WO2020237712A1 - 负极集流体、负极极片及电化学装置 - Google Patents

负极集流体、负极极片及电化学装置 Download PDF

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WO2020237712A1
WO2020237712A1 PCT/CN2019/090403 CN2019090403W WO2020237712A1 WO 2020237712 A1 WO2020237712 A1 WO 2020237712A1 CN 2019090403 W CN2019090403 W CN 2019090403W WO 2020237712 A1 WO2020237712 A1 WO 2020237712A1
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Prior art keywords
copper
current collector
negative electrode
electrode current
layer
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PCT/CN2019/090403
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English (en)
French (fr)
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刘欣
黄起森
王铈汶
盛长亮
彭佳
李铭领
刘向辉
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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 EP19930526.9A priority Critical patent/EP3972018B1/en
Priority to KR1020217034236A priority patent/KR20210143852A/ko
Priority to JP2021557695A priority patent/JP2022528846A/ja
Publication of WO2020237712A1 publication Critical patent/WO2020237712A1/zh
Priority to US17/537,516 priority patent/US20220085380A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—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
    • 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
    • H01M4/133—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
    • H01M4/64—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
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte

Definitions

  • Electrochemical devices such as lithium ion secondary batteries, have good charge and discharge performance and are environmentally friendly, and are widely used in electric vehicles and consumer electronic products.
  • the current collector is an important part of the electrochemical device. It not only provides support for the active material layer, but also collects the current generated by the active material layer for external output. Therefore, the current collector has an important influence on the performance of electrode pole pieces and electrochemical devices.
  • the embodiments of the present application provide a negative electrode current collector, a negative pole piece, and an electrochemical device, aiming to improve the mechanical properties of the negative electrode current collector, and make it have a small weight and good electrical conductivity and current collection performance.
  • an embodiment of the present application provides a negative electrode piece.
  • the negative electrode piece includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, wherein the negative electrode current collector is a negative electrode collector according to one aspect of the embodiments of the present application. fluid.
  • an embodiment of the present application provides an electrochemical device.
  • the electrochemical device includes a positive pole piece, a negative pole piece 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.
  • the negative electrode current collector, negative electrode piece and electrochemical device provided by the embodiments of the present application.
  • the negative electrode current collector includes an organic support layer and a copper-based conductive layer disposed on the organic support layer.
  • the support layer using organic materials is lighter in weight and has It is beneficial to make the negative electrode current collector and negative pole piece have a smaller weight, so that the electrochemical device has a higher weight energy density; in addition, the support layer of organic material has higher toughness, and the copper in the copper-based conductive layer
  • the base crystal grain size d is 10nm ⁇ 500nm, which makes the copper-based conductive layer and the organic support layer have a high interface bonding force, and the copper-based conductive layer can be uniformly deformed with the extension of the organic support layer, effectively preventing local stress concentration , Greatly reducing the probability of the copper-based conductive layer breaking, thereby greatly improving the fracture toughness of the negative electrode current collector, improving the mechanical properties of the negative electrode current collector, and then significantly improving the preparation process of the negative electrode current collector, the
  • Fig. 2 is a schematic structural diagram of a negative electrode current collector according to another embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of a negative electrode current collector according to another embodiment of the present application.
  • Fig. 6 is a schematic structural diagram of a negative pole piece according to an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a negative electrode current collector 10 according to an embodiment of the present application. Please refer to FIG. 1.
  • the negative electrode current collector 10 includes an organic support layer 101 and a copper-based conductive layer 102 that are stacked.
  • the organic support layer 101 has a first surface 101 a and a second surface 101 b opposite in the thickness direction, and the copper-based conductive layer 102 is disposed on the first surface 101 a and the second surface 101 b of the organic support layer 101.
  • the copper-based crystal grain size d in the copper-based conductive layer 102 is 10 nm to 500 nm.
  • the copper-based crystal grain size d in the copper-based conductive layer 102 can be tested according to the following test method: X-ray diffraction analysis is performed on the negative current collector 10, and the diffraction peak of the copper-based conductive layer 102 is measured, such as Cu (111 ) The diffraction peak of the crystal plane, according to the diffraction angle and half-height width of the diffraction peak, the copper-based crystal grain size d is calculated using the Scherrer formula. The specific formula is
  • the negative electrode current collector 10 can be subjected to X-ray diffraction analysis using instruments and methods known in the art, for example, an X-ray powder diffractometer is used to determine the X-ray diffraction spectrum in accordance with JIS K0131-1996 X-ray diffraction analysis general rules.
  • an X-ray powder diffractometer is used to determine the X-ray diffraction spectrum in accordance with JIS K0131-1996 X-ray diffraction analysis general rules.
  • the scanning 2 ⁇ angle range is 20° ⁇ 80°, and the scanning rate is 0.05°/s.
  • the negative current collector 10 of the embodiment of the present application includes an organic support layer 101 and a copper-based conductive layer 102 disposed on the organic support layer 101.
  • the support layer made of organic materials has high toughness, and the copper-based crystal grain size d in the copper-based conductive layer 102 is 10 nm to 500 nm, so that the copper-based conductive layer 102 and the organic support layer 101 have a higher interface
  • the copper-based conductive layer 102 can be uniformly deformed with the extension of the organic support layer 101, effectively preventing local stress concentration, greatly reducing the probability of the copper-based conductive layer 102 breaking, thereby greatly improving the fracture of the negative electrode current collector 10 Toughness improves the mechanical properties of the negative electrode current collector 10, prevents the negative electrode current collector 10 from breaking or forming microcracks during processing or use, thereby significantly improving the negative electrode current collector 10, the negative electrode piece 20 and the electrochemical device during the preparation process. The rate of excellence and the safety and reliability during use.
  • the range of the copper-based crystal grain size d in the copper-based conductive layer 102 can be formed by a combination of any lower limit and any upper limit, or a combination of any lower limit and any other lower limit, and can also be formed by any upper limit and any other upper limit. Combination formation.
  • the thickness D 1 of the copper-based conductive layer 102 is preferably 30 nm ⁇ D 1 ⁇ 3 ⁇ m.
  • the upper limit of the thickness D 1 of the copper-based conductive layer 102 may be selected from 3 ⁇ m, 2.5 ⁇ m, 2 ⁇ m, 1.8 ⁇ m, 1.5 ⁇ m, 1.2 ⁇ m, 1 ⁇ m, 900 nm, 750 nm, 450 nm, 250 nm, 100 nm.
  • the conductive copper layer to a thickness of 1 D 102 300nm ⁇ D 1 ⁇ 2 ⁇ m, preferably 500nm ⁇ D 1 ⁇ 1.5 ⁇ m, further to 600nm ⁇ D 1 ⁇ 1.2 ⁇ m.
  • the thickness D 1 of the copper-based conductive layer 102 and the copper-based crystal grain size d satisfy 1 ⁇ D 1 /d ⁇ 300.
  • the above relationship between the thickness D 1 of the copper-based conductive layer 102 and the copper-based crystal grain size d can enable the negative electrode current collector 10 to have better mechanical properties, as well as higher conductivity and current collection performance.
  • the copper-based conductive layer 102 includes one or more of copper (Cu) and copper alloy.
