WO2023206687A1 - 复合集流体及其制备方法、电极极片和二次电池 - Google Patents

复合集流体及其制备方法、电极极片和二次电池 Download PDF

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WO2023206687A1
WO2023206687A1 PCT/CN2022/095406 CN2022095406W WO2023206687A1 WO 2023206687 A1 WO2023206687 A1 WO 2023206687A1 CN 2022095406 W CN2022095406 W CN 2022095406W WO 2023206687 A1 WO2023206687 A1 WO 2023206687A1
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layer
sub
current collector
aluminum
composite current
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PCT/CN2022/095406
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English (en)
French (fr)
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王成豪
李学法
张国平
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江阴纳力新材料科技有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • 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
    • 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
    • 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
    • H01M4/139—Processes of manufacture
    • 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

  • the invention relates to the field of batteries, and in particular to a composite current collector and a preparation method thereof, electrode pole pieces and secondary batteries.
  • the cathode current collector of conventional non-aqueous secondary batteries uses high-purity aluminum foil, which is produced by a rolling process.
  • the surface smoothness of the pressure roller used in the rolling process is relatively high, resulting in a low surface energy on the surface of the current collector.
  • a composite current collector including: a polymer base film and an aluminum-plated layer disposed on both sides of the polymer base film; the aluminum-plated layer includes a first sub-layer and a second sub-layer; the third sub-layer is One sub-layer is closer to the polymer base film than the second sub-layer, the particle size of the aluminum particles in the first sub-layer is 10 nm to 30 nm, and the particle size of the aluminum particles in the second sub-layer is 80 nm. ⁇ 100nm.
  • each aluminum-plated layer is independently 0.3 ⁇ m to 3 ⁇ m.
  • first sub-layers there are a plurality of first sub-layers, and a plurality of the first sub-layers are sequentially stacked and arranged between the polymer base film and the second sub-layer.
  • the number of first sub-layers is ⁇ 19.
  • the thickness of the polymer base film ranges from 1 ⁇ m to 25 ⁇ m.
  • the polymer base film is selected from at least one of polyethylene, polypropylene, polymethylpentene and polyethylene terephthalate.
  • a method for preparing a composite current collector including the following steps:
  • An aluminum-plated layer is formed on both sides of the polymer base film to prepare a composite current collector; wherein the aluminum-plated layer includes a first sub-layer and a second sub-layer, and the first sub-layer is smaller than the second sub-layer.
  • the sub-layer is closer to the polymer base film, the particle size of the aluminum particles in the first sub-layer is 10 nm to 30 nm, and the particle size of the aluminum particles in the second sub-layer is 80 nm to 100 nm.
  • the aluminum plating layer is formed by vacuum evaporation or magnetron sputtering.
  • the process parameters are as follows: evaporation temperature ⁇ 600° C., vacuum degree ⁇ 0.01 Pa, coating speed > 10 m/min, and evaporation of the first sub-layer is formed The temperature is greater than the evaporation temperature at which the second sub-layer is formed.
  • the evaporation temperature for forming the first sub-layer is 700°C to 750°C
  • the evaporation temperature for forming the second sub-layer is 600°C to 700°C.
  • An electrode pole piece includes: a current collector and an active material coated on both sides of the current collector.
  • the current collector is the above-mentioned composite current collector or a composite current collector prepared by the above-mentioned preparation method of a composite current collector.
  • a secondary battery includes the above-mentioned electrode piece.
  • the above-mentioned composite current collector includes a polymer base film and an aluminum plating layer.
  • the polymer base film is used to support the aluminum plating layer.
  • the aluminum plating layer includes a two-layer structure with different particle sizes. Since the particle size of the aluminum particles in the first sub-layer is small, The high compactness ensures that the aluminum coating has high conductivity.
  • the aluminum particles in the second sub-layer are large in size and low in compactness, making the surface energy of the aluminum coating high, which can solve the problem of traditional The problem of high interface resistance of aluminum foil. Therefore, the above-mentioned composite current collector controls the particle size of particles in different sub-layers of the aluminum plating layer, so that the composite current collector can not only have high surface energy, but also ensure high conductivity. , during the coating process of active materials, the interfacial internal resistance between the battery pole piece and the current collector can be significantly improved, and the capacity and cycle performance of the lithium battery can be improved.
  • Figure 1 is a schematic structural diagram of a composite current collector according to an embodiment
  • Figure 2 is a comparative diagram of the internal resistance of lithium batteries prepared using the composite current collectors of Example 1 and Comparative Example 1.
  • the particle size of the aluminum particles refers to its median particle size.
  • a composite current collector 100 in one embodiment includes a polymer base film 110 and an aluminum plating layer 120 disposed on both sides of the polymer base film 110 .
  • the aluminum plating layer 120 includes a first sublayer 122 and The second sub-layer 124 and the first sub-layer 122 are closer to the polymer base film 110 than the second sub-layer 124.
  • the particle size of the aluminum particles in the first sub-layer 122 is 10 nm to 30 nm.
  • the size of the aluminum particles in the second sub-layer 124 is The particle size is 80nm ⁇ 100nm.
  • the particle size of the aluminum particles in the first sub-layer 122 is 10nm, 15nm, 20nm, 25nm, 30nm, 10nm ⁇ 15nm, 15nm ⁇ 20nm, 10nm ⁇ 20nm, 15nm ⁇ 25nm, 20nm ⁇ 25nm or 25nm ⁇ 30nm, etc.
  • the particle diameter of the aluminum particles in the second sub-layer 124 is 80nm, 85nm, 90nm, 95nm, 100nm, 80nm ⁇ 85nm, 85nm ⁇ 90nm, 90nm ⁇ 95nm, 95nm ⁇ 100nm, 80nm ⁇ 90nm or 85nm ⁇ 95nm.
  • first sub-layers 122 there are multiple first sub-layers 122 , and the multiple first sub-layers 122 are stacked and arranged in sequence between the polymer base film 110 and the second sub-layer 124 . Furthermore, the number of first sub-layers 122 is ⁇ 19. For example, the number of first sub-layers 122 is 2, 5, 8, 10, 12, 15, 17 or 19. Preferably, the number of first sub-layers 122 is 8-12.
