Copper alloy carrier copper foil as well as preparation method and application thereof

Abstract

The invention provides a copper alloy carrier copper foil as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, carrying out vacuum melting on a copper simple substance and a copper alloy to obtain a molten alloy; s2, upward continuous casting is conducted on the molten alloy in a magnetic field, and a copper alloy rod is obtained; s3, the copper alloy rod is continuously extruded, and a copper alloy strip blank is obtained; s4, the copper alloy strip blank is continuously rolled, and a copper alloy strip is obtained; s5, the copper alloy strip is subjected to pouring and continuous cast rolling, and a composite strip blank is obtained; and S6, the composite strip blank is subjected to finish rolling, and the copper alloy carrier copper foil is obtained after cleaning and heat treatment. The copper alloy carrier copper foil prepared by the preparation method has a uniform and fine organization structure, has excellent mechanical properties and electrical properties, and is particularly suitable for being applied to the field of lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of carrier copper foil preparation technology, and more specifically, to a copper alloy carrier copper foil, its preparation method and application. Background Technology

[0002] Copper foil, especially ultrathin copper foil, is a key basic material in the modern electronics industry, particularly in high-frequency and high-speed communications, lithium-ion batteries, and printed circuit boards (PCBs). Traditional copper foil manufacturing processes typically employ electrolysis or rolling methods.

[0003] While electrolytic copper foil can be produced in very thin layers, its microstructure is columnar, resulting in significant anisotropy. It is prone to recrystallization at high temperatures, leading to poor mechanical properties (especially ductility). Furthermore, the electrolytic production process is energy-intensive, poses a significant environmental pollution risk, and makes it difficult to produce specific copper alloy foils.

[0004] Traditional copper foil production using the rolling process typically involves a series of lengthy and separate steps, including ingot casting, hot rolling, multi-pass cold rolling, and multi-pass annealing. This long-process method has many drawbacks:

[0005] (1) High difficulty in quality control: Separation of each process and transfer and storage of materials may introduce new surface defects (such as scratches and oxidation) and internal stress, resulting in poor consistency of final product quality.

[0006] (2) Inhomogeneous structure and properties: Repeated processing and heat treatment can easily lead to uneven grain size and complex texture distribution, thereby affecting the stability of the mechanical and electrical properties of copper foil.

[0007] (3) Low production efficiency: There are many processes, a large amount of intermediate inventory and logistics transfer are required, the production cycle is long, and the energy consumption and labor cost per unit output are high.

[0008] (4) Complex composite process: When it is subsequently combined with other metals such as aluminum, an independent composite process is usually adopted, such as explosive composite or hot rolling composite, and the interface bonding quality is not easy to control.

[0009] While some publicly available patent documents, such as CN118685827A, CN120569290A9, CN120776401A, and CN120700554A, focus on improving equipment or subsequent processing methods, most are still based on traditional copper foil preparation methods. They fail to systematically integrate and innovate across the entire process, from alloy smelting to final composite rolling. In particular, there are significant gaps in existing technology regarding how to efficiently and cost-effectively prepare fine-structured, defect-free copper alloy base materials and seamlessly integrate them into subsequent rolling and composite processes.

[0010] Based on this, we have researched and developed an integrated production process for copper alloy carrier copper foil that can fundamentally improve the material microstructure, enhance product performance uniformity, and significantly increase production efficiency. This process has significant technical and economic value. Summary of the Invention

[0011] The main objective of this invention is to provide a copper alloy carrier copper foil, its preparation method, and its application, in order to solve the problems in the existing technology where the preparation process of copper alloy carrier copper foil is difficult to form a uniform and fine microstructure, resulting in the copper alloy carrier copper foil being unable to have both excellent mechanical and electrical properties, as well as the low production efficiency of the existing preparation process.

[0012] To achieve the above objectives, the present invention provides a method for preparing copper foil on a copper alloy carrier, the method comprising: step S1, vacuum melting of elemental copper and copper alloy to obtain a molten alloy; wherein the vacuum melting temperature is 1150–1250°C and the time is 1–1.5 h; step S2, continuous casting of the molten alloy in a magnetic field to obtain a copper alloy rod; wherein the magnetic field strength is 0.5–2 T and the continuous casting rate is 0.5–0.8 m / min; step S3; Step S4: Continuously extruding the copper alloy rod to obtain a copper alloy strip blank; Step S5: Continuously rolling the copper alloy strip blank to obtain a copper alloy strip; Step S6: Casting and continuously casting and rolling the copper alloy strip to obtain a composite strip blank; The composite strip blank has a double-layer or triple-layer structure, and includes one of the following composite layers: aluminum single-element layer, magnesium alloy layer, aluminum-lithium alloy layer, zinc alloy layer, tin alloy layer, lead-bismuth alloy layer, titanium alloy layer, and copper-zinc alloy layer; Step S7: Precision rolling the composite strip blank, and after cleaning and heat treatment, obtaining copper alloy carrier copper foil.

[0013] Further, in step S5, molten liquid obtained by melting metal or alloy is used for casting, the melting point of the metal or alloy is 138-1250℃, and the temperature of the molten liquid is 1150-1250℃; and / or, continuous casting and rolling is performed using a casting and rolling device, during which the temperature of the copper alloy strip is 480-580℃, and the surface temperature of the rolls in the casting and rolling device is 180-220℃; and / or, the pressure of continuous casting and rolling is 300-1500MPa, and the downward pressure is 35-45%.

[0014] Furthermore, the metal is selected from elemental aluminum; the alloy is selected from one of magnesium alloy, aluminum-lithium alloy, zinc alloy, tin alloy, and lead-bismuth alloy.

[0015] Furthermore, the composite strip blank has a double-layer structure, including a copper alloy layer and a composite layer, and the total thickness of the composite strip blank is 5 mm, and the thickness of the composite layer is 4.5 to 4.9 mm; or, the composite strip blank has a triple-layer structure, including two adjacent copper alloy layers spaced apart by the composite layer, and the total thickness of the composite strip blank is 5 mm, the thickness of the composite layer is 4.8 to 4.9 mm, and the total thickness of the two adjacent copper alloy layers is 0.2 mm.

