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CN-122025658-A - Functional copper current collector and preparation method thereof

CN122025658ACN 122025658 ACN122025658 ACN 122025658ACN-122025658-A

Abstract

The invention relates to the technical field of battery current collectors, in particular to a functional copper current collector and a preparation method thereof, wherein the functional copper current collector comprises a base film, a Ti/Cu transition layer, a nanocrystalline copper layer and a coarse-grain copper layer which are symmetrically arranged on the surfaces of two sides of the base film and are arranged outwards in sequence; the Ti/Cu transition layer comprises a Ti layer and a Cu seed layer arranged on the surface of the Ti layer. According to the functional copper current collector and the preparation method thereof, the nanocrystalline copper layer with high impurity concentration and the coarse-grain copper layer with low impurity concentration are arranged, the diffusion of impurities of the Cu seed layer from the nanocrystalline copper layer in the high-concentration area to the coarse-grain copper layer in the low-concentration area is realized through low-temperature annealing at 100-120 ℃, and the defects of a nanocrystalline area and a cavity which are not grown at an interface between copper layers are eliminated through the diffusion of impurities, so that the residual stress is reduced, and the physical performance of the functional copper current collector is improved.

Inventors

  • SHEN PENGCHENG
  • LI XUEFA

Assignees

  • 扬州纳力新材料科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260305

Claims (9)

  1. 1. A functional copper current collector is characterized by comprising, The base film (100) and the Ti/Cu transition layers (200), the nanocrystalline copper layers (300) and the coarse-grain copper layers (400) are symmetrically arranged on the surfaces of two sides of the base film (100) and are outwards arranged in sequence; the Ti/Cu transition layer (200) comprises a Ti layer (201) and a Cu seed layer (202) arranged on the surface of the Ti layer (201).
  2. 2. The functional copper current collector according to claim 1, wherein the nanocrystalline copper layer (300) has a grain size of 40-60nm and a thickness of 300-500nm, and the macrocrystalline copper layer (400) has a grain size of 0.8-1.2 μm and a thickness of 2-3 μm.
  3. 3. The functional copper current collector according to claim 2, wherein the Ti layer (201) has a thickness of 50-100nm, the Cu seed layer (202) has a thickness of 200-300nm, and the grain size is 20-30nm.
  4. 4. The functional copper current collector according to claim 1,2 or 3, wherein the raw material of the base film (100) is polypropylene, polyethylene, polyimide, polyamide or polyethylene terephthalate.
  5. 5. A method for preparing a functional copper current collector according to any one of claims 1 to 4, comprising, Depositing a Ti layer (201) on the surface of the base film (100) subjected to the activation pretreatment by magnetron sputtering, and then depositing a Cu seed layer (202) to form a magnetron film with a Ti/Cu transition layer (200); after the magnetron film is electroplated for the first time to form a nanocrystalline copper layer (300), electroplating for the second time to form a coarse-grained copper layer (400) to obtain a metal film; and annealing the metal film to obtain the functional copper current collector.
  6. 6. The method for preparing a functional copper current collector according to claim 5, wherein the activation pretreatment is oxygen plasma treatment with power of 50-100W for 30-60s.
  7. 7. The method of manufacturing a functional copper current collector according to claim 6, wherein the sputtering power of the magnetron sputter deposited Cu seed layer (202) is 5500-6500W.
  8. 8. The method for preparing a functional copper current collector according to claim 6 or 7, wherein the current density of primary electroplating is 40-60mA/cm < 2 >, the primary electroplating deposition time is 4-8 minutes, 200ppm is less than or equal to 300ppm of acetophenone as an impurity generating agent, the current density of secondary electroplating is 10-20mA/cm < 2 >, the secondary electroplating deposition time is 15-20 minutes, and the impurity generating agent acetophenone is less than or equal to 3ppm.
  9. 9. The method for preparing a functional copper current collector according to claim 8, wherein the annealing temperature is 100-120 ℃ and the annealing time is 60-120min.

Description

Functional copper current collector and preparation method thereof Technical Field The invention relates to the technical field of battery current collectors, in particular to a functional copper current collector and a preparation method thereof. Background With the rapid development of new energy and electronic technology, the cycle life, safety performance, energy density, etc. of batteries have been of great importance. The current collector is used as a very important part of the battery, and is used for collecting the current generated by the active substances of the battery so as to form a larger current to be output outwards, and the performance quality of the current collector directly influences the cycle life, the energy density, the safety and the like of the battery. The existing copper foil current collector has the following defects that in the current lithium battery and sodium battery, copper ions are continuously deposited on a copper seed layer with orderly arranged crystals, which is prepared by magnetron sputtering, to form an electroplated copper layer in the current composite current collector in the electroplating deposition process, crystal grains of the electroplated copper layer, which are formed by deposition, are randomly oriented and grown under the influence of multiple factors such as the local concentration of a solution, the tape feeding speed, the circulation speed of an electroplating solution and the like, and more defect vacancies are formed at the interface of the magnetron sputtered copper layer and the electroplated copper layer, so that the residual stress of the local interface is overlarge, the mechanical property such as the tensile strength of the functional copper current collector is reduced, and the base film component in the middle of the functional copper current collector is basically a plastic base film, so that the residual stress cannot be eliminated by conventional annealing, and the base film is shrunken or degraded due to the fact that the annealing temperature of the plastic base film exceeds the thermal deformation temperature, so that the thermal shrinkage of the functional copper current collector is seriously unusable. Disclosure of Invention The invention is provided in view of the problem that the base film of the existing composite current collector is too high in stress and too low in tensile strength. Therefore, the invention aims to provide the functional copper current collector, which reduces the residual stress of the composite current collector and improves the mechanical property of the composite current collector. In order to solve the technical problems, the invention provides the following technical scheme: In a first aspect, the invention provides a technical scheme of a functional copper current collector, which comprises a base film, and a Ti/Cu transition layer, a nanocrystalline copper layer and a coarse-grain copper layer which are symmetrically arranged on the two side surfaces of the base film and are arranged outwards in sequence, wherein the Ti/Cu transition layer comprises a Ti layer and a Cu seed layer arranged on the surface of the Ti layer. The invention provides a technical scheme of a preparation method of a functional copper current collector, which comprises the steps of depositing a Ti layer on the surface of a base film subjected to activation pretreatment through magnetron sputtering, depositing a Cu seed layer to form a magnetron film with a Ti/Cu transition layer, electroplating the magnetron film once to form a nanocrystalline copper layer, electroplating the nanocrystalline copper layer twice to form a coarse-grained copper layer to obtain a metal film, and annealing the metal film at the annealing temperature of 100-120 ℃ to obtain the functional copper current collector. According to the invention, a nanocrystalline copper layer with high concentration of impurities is generated through primary electroplating, a coarse-grain copper layer with low concentration of impurities is generated through secondary electroplating, and then low-temperature annealing at 100-120 ℃ is carried out to realize diffusion of the impurities of the copper layer of the functional copper current collector from a high concentration area to a low concentration area, so that the defects of holes at the interface between copper layers are filled and eliminated during the impurity diffusion process, the residual stress is reduced, and the mechanical performance of the functional current collector is improved. As a preferable scheme of the functional copper current collector, the thickness of the Ti layer in the Ti/Cu transition layer is 50-100nm. The Ti layer is selected as a transition layer of the base film and the copper layer, and mainly the thermal expansion coefficient of Ti is lower than that of Cu and is 8.6X10 -6/DEG C, and the thermal expansion coefficient of Ti is far smaller than that of Cu and is 16.6X10 -6/DEG C, and th