  • each aluminum plating layer 120 is ⁇ 5 ⁇ m. Furthermore, the thickness of each aluminum plating layer 120 is independently 0.3 ⁇ m to 3 ⁇ m. For example, the thickness of each aluminum plating layer 120 is independently 0.3 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 0.3 ⁇ m to 0.5 ⁇ m, 0.5 ⁇ m to 1 ⁇ m, 1 ⁇ m to 1.5 ⁇ m, 1.5 ⁇ m to 2 ⁇ m, and 2 ⁇ m.
  • the aluminum plating layer 120 is symmetrically disposed on both sides of the polymer base film 110 .
  • the aluminum-plated layer 120 can be ensured to have a high electrical conductivity, while the aluminum particles in the second sub-layer 124 have a large particle size and a low compactness. , resulting in a higher surface energy of the outermost layer of the aluminum-plated layer 120, which can well solve the problem of high interface resistance of traditional aluminum foil.
  • the purity of the aluminum-plated layer 120 is ⁇ 99.8%.
  • the thickness of the polymer base film 110 is 1 ⁇ m ⁇ 25 ⁇ m.
  • the thickness of the polymer base film 110 is 1 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 1 ⁇ m to 10 ⁇ m, 5 ⁇ m to 15 ⁇ m, 10 ⁇ m to 20 ⁇ m, 1 ⁇ m to 5 ⁇ m, 5 ⁇ m to 10 ⁇ m, 10 ⁇ m to 15 ⁇ m, 15 ⁇ m to 20 ⁇ m, 20 ⁇ m ⁇ 25 ⁇ m, etc.
  • the polymer base film 110 is selected from at least one of polyethylene, polypropylene, polymethylpentene, and polyethylene terephthalate.
  • the polymer base film 110 has a low density, which can further reduce the density of the composite current collector 100 and increase the energy density of the lithium-ion battery.
  • the peeling force between the aluminum plating layer 120 and the polymer base film 110 is ⁇ 2N/m.
  • the thickness of the composite current collector 100 is 3 ⁇ m ⁇ 30 ⁇ m.
  • the thickness of the composite current collector 100 is 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 3 ⁇ m ⁇ 5 ⁇ m, 5 ⁇ m ⁇ 10 ⁇ m, 10 ⁇ m ⁇ 15 ⁇ m, 15 ⁇ m ⁇ 20 ⁇ m, 25 ⁇ m ⁇ 30 ⁇ m, 3 ⁇ m ⁇ 10 ⁇ m, 5 ⁇ m ⁇ 15 ⁇ m. , 10 ⁇ m ⁇ 20 ⁇ m, 15 ⁇ m ⁇ 25 ⁇ m or 20 ⁇ m ⁇ 30 ⁇ m, etc.
  • the thickness of the composite current collector 100 is 3 ⁇ m ⁇ 16 ⁇ m.
  • the composite current collector 100 is a positive electrode current collector.
  • the traditional positive electrode current collector is aluminum foil, which is made by rolling process. The specific steps are as follows:
  • the aluminum liquid in the static furnace is sent to the launder, and the aluminum titanium boron wire is added in reverse direction to refine the grains. Then, pure nitrogen or pure argon gas is used to degas the aluminum liquid in the degassing box. After degassing, use Foam ceramic filter discs filter and purify aluminum liquid. The purified aluminum liquid is sent to the casting and rolling machine for casting and rolling, and a billet with a thickness of 5.0mm ⁇ 10.0mm is cast and rolled.
  • step b Cold-roll the billet obtained in step a to a thickness of 3.0 mm to 5.0 mm and then perform homogenization annealing.
  • the homogenization annealing temperature is 440°C to 490°C, and the annealing time is 20 hours to 30 hours.
  • the surface energy of the current collector surface prepared by the above traditional method is low, so that when the current collector is coating the active material of the cathode, the active material cannot effectively fit with the current collector, thereby causing the interface between the active material and the current collector to Excessive resistance affects battery performance.
  • the composite current collector of this embodiment includes a polymer base film and an aluminum plating layer.
  • the polymer base film is used to support the aluminum plating layer.
  • the aluminum plating layer includes a two-layer structure of different particle sizes. Due to the size of the aluminum particles in the first sub-layer, The small particle size and high compactness ensure that the aluminum-plated layer has high electrical conductivity.
  • the aluminum particles in the second sub-layer have large particle sizes and low compactness, resulting in a higher surface energy of the outermost layer of the aluminum-plated layer. High, which can well solve the problem of high interface resistance of traditional aluminum foil. Therefore, the above-mentioned composite current collector not only has high conductivity, but also has high surface energy, which can be significantly improved during the coating process of active materials.
  • the internal resistance at the interface between the battery pole piece and the current collector improves the capacity and cycle performance of the lithium battery.
  • the aluminum foil produced by the traditional rolling process is limited by the process, and it is difficult to make the aluminum foil very thin.
  • the polymer base film and the aluminum plating layer are combined to make the thickness of the composite current collector thinner. .
  • the surface energy of the composite current collector surface layer is >65 dynes/cm, and the electrical conductivity of the aluminum-plated layer on one side is ⁇ 3.7 ⁇ 10 6 S/M.
  • the puncture strength of the composite current collector is ⁇ 50gf, the tensile strength MD ⁇ 150MPa, the tensile strength TD ⁇ 150MPa, the elongation MD ⁇ 10%, and the elongation TD ⁇ 10%. Therefore, while ensuring conductivity and improving surface energy, the above-mentioned composite current collector also has good strength and elongation, and can be used in batteries instead of traditional aluminum foil.
  • An aluminum plating layer is formed on both sides of the polymer base film to prepare a composite current collector.
  • the aluminum plating layer includes a first sub-layer and a second sub-layer.
  • the first sub-layer is closer to the polymer base film than the second sub-layer.
  • the particle size of the aluminum particles in the first sub-layer is 10nm ⁇ 30nm.
  • the second sub-layer is The particle size of the aluminum particles in the layer is 80 nm to 100 nm.