[0016] Further, based on the weight percentage of the copper alloy, the copper alloy comprises 2.2–4.2 wt% Ni, 0.25–1.2 wt% Si, 0.05–0.3 wt% Mg, and the balance Cu; and / or, based on the weight percentage of the copper alloy layer in the copper foil carrier, the copper alloy layer comprises 2.2–4.2 wt% Ni, 0.25–1.2 wt% Si, 0.05–0.3 wt% Mg, and the balance Cu.

[0017] Furthermore, during the continuous rolling process, the temperature is 550–650℃, the pressure is 1000–1500MPa, the number of passes is 5, the reduction rate of the first pass is 35–40%, the total reduction rate of the second to fourth passes is 20–25%, the reduction rate of the fifth pass is 5–8%, and the discharge rate is 1.2–1.8 m / min.

[0018] Furthermore, during the continuous casting and rolling process, the temperature of the copper alloy strip is 500–550℃, the continuous casting and rolling pressure is 800–1200MPa, and the casting and rolling speed is 0.8–1.2m / min; and / or, the pouring temperature is 700–750℃.

[0019] Furthermore, during the finishing rolling process, the cold rolling reduction rate is 85-90%, the pressure is 1500-2000 MPa, and the rolling speed is 2.0-3.0 m / min.

[0020] Furthermore, based on the weight percentage of the copper alloy, the copper alloy comprises 1.8–2.0 wt% Be, 0–0.2 wt% Si, and the balance Cu; and / or, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier, the copper alloy layer comprises 1.8–2.0 wt% Be, 0–0.2 wt% Si, and the balance Cu.

[0021] Furthermore, during the continuous rolling process, the temperature is 600–680℃, the pressure is 1200–1800MPa, the number of passes is 5, the reduction rate of the first pass is 30–35%, the total reduction rate of the second to fourth passes is 22–28%, the reduction rate of the fifth pass is 3–6%, and the discharge rate is 1.0–1.5m / min.

[0022] Furthermore, during the continuous casting and rolling process, the temperature of the copper alloy strip is 520–580℃, the continuous casting and rolling pressure is 350–500MPa, the casting and rolling speed is 0.6–1.0m / min; and / or, the pouring temperature is 720–760℃.

[0023] Furthermore, during the finishing rolling process, the cold rolling reduction rate is 80-88%, the pressure is 2000-2800 MPa, and the rolling speed is 1.8-2.5 m / min.

[0024] Further, based on the weight percentage of the copper alloy, the copper alloy comprises 0.1 to 2.0 wt% Cr, 0.02 to 0.6 wt% Zr, and the balance Cu; and / or, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier, the copper alloy layer comprises 0.1 to 2.0 wt% Cr, 0.02 to 0.6 wt% Zr, and the balance Cu.

[0025] Furthermore, during the continuous rolling process, the temperature is 580–630℃, the pressure is 1500–2500MPa, the number of passes is 5, the reduction rate of the first pass is 32–38%, the total reduction rate of the second to fourth passes is 21–26%, the reduction rate of the fifth pass is 4–7%, and the discharge rate is 1.1–1.6 m / min.

[0026] Furthermore, during the continuous casting and rolling process, the temperature of the copper alloy strip is 480–530℃, the continuous casting and rolling pressure is 1000–1500MPa, the casting and rolling speed is 0.9–1.3m / min; and / or, the pouring temperature is 690–730℃.

[0027] Furthermore, during the finishing rolling process, the cold rolling reduction rate is 82-89%, the pressure is 2000-3000 MPa, and the rolling speed is 2.2-2.8 m / min.

[0028] Further, in step S3, the continuous extrusion temperature is 750–850°C, and the extrusion ratio is (30–50):(1–5); and / or, the width of the copper alloy strip is 620–650 mm, and the thickness is 15–18 mm; and / or, in step S6, the heat treatment is carried out under nitrogen protection, and the heat treatment temperature is 400–600°C, and the time is 3–8 h.

[0029] Furthermore, the preparation method also includes an online non-destructive testing step for the copper alloy rod to detect in real time whether there are cracks ≥0.5mm inside the copper alloy rod. Copper alloy rods that pass the test are then proceeded to step S3, while copper alloy rods that fail the test are cut off. And / or, the preparation method also includes an online four-sided milling step for the copper alloy strip blank to remove the oxide layer and cracks on its surface.

[0030] To achieve the above objectives, another aspect of the present invention provides a copper alloy carrier copper foil, which is prepared by the preparation method of the copper alloy carrier copper foil provided in this application.

[0031] Another aspect of the present invention provides an application of the copper alloy carrier copper foil provided in this application in the field of lithium-ion batteries.

[0032] Compared to the traditional upward continuous casting method, the upward continuous casting in step S2 of this application is carried out under a specific magnetic field strength. The magnetic field can drive the molten alloy to convection, thereby effectively breaking up the columnar dendrites in growth, promoting the formation of uniform and fine equiaxed crystal structure, eliminating the central porosity and macroscopic segregation common in traditional ingots, and thus obtaining a copper alloy rod that is internally dense, without pores or shrinkage cavities. This improves the uniformity of the microstructure of the final product and makes the mechanical and electrical properties of the copper alloy carrier copper foil more stable.

[0033] The preparation method described in this application integrates multiple processes such as vacuum melting, upward continuous casting, continuous extrusion, continuous rolling, casting, and continuous casting and rolling into a continuous production line. This eliminates a large number of time-consuming and energy-intensive steps such as ingot cooling and multi-pass intermediate annealing in traditional processes, shortening the production cycle from several days or even weeks in traditional processes to a few hours, and significantly improving production efficiency.

[0034] The preparation method described in this application achieves "hot delivery and hot loading", which can make full use of the material's own sensible heat for subsequent processing steps, greatly reducing the energy required for repeated heating; and there is no intermediate billet inventory, which reduces the loss during material transfer and the demand for storage space, saving factory area.