  • Copper alloy is an alloy in which copper is the main element and contains one or more additional elements.
  • the additive element is selected from titanium (Ti), vanadium (V), nickel (Ni), chromium (Cr), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), zirconium ( Zr), molybdenum (Mo), niobium (Nb), tungsten (W), silver (Ag), palladium (Pd) and cadmium (Cd).
  • the additive element is selected from titanium (Ti), vanadium (V), nickel (Ni), chromium (Cr), iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), zirconium ( Zr), molybdenum (Mo), niobium (Nb), tungsten (W), silver (Ag), palladium (Pd) and cadmium (Cd).
  • the introduction of one or more of the above-mentioned additional elements
  • the mass percentage of the copper element in the copper alloy is 80 wt% or more, more preferably 90 wt% or more, for example, 90 wt% to 95 wt%.
  • the mass percentage of the copper element in the copper alloy is within the above-mentioned range, which enables the copper alloy conductive layer to have higher conductivity, mechanical properties, processing resistance and corrosion resistance.
  • the Young's modulus E of the organic support layer 101 is preferably E ⁇ 2GPa, which makes the organic support layer 101 have good toughness and appropriate rigidity, which not only meets the requirements of the organic support layer
  • the support function of 101 on the copper-based conductive layer 102 ensures the overall strength of the negative electrode current collector 10, and also prevents the organic support layer 101 from being excessively stretched or deformed during the processing of the negative electrode current collector 10, which more effectively prevents The organic support layer 101 and the copper-based conductive layer 102 are broken.
  • the bonding strength between the organic support layer 101 and the copper-based conductive layer 102 is higher, so that the copper-based conductive layer 102 is not easy to peel off, and the negative electrode current collector 10 is improved.
  • Mechanical stability and working stability thereby improving the performance of electrochemical devices.
  • the Young's modulus E of the organic support layer 101 is preferably 2GPa ⁇ E ⁇ 20Gpa, for example 2GPa, 3GPa, 4GPa, 5GPa, 6GPa, 7GPa, 8GPa, 9GPa, 10GPa, 11GPa, 12GPa, 13GPa, 14GPa, 15GPa , 16GPa, 17GPa, 18GPa, 19GPa, 20GPa.
  • the organic support layer 101 has good toughness, appropriate rigidity, and flexibility for winding during processing.
  • the thickness D 2 of the organic support layer 101 is preferably 1 ⁇ m ⁇ D 2 ⁇ 30 ⁇ m.
  • the thickness D 2 of the organic support layer 101 is 1 ⁇ m or more.
  • the organic support layer 101 has high mechanical strength and is not prone to breakage during processing and use. It has a good support and protection effect on the copper-based conductive layer 102 and improves the negative electrode.
  • the mechanical stability and working stability of the current collector 10; the thickness D 2 of the organic support layer 101 is less than 30 ⁇ m, which is beneficial to make the electrochemical device have a smaller volume and a lower weight, thereby increasing the volume energy density of the electrochemical device And weight energy density.
  • the upper limit of the thickness D 2 of the organic support layer 101 can be selected from 30 ⁇ m, 25 ⁇ m, 20 ⁇ m, 18 ⁇ m, 15 ⁇ m, 12 ⁇ m, 10 ⁇ m, 8 ⁇ m, and the lower limit can be selected from 1 ⁇ m, 1.5 ⁇ m. , 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 9 ⁇ m, 16 ⁇ m.
  • the range of the thickness D 2 of the organic support layer 101 can be formed by the combination of any lower limit and any upper limit, or by a combination of any lower limit and any other lower limit, and can also be formed by any upper limit. The value is formed by combining any other upper limit value.
  • the thickness D 2 of the organic support layer 101 is 1 ⁇ m ⁇ D 2 ⁇ 15 ⁇ m, preferably not more than 10 ⁇ m, especially not more than 8 ⁇ m, the weight energy density and volume energy density of the electrochemical device can be made higher, and the copper
  • the d value and D 1 /d of the base conductive layer 102 within the above range will be able to better improve the mechanical properties of the negative electrode current collector 10, and make the negative electrode current collector 10 have both higher conductivity and current collecting performance, and At this time, the d value, D 1 /d, etc. of the copper-based conductive layer 102 have more obvious effects on the mechanical properties and mechanical properties of the negative electrode current collector 10.
  • the organic support layer 101 adopts one or more of polymer materials and polymer-based composite materials.
  • polystyrene resins for example, polyamides, polyimides, polyesters, polyolefins, polyalkynes, siloxane polymers, polyethers, polyols, polysulfones, polyamides, etc.
  • Carbohydrate polymers amino acid polymers, polysulfur nitrides, aromatic ring polymers, aromatic heterocyclic polymers, epoxy resins, phenolic resins, their derivatives, their cross-linked products and their copolymers One or more of.
  • polymer material is, for example, polycaprolactam (commonly known as nylon 6), polyhexamethylene adipamide (commonly known as nylon 66), polyparaphenylene terephthalamide (PPTA), polyisophthalamide M-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), Polytetrafluoroethylene (PTEE), polystyrene sulfonate (PSS), polyacetylene (PA), silicone rubber, polyoxymethylene (POM), polyphenylene oxide (PPO), polyphenylene sulfide Ether (PPS),
  • the polymer-based composite material may include the above-mentioned polymer materials and additives, and the additives may be one or more of metal materials and inorganic non-metal materials.
  • metal material additives 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 material additives 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 One or more of ceramic materials and ceramic composite materials.
  • the carbon-based material additives are, for example, one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • additives it may also be a carbon-based material coated with a metal material, such as one or more of nickel-coated graphite powder and nickel-coated carbon fiber.
  • the organic support layer 101 adopts one or more of insulating polymer materials and insulating polymer-based composite materials.
  • the volume resistivity of the organic support layer 101 is relatively high, which is beneficial to improve the safety performance of the electrochemical device.
  • the organic support layer 101 includes polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polystyrene sulfonate One or more of sodium (PSS) and polyimide (PI).
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PEN polyethylene naphthalate
  • PSS polystyrene sulfonate
  • PSS polystyrene sulfonate
  • PSS polystyrene sulfonate
  • PSS polystyrene sulfonate
  • PI polyimide
  • the organic 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.
  • FIGS. 3 to 5 show that there is a copper-based conductive layer 102 on a single side of the organic support layer 101, one or the other of the two opposite surfaces in the thickness direction of the copper-based conductive layer 102
  • a protective layer 103 on the two, but in other embodiments, the copper-based conductive layer 102 may also be provided on the two opposite surfaces of the organic support layer 101, which may be in the thickness direction of any copper-based conductive layer 102.
  • a protective layer 103 is provided on one or both of the two opposite surfaces, or a protective layer 103 is provided on one or both of the two opposite surfaces in the thickness direction of the two copper-based conductive layers 102. .
  • the protective layer 103 includes 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 aforementioned 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, and further is carbon black, carbon nano One or more of tube, acetylene black and graphene.
  • the protective layer 103 preferably adopts one or more of metals and metal oxides, which can improve the performance of the negative electrode current collector 10.