  • the aluminum plating layer is formed by vacuum evaporation or magnetron sputtering. Further, an aluminum plating layer is formed using high-purity aluminum ingots (purity ⁇ 99.8%) as raw material.
  • the process parameters are as follows: evaporation temperature ⁇ 600° C., vacuum degree ⁇ 0.01 Pa, and evaporation speed > 10 m/min. Further, the vacuum degree is 0.002Pa ⁇ 0.005Pa, and the evaporation speed is 80m/min ⁇ 120m/min.
  • the evaporation temperature in the process of forming the first sub-layer is greater than the evaporation temperature in the process of forming the second sub-layer.
  • the particle size of the aluminum particles in the first sub-layer and the second sub-layer is controlled by controlling the temperature during the formation of the first sub-layer and the second sub-layer. Further, the evaporation temperature in the process of forming the first sub-layer is 700°C to 750°C, and the evaporation temperature in the process of forming the second sub-layer is 600°C to 700°C.
  • first sub-layers there are multiple first sub-layers, and the multiple first sub-layers are stacked in sequence and arranged between the polymer base film and the second sub-layer.
  • the number of first sub-layers is ⁇ 19.
  • the number of first sub-layers is 2, 5, 8, 10, 12, 15, 17 or 19.
  • the number of first sub-layers is 8-12.
  • the thickness of each aluminum plating layer is ⁇ 5 ⁇ m. Further, the thickness of each aluminum plating layer is independently 0.3 ⁇ m to 3 ⁇ m. For example, the thickness of each aluminum plating layer is independently 0.3 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 0.3 ⁇ m to 0.5 ⁇ m, 0.5 ⁇ m to 1 ⁇ m, 1 ⁇ m to 1.5 ⁇ m, 1.5 ⁇ m to 2 ⁇ m, 2 ⁇ m to 2.5 ⁇ m, 2.5 ⁇ m ⁇ 3 ⁇ m, 0.3 ⁇ m ⁇ 1 ⁇ m, 0.5 ⁇ m ⁇ 1.5 ⁇ m, 1 ⁇ m ⁇ 2 ⁇ m, 1.5 ⁇ m ⁇ 2.5 ⁇ m, 2 ⁇ m ⁇ 3 ⁇ m, etc. Furthermore, the aluminum plating layer is symmetrically disposed on both sides of the polymer base film 110 .
  • the thickness of the polymer base film is 1 ⁇ m to 25 ⁇ m.
  • the thickness of the polymer base film is 1 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 1 ⁇ m ⁇ 10 ⁇ m, 5 ⁇ m ⁇ 15 ⁇ m, 10 ⁇ m ⁇ 20 ⁇ m, 1 ⁇ m ⁇ 5 ⁇ m, 5 ⁇ m ⁇ 10 ⁇ m, 10 ⁇ m ⁇ 15 ⁇ m, 15 ⁇ m ⁇ 20 ⁇ m, 20 ⁇ m ⁇ 25 ⁇ m, etc.
  • the polymer base film is selected from at least one of polyethylene, polypropylene, polymethylpentene and polyethylene terephthalate.
  • the polymer base film has a low density, which can further reduce the density of the composite current collector 100 and increase the energy density of the lithium-ion battery.
  • the peeling force between the aluminum plating layer and the polymer base film is ⁇ 2N/m.
  • the thickness of the composite current collector is 3 ⁇ m to 30 ⁇ m.
  • the thickness of the composite current collector is 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 3 ⁇ m ⁇ 5 ⁇ m, 5 ⁇ m ⁇ 10 ⁇ m, 10 ⁇ m ⁇ 15 ⁇ m, 15 ⁇ m ⁇ 20 ⁇ m, 25 ⁇ m ⁇ 30 ⁇ m, 3 ⁇ m ⁇ 10 ⁇ m, 5 ⁇ m ⁇ 15 ⁇ m, 10 ⁇ m ⁇ 20 ⁇ m, 15 ⁇ m ⁇ 25 ⁇ m or 20 ⁇ m ⁇ 30 ⁇ m, etc.
  • the thickness of the composite current collector is 3 ⁇ m to 16 ⁇ m.
  • the composite current collector is a positive electrode current collector.
  • the polymer base film is unrolled under an unwinding tension of 5N to 30N. After the aluminum plating layer is formed, a winding step is also included.
  • the winding tension is 5N ⁇ 25N.
  • the preparation method of the above composite current collector is simple, and through multiple evaporation, the aluminum plating layer includes a two-layer structure with different particle sizes. Since the aluminum particles in the first sub-layer have small particle sizes and high compactness, it can ensure The aluminum-plated layer has high electrical conductivity. The aluminum particles in the second sub-layer are large in size and low in density, which makes the surface energy of the aluminum-plated layer higher. It can well solve the problem of high interface resistance of traditional aluminum foil. Therefore, the composite current collector prepared by the above method not only has high conductivity, but also has high surface energy. During the coating process of active materials, the interfacial internal resistance between the battery pole piece and the current collector can be significantly improved. , improve the capacity and cycle performance of lithium batteries.
  • An electrode pole piece in one embodiment includes a current collector and an active material coated on both sides of the current collector.
  • the current collector is the composite current collector in the above embodiment. Further, the electrode piece is a positive electrode piece.
  • the active material may be a cathode active material commonly used in the field, which will not be described again here.
  • a secondary battery includes the above-mentioned electrode tab.
  • the above-mentioned electrode piece is a positive electrode piece.
  • the secondary battery also includes a negative electrode plate, a separator and an electrolyte.
  • the specific negative electrode plate, separator and electrolyte may be those commonly used in the art, and will not be described in detail here.
  • the secondary battery is a non-aqueous secondary battery, such as a lithium battery.
  • the secondary battery of this embodiment has lower interfacial internal resistance, higher capacity and excellent cycle performance.
  • This embodiment provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, of which the first 15 times are evaporated to obtain 15 first sub-layers.
  • the particle size of the aluminum particles in each first sub-layer is 20nm, and the 16th evaporation is used to obtain the second sub-layer.