[0035] Furthermore, the preparation method provided in this application is applicable to various types of copper alloys, exhibiting good versatility. Moreover, compared to traditional aluminum composite layers, the composite layers in this application include one of the following: magnesium alloy layer, aluminum-lithium alloy layer, zinc alloy layer, tin alloy layer, lead-bismuth alloy layer, titanium alloy layer, and copper-zinc alloy layer, resulting in strong process scalability. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 A process flow diagram for the preparation of copper foil on a copper alloy carrier in Example 1 is shown. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0039] As described in the background art, existing copper alloy carrier copper foil preparation processes suffer from difficulties in forming a uniform and fine microstructure, resulting in copper alloy carrier copper foils that cannot simultaneously possess excellent mechanical and electrical properties, as well as low production efficiency. To address these technical problems, the first aspect of this application provides a method for preparing copper alloy carrier copper foil, comprising: step S1, vacuum melting of elemental copper and copper alloy to obtain a molten alloy; wherein the vacuum melting temperature is 1150–1250℃, and the time is 1–1.5 h; step S2, upward continuous casting of the molten alloy in a magnetic field to obtain a copper alloy rod; wherein the magnetic field strength is 0.5–2 T, and the continuous casting rate is 0.5–0.8 m / min; step... Step S3: Continuously extrude the copper alloy rod to obtain a copper alloy strip billet; Step S4: Continuously roll the copper alloy strip billet to obtain a copper alloy strip; Step S5: Cast and continuously cast the copper alloy strip to obtain a composite strip billet; The composite strip billet has a double-layer or triple-layer structure, including one of the following composite layers: aluminum single-element layer, magnesium alloy layer, aluminum-lithium alloy layer, zinc alloy layer, tin alloy layer, lead-bismuth alloy layer, titanium alloy layer, and copper-zinc alloy layer; Step S6: Fine roll the composite strip billet, and after cleaning and heat treatment, obtain copper alloy carrier copper foil.

[0040] In step S1 of this application, the copper-containing raw material is first vacuum-melted. This process, carried out under vacuum conditions, effectively avoids the introduction of impurities, resulting in a molten alloy. In step S2, the molten alloy is continuously cast upwards in a magnetic field to obtain a dense copper alloy rod free of porosity and shrinkage cavities. In step S3, the copper alloy rod is continuously extruded to extend it into a strip-shaped copper alloy billet; then, in step S4, it is continuously rolled to obtain a copper alloy strip; then, in step S5, casting and continuous casting-rolling are performed sequentially to obtain a composite strip billet with a double-layer or triple-layer structure. Finally, the composite strip billet is precision rolled, cleaned, and heat-treated to obtain a copper alloy carrier copper foil.

[0041] Traditional upward casting is a continuous casting method that utilizes the cooling and crystallization mechanism of molten metal to slowly extract solid metal wires of a certain shape from the molten metal or alloy. Compared to the traditional upward casting method, the upward casting in step S2 of this application is carried out under a specific magnetic field strength. This magnetic field drives the molten alloy to convection, effectively breaking up the growing columnar dendrites, promoting the formation of uniform, fine equiaxed crystal structures, and eliminating the central porosity and macroscopic segregation common in traditional ingots. This results in a dense, non-porous, and non-shrinkage-cavity copper alloy rod, thereby improving the uniformity of the final product's microstructure and making the mechanical and electrical properties of the copper alloy carrier copper foil more stable.

[0042] The preparation method described in this application integrates multiple processes such as vacuum melting, upward continuous casting, continuous extrusion, continuous rolling, casting, and continuous casting and rolling into a continuous production line. This eliminates a large number of time-consuming and energy-intensive steps such as ingot cooling and multi-pass intermediate annealing in traditional processes, shortening the production cycle from several days or even weeks in traditional processes to a few hours, and significantly improving production efficiency.

[0043] The preparation method described in this application achieves "hot delivery and hot loading", which can make full use of the material's own sensible heat for subsequent processing steps, greatly reducing the energy required for repeated heating; and there is no intermediate billet inventory, which reduces the loss during material transfer and the demand for storage space, saving factory area.

[0044] Furthermore, the preparation method provided in this application is not only applicable to various types of copper alloys and has good versatility; moreover, compared with traditional aluminum composite layers, the composite layers in this application include one of magnesium alloy layers, aluminum-lithium alloy layers, zinc alloy layers, tin alloy layers, lead-bismuth alloy layers, titanium alloy layers, and copper-zinc alloy layers, and the process has strong scalability.

[0045] In a preferred embodiment, step S2 is performed using an upward continuous casting machine equipped with an external double-layer annular winding coil that fits tightly against the outer wall of the graphite mold to achieve efficient magnetic field coupling.

[0046] In order to increase the convection intensity of the molten alloy, break up the columnar dendrites in growth, promote the formation of uniform and fine equiaxed crystal structure, and eliminate the central porosity and macroscopic segregation common in traditional ingots, preferably, the coil has an operating frequency of 4 to 8 Hz, an operating current of 300 to 500 A, and a power of 10 to 20 kW.

[0047] In a preferred embodiment, in step S5, molten metal or alloy is used for casting. The melting point of the metal or alloy is 138–1250°C, and the temperature of the molten liquid is 1150–1250°C. Using an alloy with the above melting point facilitates melting to obtain the molten liquid, and is compatible with existing casting and rolling temperatures, allowing for implementation without modifying existing equipment. Furthermore, limiting the temperature of the molten liquid within the above range improves its fluidity, thus facilitating casting.

[0048] The composite structure formed by low-melting-point, low-density alloys and copper alloy layers offers lightweight advantages. Furthermore, copper alloy carrier foils made using such alloys are suitable for cryogenic service environments. In a preferred embodiment, the metal is selected from elemental aluminum; the alloy includes, but is not limited to, magnesium alloys, aluminum-lithium alloys, zinc alloys, tin alloys, and lead-bismuth alloys. Compared to other types, using the aforementioned alloys improves the mechanical strength and conductivity of the final copper alloy carrier foil, and better meets the requirements for lightweight design.

[0049] In a preferred embodiment, continuous casting and rolling is performed using a casting and rolling apparatus. During the continuous casting and rolling process, the temperature of the copper alloy strip is 480–580°C, and the surface temperature of the rolls in the casting and rolling apparatus is 180–220°C. The temperatures of the copper alloy strip and the rolls during continuous casting and rolling include, but are not limited to, the above-mentioned ranges. Limiting these temperatures to these ranges helps to improve the metallurgical bonding interface and enhance the structural stability of the composite strip.