  • the metal protective layer and the metal oxide protective layer have high corrosion resistance, high hardness and large specific surface area, which can effectively prevent the copper-based conductive layer 102 from chemical corrosion or mechanical damage, and enhance the strength of the negative electrode current collector 10. Improve the stability and service life of the negative electrode current collector 10; at the same time, it can further improve the interface between the copper-based conductive layer 102 and the organic support layer 101 or the negative electrode active material layer 20 (shown in Figure 6), and improve the performance of the electrochemical device .
  • a protective layer 103 (hereinafter referred to as the upper protective layer) is provided on the surface of the copper-based conductive layer 102 facing away from the organic support layer 101 to protect the copper-based conductive layer 102 from chemical corrosion and mechanical damage.
  • the interface between the anode current collector 10 and the anode active material layer 20 is improved, and the binding force between the anode current collector 10 and the anode active material layer 20 is improved.
  • the upper protective layer is a metal protective layer or a metal oxide protective layer, the above effects can be better exerted.
  • the upper protective layer is a metal oxide protective layer, it can more obviously protect against chemical corrosion and mechanical damage.
  • the upper protective layer may be a double-layer protective layer of a metal protective layer and a metal oxide protective layer, preferably a metal protective layer is provided on the surface of the copper-based conductive layer 102 facing away from the organic support layer 101, and the metal A metal oxide protective layer is further provided on the surface of the protective layer facing away from the organic support layer 101, so as to better improve the conductivity, corrosion resistance and mechanical damage prevention of the negative electrode current collector 10.
  • the negative electrode current collector 10 includes an organic support layer 101, a copper-based conductive layer 102 and a protective layer 103 that are stacked.
  • the organic support layer 101 has a first surface 101a and a second surface 101b opposite to each other in the thickness direction
  • the copper-based conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the organic support layer 101
  • the protective layer 103 is stacked on the surface of the copper-based conductive layer 102 facing the organic support layer 101.
  • a protective layer 103 (hereinafter referred to as the lower protective layer) is provided on the surface of the copper-based conductive layer 102 facing the organic support layer 101.
  • the lower protective layer protects the copper-based conductive layer 102 from chemical corrosion and mechanical damage.
  • the bonding force between the copper-based conductive layer 102 and the organic support layer 101 can be improved, the copper-based conductive layer 102 and the organic support layer 101 can be prevented from being separated, and the support and protection effect of the copper-based conductive layer 102 can be improved.
  • the lower protective layer is a metal oxide protective layer.
  • the metal oxide protective layer has a larger specific surface area and higher hardness, which is more conducive to improving the bonding force between the copper-based conductive layer 102 and the organic support layer 101, and The strength of the negative current collector 10.
  • the lower protective layer is a metal protective layer, it can improve the bonding force between the copper-based conductive layer 102 and the organic support layer 101, increase the strength of the negative electrode current collector 10, and better reduce the pole pieces.
  • the polarization increases the conductivity of the negative electrode current collector 10.
  • the lower protective layer is preferably a metal protective layer.
  • the negative electrode current collector 10 includes an organic support layer 101, a copper-based conductive layer 102 and a protective layer 103 that are stacked.
  • the organic support layer 101 has a first surface 101a and a second surface 101b opposite to each other in the thickness direction
  • the copper-based conductive layer 102 is stacked on at least one of the first surface 101a and the second surface 101b of the organic support layer 101
  • the protective layer 103 is stacked on the surface of the copper-based conductive layer 102 facing away from the organic support layer 101 and on the surface facing the organic support layer 101.
  • the protective layer 103 is provided on both surfaces of the copper-based conductive layer 102 to more fully protect the copper-based conductive layer 102, so that the negative electrode current collector 10 has a higher comprehensive performance.
  • the materials of the protective layers 103 on the two surfaces of the copper-based 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 . If the protective layer 103 is too thin, it will not be sufficient to protect the copper-based conductive layer 102; if it is too thick, the energy density of the electrochemical device will be reduced.
  • the upper limit value of 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, and the lower limit value may be 1nm, 2nm, 5nm, 8nm, 10nm, 12nm, 15nm, 18nm.
  • the range of the thickness D 3 of the protective layer 103 can be formed by a combination of any lower limit and any upper limit, or a combination of any lower limit and any other lower limit, and can also be formed by any upper limit. Combined with any other upper limit value.
  • the protective layer 103 both surfaces of the copper conductive layer 102 are provided, the protective layer has a thickness D a of 1nm ⁇ D a ⁇ 200nm, and D a ⁇ 0.1D 1; lower protective layer thickness D b is 1nm ⁇ D b ⁇ 200nm, and D b ⁇ 0.1D 1 .
  • D a > D b which is beneficial for the upper protective layer and the lower protective layer to cooperate with the copper-based conductive layer 102 to protect the copper-based conductive layer 102 from chemical corrosion and mechanical damage, while enabling the electrochemical device to have higher energy density.
  • 0.5D a ⁇ D b ⁇ 0.8D a which can better exert the cooperative protection effect of the upper protective layer and the lower protective layer.
  • the elongation at break of the negative electrode current collector 10 is greater than or equal to 3%.
  • the negative electrode current collector 10 with a breaking elongation greater than or equal to 3% has higher fracture toughness, which greatly reduces the probability of fracture and cracks in the copper-based conductive layer 102 during processing and use, thereby improving the negative electrode current collector 10.
  • the elongation at break can be measured by a method known in the art.
  • the negative electrode current collector 10 is cut into a sample of 15mm ⁇ 200mm and stretched using a high-speed rail tension machine at room temperature and pressure (25°C, 0.1MPa) For testing, set the initial position so that the length of the sample between the clamps is 50mm long, and the tensile speed is 5mm/min. Record the device displacement y (mm) at tensile fracture, and finally calculate the elongation at break (y/50) ⁇ 100 %.
  • the copper-based conductive layer 102 may be formed on the organic support by at least one of mechanical rolling, bonding, vapor deposition, electroless plating, and electroplating.
  • the copper-based conductive layer 102 is preferably a vapor-deposited layer or an electroplated layer, which is beneficial to make the copper-based crystal grain size d in the copper-based conductive layer 102 be 10nm-500nm Within the range, and make the copper-based conductive layer 102 and the organic support layer 101 have a higher binding force, and improve the mechanical properties and conductivity of the negative electrode current collector 10.
  • the above-mentioned vapor deposition method is preferably a physical vapor deposition method.
  • the physical vapor deposition method is preferably at least one of an evaporation method and a sputtering method, wherein 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 copper-based conductive layer 102 by a vacuum evaporation method includes: placing the organic support layer 101 with a surface cleaning treatment in a vacuum plating chamber, and melting the metal wires 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 plating chamber, and is finally deposited on the organic support layer 101 to form the copper-based conductive layer 102.
  • FIG. 6 is a schematic structural diagram of a negative pole piece 30 according to an embodiment of the present application. Please refer to FIG. 6.
  • the negative pole piece 30 includes a stacked negative current collector 10 and the negative active material layer 20, wherein the negative current collector 10 is the negative current collector 10 of the first aspect of the embodiments of the application.
  • the negative electrode piece 30 includes a negative electrode current collector 10 and a negative electrode active material layer 20 that are stacked.
  • the negative electrode current collector 10 includes two opposite surfaces in its thickness direction.
  • the negative electrode active material layer 20 is stacked. On both surfaces of the negative electrode current collector 10.