  • the particle size of the aluminum particles in the second sub-layer is 85nm.
  • the process parameters during the evaporation process are as follows: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first 15 times was 700°C
  • the evaporation temperature for the 16th time was 620°C.
  • This embodiment provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires two evaporation times.
  • the first evaporation is to obtain the first sub-layer.
  • the particle size of the aluminum particles in the first sub-layer is 20nm.
  • the second evaporation is to obtain the second sub-layer.
  • the second sub-layer is The particle size of the aluminum particles in the layer is 85 nm.
  • the process parameters during the evaporation process are as follows: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first time is 700°C
  • the evaporation temperature for the second time is 620°C.
  • This embodiment provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, of which the first 15 times are evaporated to obtain 15 first sub-layers.
  • the particle size of the aluminum particles in each first sub-layer is 10nm, and the 16th evaporation is used to obtain the second sub-layer.
  • the particle size of the aluminum particles in the second sub-layer is 100nm.
  • the process parameters during the evaporation process are as follows: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first 15 times was 740°C
  • the evaporation temperature for the 16th time was 650°C.
  • Comparative Example 1 provides a method of manufacturing a traditional aluminum foil cathode current collector with a thickness of 8 microns.
  • the preparation process is as follows:
  • the electrolytic aluminum melt is sent to the smelting furnace, aluminum ingots accounting for 30% of the total weight of the electrolytic aluminum melt are added, the melt temperature is controlled to 770°C, and the mass percentage of each element component in the melt is adjusted to Si 0.15%, Fe 0.48%, Cu 0.13%, Mn 1.3%, Ti 0.03%, and the balance is Al; use pure nitrogen or pure argon to spray the refining agent into the melt for refining, stir evenly, the refining time is 9 minutes, and then let it stand For 20 minutes, remove the scum on the surface of the aluminum liquid, pour it into the static furnace, and control the temperature in the static furnace to 755°C; send the aluminum liquid in the static furnace into the launder, and add aluminum titanium boron wire in the reverse direction for grain refinement.
  • step (2) Cold-roll the billet obtained in step (1) to a thickness of 4.0 mm and then perform homogenization annealing.
  • the homogenization annealing temperature is 470°C and the annealing time is 25 hours.
  • Comparative Example 2 provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, and the particle size of the aluminum particles in the layer obtained each time is 20nm.
  • the process parameters during the evaporation process are as follows: the evaporation temperature is 700°C, the vacuum degree is 5 ⁇ 10 -2 Pa, and the evaporation speed is 50m/min.
  • Comparative Example 3 provides a composite current collector with a thickness of 8 microns, including a polymer base film PP with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • Comparative Example 4 provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, of which 15 first sub-layers are obtained by evaporation in the first 15 times.
  • the particle size of the aluminum particles in each first sub-layer is 85nm.
  • the second sub-layer is obtained in the 16th evaporation.
  • the particle size of the aluminum particles in the second sub-layer is 20nm.
  • the process parameters during the evaporation process are: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first 15 times was 620°C
  • the evaporation temperature for the 16th time was 700°C.
  • Comparative Example 5 provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, of which the first 15 times are evaporated to obtain 15 first sub-layers.
  • the particle size of the aluminum particles in each first sub-layer is 50nm, and the 16th evaporation is used to obtain the second sub-layer.
  • the particle size of the aluminum particles in the second sub-layer is 85nm.
  • the process parameters during the evaporation process are as follows: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first 15 times was 720°C
  • the evaporation temperature for the 16th time was 620°C.
  • Comparative Example 6 provides a composite current collector with a thickness of 8 microns, including a polymer base film PET with a thickness of 6 microns and an aluminum plating layer symmetrically arranged on both sides of the polymer base film.
  • the thickness of the aluminum plating layer on one side is 1 micron.
  • the unwinding tension of the polymer base film is 8N.
  • the aluminum plating layer on one side requires 16 evaporation times, of which the first 15 times are evaporated to obtain 15 first sub-layers.
  • the particle size of the aluminum particles in each first sub-layer is 20nm, and the 16th evaporation is used to obtain the second sub-layer.
  • the particle size of the aluminum particles in the second sub-layer is 120nm.
  • the process parameters during the evaporation process are as follows: vacuum degree is 5 ⁇ 10 -2 Pa, and evaporation speed is 50m/min.
  • the evaporation temperature for the first 15 times is 700°C
  • the evaporation temperature for the 16th time is 600°C.
  • the performance of the composite current collectors obtained in the above examples and comparative examples was tested, and the test results were obtained as shown in Table 1 below.
  • a four-probe tester was used to test the conductivity of the aluminum-plated layer on one side, and a dyne pen was used to test the surface energy of the aluminum-plated layer.
  • the composite current collector was combined with the positive active material to obtain a positive electrode sheet, which was assembled with the negative electrode sheet, electrolyte, and separator to form a lithium battery.
  • the internal resistance of the lithium battery (capacity 50Ah) and the capacity retention rate after 1,000 cycles were tested.
  • the internal resistance results of lithium batteries prepared using the current collectors of Example 1 and Comparative Example 1 are shown in Figure 2.
  • the composite current collector of the embodiment can increase the surface energy while ensuring the conductivity, thereby improving the capacity retention rate of the battery and reducing the internal resistance.