[0050] In a preferred embodiment, the pressure of continuous casting and rolling is 300–1500 MPa, and the reduction is 35–45%. The pressure and reduction of continuous casting and rolling include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial to improving the machinability of copper alloy strips and also to improving the robustness of the metallurgical alloy interface.

[0051] The composite strip blank obtained in this application can be a two-layer or three-layer structure. In a preferred embodiment, the composite strip blank has a two-layer structure, including a copper alloy layer and a composite layer, and the total thickness of the composite strip blank is 5 mm, while the thickness of the composite layer is 4.5–4.9 mm; alternatively, the composite strip blank has a three-layer structure, including two adjacent copper alloy layers spaced apart by the composite layer, and the total thickness of the composite strip blank is 5 mm, the thickness of the composite layer is 4.8–4.9 mm, and the total thickness of the two adjacent copper alloy layers is 0.2 mm. Compared to other ranges, limiting the thickness of the composite strip blank and the composite layer to the aforementioned ranges is beneficial for improving the mechanical strength and conductivity of the copper alloy carrier copper foil, and for broadening its application scenarios.

[0052] In a preferred embodiment, the copper alloy comprises 2.2–4.2 wt% Ni, 0.25–1.2 wt% Si, 0.05–0.3 wt% Mg, and the balance Cu, based on the weight percentage of the copper alloy.

[0053] In a preferred embodiment, the copper alloy layer comprises 2.2–4.2 wt% Ni, 0.25–1.2 wt% Si, 0.05–0.3 wt% Mg, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier. Preferably, the material of the copper alloy layer is C7025 copper alloy.

[0054] To ensure more stable continuous rolling results, while improving material plasticity, the synergistic effects of work hardening, dynamic recovery, and recrystallization are used to improve the regularity of the copper alloy strip's shape and the fineness of its microstructure. Preferably, during continuous rolling, the temperature is 550–650℃, the pressure is 1000–1500 MPa, the number of passes is 5, the reduction rate of the first pass is 35–40%, the total reduction rate of the second to fourth passes is 20–25%, the reduction rate of the fifth pass is 5–8%, and the discharge rate is 1.2–1.8 m / min.

[0055] It should be noted that the total reduction rate of the 2nd to 4th passes in this application refers to the cumulative reduction rate of the 2nd, 3rd and 4th passes.

[0056] To improve the strength of the metallurgical bonding interface in the composite strip, and to enhance the structural stability of the composite strip, reduce defects, and improve thickness accuracy, preferably, during the continuous casting and rolling process, the temperature of the copper alloy strip is 500–550℃, the continuous casting and rolling pressure is 800–1200MPa, and the casting and rolling speed is 0.8–1.2m / min.

[0057] Casting refers to pouring molten liquid onto the base material (i.e., copper alloy strip) that needs to be composited, and then performing plastic deformation processing through continuous casting and rolling to combine the copper alloy strip with the alloy, thereby obtaining a composite strip billet.

[0058] To improve the fluidity of the molten liquid, the pouring temperature is preferably 700–750°C.

[0059] To improve the mechanical strength of copper foil on a copper alloy carrier, preferably, during the finishing rolling process, the cold rolling reduction rate is 85-90%, the pressure is 1500-2000 MPa, and the rolling speed is 2.0-3.0 m / min.

[0060] In a preferred embodiment, the copper alloy comprises 1.8 to 2.0 wt% Be, 0 to 0.2 wt% Si, and the balance Cu, based on the weight percentage of the copper alloy.

[0061] In a preferred embodiment, the copper alloy layer comprises 1.8–2.0 wt% Be, 0–0.2 wt% Si, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier. Preferably, the material of the copper alloy layer is C17200 beryllium copper.

[0062] To ensure more stable continuous rolling results, while improving material plasticity, the synergistic effects of work hardening, dynamic recovery, and recrystallization are used to improve the regularity of the copper alloy strip's shape and the fineness of its microstructure. Preferably, during continuous rolling, the temperature is 600–680℃, the pressure is 1200–1800 MPa, the number of passes is 5, the reduction rate of the first pass is 30–35%, the total reduction rate of the second to fourth passes is 22–28%, the reduction rate of the fifth pass is 3–6%, and the discharge rate is 1.0–1.5 m / min.

[0063] To improve the strength of the metallurgical bonding interface in the composite strip, and to enhance the structural stability of the composite strip, reduce defects, and improve thickness accuracy, preferably, during the continuous casting and rolling process, the temperature of the copper alloy strip is 520–580℃, the continuous casting and rolling pressure is 350–500MPa, and the casting and rolling speed is 0.6–1.0m / min.

[0064] To improve the fluidity of the molten liquid, the pouring temperature is preferably 720–760°C.

[0065] To improve the mechanical strength of copper foil on a copper alloy carrier, preferably, during the finishing rolling process, the cold rolling reduction rate is 80-88%, the pressure is 2000-2800 MPa, and the rolling speed is 1.8-2.5 m / min.

[0066] In a preferred embodiment, the copper alloy comprises 0.1 to 2.0 wt% Cr, 0.02 to 0.6 wt% Zr, and the balance Cu, based on the weight percentage of the copper alloy.

[0067] In a preferred embodiment, the copper alloy layer comprises 0.1–2.0 wt% Cr, 0.02–0.6 wt% Zr, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier. Preferably, the material of the copper alloy layer is chromium-zirconium copper (CuCrZr).

[0068] To ensure more stable continuous rolling results, while improving material plasticity, the synergistic effects of work hardening, dynamic recovery, and recrystallization are used to improve the regularity of the copper alloy strip's shape and the fineness of its microstructure. Preferably, during continuous rolling, the temperature is 580–630℃, the pressure is 1500–2500 MPa, the number of passes is 5, the reduction rate of the first pass is 32–38%, the total reduction rate of the second to fourth passes is 21–26%, the reduction rate of the fifth pass is 4–7%, and the discharge rate is 1.1–1.6 m / min.

[0069] To improve the strength of the metallurgical bonding interface in the composite strip, and to enhance the structural stability of the composite strip, reduce defects, and improve thickness accuracy, preferably, during the continuous casting and rolling process, the temperature of the copper alloy strip is 480–530℃, the continuous casting and rolling pressure is 1000–1500MPa, and the casting and rolling speed is 0.9–1.3m / min.

