2％时，金属导电层102的方块电阻增长率T为T≤10％，如T为10％、9％、8％、7％、6％、5％、4％、3％、2％、1％、0.5％或0。优选地，T≤5％。更优选地，T≤2％。更优选地，T≤1％。
负极集流体10在负极极片及电化学装置的加工及使用过程中，例如极片的辊压或电池膨胀过程中，有时会被拉伸。使负极集流体10的拉伸应变为2％时，金属导电层102的方块电阻增长率T为10％以下，能够有效防止金属导电层102因拉伸形变而导致的电阻急剧增大，保证负极集流体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，从而使电化学装置具有较高的电化学性能，其中具有较高的倍率性能及循环性能。
上述金属导电层102的方块电阻增长率T可以随着负极集流体10的支撑层101和金属导电层102的选材、性能、厚度，以及支撑层101与金属导电层102之间的结合力等的变化而变化。
在一些实施例中，金属导电层102的厚度D 1优选为300nm≤D 1≤2μm，如2μm、1.8μm、1.5μm、1.2μm、1μm、900nm、800nm、700nm、600nm、 500nm、450nm、400nm、350nm或300nm。金属导电层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≤1.5μm。更优选地，D 1为800nm≤D 1≤1.2μm。
金属导电层102的厚度优选为2μm以下，再优选1.5μm以下，更优选为1.2μm以下，负极集流体10具有显著降低的重量，有利于改善电化学装置的重量能量密度。金属导电层102的厚度优选为300nm以上，再优选为500nm以上，更优选为800nm以上，有利于使负极集流体10具有良好的导电和集流的性能，并且在负极集流体10加工及使用过程中不易发生破损，使负极集流体10具有良好的机械稳定性及较高的使用寿命。
在一些实施例中，请参照图4至图9，负极集流体10进一步还可以包括保护层103。具体地，金属导电层102在自身厚度方向上包括相对的两个表面，保护层103层叠设置于金属导电层102的两个表面中的任意一者或两者上，以保护金属导电层102，防止金属导电层102发生化学腐蚀或机械破坏等损害，保证负极集流体10具有较高的工作稳定性及使用寿命。此外，保护层103还能够增强负极集流体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。其中，采用金属材料的保护层103为金属保护层；采用金属氧化物材料的保护层103为金属氧化物保护层。
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，负极集流体10包括层叠设置的支 撑层101、金属导电层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，金属导电层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层叠设置于金属导电层102的背向支撑层101的表面。
在金属导电层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)，对金属导电层102起到防化学腐蚀、防机械破坏的保护作用，还能够改善负极集流体10与负极活性材料层之间的界面，提高负极集流体10与负极活性材料层之间的结合力。
在一些实施例中，负极集流体10的上保护层可以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，可以更好地保护金属导电层102。
进一步地，负极集流体10的上保护层优选为金属保护层，金属保护层可以提高负极集流体10的导电性能，能够减小电池极化，降低负极析锂的风险，提高电化学装置的循环性能及安全性能。
进一步地，负极集流体10的上保护层更优选为双层保护层，即一层金属保护层和一层金属氧化物保护层形成的复合层，其中优选地，金属保护层设置于金属导电层102背向支撑层101的表面，金属氧化物保护层设置于金属保护层背向支撑层101的表面，这样可以同时改善负极集流体10的导电性能、抗腐蚀性能、以及金属导电层102与负极活性材料层之间的界面等，能够得到综合性能更好的负极集流体10。
作为另一些示例，请参照图6和图7，负极集流体10包括层叠设置的支撑层101、金属导电层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，金属导电层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层叠设置于金属导电层102的朝向支撑层101的表面。
在金属导电层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)，下保护层对金属导电层102起到防化学腐蚀、防机械损害的保护作用的同时，还能够提高金属导电层102与支撑层101之间的结合力，防止金属导电层102与支撑层101分离，提高支撑层101对金属导电 层102的支撑保护作用。
可选地，下保护层为金属氧化物或金属保护层。金属氧化物保护层的耐腐蚀性能较高，且其比表面积大，能够更加提高金属导电层102与支撑层101之间的界面结合力，从而使下保护层更好的起到对金属导电层102的保护作用，提高电化学装置的性能，且金属氧化物保护层的硬度更高、机械强度更好，更加有利于提高负极集流体10的强度。金属保护层可以在对金属导电层102起到防化学腐蚀、防机械损害的保护作用的同时，还能够提高负极集流体10的导电性能，能够减小电池极化，降低负极析锂的风险，提高电化学装置的循环性能及安全性能。因此，负极集流体10的下保护层优选为金属保护层。
作为又一些示例，请参照图8和图9，负极集流体10包括层叠设置的支撑层101、金属导电层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，金属导电层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层叠设置于金属导电层102的背向支撑层101的表面以及朝向支撑层101的表面上。
在金属导电层102的两个表面上均设置保护层103，更加充分地保护金属导电层102，使负极集流体10具有较高的综合性能。