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Abstract

本发明涉及一种复合集流体及其制备方法、电极极片和二次电池。上述复合集流体包括：聚合物基膜和设置在聚合物基膜两侧表面之上的镀铝层，镀铝层包括第一子层和第二子层，第一子层较第二子层更靠近聚合物基膜，第一子层中铝颗粒的粒径为10nm～30nm，第二子层中铝颗粒的粒径为80nm～100nm。上述复合集流体不仅具有较高的导电率，同时还具有较高的表面能，在活性物质的涂覆过程中，可以明显改善电池极片与集流体之间的界面内阻，提高锂电池的容量和循环性能。

Description

复合集流体及其制备方法、电极极片和二次电池 技术领域
本发明涉及电池领域，特别是涉及一种复合集流体及其制备方法、电极极片和二次电池。
背景技术
常规的非水性二次电池的正极集流体采用的是高纯铝箔，其采用压轧工艺制作。为了保证铝箔的平整度，压轧工艺中所采用的压辊表面的光滑度较高，导致集流体表面的表面能较低，致使集流体在涂覆正极的活性物质时，活性物质不能与集流体进行有效的贴合，进而使得活性物质与集流体之间的界面电阻过大，影响电池性能。
发明内容
基于此，有必要提供一种能够使集流体的表面能高，与活性物质之间的界面电阻小的复合集流体。
此外，还有必要提供一种复合集流体的制备方法、包括该复合集流体的电极极片和二次电池。
一种复合集流体，包括：聚合物基膜和设置在所述聚合物基膜两侧表面之上的镀铝层，所述镀铝层包括第一子层和第二子层，所述第一子层较所述第二子层更靠近所述聚合物基膜，所述第一子层中铝颗粒的粒径为10nm～30nm，所述第二子层中铝颗粒的粒径为80nm～100nm。
在其中一个实施例中，各所述镀铝层的厚度独立地为0.3μm～3μm。
在其中一个实施例中，所述第一子层有多个，多个所述第一子层依次层叠排列在所述聚合物基膜和所述第二子层之间。
在其中一个实施例中，所述第一子层的个数≤19。
在其中一个实施例中，所述聚合物基膜的厚度为1μm～25μm。
在其中一个实施例中，所述聚合物基膜选自聚乙烯、聚丙烯、聚甲基戊烯 及聚对苯二甲酸乙二醇酯中的至少一种。
一种复合集流体的制备方法，包括如下步骤：
在聚合物基膜的两侧表面上均形成镀铝层，制备复合集流体；其中，所述镀铝层包括第一子层和第二子层，所述第一子层较所述第二子层更靠近所述聚合物基膜，所述第一子层中铝颗粒的粒径为10nm～30nm，所述第二子层中铝颗粒的粒径为80nm～100nm。
在其中一个实施例中，采用真空蒸镀或磁控溅射的方式形成所述镀铝层。
在其中一个实施例中，形成所述镀铝层的过程中，工艺参数如下：蒸发温度≥600℃，真空度＜0.01Pa，镀膜速度＞10m/min，且形成所述第一子层的蒸发温度大于形成所述第二子层的蒸发温度。
形成所述第一子层的蒸发温度为700℃～750℃，形成所述第二子层的蒸发温度为600℃～700℃。
一种电极极片，包括：集流体和涂覆在所述集流体两侧的活性材料，所述集流体为上述的复合集流体或上述的复合集流体的制备方法制备的复合集流体。
一种二次电池，包括上述的电极极片。
上述复合集流体包括聚合物基膜和镀铝层，聚合物基膜用于支撑镀铝层，镀铝层包括不同粒径的两层结构，由于第一子层中铝颗粒的粒径小，紧密度较高，可保证镀铝层具有较高的电导率，第二子层中铝颗粒的粒径大，紧密度较低，使得镀铝层的表面能较高，可以很好地解决传统铝箔界面电阻高的问题，因此，上述复合集流体通过控制镀铝层的不同子层中颗粒的粒径，使得复合集流体在具有较高的表面能的同时，还能保证较高的导电率，在活性物质的涂覆过程中，可以明显改善电池极片与集流体之间的界面内阻，提高锂电池的容量和循环性能。
附图说明
图1为一实施方式的复合集流体的结构示意图；
图2为用实施例1和对比例1的复合集流体所制备的锂电池的内阻比较图。
具体实施方式
为了便于理解本发明，下面将结合具体实施方式对本发明进行更全面的描述。具体实施方式中给出了本发明的较佳的实施例。但是，本发明可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本发明的公开内容的理解更加透彻全面。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术语只是为了描述具体地实施例的目的，不是旨在于限制本发明。
在本文中，铝颗粒的粒径是指其中位粒径。
请参阅图1，一实施方式的复合集流体100，包括聚合物基膜110和设置在聚合物基膜110两侧表面之上的镀铝层120，镀铝层120包括第一子层122和第二子层124，第一子层122较第二子层124更靠近聚合物基膜110，第一子层122中铝颗粒的粒径为10nm～30nm，第二子层124中铝颗粒的粒径为80nm～100nm。
具体地，第一子层122中铝颗粒的粒径为10nm、15nm、20nm、25nm、30nm、10nm～15nm、15nm～20nm、10nm～20nm、15nm～25nm、20nm～25nm或25nm～30nm等。第二子层124中铝颗粒的粒径为80nm、85nm、90nm、95nm、100nm、80nm～85nm、85nm～90nm、90nm～95nm、95nm～100nm、80nm～90nm或85nm～95nm。
进一步地，第一子层122有多个，多个第一子层122依次层叠排列在聚合物基膜110和第二子层124之间。更进一步地，第一子层122的个数≤19。例如，第一子层122的个数为2、5、8、10、12、15、17或19。优选地，第一子层122的个数为8～12。
其中，各镀铝层120的厚度≤5μm。进一步地，各镀铝层120的厚度独立地为0.3μm～3μm。例如，各镀铝层120的厚度独立地为0.3μm、0.5μm、1μm、1.5μm、2μm、2.5μm、0.3μm～0.5μm、0.5μm～1μm、1μm～1.5μm、1.5μm～2μm、2μm～2.5μm、2.5μm～3μm、0.3μm～1μm、0.5μm～1.5μm、1μm～2μm、1.5μm～2.5μm、2μm～3μm等。更进一步地，镀铝层120对称地设置在聚合物基膜110的两侧表面上。
由于第一子层122中铝颗粒的粒径小，紧密度较高，可保证镀铝层120具有较高的电导率，而第二子层124中铝颗粒的粒径大，紧密度较低，导致镀铝层120的最外层的表面能较高，可以很好地解决传统铝箔界面电阻高的问题。