[0070] To improve the fluidity of the molten liquid, the pouring temperature is preferably 690–730°C.

[0071] To improve the mechanical strength of copper foil on a copper alloy carrier, preferably, during the finishing rolling process, the cold rolling reduction rate is 82-89%, the pressure is 2000-3000 MPa, and the rolling speed is 2.2-2.8 m / min.

[0072] In a preferred embodiment, the continuous extrusion temperature in step S3 is 750–850°C, and the extrusion ratio is (30–50):(1–5). The continuous extrusion temperature and extrusion ratio include, but are not limited to, the above ranges. Limiting them to the above ranges is beneficial to improving the plasticity of the copper alloy rod during the extrusion process, making it easier to obtain copper alloy strip blanks.

[0073] In a preferred embodiment, the copper alloy strip has a width of 620–650 mm and a thickness of 15–18 mm.

[0074] In a preferred embodiment, in step S6, the heat treatment is carried out under nitrogen protection at a temperature of 400–600°C for 3–8 hours. The temperature and time of the heat treatment include, but are not limited to, the above ranges; limiting them within these ranges is beneficial for improving the mechanical and electrical properties of the copper foil on the copper alloy carrier.

[0075] In a preferred embodiment, the method for preparing the copper foil of the copper alloy carrier provided in this application further includes an online non-destructive testing step for the copper alloy rod, so as to detect in real time whether there are cracks ≥0.5mm inside the copper alloy rod. The copper alloy rod that passes the test proceeds to step S3, and the copper alloy rod that fails the test is cut off.

[0076] In a preferred embodiment, the method for preparing the copper alloy carrier copper foil provided in this application further includes an online four-sided milling step of the copper alloy strip blank to remove the oxide layer and cracks on its surface, thereby obtaining a smooth copper alloy strip.

[0077] The second aspect of this application also provides a copper alloy carrier copper foil, which is prepared using the method described above. The copper alloy carrier copper foil prepared by the method described above has a uniform and fine microstructure, exhibiting excellent mechanical and electrical properties, making it particularly suitable for application in the lithium-ion battery field. It should be noted that due to the special nature of the alloy field and limitations of existing testing and characterization methods, it is difficult to comprehensively and quantitatively characterize the complex microstructure of the obtained copper alloy carrier copper foil. However, experiments show that the copper alloy carrier copper foil obtained in this application has superior mechanical and electrical properties.

[0078] In a preferred embodiment, the copper alloy carrier copper foil has a surface roughness Ra ≤ 0.35 μm, tensile strength ≥ 650 MPa, elongation ≥ 6%, and electrical conductivity ≥ 36% IACS, wherein the interfacial bonding strength (peel strength) between the copper alloy layer and the composite layer is ≥ 10 N / cm. The performance indicators of the copper alloy carrier copper foil provided in this application are far superior to those of carrier copper foil produced by traditional processes.

[0079] A third aspect of this application also provides the application of copper alloy carrier copper foil in the field of lithium-ion batteries. The copper alloy carrier copper foil provided in this application possesses both excellent mechanical and electrical properties, making it particularly suitable for application in the field of lithium-ion batteries.

[0080] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0081] Example 1

[0082] A method for preparing copper foil on a copper alloy carrier, comprising as follows: Figure 1 The steps shown are as follows:

[0083] (1) Copper and copper alloy were vacuum melted at 1200℃ for 1.2 h to obtain a molten alloy; the copper alloy consisted of 3.0 wt% Ni, 1.0 wt% Si, 0.15 wt% Mg and balance Cu;

[0084] (2) The molten alloy obtained in step (1) is introduced into the upward continuous casting machine (Shanghai Pudong Junyi Electrical Machinery Co., Ltd., model: SL28-QW3-SB-8 / 20). The continuous casting rate of the upward continuous casting is 0.5m / min, and a copper alloy rod with a diameter of 30mm is obtained. The upward continuous casting machine includes a graphite mold and an external double-layer ring-wound coil that is closely attached to the outer wall of the graphite mold. The working frequency is set to 5Hz, the working current is 400A, the power is 15kW, and the magnetic field strength of the magnetic field generated by the coil is 1T.

[0085] (3) Use online non-destructive testing equipment to perform ultrasonic testing on the copper alloy rods obtained in step (2). If the copper alloy rods with internal cracks of ≥0.5mm are detected in real time, they are unqualified products and are cut off so that the remaining qualified copper alloy rods can be used for subsequent steps.

[0086] (4) The qualified copper alloy rod in step (3) is continuously extruded at 800℃, and the extrusion ratio is set to 40:1 to obtain a copper alloy strip blank with a width of 650mm and a thickness of 17mm; the copper alloy strip blank is milled online on four sides, and the milling depth of each side is 0.5mm.

[0087] (5) The copper alloy strip blank obtained in step (4) is continuously rolled to obtain a copper alloy strip with a thickness of 0.5 mm; wherein the rolling temperature is 620℃, the pressure is 1200MPa, the number of passes is 5, and the reduction rate of the first pass is 36%, the reduction rate of the second pass is 8%, the reduction rate of the third pass is 8%, the reduction rate of the fourth pass is 8%, the reduction rate of the fifth pass is 6%, and the discharge rate is 1.5 m / min;

[0088] (6) Keep the temperature of the copper alloy strip obtained in step (5) at 500°C, and continuously cast and roll it while pouring molten aluminum liquid. The pressure is 1000MPa and the casting and rolling speed is 1.0m / min to obtain a composite strip blank with a thickness of 5mm. The composite strip blank has a double-layer structure, including an aluminum single layer with a thickness of 4.5mm and a copper alloy layer with a thickness of 0.5mm.

[0089] (7) The composite strip blank obtained in step (6) is precision rolled at 120°C, wherein the cold rolling reduction rate is 85%, the pressure is 1800MPa, and the rolling speed is 2.5m / min; then online degreasing and cleaning are performed, followed by heat treatment at 480°C for 5h, and copper alloy carrier copper foil is obtained after slitting.

[0090] The copper alloy layer comprises 3.0 wt% Ni, 1.0 wt% Si, 0.15 wt% Mg, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier.

