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CN-122025656-A - Composite current collector, preparation method thereof, pole piece and battery

CN122025656ACN 122025656 ACN122025656 ACN 122025656ACN-122025656-A

Abstract

The application relates to a composite current collector, a preparation method thereof, a pole piece and a battery, and belongs to the technical field of batteries. According to the preparation method, the first base film and the second base film with different corrosion resistance are spliced to form the composite base film, the metal seed layers are formed on the surfaces of the two opposite sides of the composite base film by adopting a magnetron sputtering or vacuum evaporation process, at least part of the first base film is removed by utilizing selective corrosion, the metal seed layers corresponding to the removed parts of the first base film can be contacted and conducted after rolling, and finally the metal layers are formed by thickening and depositing on the surfaces of the metal seed layers, so that the tab area and the coating area can be integrally formed on the composite current collector in situ, the problem that the tab welding of the composite current collector needs to be switched is effectively solved, and the preparation method has the advantages of simple process, low cost, firm interface combination, good product flexibility and high reliability, and can be effectively applied to the preparation of the lithium ion battery with high safety and high energy density.

Inventors

  • CHENG XUNLIANG
  • ZHANG SHUANG
  • GAO JIE
  • LI XIAOBO

Assignees

  • 苏州臻锂新材科技有限公司

Dates

Publication Date
20260512
Application Date
20260225

Claims (10)

  1. 1. The preparation method of the composite current collector is characterized by comprising the following steps of: S1, providing a composite base film, wherein the composite base film comprises at least one first base film and at least one second base film which are arranged in parallel along a first direction, and the materials of the first base film and the second base film are different; S2, respectively forming a first metal seed layer and a second metal seed layer on the surfaces of two opposite sides of the composite base film by adopting a magnetron sputtering or vacuum evaporation process to obtain a first intermediate; s3, placing the first intermediate in a chemical corrosive agent for selective corrosion treatment to remove at least part of the first base film and keep the second base film, so as to obtain a second intermediate; S4, rolling the second intermediate to enable the corresponding part of the first metal seed layer where the first base film is removed to be in contact with and conducted with the second metal seed layer; S5, respectively thickening and depositing the surfaces of the first metal seed layer and the second metal seed layer to form the first metal layer and the second metal layer to obtain a composite current collector, wherein a conducting partial area is defined as a tab area along the thickness direction, and the other partial area corresponding to the second base film is defined as a coating area.
  2. 2. The method according to claim 1, wherein in step S3, a part of the first base film is removed by selective etching treatment, and a plurality of through holes are formed in the first base film, wherein optionally, the hole diameter of the through holes is 0.1 μm to 100 μm; or, in step S3, the first base film is completely removed by a selective etching treatment.
  3. 3. The method according to claim 1, wherein the first base film comprises at least one of an ester group-containing polymer, an amide group-containing polymer, and a nitrile group-containing polymer, and the second base film comprises a polyolefin polymer, and the chemical etchant in step S3 is an alkaline etchant; Optionally, the material of the first base film comprises at least one of polyethylene terephthalate, polycarbonate, polyamide or polyacrylonitrile, the material of the second base film comprises at least one of polypropylene or polyethylene, and the chemical etchant comprises at least one of methanol solution of lithium methoxide, ethanol solution of lithium ethoxide, ethanol solution of sodium hydroxide and ethylenediamine solution of sodium hydroxide.
  4. 4. The preparation method according to claim 3, wherein the concentration of the alkaline etchant is 0.1mol/L to 2.5mol/L, the temperature of the selective etching treatment is 25 ℃ to 60 ℃ and the time is 5min to 60min; Optionally, the thickness of the first base film and the second base film is 3 μm to 10 μm independently.
  5. 5. The method according to claim 1, wherein in step S4, the rolling pressure is 1mpa to 100mpa.
  6. 6. The preparation method of claim 1, wherein in the step S2, a magnetron sputtering process is adopted, the vacuum degree of a film coating chamber is 0.1 Pa-1 Pa, the sputtering power is 0.1 kW-10 kW, the film feeding speed of a film material is 0.1 m/min-5 m/min, and the temperature of a cooling roller is-25 ℃ to 0 ℃; or, in the step S2, a vacuum evaporation process is adopted, the vacuum degree of a film coating cavity is more than 10 -3 Pa, the distance between evaporation sources is 10 cm-25 cm, and the deposition time is 5 m/min-100 m/min; Optionally, the thicknesses of the first metal seed layer and the second metal seed layer are each independently 10 nm-100 nm; Optionally, the materials of the first metal seed layer and the second metal seed layer are at least one of copper or aluminum independently; optionally, before the step S2, the method further comprises the step of carrying out plasma treatment on the composite base film; Optionally, the first base film has a first surface and a second surface in a thickness direction, the second base film has a third surface and a fourth surface in the thickness direction, the first surface and the third surface are flush, and the second surface and the fourth surface are flush.
  7. 7. The method according to claim 1, wherein in step S5, water electroplating, electroless plating or magnetron sputtering is used to form the first metal layer and the second metal layer on the surfaces of the first metal seed layer and the second metal seed layer by thickening and depositing, respectively; Optionally, the thickness of the first metal layer and the second metal layer is1 μm to 6 μm independently; optionally, the material of the first metal layer and the second metal layer is at least one of copper or aluminum independently.
  8. 8. A composite current collector prepared by the method of any one of claims 1 to 7.
  9. 9. A pole piece comprising a composite current collector as claimed in claim 8 and an active material layer disposed on at least one side surface of the composite current collector.
  10. 10. A battery comprising a pole piece as claimed in claim 9.