可以理解的是，金属导电层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，能够对金属导电层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，当金属导电层102的两个表面均设置有保护层103时，即在金属导电层102的两个表面上分别设置有上保护层及下保护层，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＞D b，有利于保护层103对金属导电层102起到良好的保护作用，并且使电化学装置具有较高的重量能量密度。更优选地，0.5D a≤D b≤0.8D a。
金属导电层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法，即金属导电层102优选为气相沉积层或电镀层，这样可以更好地实现金属导电层102与支撑层101之间的紧密结合，有效地发挥支撑层101对金属导电层102的支撑及保护作用。
优选地，支撑层101与金属导电层102之间的结合力F≥100N/m，更优选为F≥400N/m。
例如，通过气相沉积法将金属导电层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，可以使金属导电层102的密度与金属导电层102的材料的本征密度之比满足前文所述的要求；进一步可以使负极集流体10被拉伸时，金属导电层102的方块电阻增长率满足前文所述的要求。
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金属导电层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，形成金属导电层102。
通过机械辊轧形成金属导电层102的工艺可以包括：将金属片置于机械辊中，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。
通过粘结形成金属导电层102的工艺可以包括：将金属片置于机械辊 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金属导电层102粘结于支撑层101的表面，并烘干，使两者紧密结合。
当负极集流体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金属导电层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，即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金属导电层102上，有利于使金属导电层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对负极集流体10的保护作用，并保证负极集流体10具有较高的工作性能。
本申请实施例中，负极集流体的拉伸应变设为ε，则ε＝ΔL/L×100％，其中，ΔL是负极集流体被拉伸产生的伸长量，L是负极集流体的原长，即被拉伸之前的长度。
负极集流体的拉伸应变ε为2％时，金属导电层的方块电阻增长率T可以采用本领域已知的方法测定，作为示例，取负极集流体裁剪成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的2％，之后取下拉伸后的样品，测试夹具之间金属导电层的方块电阻，记录为R 2，根据公式T＝(R 2-R 1)/R 1×100％，计算得到负极集流体的拉伸应变为2％时金属导电层的方块电阻增长率T。
其中采用四探针法测试金属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，使探针与金属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 平均值记录为金属导电层的方块电阻值。
金属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为金属导电层的方块电阻，单位为Ω；d为金属导电层以m为单位的厚度。可以参照前文所述的四探针法测试金属导电层的方块电阻R S，在此不再赘述。
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ξ＝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。
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 T1410-2006)，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。
支撑层的断裂伸长率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为(y/50)×100％。金属导电层的断裂伸长率可以采用同样的方法方便地测定。
可以采用本领域已知的方法测试支撑层与金属导电层之间的结合力F，例如选用金属导电层设置于支撑层一面上的负极集流体为待测样品，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金属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计算得到金属导电层与支撑层之间的结合力F(N/m)。
负极极片
本申请实施例第二方面提供一种负极极片，包括层叠设置的负极集流体及负极活性材料层，其中负极集流体为本申请实施例第一方面的负极集流体10。
本申请实施例的负极极片，由于采用了本申请实施例第一方面的负极集流体10，与传统的负极极片相比，具有较高的重量能量密度及良好的电化学性能。
作为示例，负极极片包括层叠设置的支撑层101、金属导电层102及负极活性材料层，支撑层101包括相对的第一表面101a和第二表面101b，金属导电层102层叠设置于支撑层101的第一表面101a和/或第二表面101b上，负极活性材料层设置于金属导电层102的背向支撑层101的表面上。
本申请实施例的负极极片，负极活性材料层可以采用本领域已知的负极活性材料。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、SnO2、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，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。