[0091] Example 2

[0092] The difference from Example 1 is that in step (2), the continuous casting rate of the upward continuous casting is 0.5 m / min and the magnetic field strength is 0.5 T.

[0093] Example 3

[0094] The difference from Example 1 is that in step (2), the continuous casting rate of the upward continuous casting is 0.8 m / min and the magnetic field strength is 2 T.

[0095] Example 4

[0096] The difference from Example 1 is that in step (5), during the continuous rolling process, the temperature is 550℃, the pressure is 1000MPa, the number of passes is 5, the reduction rate of the first pass is 35%, the total reduction rate of the second to fourth passes is 20%, the reduction rate of the fifth pass is 5%, and the discharge rate is 1.2m / min.

[0097] Example 5

[0098] The difference from Example 1 is that in step (5), during the continuous rolling process, the temperature is 650℃, the pressure is 1500MPa, the number of passes is 5, the reduction rate of the first pass is 40%, the total reduction rate of the second to fourth passes is 25%, the reduction rate of the fifth pass is 8%, and the discharge rate is 1.8m / min.

[0099] Example 6

[0100] The difference from Example 1 is that in step (5), during the continuous rolling process, there are 3 passes, the first pass has a reduction rate of 35%, the second pass has a reduction rate of 20%, and the third pass has a reduction rate of 5%.

[0101] Example 7

[0102] The difference from Example 1 is that in step (6), the pouring temperature is 700℃; during the continuous casting and rolling process, the temperature of the copper alloy strip is 500℃, the pressure is 800MPa, and the casting and rolling speed is 0.8m / min.

[0103] Example 8

[0104] The difference from Example 1 is that in step (6), the pouring temperature is 750°C; during the continuous casting and rolling process, the temperature of the copper alloy strip is 550°C, the pressure is 1200MPa, and the casting and rolling speed is 1.2m / min.

[0105] Example 9

[0106] The difference from Example 1 is that in step (6), the pouring temperature is 600℃; during the continuous casting and rolling process, the temperature of the copper alloy strip is 480℃, the pressure is 700MPa, and the casting and rolling speed is 0.4m / min.

[0107] Example 10

[0108] The difference from Example 1 is that in step (7), during the finishing rolling process, the cold rolling reduction rate is 85%, the pressure is 1500MPa, the casting and rolling speed is 2.0m / min, the heat treatment temperature is 400℃, and the time is 3h.

[0109] Example 11

[0110] The difference from Example 1 is that in step (7), during the finishing rolling process, the cold rolling reduction rate is 90%, the pressure is 2000MPa, the casting and rolling speed is 3.0m / min, the heat treatment temperature is 600℃, and the time is 8h.

[0111] Example 12

[0112] The difference from Example 1 is that in step (7), during the finishing rolling process, the cold rolling reduction rate is 60%, the pressure is 1000MPa, the casting and rolling speed is 1.0m / min, the heat treatment temperature is 300℃, and the time is 2h.

[0113] Example 13

[0114] A method for preparing copper foil on a copper alloy carrier, comprising:

[0115] (1) Copper and copper alloy were vacuum melted at 1220℃ for 1.3 h to obtain a molten alloy; the copper alloy consisted of 1.9 wt% Be, 0.1 wt% Si and the balance Cu;

[0116] (2) The molten alloy obtained in step (1) is introduced into the upward continuous casting machine (Shanghai Pudong Junyi Electrical Machinery Co., Ltd., model: SL28-QW3-SB-8 / 20). The continuous casting rate of the upward continuous casting is 0.6m / min, and a copper alloy rod with a diameter of 30mm is obtained. The upward continuous casting machine includes a graphite mold and an external double-layer ring-wound coil that is closely attached to the outer wall of the graphite mold. The working frequency is set to 6Hz, the working current is 420A, the power is 17kW, and the magnetic field strength of the magnetic field generated by the coil is 1.2T.

[0117] (3) Use online non-destructive testing equipment to perform ultrasonic testing on the copper alloy rods obtained in step (2). If the copper alloy rods with internal cracks of ≥0.5mm are detected in real time, they are unqualified products and are cut off so that the remaining qualified copper alloy rods can be used for subsequent steps.

[0118] (4) The qualified copper alloy rod in step (3) is continuously extruded at 810℃, and the extrusion ratio is set to 40:1 to obtain a copper alloy strip blank with a width of 650mm and a thickness of 17mm; the copper alloy strip blank is milled on four sides online, and the milling depth of each side is 0.5mm.

[0119] (5) The copper alloy strip blank obtained in step (4) is continuously rolled to obtain a copper alloy strip with a thickness of 0.5 mm; wherein the rolling temperature is 620℃, the pressure is 1500MPa, the number of passes is 5, and the reduction rate of the first pass is 32%, the reduction rate of the second pass is 8%, the reduction rate of the third pass is 8%, the reduction rate of the fourth pass is 8%, the reduction rate of the fifth pass is 5%, and the discharge rate is 1.2 m / min;

[0120] (6) Keep the temperature of the copper alloy strip obtained in step (5) at 500°C, and continuously cast and roll it while pouring molten aluminum liquid. The pressure is 400 MPa and the casting and rolling speed is 0.8 m / min to obtain a composite strip blank with a thickness of 5 mm. The composite strip blank has a double-layer structure, including an aluminum single layer with a thickness of 4.5 mm and a copper alloy layer with a thickness of 0.5 mm.

[0121] (7) The composite strip blank obtained in step (6) is precision rolled at 120°C, wherein the cold rolling reduction rate is 85%, the pressure is 2400MPa, and the rolling speed is 2m / min; then online degreasing and cleaning are performed, followed by heat treatment at 460°C for 4h, and copper alloy carrier copper foil is obtained after slitting.

[0122] The copper alloy layer comprises 1.9 wt% Be, 0.1 wt% Si, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier.

[0123] Example 14

[0124] A method for preparing copper foil on a copper alloy carrier, comprising:

[0125] (1) Copper and copper alloy were vacuum melted at 1240℃ for 1.4 h to obtain a molten alloy; the copper alloy contained 1.8wt% Cr, 0.2wt% Zr and the balance Cu;

[0126] (2) The molten alloy obtained in step (1) is introduced into the upward continuous casting machine (Shanghai Pudong Junyi Electrical Machinery Co., Ltd., model: SL28-QW3-SB-8 / 20). The continuous casting rate of the upward continuous casting is 0.8m / min, and a copper alloy rod with a diameter of 30mm is obtained. The upward continuous casting machine includes a graphite mold and an external double-layer ring-wound coil that is closely attached to the outer wall of the graphite mold. The working frequency is set to 7Hz, the working current is 460A, the power is 18kW, and the magnetic field strength of the magnetic field generated by the coil is 1.8T.