Description

Composite current collector, preparation method thereof, pole piece and battery Technical Field The application relates to the technical field of batteries, in particular to a composite current collector, a preparation method thereof, a pole piece and a battery. Background The composite current collector has a sandwich structure of a metal layer, a polymer layer and a metal layer, and is light in weight, low in cost and high in energy density, and can effectively inhibit thermal runaway, improve the safety of a battery and the like, so that the composite current collector becomes a research hot spot of key materials of the current lithium ion battery. However, since the polymer (such as PET and PP) layer in the middle of the composite current collector is an insulator, conduction between the upper and lower metal layers is not possible during tab welding. The current common solution in industry is to weld a section of pure metal foil (such as pure copper foil or pure aluminum foil) as a switching piece at least at one side edge of the composite current collector by adopting ultrasonic roll welding and other processes, and then weld the tab to the switching piece. However, the transfer welding process increases the complexity of the process, increases the production cost and the material cost, introduces additional connection resistance and potential failure points, and has lower reliability. Disclosure of Invention Aiming at the defects of the prior art, the application provides a composite current collector, a preparation method thereof, a pole piece and a battery, so as to effectively solve the problems of complex preparation process, high cost and insufficient connection reliability of a tab area and a coating area of the conventional composite current collector. In a first aspect, an embodiment of the present application provides a method for preparing a composite current collector, including the steps of: S1, providing a composite base film, wherein the composite base film comprises at least one first base film and at least one second base film which are arranged in parallel along a first direction, and the materials of the first base film and the second base film are different; s2, respectively forming a first metal seed layer and a second metal seed layer on the surfaces of two opposite sides of the composite base film by adopting a magnetron sputtering or vacuum evaporation process to obtain a first intermediate; S3, placing the first intermediate in a chemical etchant for selective etching treatment to remove at least part of the first base film and keep the second base film, so as to obtain a second intermediate; s4, rolling the second intermediate to enable the corresponding part of the first metal seed layer and the second metal seed layer at the removed part of the first base film to be in contact and conducted; S5, respectively thickening and depositing the surfaces of the first metal seed layer and the second metal seed layer to form the first metal layer and the second metal layer to obtain the composite current collector, wherein a part area where the first metal layer and the second metal layer are conducted is defined as a tab area, and the other part area corresponding to the second base film is defined as a coating area along the thickness direction. According to the technical scheme, the lug area and the coating area can be formed in situ in the composite current collector by adopting chemical corrosion and rolling, so that a transfer welding process can be omitted, and the chemical corrosion and rolling unit can be conveniently integrated into the existing battery preparation production line, so that continuous production is realized, the preparation process is simplified, and the production cost is reduced. And the lug area and the coating area are integrally formed, so that stress concentration at the junction of the lug area and the coating area is reduced, the structural stability is improved, the connection resistance is effectively reduced, and the reliability is enhanced. The first base film and the second base film are limited to be different in material, namely different in corrosion resistance, namely, corresponding chemical corroding agents can be used for carrying out selective corrosion treatment, so that at least part of the first base film is effectively removed, and the second base film is completely reserved. The first metal seed layer and the second metal seed layer are formed by limiting the adoption of a magnetron sputtering or vacuum evaporation process, and the metal layers formed by the magnetron sputtering or vacuum evaporation process are of island-shaped growth or columnar crystal growth structures, so that point defects, dislocation, nano-pores, more grain boundary gaps and other defect structures naturally exist in the layers, chemical corrosive agents smoothly permeate and diffuse into the first base film for corrosion, and at least part of the first base