进一步地，镀铝层120的纯度≥99.8％。
具体地，聚合物基膜110的厚度为1μm～25μm。例如，聚合物基膜110的厚度为1μm、5μm、10μm、15μm、20μm、25μm、1μm～10μm、5μm～15μm、10μm～20μm、1μm～5μm、5μm～10μm、10μm～15μm、15μm～20μm、20μm～25μm等。
具体地，聚合物基膜110选自聚乙烯、聚丙烯、聚甲基戊烯及聚对苯二甲酸乙二醇酯中的至少一种。上述聚合物基膜110的密度低，能够进一步降低复合集流体100的密度，提高锂离子电池的能量密度。
在其中一个实施例中，镀铝层120与聚合物基膜110之间的剥离力≥2N/m。
具体地，复合集流体100的厚度为3μm～30μm。例如，复合集流体100的厚度为3μm、5μm、10μm、15μm、20μm、25μm、30μm、3μm～5μm、5μm～10μm、10μm～15μm、15μm～20μm、25μm～30μm、3μm～10μm、5μm～15μm、10μm～20μm、15μm～25μm或20μm～30μm等。优选地，复合集流体100的厚度为3μm～16μm。
进一步地，在本实施方式中，复合集流体100为正极集流体。
传统的正极集流体为铝箔，铝箔采用压轧工艺制作，具体步骤如下：
a、将电解铝熔液送至熔炼炉，加入占电解铝熔液总重量20％～40％的铝锭，控制熔体温度为750℃～780℃，调整熔体中各元素成分的质量百分比为Si:0.1％～0.15％、Fe 0.45％～0.5％、Cu 0.1％～0.15％、Mn 1.1％～1.2％、Ti:0.02％～0.04％、余量为Al。采用纯氮气或纯氩气向熔体中喷精炼剂进行精炼，充分搅拌均匀，精炼时间为8分钟～10分钟，然后静置15分钟25分钟，除去铝液表面的浮渣，然后倒入静置炉内，控制静置炉内温度为750℃～760℃。将静置炉中的铝液送入流槽中，逆向加入铝钛硼丝进行晶粒细化，然后在除气箱内用纯氮气或纯氩气对铝液进行除气处理，除气后采用泡沫陶瓷过滤片对铝液进行过滤净化处理。净化后的铝液送铸轧机铸轧，铸轧出厚度为5.0mm～10.0mm的坯料。
b、将步骤a得到的坯料冷轧至3.0mm～5.0mm厚度后进行均匀化退火，均 匀化退火温度为440℃～490℃，退火时间为20小时～30小时。
c、将均匀化退火后的坯料冷轧至0.2mm～0.6mm厚度，然后进行再结晶退火，再结晶退火的温度为270℃～330℃，退火时间为12小时～19小时。
d、将再结晶退火后的坯料轧至阳极铝箔所需厚度即可。
上述传统方法所制备的集流体表面的表面能较低，致使集流体在涂覆正极的活性物质时，活性物质不能与集流体进行有效的贴合，进而使得活性物质与集流体之间的界面电阻过大，影响电池性能。
而本实施方式的复合集流体包括聚合物基膜和镀铝层，聚合物基膜用于支撑镀铝层，镀铝层包括不同粒径的两层结构，由于第一子层中铝颗粒的粒径小，紧密度较高，可保证镀铝层具有较高的电导率，第二子层中铝颗粒的粒径大，紧密度较低，导致镀铝层的最外层的表面能较高，可以很好地解决传统铝箔界面电阻高的问题，因此，上述复合集流体不仅具有较高的导电率，同时还具有较高的表面能，在活性物质的涂覆过程中，可以明显改善电池极片与集流体之间的界面内阻，提高锂电池的容量和循环性能。
另外，传统的压轧工艺制作的铝箔受工艺的限制，铝箔很难做到很薄，而在本实施方式中，将聚合物基膜与镀铝层复合，能够使复合集流体的厚度较薄。
具体地，在本实施方式中，复合集流体表层的表面能＞65达因/cm，单侧镀铝层的电导率≥3.7×10 6S/M。复合集流体的穿刺强度≥50gf，拉伸强度MD≥150MPa，拉伸强度TD≥150MPa，延伸率MD≥10％，延伸率TD≥10％。因此，上述复合集流体在保证电导率，提高表面能的同时，还具有较好的强度和延伸率，能够代替传统的铝箔应用在电池中。
一实施方式的复合集流体的制备方法，包括如下步骤：
在聚合物基膜的两侧均形成镀铝层，制备复合集流体。
其中，镀铝层包括第一子层和第二子层，第一子层较第二子层更靠近聚合物基膜，第一子层中铝颗粒的粒径为10nm～30nm，第二子层中铝颗粒的粒径为80nm～100nm。
具体地，采用真空蒸镀的方式或磁控溅射的方式形成镀铝层。进一步地，以高纯铝锭(纯度≥99.8％)为原料形成镀铝层。
在其中一个实施例中，形成镀铝层的过程中，工艺参数如下：蒸发温度≥600℃，真空度＜0.01Pa，蒸镀速度＞10m/min。进一步地，真空度为0.002Pa～0.005Pa，蒸镀速度为80m/min～120m/min。
进一步地，形成第一子层的过程中的蒸发温度大于形成第二子层的过程中的蒸发温度。通过控制第一子层和第二子层形成过程中的温度控制第一子层和第二子层中铝颗粒的粒径。进一步地，形成第一子层的过程中的蒸发温度为700℃～750℃，形成第二子层的过程中的蒸发温度为600℃～700℃。
在一些实施例中，第一子层有多个，多个第一子层依次层叠排列在聚合物基膜和第二子层之间。更进一步地，第一子层的个数≤19。例如，第一子层的个数为2、5、8、10、12、15、17或19。优选地，第一子层的个数为8～12。
具体地，各镀铝层的厚度≤5μm。进一步地，各镀铝层的厚度独立地为0.3μm～3μm。例如，各镀铝层的厚度独立地为0.3μm、0.5μm、1μm、1.5μm、2μm、2.5μm、0.3μm～0.5μm、0.5μm～1μm、1μm～1.5μm、1.5μm～2μm、2μm～2.5μm、2.5μm～3μm、0.3μm～1μm、0.5μm～1.5μm、1μm～2μm、1.5μm～2.5μm、2μm～3μm等。更进一步地，镀铝层对称地设置在聚合物基膜110的两侧表面上。
具体地，聚合物基膜的厚度为1μm～25μm。例如，聚合物基膜的厚度为1μm、5μm、10μm、15μm、20μm、25μm、1μm～10μm、5μm～15μm、10μm～20μm、1μm～5μm、5μm～10μm、10μm～15μm、15μm～20μm、20μm～25μm等。
具体地，聚合物基膜选自聚乙烯、聚丙烯、聚甲基戊烯及聚对苯二甲酸乙二醇酯中的至少一种。上述聚合物基膜的密度低，能够进一步降低复合集流体100的密度，提高锂离子电池的能量密度。