[0127] (3) Use online non-destructive testing equipment to perform ultrasonic testing on the copper alloy rods obtained in step (2). If the copper alloy rods with internal cracks of ≥0.5mm are detected in real time, they are unqualified products and are cut off so that the remaining qualified copper alloy rods can be used for subsequent steps.

[0128] (4) The qualified copper alloy rod in step (3) is continuously extruded at 820℃, and the extrusion ratio is set to 40:1 to obtain a copper alloy strip blank with a width of 650mm and a thickness of 17mm; the copper alloy strip blank is milled online on four sides, and the milling depth of each side is 0.5mm.

[0129] (5) The copper alloy strip blank obtained in step (4) is continuously rolled to obtain a copper alloy strip with a thickness of 0.5 mm; wherein the rolling temperature is 620℃, the pressure is 2200MPa, the number of passes is 5, and the reduction rate of the first pass is 36%, the reduction rate of the second pass is 10%, the reduction rate of the third pass is 8%, the reduction rate of the fourth pass is 6%, the reduction rate of the fifth pass is 6%, and the discharge rate is 1.2 m / min;

[0130] (6) Keep the temperature of the copper alloy strip obtained in step (5) at 500°C, and continuously cast and roll it while pouring molten aluminum liquid. The pressure is 1200MPa and the casting and rolling speed is 1.1m / min to obtain a composite strip blank with a thickness of 5mm. The composite strip blank has a double-layer structure, including an aluminum single layer with a thickness of 4.5mm and a copper alloy layer with a thickness of 0.5mm.

[0131] (7) The composite strip blank obtained in step (6) is precision rolled at 100°C, wherein the cold rolling reduction rate is 86%, the pressure is 2600MPa, and the rolling speed is 2.6m / min; then online degreasing and cleaning are performed, followed by heat treatment at 480°C for 6h, and copper alloy carrier copper foil is obtained after slitting.

[0132] The copper alloy layer comprises 1.8 wt% Cr, 0.2 wt% Zr, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil of the copper alloy carrier.

[0133] Comparative Example 1

[0134] The difference from Example 1 is that in step (2), the upward continuous casting machine does not include an external double-layer annular winding coil, and the upward continuous casting process is carried out under the condition of no magnetic field.

[0135] The copper alloy carrier copper foils prepared in all the above embodiments and comparative examples of this application were subjected to surface roughness (Ra), tensile strength, elongation, conductivity, and peel strength tests. All the above tests were performed in accordance with GB / T 29847-2025 "Test Methods for Copper Foil for Printed Circuit Boards", and the test results are shown in Table 1.

[0136] Table 1

[0137]

[0138] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0139] Compared to the traditional upward continuous casting method, the upward continuous casting in step S2 of this application is carried out under a specific magnetic field strength. The magnetic field can drive the molten alloy to convection, thereby effectively breaking up the growing columnar dendrites, promoting the formation of uniform and fine equiaxed crystal structure, eliminating the central porosity and macroscopic segregation common in traditional ingots, and thus obtaining a copper alloy rod with dense internal structure, no pores and no shrinkage cavities. This improves the uniformity of the microstructure of the final product and makes the mechanical and electrical properties of the copper alloy carrier copper foil more stable.

[0140] The preparation method described in this application integrates multiple processes such as vacuum melting, upward continuous casting, continuous extrusion, continuous rolling, casting, and continuous casting and rolling into a continuous production line. This eliminates a large number of time-consuming and energy-intensive steps such as ingot cooling and multi-pass intermediate annealing in traditional processes, shortening the production cycle from several days or even weeks in traditional processes to a few hours, and significantly improving production efficiency.

[0141] The preparation method described in this application achieves "hot delivery and hot loading", which can make full use of the material's own sensible heat for subsequent processing steps, greatly reducing the energy required for repeated heating; and there is no intermediate billet inventory, which reduces the loss during material transfer and the demand for storage space, saving factory area.

[0142] Furthermore, the preparation method provided in this application is applicable to various types of copper alloys, exhibiting good versatility. Moreover, compared to traditional aluminum composite layers, the composite layers in this application include one of the following: magnesium alloy layer, aluminum-lithium alloy layer, zinc alloy layer, tin alloy layer, lead-bismuth alloy layer, titanium alloy layer, and copper-zinc alloy layer, resulting in strong process scalability.

[0143] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0144] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing copper foil on a copper alloy carrier, characterized in that, The preparation method includes: Step S1: Vacuum melting of elemental copper and copper alloy to obtain molten alloy; wherein the vacuum melting temperature is 1150-1250℃ and the time is 1-1.5h. Step S2: The molten alloy is continuously cast upwards in a magnetic field to obtain a copper alloy rod; wherein the magnetic field strength is 0.5 to 2T, and the continuous casting rate of the upward casting is 0.5 to 0.8 m / min. Step S3: The copper alloy rod is continuously extruded to obtain a copper alloy strip billet; Step S4: The copper alloy strip billet is continuously rolled to obtain a copper alloy strip; Step S5: Casting and continuous casting and rolling of the copper alloy strip to obtain a composite strip billet; the composite strip billet has a double-layer or triple-layer structure, and includes one of the following composite layers: aluminum single-element layer, magnesium alloy layer, aluminum-lithium alloy layer, zinc alloy layer, tin alloy layer, lead-bismuth alloy layer, titanium alloy layer, and copper-zinc alloy layer. Step S6: The composite strip blank is precision rolled, and after cleaning and heat treatment, the copper alloy carrier copper foil is obtained.