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以及可选的导电剂和粘结剂分散于溶剂中，溶剂可以是N-甲基吡咯烷酮(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。
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，其中负极极片为本申请实施例第二方面的负极极片。在一些实施例中，参照图10所示。
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负极极片，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及良好的电化学性能。
上述正极极片可以是包括正极集流体及设置于正极集流体上的正极活性材料层。
正极集流体可以为包括铝、铝合金、镍、镍合金、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。
正极活性材料层可以采用本领域已知的正极活性材料。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以及可选的导电剂及粘结剂分散于溶剂(例如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。
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，得到电芯，也可以是经卷绕后得到电芯；将电芯置于包装外壳中，注入电解液并封口，制备电化学装置。
电池模块
本申请实施例的第四方面提供一种电池模块，其包括本申请第三方面所述的任意一种或几种电化学装置。
进一步，包括在所述电池模块中的电化学装置的数量可以根据电池模块的应用和容量进行调节。
在一些实施例中，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。
电池包
本申请实施例的第五方面提供一种电池包，其包括本申请第四方面所述的任意一种或几种电池模块。也就是，该电池包包括本申请第三方面所述的任意一种或几种电化学装置。
所述电池包中电池模块的数量可以根据电池包的应用和容量进行调节。
在一些实施例中，请参照图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。
设备
本申请第六方面提供一种设备，其包括本申请第三方面所述的任意一种或几种电化学装置。所述电化学装置可以用作所述设备的电源。
优选地，所述设备可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
例如，图14示出了一种包含本申请的电化学装置的设备，该设备为纯电动车、混合动力电动车、或插电式混合动力电动车等，本申请的电化学装置为该设备供电。
上述电池模块、电池包和设备包括本申请提供的电化学装置，因而至少具有与所述电化学装置相同的优势，在此不再详细描述。
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
负极集流体的制备
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铜丝熔化蒸发，蒸发后的金属经过真空镀室内的冷却系统，最后沉积于支撑层的两个表面，形成金属导电层。
可以通过调整金属导电层的材料、厚度、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，使得金属导电层的密度与金属导电层的材料的本征密度之比具有不同的值，以及使得负极集流体具有不同的T值。
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。
常规负极集流体
厚度为8μm的铜箔。
常规负极极片的制备
与本申请实施例的负极极片不同的是，采用常规负极集流体。
正极集流体
厚度为12μm的铝箔。
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。
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，然后卷绕成电芯并装入包装外壳中，将上述电解液注入到电芯中，之后经过密封、静置、热冷压、化成等工序，得到锂离子二次电池。
测试部分
1.负极集流体的测试
(1)电性能测试
对负极集流体进行过流测试，包括：将负极集流体剪裁成100mm幅宽，在幅宽方向正中的位置涂布80mm宽的负极活性材料层并辊压制作成负极极片，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4A电流通过极片，保持1h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，记录测试通过率。
(2)按照前文所述的测试方法对负极集流体进行其他测试。
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)倍率性能测试
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，再以1C倍率恒流放电至3.0V，测试得到锂离子二次电池1C倍率放电容量。
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，再以4C倍率恒流放电至3.0V，测试得到锂离子二次电池4C倍率放电容量。
锂离子二次电池4C倍率容量保持率(％)＝4C倍率放电容量/1C倍率放电容量×100％
测试结果
1.本申请负极集流体的电性能
表1
Figure PCTCN2019121587-appb-000002
Figure PCTCN2019121587-appb-000003
表1中：
比值是金属导电层的密度ρ 1与金属导电层的材料的本征密度ρ 2之比；铜合金的成分为：铜95wt％，镍5wt％；
支撑层的体积电阻率均为2.1×10 14Ω·m，支撑层的厚度D 2均为8μm。对表1中的负极集流体进行电性能测试，测试结果示于表2。
表2
Figure PCTCN2019121587-appb-000004