  • the negative active material layer 20 may also be stacked on any one of the two surfaces of the negative current collector 10.
  • the negative electrode active material layer 20 may further include a conductive agent, and the type of the conductive agent is not limited in this application.
  • 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 20 may further include a binder, and the type of the binder is not limited in this application.
  • 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 30 can be prepared according to conventional methods in the art. Generally, the negative electrode active material and optional conductive agent, binder and thickener 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 10, after drying and other processes, the negative pole piece 30 is obtained.
  • the electrochemical device of the embodiment of the present application has higher comprehensive electrochemical performance, and it has higher energy density, rate performance, and cycle performance. And safety performance.
  • the above-mentioned positive pole piece may include a positive electrode current collector and a positive electrode active material layer.
  • the positive electrode current collector may use one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
  • the positive electrode active material used in lithium ion secondary batteries can be one or more of composite oxides obtained by adding other transition metals or non-transition metals or non-metals to lithium transition metal composite oxides and lithium transition metal composite oxides.
  • the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg.
  • the positive electrode active material may be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-containing olivine structure One or more of phosphates.
  • the positive electrode active material layer may further include a binder, and the type of the binder is not limited in this application.
  • 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 electrolyte may be a solid electrolyte or a non-aqueous electrolyte, such as dispersing an electrolyte salt in an organic solvent to form an electrolyte.
  • an organic solvent is used as a medium for transporting ions in an electrochemical reaction, and any organic solvent in the art can be used.
  • the electrolyte salt can be any electrolyte salt 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
  • isolation membrane When the electrochemical device adopts the electrolyte, it is also necessary to provide a separator between the positive pole piece and the negative pole piece to play a role of isolation.
  • type of isolation membrane there is no particular limitation on the type of isolation membrane, and any well-known porous structure isolation membrane with good chemical and mechanical stability can be selected, such as glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multilayer composite film. When the isolation film is a multilayer composite film, the materials of each layer may be the same or different.
  • the negative active material graphite, conductive carbon black, thickener sodium carboxymethyl cellulose (CMC), and binder styrene butadiene rubber emulsion (SBR) are fully mixed in an appropriate amount of deionized water at a weight ratio of 96.5:1.0:1.0:1.5 Stirring and mixing to form a uniform negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector and drying and other steps to obtain a negative electrode pole piece.
  • 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) with a volume ratio of 3:7 are uniformly mixed to obtain an organic solvent, and then 1 mol/L LiPF6 is uniformly dissolved in the above organic solvent.
  • the positive pole piece, the separator film, and the negative pole piece are stacked in sequence.
  • the separator uses a PP/PE/PP composite film, which is then wound into a cell and packed into a packaging shell. The above electrolyte is injected into the cell. And sealed to obtain a lithium ion secondary battery.
  • the wavelength of the rays is 20° ⁇ 80°, the scanning rate is 0.05°/s, and the X-ray diffraction spectrum of the copper-based conductive layer is measured.
  • the copper-based crystal grain size d is calculated using the Scherrer formula.
  • 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 lithium ion secondary battery was subjected to 1000 charge-discharge cycles according to the above method, the discharge capacity of the 1000th cycle was recorded, and the capacity retention rate of the lithium ion secondary battery after 1000 1C/1C cycles was calculated.