在其中一个实施例中，镀铝层与聚合物基膜之间的剥离力≥2N/m。
具体地，复合集流体的厚度为3μm～30μm。例如，复合集流体的厚度为3μm、5μm、10μm、15μm、20μm、25μm、30μm、3μm～5μm、5μm～10μm、10μm～15μm、15μm～20μm、25μm～30μm、3μm～10μm、5μm～15μm、10μm～20μm、15μm～25μm或20μm～30μm等。优选地，复合集流体的厚度为3μm～16μm。
进一步地，在本实施方式中，复合集流体为正极集流体。
进一步地，聚合物基膜在5N～30N的放卷张力下进行放卷。形成镀铝层后 还包括收卷的步骤。收卷的张力为5N～25N。
上述复合集流体的制备方法工艺简单，且通过多次蒸镀，使镀铝层包括不同粒径的两层结构，由于第一子层中铝颗粒的粒径小，紧密度较高，可保证镀铝层具有较高的电导率，第二子层中铝颗粒的粒径大，紧密度较低，使得镀铝层的表面能较高，可以很好地解决传统铝箔界面电阻高的问题，因此，上述方法制备的复合集流体不仅具有较高的导电率，同时还具有较高的表面能，在活性物质的涂覆过程中，可以明显改善电池极片与集流体之间的界面内阻，提高锂电池的容量和循环性能。
一实施方式的电极极片，包括：集流体和涂覆在集流体两侧的活性物质，该集流体为上述实施方式的复合集流体。进一步地，该电极极片为正极极片。活性物质可以为本领域常用的正极活性物质，在此不再赘述。
一实施方式的二次电池，包括上述的电极极片。具体地，上述电极极片为正极极片。该二次电池还包括负极极片、隔膜和电解液。具体的负极极片、隔膜和电解液可以为本领域常用的，在此不再赘述。
在其中一个实施例中，该二次电池为非水性二次电池，例如为锂电池。本实施方式的二次电池具有较低的界面内阻，较高的容量和优异的循环性能。
以下为具体实施例部分：
实施例1
本实施例提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，其中前15次蒸镀得到15个第一子层，每个第一子层中铝颗粒的粒径为20nm，第16次蒸镀得到第二子层，第二子层中铝颗粒的粒径为85nm。蒸镀过程中的 工艺参数如下：真空度为5×10 -2Pa，蒸镀速度为50m/min。前15次的蒸发温度为700℃，第16次的蒸发温度为620℃。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到本实施例的复合集流体。
实施例2
本实施例提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀2次，其中第1次蒸镀得到第一子层，第一子层中铝颗粒的粒径为20nm，第2次蒸镀得到第二子层，第二子层中铝颗粒的粒径为85nm。蒸镀过程中的工艺参数如下：真空度为5×10 -2Pa，蒸镀速度为50m/min。第1次的蒸发温度为700℃，第2次的蒸发温度为620℃
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到本实施例的复合集流体。
实施例3
本实施例提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，其中前15次蒸镀得到15个第一子层，每个第一子层中铝颗粒的粒径为10nm，第16次蒸镀得到第二子层，第二子层中铝颗粒的粒径为100nm。蒸镀过程中的 工艺参数如下：真空度为5×10 -2Pa，蒸镀速度为50m/min。前15次的蒸发温度为740℃，第16次的蒸发温度为650℃。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到本实施例的复合集流体。
对比例1
对比例1提供一种制造厚度为8微米的传统铝箔正极集流体，制备过程具体如下：
(1)电解铝熔液送至熔炼炉，加入占电解铝熔液总重量30％的铝锭，控制熔体温度为770℃，调整熔体中各元素成分的质量百分比为Si 0.15％、Fe 0.48％、Cu 0.13％、Mn 1.3％、Ti 0.03％、余量为Al；采用纯氮气或纯氩气向熔体中喷精炼剂进行精炼，充分搅拌均匀，精炼时间为9分钟，然后静置20分钟，除去铝液表面的浮渣，倒入静置炉内，控制静置炉内温度为755℃；将静置炉中的铝液送入流槽中，逆向加入铝钛硼丝进行晶粒细化，然后在除气箱内用纯氮气或纯氩气对铝液进行除气处理，除气后采用泡沫陶瓷过滤片对铝液进行过滤净化处理；净化后的铝液送铸轧机铸轧，铸轧出厚度为4.0mm的坯料。
(2)将步骤(1)得到的坯料冷轧至4.0mm厚度后进行均匀化退火，均匀化退火温度为470℃，退火时间为25小时。
(3)将均匀化退火后的坯料冷轧至0.5mm厚度，然后进行再结晶退火，再结晶退火的温度为300℃，退火时间为15小时。
(4)将再结晶退火后的坯料轧至8微米铝箔，得到对比例1的集流体。
对比例2
对比例2提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面， 得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，每次所得到的层中铝颗粒的粒径均为20nm。蒸镀过程中的工艺参数如下：蒸发温度为700℃，真空度为5×10 -2Pa，蒸镀速度为50m/min。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到对比例2的复合集流体。
对比例3
对比例3提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PP和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，每次所得到的层中铝颗粒的粒径均为85nm。蒸镀过程中的工艺参数如下：蒸发温度为620℃，真空度为5×10 -2Pa，蒸镀速度为50m/min。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到对比例3的复合集流体。
对比例4
