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CN-121983583-A - Composite current collector with metal material functional layer, preparation method thereof, pole piece and battery

CN121983583ACN 121983583 ACN121983583 ACN 121983583ACN-121983583-A

Abstract

The invention discloses a composite current collector with a metal material functional layer, a preparation method thereof, a pole piece and a battery, wherein the composite current collector comprises a base film layer, a metal layer on at least one side surface of the base film layer and a functional layer arranged on one side surface of the metal layer far away from the base film layer, the functional layer comprises a metal material, the thickness relation ratio of the functional layer to the metal layer is 0.5-10:1, the thickness range of the functional layer is 0.5-10 mu m, and the relation between the resistivity R1 of the functional layer and the resistivity R2 of the metal layer is 10 5 Ω M > R1> R2. According to the invention, through the three-layer structure design of the base film layer, the metal layer and the metal material functional layer, the multi-dimensional parameter gradient control is adopted, so that the core problems that the conductivity and the protection performance of the traditional composite current collector are difficult to be compatible, the interface combination is weak, the high-temperature stability is poor and the like are effectively solved, and the dual targets of performance balance and industrialization adaptation are realized.

Inventors

  • HE TINGTING
  • XIA JIANZHONG
  • ZHU ZHONGYA
  • ZENG LAIYUAN
  • LIU HAO
  • LI XUEFA

Assignees

  • 扬州纳力新材料科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260213

Claims (10)

  1. 1. A composite current collector with a metal material functional layer is characterized by comprising a base film layer, a metal layer on at least one side surface of the base film layer and a functional layer arranged on one side surface of the metal layer far away from the base film layer, wherein the functional layer contains a metal material; The thickness relation ratio of the functional layer to the metal layer is 0.5-10:1, the thickness range of the functional layer is 0.5-10 mu m, and the relation between the resistivity R1 of the functional layer and the resistivity R2 of the metal layer is 10 5 Ω m>R1>R2。
  2. 2. The composite current collector having a functional layer of a metal material according to claim 1, wherein the relation between the particle diameter of the functional layer and the particle diameter of the metal layer is that the average particle diameter of the functional layer is not more than 0.17.
  3. 3. The composite current collector with metal material functional layer of claim 1 wherein the difference in lattice constants between the functional layer and the metal layer at the interface therebetween is no more than 30%.
  4. 4. The composite current collector of claim 1 wherein said base film layer has a thermal conductivity of < the functional layer has a thermal conductivity of < the metal layer.
  5. 5. The composite current collector with the metal material functional layer of claim 4, wherein the base film layer comprises at least one of a carbon material and an organic material, the thermal conductivity of the base film layer is 0.1-50W/mK, the thermal conductivity of the functional layer is 50-100W/mK, and the thermal conductivity of the metal layer is more than 200W/mK.
  6. 6. The method for preparing the composite current collector with the metal material functional layer according to any one of claims 1 to 5, which is characterized by comprising the following steps: s1, preparing a priming transition layer on a high polymer film substrate; s2, preparing a metal layer on the surface of the metal bottoming transition layer; s3, preparing a functional layer containing metal materials on the surface of the metal layer; and S4, performing heat treatment at the temperature of 500-800 ℃ to control the grain growth rate of the functional layer within the range of 1-50 mu m/h, and cooling to obtain the final composite current collector.
  7. 7. The method for preparing a composite current collector with a metal material functional layer according to claim 6, wherein the heat treatment in the step S4 specifically comprises the following gradient stages: The first gradient stage is to raise the temperature of the initial composite current collector to 650-800 ℃ at a rate of 100-120 ℃ per minute, and keep the temperature for 2-5 minutes, wherein the grain growth rate of the metal layer is 25-50 mu m/h, the grain size is 2-3 mu m, the inner side metal material closest to the metal layer in the functional layer obtains the energy transferred by the metal layer, and the energy is rapidly recrystallized, the grain growth rate is 40-50 mu m/h, and the grain size is 0.8-1.5 mu m; And a second gradient stage, namely cooling to 450-600 ℃ at a speed of 15-25 ℃ per minute, and preserving heat for 4-6 minutes at the temperature, wherein the grain growth speed of the metal layer is reduced to 10-20 mu m/h, the grain size of the metal layer continues to slowly grow to 3-5 mu m, the inner side metal material grains close to the metal layer in the functional layer gradually stop growing, the metal material grains in the middle part mainly grow at the stage, the growth speed is 20-30 mu m/h, and the grain size of the formed grains is 0.2-1 mu m.
  8. 8. The method for preparing the composite current collector with the metal material functional layer, which is disclosed in claim 6, is characterized in that after the heat treatment in the step S4 is stopped, the temperature is reduced to below 300 ℃ at the cooling rate of 10-15 ℃ per minute, the growth of crystal grains of the metal layer is basically stopped, the growth of the crystal grains of the metal material in the middle part of the functional layer is gradually stopped, the crystal grains of the metal material at the outermost side mainly grow at the stage, the growth rate is 1-10 mu m/h, and the grain size of the finally formed crystal grains is less than or equal to 100nm.
  9. 9. A pole piece characterized by comprising the composite current collector with the metal material functional layer prepared by the method of any one of claims 1-5 or 6-8.
  10. 10. A battery comprising the electrode sheet of claim 9.