  • 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 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 upper protective layer of the negative current collector 7-14 adopts a double-layer protective layer. Specifically, a 25nm thick nickel protective layer (ie, the lower layer) is provided on the surface of the copper-based conductive layer facing away from the organic support layer, and the nickel protective layer A 25nm thick nickel oxide protective layer (that is, the upper layer) is provided on the surface facing away from the organic support layer.
  • composition of the copper alloy in Table 5 is: 95wt% copper and 5wt% nickel.

Abstract

本申请公开了一种负极集流体、负极极片及电化学装置，负极集流体包括有机支撑层以及设置于有机支撑层的至少一个表面上的铜基导电层，铜基导电层中的铜基晶粒尺寸d为10nm～500nm。本申请提供的负极集流体具有良好的力学性能，同时兼具较小的重量及良好的导电和集流的性能，从而能够提高负极集流体、负极极片及电化学装置的制备优率和使用过程中的安全性及可靠性，并且有利于使电化学装置具有较高的重量能量密度以及良好的电化学性能。

Description

负极集流体、负极极片及电化学装置
相关申请的交叉引用
本申请要求享有于2019年05月31日提交的名称为“负极集流体、负极极片及电化学装置”的中国专利申请201910473184.6的优先权，该申请的全部内容通过引用并入本文中。
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、负极极片及电化学装置。
背景技术
电化学装置，例如锂离子二次电池，具备良好的充放电性能、且环境友好，被广泛地应用于电动汽车以及消费类电子产品中。集流体是电化学装置中重要的组成部分，其既为活性物质层提供支撑，又用于将活性物质层产生的电流汇集起来以便对外输出。因此，集流体对电极极片及电化学装置的性能具有重要影响。
基于此，本申请提出一种性能优良的负极集流体、负极极片及电化学装置。
发明内容
本申请实施例提供一种负极集流体、负极极片及电化学装置，旨在提高负极集流体的力学性能，并使其兼具较小的重量及良好的导电和集流的性能。
一方面，本申请实施例提供一种负极集流体，负极集流体包括有机支撑层以及设置于有机支撑层的至少一个表面上的铜基导电层，铜基导电层中的铜基晶粒尺寸d为10nm～500nm。
第二方面，本申请实施例提供一种负极极片，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物质层，其中负极集流体为根据本申请实施例一方面的负极集流体。
第三方面，本申请实施例提供一种电化学装置，电化学装置包括正极极片、负极极片及电解质，其中负极极片为根据本申请实施例第二方面的负极极片。
本申请实施例提供的负极集流体、负极极片及电化学装置，负极集流体包括有机支撑层以及设置于有机支撑层上的铜基导电层，采用有机材料的支撑层其重量较轻，有利于使得该负极集流体和负极极片具有较小的重量，从而使得电化学装置具有较高的重量能量密度；此外，采用有机材料的支撑层其韧性较高，同时铜基导电层中的铜基晶粒尺寸d为10nm～500nm，使得铜基导电层与有机支撑层之间具有较高的界面结合力，并且铜基导电层能够随有机支撑层的延展发生均匀变形，有效防止局部应力集中，大大减小铜基导电层发生断裂的几率，从而大幅度提高负极集流体的断裂韧性，改善该负极集流体的力学性能，进而显著提高负极集流体、负极极片及电化学装置在制备过程中的优率以及使用过程中的安全性和可靠性；又由于铜基导电层中的铜基晶粒尺寸d为10nm～500nm，同时保证了该负极集流体具有良好的导电和集流的性能，从而有利于保证电化学装置具有良好的电化学性能。
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为根据本申请一个实施例的负极集流体的结构示意图。
图2为根据本申请另一个实施例的负极集流体的结构示意图。
图3为根据本申请另一个实施例的负极集流体的结构示意图。
图4为根据本申请另一个实施例的负极集流体的结构示意图。
图5为根据本申请另一个实施例的负极集流体的结构示意图。
图6为根据本申请一个实施例的负极极片的结构示意图。
标号说明：
10、负极集流体；
101、有机支撑层；
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、铜基导电层；
103、保护层；
20、负极活性物质层；
30、负极极片。
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。
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。图1为根据本申请实施例的一种负极集流体10的结构示意图，请参照图1，负极集流体10包括层叠设置的有机支撑层101及铜基导电层102。
其中，在有机支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，铜基导电层102设置于有机支撑层101的第一表面101a和第二表面101b。
可以理解的是，铜基导电层102还可以是设置于有机支撑层101的第一表面101a及第二表面101b中的任意一者上，例如，铜基导电层102设置于有机支撑层101的第一表面101a，当然，铜基导电层102也可以是设置于有机支撑层101的第二表面101b。
并且，铜基导电层102中的铜基晶粒尺寸d为10nm～500nm。
在本文中，铜基导电层102中的铜基晶粒尺寸d可以按如下测试方法进行测试：对负极集流体10进行X射线衍射分析，测定铜基导电层102的衍射峰，例如Cu(111)晶面的衍射峰，根据衍射峰的衍射角及半高宽，利用谢乐(Scherrer)公式计算得到铜基晶粒尺寸d。具体公式为
d＝Kγ/(Bcosθ)
式中，K为谢乐常数，取K＝0.89；B为衍射峰的半高宽，在计算过程中需转换为弧度(rad)；θ为衍射角；γ为X射线波长，为0.154056nm。
可以用本领域公知的仪器及方法对负极集流体10进行X射线衍射分析，例如采用X射线粉末衍射仪，依据JIS K0131-1996X射线衍射分析通则测定X射线衍射光谱。作为示例，使用德国Bruker AxS公司的Bruker D8Discover型X射线衍射仪，以CuK α射线为辐射源，射线波长
Figure PCTCN2019090403-appb-000001
扫描2θ角范围为20°～80°，扫描速率为0.05°/s。
本申请实施例的负极集流体10包括有机支撑层101以及设置于有机支撑层101上的铜基导电层102。
由于有机支撑层101的密度比金属(例如铜)的密度小，因此较传统的铜箔集流体而言，根据本申请的负极集流体可有利于降低电化学装置的 重量，从而使电化学装置的能量密度得到显著提高。
另外，采用有机材料的支撑层其韧性较高，同时铜基导电层102中的铜基晶粒尺寸d为10nm～500nm，使得铜基导电层102与有机支撑层101之间具有较高的界面结合力，并且铜基导电层102能够随有机支撑层101的延展发生均匀变形，有效防止局部应力集中，大大减小铜基导电层102发生断裂的几率，从而大幅度提高负极集流体10的断裂韧性，改善了负极集流体10的力学性能，防止在加工或使用过程中负极集流体10发生断裂或形成微裂纹，进而显著提高负极集流体10、负极极片20及电化学装置在制备过程中的优率以及使用过程中的安全性和可靠性。
由于铜基导电层102中的铜基晶粒尺寸d为10nm～500nm，同时保证了铜基导电层102具有良好的导电性能，从而保证负极集流体10具有良好的导电和集流的性能，有利于使负极极片20及电化学装置具有低阻抗、并减小负极极化，使得电化学装置具有较高的电化学性能，其中电化学装置具有较高的倍率性能及循环性能。
在一些可选的实施例中，铜基导电层102中的铜基晶粒尺寸d的上限值可以选自500nm、450nm、400nm、350nm、300nm、250nm、200nm、150nm、100nm、80nm、50nm，下限值可以选自380nm、320nm、280nm、240nm、180nm、120nm、90nm、70nm、30nm、10nm。铜基导电层102中的铜基晶粒尺寸d的范围可以是由前述任意下限与任意上限组合形成，也可以是由任意下限与任意其它下限组合形成，同样可以是由任意上限与任意其它上限组合形成。
优选地，铜基导电层102中的铜基晶粒尺寸d为30nm～300nm，更优选为50nm～150nm。铜基导电层102具有该种铜基晶粒尺寸d，能够使负极集流体10更好地发挥上述效果。
本申请实施例的负极集流体10，铜基导电层102的厚度D 1优选为30nm≤D 1≤3μm。
本申请实施例的负极集流体10，将厚度较小的铜基导电层102设置于有机支撑层101的表面，较传统金属集流体(如铜箔)能够显著降低负极集流体10的重量，从而有利于降低电化学装置的重量，使电化学装置的 能量密度得到显著提高。
另外，铜基导电层102的厚度D 1优选为30nm≤D 1≤3μm，使得铜基导电层102具有良好的导电性能，有利于保证负极集流体10具有良好的导电和集流的性能，从而保证电化学装置的良好的电化学性能；并且使得铜基导电层102在加工及使用过程中不易发生断裂，使负极集流体10具有较高的断裂韧性，保证负极集流体10具有较好的机械稳定性和工作稳定性。此外，铜基导电层102的厚度D 1在上述范围内，在电化学装置发生穿钉等异常情况下，铜基导电层102产生的毛刺较小，从而可降低产生的金属毛刺与对电极接触的风险，进而改善电化学装置的安全性能。