对比例4提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，其中前15次蒸镀得到15个第一子层，每个第一子层中铝颗粒的粒径为85nm，第16次蒸镀得到第二子层，第二子层中铝颗粒的粒径为20nm。蒸镀过程中的工艺参数为：真空度为5×10 -2Pa，蒸镀速度为50m/min。前15次的蒸发温度为 620℃，第16次的蒸发温度为700℃。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到对比例4的复合集流体。
对比例5
对比例5提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，其中前15次蒸镀得到15个第一子层，每个第一子层中铝颗粒的粒径为50nm，第16次蒸镀得到第二子层，第二子层中铝颗粒的粒径为85nm。蒸镀过程中的工艺参数如下：真空度为5×10 -2Pa，蒸镀速度为50m/min。前15次的蒸发温度为720℃，第16次的蒸发温度为620℃。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到对比例5的复合集流体。
对比例6
对比例6提供一种8微米厚度的复合集流体，包括6微米厚度的聚合物基膜PET和对称设置在聚合物基膜两侧的镀铝层，单侧镀铝层的厚度为1微米，制备过程具体如下：
(1)选取6微米厚度的聚合物基膜PET及纯度为99.9％的高纯铝锭。
(2)将聚合物基膜以及高纯铝锭分别投入到真空蒸镀装置上。
(3)将高纯铝锭通过真空蒸镀装置把铝镀到聚合物基膜的上下两个表面，得到镀铝层。其中，聚合物基膜的放卷张力为8N。单侧镀铝层需要蒸镀16次，其中前15次蒸镀得到15个第一子层，每个第一子层中铝颗粒的粒径为20nm，第16次蒸镀得到第二子层，第二子层中铝颗粒的粒径为120nm。蒸镀过程中的工艺参数如下：真空度为5×10 -2Pa，蒸镀速度为50m/min。前15次的蒸发温度 为700℃，第16次的蒸发温度为600℃。
(4)蒸镀完成后进行收卷作业，收卷张力为6N，得到对比例6的复合集流体。
对上述实施例和对比例所得到的复合集流体的性能进行测试，得到如下表1所示的测试结果。其中，采用四探针测试仪对单侧镀铝层的电导率进行测试，采用达因笔对镀铝层的表面能进行测试。将复合集流体与正极活性材料复合得到正极极片，并与负极极片、电解液、隔膜组装成锂电池，测试锂电池(容量50Ah)的内阻及循环1000周后的容量保持率。用实施例1和对比例1的集流体所制备的锂电池的内阻结果如图2所示。
表1实施例和对比例的测试数据
Figure PCTCN2022095406-appb-000001
从上述实验数据中可以看出，采用实施例的复合集流体能够在保证电导率的同时，提高表面能，进而提高电池的容量保持率，降低内阻。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技 术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本发明的几种实施方式，便于具体和详细地理解本发明的技术方案，但并不能因此而理解为对发明专利保护范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。应当理解，本领域技术人员在本发明提供的技术方案的基础上，通过合乎逻辑的分析、推理或有限的试验得到的技术方案，均在本发明所附权利要求的保护范围内。因此，本发明专利的保护范围应以所附权利要求的内容为准，说明书及附图可以用于解释权利要求的内容。

Claims (12)

  1. 一种复合集流体，其特征在于，包括：聚合物基膜和设置在所述聚合物基膜两侧表面之上的镀铝层，所述镀铝层包括第一子层和第二子层，所述第一子层较所述第二子层更靠近所述聚合物基膜，所述第一子层中铝颗粒的粒径为10nm～30nm，所述第二子层中铝颗粒的粒径为80nm～100nm。
  2. 根据权利要求1所述的复合集流体，其特征在于，各所述镀铝层的厚度独立地为0.3μm～3μm。
  3. 根据权利要求1所述的复合集流体，其特征在于，所述第一子层有多个，多个所述第一子层依次层叠排列在所述聚合物基膜和所述第二子层之间。
  4. 根据权利要求3所述的复合集流体，其特征在于，所述第一子层的个数≤19。
  5. 根据权利要求1～4任一项所述的复合集流体，其特征在于，所述聚合物基膜的厚度为1μm～25μm。
  6. 根据权利要求1～4任一项所述的复合集流体，其特征在于，所述聚合物基膜选自聚乙烯、聚丙烯、聚甲基戊烯及聚对苯二甲酸乙二醇酯中的至少一种。
  7. 一种复合集流体的制备方法，其特征在于，包括如下步骤：
    在聚合物基膜的两侧表面上均形成镀铝层，制备复合集流体；其中，所述镀铝层包括第一子层和第二子层，所述第一子层较所述第二子层更靠近所述聚合物基膜，所述第一子层中铝颗粒的粒径为10nm～30nm，所述第二子层中铝颗粒的粒径为80nm～100nm。
  8. 根据权利要求7所述的复合集流体的制备方法，其特征在于，采用真空蒸镀或磁控溅射的方式形成所述镀铝层。
  9. 根据权利要求8所述的复合集流体的制备方法，其特征在于，形成所述镀铝层的过程中，工艺参数如下：蒸发温度≥600℃，真空度＜0.01Pa，镀膜速度＞10m/min，且形成所述第一子层的蒸发温度大于形成所述第二子层的蒸发温度。
  10. 根据权利要求9所述的复合集流体的制备方法，其特征在于，形成所述第一子层的蒸发温度为700℃～750℃，形成所述第二子层的蒸发温度为600℃～700℃。
  11. 一种电极极片，其特征在于，包括：集流体和涂覆在所述集流体两侧的活性材料，所述集流体为权利要求1～6任一项所述的复合集流体或权利要求7～10任一项所述的复合集流体的制备方法制备的复合集流体。
  12. 一种二次电池，其特征在于，包括权利要求11所述的电极极片。
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CN110943228A (zh) * 2019-05-31 2020-03-31 宁德时代新能源科技股份有限公司 负极集流体、负极极片及电化学装置
CN114361461A (zh) * 2022-01-10 2022-04-15 上海恩捷新材料科技有限公司 柔性集流体芯层、集流体、极片和电池及其制备方法

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