Description

Composite current collector with metal material functional layer, preparation method thereof, pole piece and battery Technical Field The invention relates to the technical field of batteries, in particular to a composite current collector with a metal material functional layer, a preparation method of the composite current collector, a pole piece and a battery. Background Current mainstream current collector technology mainly employs a single metal foil or a simple composite structure. Single metal foil current collectors are typically fabricated by rolling or electrolytic processes using pure copper or pure aluminum foil, between 6 and 20 microns thick. Such materials rely on the electrical conductivity of the metal itself, but are not uniform in grain size and are easily roughened at high temperatures, resulting in insufficient mechanical strength and high temperature stability. The simple composite structure current collector is formed by compounding a metal layer (such as copper and aluminum) and a polymer base film (such as PET and PP). Although the structure combines the conductivity of metal and the flexibility of a polymer base film, the structure has obvious problems that the interface bonding force between a metal layer and the base film is weak, delamination is easy to occur during high-temperature treatment, and the grain growth of the metal layer is uncontrollable, so that the conductivity and the strength are difficult to balance. The main defects of the prior art include uncontrollable grain growth, excessively high grain growth rate or excessively low grain growth rate during high-temperature heat treatment of the traditional metal layer, coarsening of grains, embrittlement of materials and reduction of conductivity caused by excessively high growth rate, high energy consumption and low production efficiency, poor interface performance, unmatched thermal expansion coefficients of the metal layer and the functional layer or the base film, easiness in generating microcracks during heat circulation, insufficient compactness of the functional layer, incapability of effectively blocking element diffusion, limitation of comprehensive performance, difficulty in considering conductivity and mechanical strength, poor mechanical stability when high conductivity is required, and high resistivity when high strength is required. Disclosure of Invention The invention aims to provide a composite current collector with a metal material functional layer, a preparation method thereof, a pole piece and a battery, and the improvement of high-temperature stability, interface optimization and performance balance of the existing current collector is realized. In order to achieve the above purpose, the technical scheme provided by the invention is as follows: the first aspect of the application provides a composite current collector with a metal material functional layer, which comprises a base film layer, a metal layer arranged on at least one side surface of the base film layer and a functional layer arranged on one side surface of the metal layer far away from the base film layer, wherein the functional layer comprises a metal material; The thickness relation ratio of the functional layer to the metal layer is 0.5-10:1, the thickness range of the functional layer is 0.5-10 mu m, and the relation between the resistivity R1 of the functional layer and the resistivity R2 of the metal layer is 10 5Ωm>R1>R2。 In order to optimize the technical scheme, the specific limitations adopted further comprise: the relation between the grain diameter of the functional layer and the grain diameter of the metal layer is that the average grain diameter of the functional layer is less than or equal to the average grain diameter of the metal layer multiplied by 0.17. The lattice constant difference of the functional layer and the metal layer at the interface of the functional layer and the metal layer is less than or equal to 30 percent. Further, the thermal conductivity of the base film layer is < the thermal conductivity of the functional layer is < the thermal conductivity of the metal layer. Further, the thermal conductivity of the base film layer is 0.1-50W/mK, the thermal conductivity of the functional layer is 50-100W/mK, and the thermal conductivity of the generic layer is more than 200W/mK. The second aspect of the present application provides a method for preparing a composite current collector having a functional layer of a metal material, comprising the steps of: s1, preparing a priming transition layer on a high polymer film substrate; s2, preparing a metal layer on the surface of the metal bottoming transition layer; s3, preparing a functional layer containing metal materials on the surface of the metal layer; and S4, performing heat treatment at the temperature of 500-800 ℃ to control the grain growth rate of the functional layer within the range of 1-50 mu m/h, and cooling to obtain the final composite current collec