在一些可选的实施例中，铜基导电层102的厚度D 1的上限可以选自3μm、2.5μm、2μm、1.8μm、1.5μm、1.2μm、1μm、900nm、750nm、450nm、250nm、100nm，下限可以选自1.6μm、1μm、800nm、600nm、400nm、300nm、150nm、100nm、80nm、30nm，铜基导电层102的厚度D 1的范围可以是由前述任意下限与任意上限组合形成，也可以是由任意下限与任意其它下限组合形成，同样可以是由任意上限与任意其它上限组合形成。
更优选地，铜基导电层102的厚度D 1为300nm≤D 1≤2μm，优选为500nm≤D 1≤1.5μm，进一步的为600nm≤D 1≤1.2μm。
在一些实施例中，铜基导电层102的厚度D 1与铜基晶粒尺寸d之间满足1≤D 1/d≤300。铜基导电层102的厚度D 1与铜基晶粒尺寸d之间满足上述关系，能够使负极集流体10具有更好的力学性能，并兼具更高的导电和集流的性能。
在一些可选的实施例中，上述D 1/d的上限值可选自300、280、250、230、220、200、190、170、150、120、100、80、60、50、48，下限值可选自1、2、3、5、6、8、10、12、15、18、20、22、25、30、33、35、37、40、42、45。D 1/d的范围可以是由前述任意下限值与任意上限值组合形成，也可以是由任意下限值与任意其它下限值组合形成，同样可以是由任意上限值与任意其它上限值组合形成。
优选地，铜基导电层102的厚度D 1与铜基晶粒尺寸d之间满足2≤ D 1/d≤100，更优选地为3≤D 1/d≤50。
本申请实施例的负极集流体10，铜基导电层102包括铜(Cu)及铜合金中的一种或多种。
铜合金是以铜为主元素且含有一种或多种添加元素的合金。作为优选地，添加元素选自钛(Ti)、钒(V)、镍(Ni)、铬(Cr)、铁(Fe)、钴(Co)、锰(Mn)、锌(Zn)、锆(Zr)、钼(Mo)、铌(Nb)、钨(W)、银(Ag)、钯(Pd)及镉(Cd)。引入上述一种或多种添加元素，能够提高铜合金导电层的力学性能、耐加工性能及耐蚀性能。
进一步优选地，铜合金中铜元素的质量百分含量为80wt％以上，更优选地为90wt％以上，例如为90wt％～95wt％。铜合金中铜元素的质量百分含量在上述范围内，能够使铜合金导电层兼具较高的导电性能、力学性能、耐加工性能及耐蚀性能。
本申请实施例的负极集流体10，有机支撑层101的杨氏模量E优选为E≥2GPa，这使得有机支撑层101具有良好的韧性的同时，还具有适当的刚性，既满足有机支撑层101对铜基导电层102的支撑作用，确保负极集流体10的整体强度，又能使有机支撑层101在负极集流体10的加工过程中不会发生过大的延展或变形，更加有效地防止有机支撑层101及铜基导电层102发生断带，同时有机支撑层101和铜基导电层102之间的结合牢固度更高，使铜基导电层102不易发生剥离，提高负极集流体10的机械稳定性和工作稳定性，从而使电化学装置的性能得到提高。
进一步地，有机支撑层101的杨氏模量E优选为2GPa≤E≤20Gpa，例如为2GPa、3GPa、4GPa、5GPa、6GPa、7GPa、8GPa、9GPa、10GPa、11GPa、12GPa、13GPa、14GPa、15GPa、16GPa、17GPa、18GPa、19GPa、20GPa。该种有机支撑层101具有良好的韧性、适当的刚性，以及在加工过程中进行卷绕的柔性。
有机支撑层101的杨氏模量E可以采用本领域已知的方法测定。作为示例，取有机支撑层101裁剪成15mm×200mm的样品，用万分尺量取样品的厚度h(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L(N)，设备位移y(mm)，则应力ε(GPa)＝L/(15×h)，应变η＝y/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。
本申请实施例的负极集流体10，有机支撑层101的厚度D 2优选为1μm≤D 2≤30μm。有机支撑层101的厚度D 2为1μm以上，有机支撑层101具有较高的机械强度，在加工及使用过程中不易发生断裂，对铜基导电层102起到良好的支撑和保护作用，提高负极集流体10的机械稳定性和工作稳定性；有机支撑层101的厚度D 2为30μm以下，有利于使电化学装置具有较小的体积及较低的重量，从而提高电化学装置的体积能量密度和重量能量密度。
在一些可选的实施例中，有机支撑层101的厚度D 2的上限值可以选自30μm、25μm、20μm、18μm、15μm、12μm、10μm、8μm，下限值可以选自1μm、1.5μm、2μm、3μm、4μm、5μm、6μm、7μm、9μm、16μm。有机支撑层101的厚度D 2的范围可以是由前述任意下限值与任意上限值组合形成，也可以是由任意下限值与任意其它下限值组合形成，同样可以是由任意上限值与任意其它上限值组合形成。
更优选地，有机支撑层101的厚度D 2为1μm≤D 2≤15μm，优选为1μm≤D 2≤10μm，优选为1μm≤D 2≤8μm，优选为2μm≤D 2≤8μm，更优选为2μm≤D 2≤6μm。当有机支撑层101的厚度D 2为1μm≤D 2≤15μm，优选为不超过10μm，尤其是不超过8μm时，可以使得电化学装置的重量能量密度及体积能量密度更高，同时通过使铜基导电层102的d值及D 1/d在上述范围内，将能够更好地改善负极集流体10的力学性能，并使得负极集流体10兼具较高的导电和集流的性能，且此时铜基导电层102的d值、D 1/d等对于负极集流体10的力学性能、机械性能等方面的影响也更加明显。
本申请实施例的负极集流体10，有机支撑层101采用高分子材料及高分子基复合材料中的一种或多种。
作为上述高分子材料，例如是聚酰胺类、聚酰亚胺类、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，上述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(Polyacetylene，简称PA)、硅橡胶(Silicone rubber)、聚甲醛(POM)、聚苯醚(PPO)、聚苯硫醚(PPS)、聚乙二醇(PEG)、纤维素、淀粉、蛋白质、聚苯、聚吡咯(PPy)、聚苯胺(PAN)、聚噻吩(PT)、聚吡啶(PPY)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)、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，可以是包括上述的高分子材料和添加剂，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。
作为金属材料添加剂，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。
作为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。其中碳基材料添加剂例如是石墨、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。
作为上述添加剂，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，有机支撑层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。该种有机支撑层101的体积电阻率较高，有利于提高 电化学装置的安全性能。
进一步地，有机支撑层101包括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，有机支撑层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。
图2为根据本申请实施例的另一种负极集流体10的结构示意图，请参照图2，有机支撑层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。复合层结构的有机支撑层101具有相对的第一表面101a和第二表面101b，铜基导电层102层叠设置在有机支撑层101的第一表面101a和第二表面101b。当然，铜基导电层102可以是仅设置于有机支撑层101的第一表面101a，也可以是仅设置于有机支撑层101的第二表面101b。
当有机支撑层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。
本申请实施例的负极集流体10进一步可选地包括保护层103。请参照图3至图5，铜基导电层102在自身厚度方向上包括相对的两个表面，保护层103层叠设置于铜基导电层102的两个表面中的任意一者或两者上，以保护铜基导电层102，防止铜基导电层102发生化学腐蚀或机械破坏等损害，保证负极集流体10的工作稳定性及使用寿命，从而有利于电化学装置具有较高的安全性能及电化学性能。此外，保护层103还能够增强负极集流体10的强度。
可以理解的是，尽管图3至图5中示出了在有机支撑层101的单面具有铜基导电层102，在铜基导电层102自身厚度方向上相对的两个表面中的一者或两者上具有保护层103，但在其他的实施例中，还可以在有机支撑层101相对的两个表面分别具有铜基导电层102，可以是在任意一个铜基导电层102自身厚度方向上相对的两个表面中的一者或两者上具有保护层103，也可以是在两个铜基导电层102自身厚度方向上相对的两个表面中的一者或两者上具有保护层103。
保护层103包括金属、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、石墨烯及碳纳米纤维中的一种或多种，进一步地为炭黑、碳纳米管、乙炔黑及石墨烯中的一种或多种。
进一步地，保护层103优选采用金属及金属氧化物中的一种或多种，能够提高负极集流体10的性能。
金属保护层及金属氧化物保护层的耐腐蚀性能较高，且硬度高、比表面积大，能够有效防止铜基导电层102发生化学腐蚀或机械破坏等损害，并增强负极集流体10的强度，提高负极集流体10的稳定性及使用寿命；同时还能够进一步改善铜基导电层102与有机支撑层101或负极活性物质层20(如图6所示)之间界面，提高电化学装置的性能。