Figure PCTCN2019121587-appb-000005
从表2中的数据可以看到，当金属导电层的密度与金属导电层的材料的本征密度之比小于0.7时，负极集流体的电性能较差，例如对比负极极片，在过流测试中通过率较低，在电池产品中实用价值不大。而本申请实施例的负极集流体，金属导电层的密度与金属导电层的材料的本征密度之比为0.7以上，负极集流体的电性能较好，负极极片在过流测试中通过率显著提高。
进一步地，当负极集流体的拉伸应变为2％，金属导电层的方块电阻增长率T为10％以下，负极集流体的电性能更好，在过流测试中通过率更高。优选地，T≤5％。优选地，T≤2％。更优选地，T≤1％。
因此，采用本申请实施例的负极集流体能够提高电池的电化学性能。
2.本申请负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3
Figure PCTCN2019121587-appb-000006
表1中，负极集流体重量百分数是单位面积负极集流体重量除以单位面积常规负极集流体重量的百分数。
相较于传统的铜箔负极集流体，采用本申请的负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。
3.保护层的作用
表4
Figure PCTCN2019121587-appb-000007
表4中：负极集流体是在表3中负极集流体20的基础上设置保护层；
镍基合金中含有：镍90wt％，铬10wt％；
双层保护层包括设置于金属导电层背向支撑层的表面的镍保护层，厚度为25nm；以及设置于镍保护层背向支撑层的表面的氧化镍保护层，厚度为25nm。
表5
Figure PCTCN2019121587-appb-000008
Figure PCTCN2019121587-appb-000009
由表5可知，采用本申请实施例负极集流体的电池的循环寿命及倍率性能良好，与采用常规负极集流体电池的循环性能及倍率性能相当。这说明采用本申请实施例的负极集流体不会对负极极片和电池的电化学性能有明显的不利影响。尤其是设置有保护层的负极集流体制成的电池，45℃、1C/1C循环1000次后的容量保持率及4C倍率容量保持率进一步获得提升，说明电池的可靠性更好。
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 (13)

  1. 一种负极集流体，其特征在于，包括：
    支撑层，在所述支撑层的厚度方向上包括相对的两个表面；
    金属导电层，设置于所述支撑层的两个所述表面中的至少一者上；
    其中，所述金属导电层的密度与所述金属导电层的材料的本征密度之比大于或等于0.7，所述金属导电层的材料为铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。
  2. 根据权利要求1所述的负极集流体，其特征在于，
    所述金属导电层的材料为铜或铜合金，所述金属导电层的密度为6.5g/cm 3～8.96g/cm 3，优选为8.0g/cm 3～8.96g/cm 3；和/或，
    所述金属导电层为气相沉积层或电镀层。
  3. 根据权利要求1所述的负极集流体，其特征在于，所述金属导电层的厚度D 1为300nm≤D 1≤2μm，优选为500nm≤D 1≤1.5μm，更优选为800nm≤D 1≤1.2μm；和/或，
    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1.9GPa≤E≤20GPa。
  4. 根据权利要求1所述的负极集流体，其特征在于，所述金属导电层的体积电阻率为1.3×10 -8Ω·m～1.3×10 -7Ω·m，优选的为1.3×10 -8Ω·m～3.3×10 -8Ω·m。
  5. 根据权利要求1所述的负极集流体，其特征在于，所述负极集流体的拉伸应变为2％时，所述金属导电层的方块电阻增长率T为T≤10％，优选为T≤5％，优选为T≤2％，更优选为T≤1％。
  6. 根据权利要求1所述的负极集流体，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、及上述材料的衍生物、上述材料的交联物及上述材料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。
  7. 根据权利要求1所述的负极集流体，其特征在于，进一步包括保护层，所述保护层设置于所述金属导电层自身厚度方向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；和/或，
    优选地，所述保护层的厚度D 3为1nm≤D 3≤200nm，且所述保护层的厚度D 3与所述金属导电层的厚度D 1之间满足D 3≤0.1D 1。
  8. 根据权利要求7所述的负极集流体，其特征在于，所述保护层包括设置于所述金属导电层背向所述支撑层的表面的上保护层、以及设置于所述金属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，优选地，0.5D a≤D b≤0.8D a；和/或，
    优选地，所述上保护层为金属保护层；和/或，
    优选地，所述下保护层为金属保护层；和/或，
    优选地，所述上保护层为双层保护层，所述双层保护层包括设置于所述金属导电层背向所述支撑层的表面的金属保护层、以及设置于所述金属保护层背向所述支撑层的表面的金属氧化物保护层。
  9. 一种负极极片，其特征在于，所述负极极片包括负极集流体以及设置于所述负极集流体上的负极活性材料层，其中所述负极集流体为如权利要求1至8任一项所述的负极集流体。
  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，其中所述负极极片为如权利要求9所述的负极极片。
  11. 一种电池模块，其特征在于，包括权利要求10所述的电化学装置。
  12. 一种电池包，其特征在于，包括权利要求11所述的电池模块。
  13. 一种设备，其特征在于，包括权利要求10所述的电化学装置，所述电化学装置用作所述设备的电源；
    优选的，所述设备包括移动设备、电动车辆、电气列车、卫星、船舶及储能系统。
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