2. The method for preparing copper foil on a copper alloy carrier according to claim 1, characterized in that, In step S5, the casting is performed using a molten liquid obtained by melting a metal or alloy, wherein the melting point of the metal or alloy is 138–1250°C, and the temperature of the molten liquid is 1150–1250°C; and / or, The continuous casting and rolling is performed using a casting and rolling apparatus, wherein the temperature of the copper alloy strip during the continuous casting and rolling process is 480–580°C, and the surface temperature of the rolls in the casting and rolling apparatus is 180–220°C; and / or, The pressure of the continuous casting and rolling is 300-1500 MPa, and the downward pressure is 35-45%.

3. The method for preparing copper foil on a copper alloy carrier according to claim 2, characterized in that, The metal is selected from elemental aluminum; the alloy is selected from magnesium alloy, aluminum-lithium alloy, zinc alloy, tin alloy, and lead-bismuth alloy.

4. The method for preparing copper foil on a copper alloy carrier according to claim 2, characterized in that, The composite strip blank has a double-layer structure, including a copper alloy layer and the composite layer, and the total thickness of the composite strip blank is 5 mm, while the thickness of the composite layer is 4.5–4.9 mm; or, The composite strip blank has a three-layer structure, including two adjacent copper alloy layers spaced apart by the composite layer, and the total thickness of the composite strip blank is 5 mm, the thickness of the composite layer is 4.8 to 4.9 mm, and the total thickness of the two adjacent copper alloy layers is 0.2 mm.

5. The method for preparing copper foil on a copper alloy carrier according to claim 1, characterized in that, The copper alloy comprises 2.2–4.2 wt% Ni, 0.25–1.2 wt% Si, 0.05–0.3 wt% Mg, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil carrier.

6. The method for preparing copper foil on a copper alloy carrier according to claim 5, characterized in that, During the continuous rolling process, the temperature is 550-650℃, the pressure is 1000-1500MPa, the number of passes is 5, the reduction rate of the first pass is 35-40%, the total reduction rate of the second to fourth passes is 20-25%, the reduction rate of the fifth pass is 5-8%, and the discharge rate is 1.2-1.8m / min.

7. The method for preparing copper foil on a copper alloy carrier according to claim 5, characterized in that, During the continuous casting and rolling process, the temperature of the copper alloy strip is 500-550℃, the pressure of the continuous casting and rolling is 800-1200MPa, and the casting and rolling speed is 0.8-1.2m / min; and / or, the pouring temperature is 700-750℃.

8. The method for preparing copper foil on a copper alloy carrier according to claim 5, characterized in that, During the finishing rolling process, the cold rolling reduction rate is 85-90%, the pressure is 1500-2000 MPa, and the rolling speed is 2.0-3.0 m / min.

9. The method for preparing copper foil on a copper alloy carrier according to claim 1, characterized in that, The copper alloy comprises 1.8 to 2.0 wt% Be, 0 to 0.2 wt% Si, and the balance Cu, based on its weight percentage as a percentage of the copper alloy layer in the copper foil carrier.

10. The method for preparing copper foil on a copper alloy carrier according to claim 9, characterized in that, During the continuous rolling process, the temperature is 600-680℃, the pressure is 1200-1800MPa, the number of passes is 5, the reduction rate of the first pass is 30-35%, the total reduction rate of the second to fourth passes is 22-28%, the reduction rate of the fifth pass is 3-6%, and the discharge rate is 1.0-1.5m / min.

11. The method for preparing copper foil on a copper alloy carrier according to claim 9, characterized in that, During the continuous casting and rolling process, the temperature of the copper alloy strip is 520–580°C, the pressure of the continuous casting and rolling is 350–500 MPa, and the casting and rolling speed is 0.6–1.0 m / min; and / or, the pouring temperature is 720–760°C.

12. The method for preparing copper foil on a copper alloy carrier according to claim 9, characterized in that, During the finishing rolling process, the cold rolling reduction rate is 80-88%, the pressure is 2000-2800 MPa, and the rolling speed is 1.8-2.5 m / min.

13. The method for preparing copper foil on a copper alloy carrier according to claim 1, characterized in that, The copper alloy comprises 0.1 to 2.0 wt% Cr, 0.02 to 0.6 wt% Zr, and the balance Cu, based on the weight percentage of the copper alloy layer in the copper foil carrier.

14. The method for preparing copper foil on a copper alloy carrier according to claim 13, characterized in that, During the continuous rolling process, the temperature is 580-630℃, the pressure is 1500-2500MPa, the number of passes is 5, the reduction rate of the first pass is 32-38%, the total reduction rate of the second to fourth passes is 21-26%, the reduction rate of the fifth pass is 4-7%, and the discharge rate is 1.1-1.6m / min.

15. The method for preparing copper foil on a copper alloy carrier according to claim 13, characterized in that, During the continuous casting and rolling process, the temperature of the copper alloy strip is 480–530°C, the pressure of the continuous casting and rolling is 1000–1500 MPa, and the casting and rolling speed is 0.9–1.3 m / min; and / or, the pouring temperature is 690–730°C.

16. The method for preparing copper foil on a copper alloy carrier according to claim 13, characterized in that, During the finishing rolling process, the cold rolling reduction rate is 82-89%, the pressure is 2000-3000 MPa, and the rolling speed is 2.2-2.8 m / min.

17. The method for preparing copper foil on a copper alloy carrier according to any one of claims 1 to 16, characterized in that, In step S3, the continuous extrusion temperature is 750–850°C, and the extrusion ratio is (30–50):(1–5); and / or, the width of the copper alloy strip is 620–650 mm, and the thickness is 15–18 mm; and / or, In step S6, the heat treatment is carried out under nitrogen protection, and the temperature of the heat treatment is 400-600℃, and the time is 3-8h.

18. The method for preparing copper foil on a copper alloy carrier according to any one of claims 1 to 16, characterized in that, The preparation method further includes an online non-destructive testing step on the copper alloy rod to detect in real time whether there are cracks ≥0.5mm inside the copper alloy rod. Copper alloy rods that pass the test are then proceeded to step S3; copper alloy rods that fail the test are cut off; and / or, The preparation method further includes an online four-sided milling step of the copper alloy strip blank to remove the oxide layer and cracks on its surface.

19. A copper alloy carrier copper foil, characterized in that, The copper alloy carrier copper foil is prepared by the method described in any one of claims 1 to 18.

20. The application of the copper alloy carrier copper foil of claim 19 in the field of lithium-ion batteries.

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