作为一些示例，请参照图3，负极集流体10包括层叠设置的有机支撑层101、铜基导电层102和保护层103。其中，在有机支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，铜基导电层102层叠设置于有机支撑层101的第一表面101a及第二表面101b中的至少一者上，保护层103层叠设置于铜基导电层102的背向有机支撑层101的表面。
在铜基导电层102的背向有机支撑层101的表面上设置保护层103(下文简称为上保护层)，对铜基导电层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与负极活性物质层20之间的界面，提高负极集流体10与负极活性物质层20之间的结合力。若上保护层 为金属保护层或金属氧化物保护层，可以更好地发挥上述效果。
进一步地，若上保护层为金属保护层，则还可明显地降低界面电阻，提高负极集流体10与负极活性物质层201之间的导电性能，减小负极极化，提高电化学装置的性能。
或进一步地，若上保护层为金属氧化物保护层，则可以更明显地起到防化学腐蚀、防机械破坏的保护作用。
进一步地，上保护层可以为金属保护层和金属氧化物保护层的双层保护层，优选为在铜基导电层102的背向有机支撑层101的表面上设置金属保护层，并在该金属保护层的背向有机支撑层101的表面上再设置金属氧化物保护层，从而更好地起到改善负极集流体10的导电性能、耐腐蚀性能以及防机械破坏等作用。
作为另一些示例，请参照图4，负极集流体10包括层叠设置的有机支撑层101、铜基导电层102和保护层103。其中，在有机支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，铜基导电层102层叠设置于有机支撑层101的第一表面101a及第二表面101b中的至少一者上，保护层103层叠设置于铜基导电层102的朝向有机支撑层101的表面。
在铜基导电层102的朝向有机支撑层101的表面上设置保护层103(下文简称为下保护层)，下保护层对铜基导电层102起到防化学腐蚀、防机械损害的保护作用的同时，还能够提高铜基导电层102与有机支撑层101的结合力，防止铜基导电层102与有机支撑层101分离，提高对铜基导电层102的支撑保护作用。
进一步地，下保护层为金属氧化物保护层，金属氧化物保护层的比表面积更大、硬度更高，更加有利于提高铜基导电层102与有机支撑层101之间的结合力，以及提高负极集流体10的强度。
或进一步地，若下保护层为金属保护层，则可以在改善铜基导电层102与有机支撑层101之间的结合力、提高负极集流体10的强度的同时，更好地减小极片的极化，增强负极集流体10的导电能力。
下保护层优选为金属保护层。
作为又一些示例，请参照图5，负极集流体10包括层叠设置的有机支撑层101、铜基导电层102和保护层103。其中，在有机支撑层101的厚度方向上具有相对的第一表面101a和第二表面101b，铜基导电层102层叠设置于有机支撑层101的第一表面101a及第二表面101b中的至少一者上，保护层103层叠设置于铜基导电层102的背向有机支撑层101的表面及朝向有机支撑层101的表面上。
在铜基导电层102的两个表面上均设置保护层103，更加充分地保护铜基导电层102，使负极集流体10具有较高的综合性能。
可以理解的是，铜基导电层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。如果保护层103太薄，则不足以起到保护铜基导电层102的作用；太厚，则会降低电化学装置的能量密度。
在一些实施例中，保护层103的厚度D 3的上限值可以为200nm、180nm、150nm、120nm、100nm、80nm、60nm、55nm、50nm、45nm、40nm、30nm、20nm，下限值可以为1nm、2nm、5nm、8nm、10nm、12nm、15nm、18nm。保护层103的厚度D 3的范围可以是由前述任意下限值与任意上限值组合形成，也可以是由任意下限值与任意其它下限值组合形成，同样可以是由任意上限值与任意其它上限值组合形成。
更优选地，保护层103的厚度D 3为5nm≤D 3≤200nm，更优选地为10nm≤D 3≤200nm。
进一步地，当铜基导电层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＞D b，有利于上保护层及下保护层协同对铜基导电层102起到良好的防化学腐蚀、防机械损害的保护作用，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，能够更好的发挥上保护层及下保护层的协同保护作用。
本申请实施例中，负极集流体10的断裂伸长率大于或等于3％。断裂 伸长率大于或等于3％的负极集流体10具有较高的断裂韧性，大大减小其在加工及使用过程中发生断裂及铜基导电层102中产生裂纹的几率，从而提高负极集流体10、负极极片20及电化学装置在制备过程中的优率以及使用过程中的安全性和可靠性。
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，取负极集流体10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5mm/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％。
本申请实施例中，铜基导电层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有机支撑层101上，其中优选气相沉积法及电镀法，即铜基导电层102优选为气相沉积层或电镀层，从而有利于使铜基导电层102中的铜基晶粒尺寸d在10nm～500nm的范围内，以及使得铜基导电层102与有机支撑层101之间具有较高的结合力，提高负极集流体10的力学性能及导电性能。
上述气相沉积法优选为物理气相沉积法。物理气相沉积法优选蒸发法及溅射法中的至少一种，其中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铜基导电层102，包括：将经过表面清洁处理的有机支撑层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，最后沉积于有机支撑层101上，形成铜基导电层102。
当具有保护层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铜基导电层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 形成于铜基导电层102上，有利于使铜基导电层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的工作性能。
当铜基导电层102与有机支撑层101之间设置有保护层103(即下保护层)时，还可以是先将下保护层形成于有机支撑层101上，再将铜基导电层102形成于下保护层上。下保护层可以是通过气相沉积法及涂布法中的至少一种手段形成于有机支撑层101上，其中优选气相沉积法。铜基导电层102可以是通过机械辊轧、粘结、气相沉积法及化学镀中的至少一种手段形成于下保护层上，其中优选气相沉积法。
负极极片
本申请实施例第二方面提供一种负极极片30，图6为根据本申请实施例的一种负极极片30的结构示意图，请参照图6，负极极片30包括层叠设置的负极集流体10及负极活性物质层20，其中负极集流体10为本申请实施例第一方面的负极集流体10。
由于采用了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30具有较高的力学性能，以及较高的制备优率以及较高的使用安全性和可靠性，同时兼具低重量及较高的电化学性能。
作为一个示例，请参照图6，负极极片30包括层叠设置的负极集流体10及负极活性物质层20，负极集流体10在自身厚度方向包括相对的两个表面，负极活性物质层20层叠设置于负极集流体10的两个表面上。
可以理解的是，负极活性物质层20还可以是层叠设置于负极集流体10的两个表面中的任意一者上。
本申请实施例的负极极片30，负极活性物质层20可以采用本领域任意的负极活性材料，本申请不做限制。
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，负极活性物质层20还可以包括导电剂，本申请对导电剂的 种类不做限制。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，负极活性物质层20还可以包括粘结剂，本申请对粘结剂的种类不做限制。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30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、粘结剂及增稠剂分散于溶剂中，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10上，经烘干等工序后，得到负极极片30。
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、负极极片和电解质，其中负极极片为本申请实施例第二方面的负极极片。
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负极极片，本申请实施例的电化学装置具有较高的综合电化学性能，其具有较高的能量密度、倍率性能、循环性能及安全性能。
上述正极极片可以是包括正极集流体及正极活性物质层。
正极集流体可以采用铝、铝合金、铜、铜合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种。
正极活性物质层可以采用本领域任意的正极活性材料，本申请不做限制。
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、锂过渡金属复合氧化物添加其它过渡金属或非过渡金属或非金属得到的复合氧化物中的一种或多种。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。
作为示例，正极活性物质可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、橄榄石结构的含锂磷酸盐中的一种或多种。例如，锂过渡金属复合氧化物为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，正极活性物质层还可以包括粘结剂，本申请对粘结剂的种类不做限制。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，正极活性物质层还可以包括导电剂，本申请对导电剂的种类不做限制。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。
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。
本申请实施例的电化学装置中，电解质可以采用固体电解质，也可以采用非水电解液，如将电解质盐分散于有机溶剂中形成电解液。
上述电解液中，有机溶剂作为在电化学反应中传输离子的介质，可以采用本领域任意的有机溶剂。电解质盐作为离子的供源，可以是本领域任意的电解质盐。
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。
电解液中还可选地包括添加剂，其中对添加剂的种类没有具体的限制，可根据需求进行选择。作为示例，添加剂碳酸亚乙烯酯(VC)、碳酸乙烯亚乙酯(VEC)、氟代碳酸乙烯酯(FEC)、丁二腈(SN)、己二腈(ADN)、1,3-丙烯磺酸内酯(PST)、三(三甲基硅烷)磷酸酯(TMSP)及三(三甲基硅烷)硼酸酯(TMSB)中的一种或多种。
电化学装置采用电解液时，还需要在正极极片和负极极片之间设置隔离膜，起到隔离的作用。对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜，例如玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或多种。隔离膜可以是单层薄膜，也可以是多层复合薄膜。隔离膜为多层复合薄膜时，各层的材料可以相同，也可以不同。
将上述正极极片、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。
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
选取预定厚度的有机支撑层并进行表面清洁处理，将经过表面清洁处理的有机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，最后沉积于有机支撑层的两个表面，形成铜基导电层。
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。
正极集流体的制备
采用厚度为12μm的铝箔。
常规正极极片的制备
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LiPF6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、负极极片依次层叠设置，其中隔离膜采用PP/PE/PP复合薄膜，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，并封口，得到锂离子二次电池。
测试部分
1.负极集流体的测试
1)铜基导电层中的铜基晶粒尺寸d的测试
使用德国Bruker AxS公司的Bruker D8Discover型X射线衍射仪，以CuK α射线为辐射源，射线波长
Figure PCTCN2019090403-appb-000002
扫描2θ角范围为20°～80°，扫描速率为0.05°/s，测定铜基导电层的X射线衍射光谱。根据X射线衍射光谱中Cu(111)晶面的衍射峰的衍射角及半高宽，利用谢乐公式计算得到铜基晶粒尺寸d。
2)有机支撑层的杨氏模量E的测试
取有机支撑层裁剪成15mm×200mm的样品，用万分尺量取样品的厚度h(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L(N)，设备位移y(mm)，则应力ε(GPa)＝L/(15×h)，应变η＝y/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。
3)负极集流体的断裂伸长率测试
取负极集流体裁剪成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5mm/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％。
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。将锂离子二次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，计算锂离子二次电池1C/1C循环1000次后的容量保持率。
锂离子二次电池1C/1C循环1000次的容量保持率(％)＝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.本申请负极集流体在改善电化学装置的重量能量密度方面的作用
表1
Figure PCTCN2019090403-appb-000003
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。
2.保护层对于本申请的负极集流体及电化学装置的电化学性能方面 的作用
表2
Figure PCTCN2019090403-appb-000004
表2中的负极集流体是在表1中负极集流体7的基础上设置保护层。
负极集流体7-14的上保护层采用双层保护层，具体为在铜基导电层的背向有机支撑层的表面上设置有25nm厚的镍保护层(即下层)，并在镍保护层的背向有机支撑层的表面上设置有25nm厚的氧化镍保护层(即上层)。
表3
Figure PCTCN2019090403-appb-000005
Figure PCTCN2019090403-appb-000006
表4
Figure PCTCN2019090403-appb-000007
Figure PCTCN2019090403-appb-000008
由表4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。
3.铜基导电层的铜基晶粒尺寸d、以及厚度D 1与铜基晶粒尺寸d的比值等对于负极集流体的影响
通过调节生产铜基导电层的沉积温度、沉积速率、沉积时间等，得到不同铜基晶粒尺寸d、及不同厚度D 1的铜基导电层。
表5
Figure PCTCN2019090403-appb-000009
Figure PCTCN2019090403-appb-000010
表5中铜合金的成分为：铜95wt％和镍5wt％。
从表5的结果可看出，若铜基导电层的铜基晶粒尺寸d值过小，则负极集流体的力学性能较差，断裂伸长率较小，易于断裂，因此负极集流体、负极极片及电化学装置在制备过程中的优率较差，并导致负极集流体、负极极片及电化学装置在使用过程中的安全性和可靠性较差。此外，D 1/d值也会对负极集流体的力学性能产生影响。
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 (10)

  1. 一种负极集流体，其中，包括有机支撑层以及设置于所述有机支撑层的至少一个表面上的铜基导电层，所述铜基导电层中的铜基晶粒尺寸d为10nm～500nm。
  2. 根据权利要求1所述的负极集流体，其中，所述铜基导电层的厚度D 1与所述铜基晶粒尺寸d之间满足1≤D 1/d≤300，优选为2≤D 1/d≤100，更优选为3≤D 1/d≤50；和/或，
    所述铜基导电层中的铜基晶粒尺寸d为30nm～300nm，优选为50nm～150nm。
  3. 根据权利要求1所述的负极集流体，其中，所述有机支撑层的杨氏模量E为E≥2GPa，优选为2GPa≤E≤20GPa。
  4. 根据权利要求1所述的负极集流体，其中，所述负极集流体的断裂伸长率大于或等于3％。
  5. 根据权利要求1所述的负极集流体，其中，所述铜基导电层的厚度D 1为30nm≤D 1≤3μm，优选为300nm≤D 1≤2μm，优选为500nm≤D 1≤1.5μm，更优选为600nm≤D 1≤1.2μm；和/或，
    所述有机支撑层的厚度D 2为1μm≤D 2≤30μm，优选为1μm≤D 2≤15μm，优选为1μm≤D 2≤10μm，优选为1μm≤D 2≤8μm，优选为2μm≤D 2≤8μm，更优选为2μm≤D 2≤6μm。
  6. 根据权利要求1所述的负极集流体，其中，所述铜基导电层包括铜及铜合金中的一种或多种；
    所述铜合金包含铜元素及添加元素，所述添加元素优选为钛、钒、镍、铬、铁、钴、锰、锌、锆、钼、铌、钨、银、钯及镉中的一种或多种，所述铜合金中铜元素的质量百分含量优选为80wt％以上；
    优选地，所述铜基导电层为气相沉积层或电镀层。
  7. 根据权利要求1所述的负极集流体，其中，所述有机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；
    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、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；
    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。
  8. 根据权利要求1所述的负极集流体，其中，进一步包括保护层，所述保护层设置于所述铜基导电层自身厚度方向上相对的两个表面中的至少一者上；
    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，优选包括镍、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，且所述保护层的厚度D 3与所述铜基导电层的厚度D 1之间满足D 3≤0.1D 1。
  9. 一种负极极片，其中，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物质层，其中所述负极集流体为权利要求1至8任一项所述的负极集流体。
  10. 一种电化学装置，其中，包括正极极片、负极极片及电解质，其中所述负极极片为权利要求9所述的负极极片。
PCT/CN2019/090403 2019-05-31 2019-06-06 负极集流体、负极极片及电化学装置 WO2020237712A1 (zh)

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