High-conductivity graphene / copper composite cable and preparation method thereof

Abstract

The invention belongs to the technical field of graphene composite material preparation, and particularly relates to a high-conductivity graphene / copper composite cable and a preparation method thereof. The preparation method comprises the following steps: S1, carrying out surface cleaning on a copper wire substrate by adopting an argon ion beam at a preset grazing incidence angle to obtain a clean copper wire substrate; s2, performing surface stepped reconstruction on the clean copper wire substrate to obtain a surface reconstructed copper wire substrate; s3, arranging the surface-reconstructed copper wire matrix in a preset crystal orientation, performing graphene oriented growth treatment to obtain a composite wire, and performing graphene oriented growth treatment by adopting a gas-phase pulse chemical vapor deposition method or a liquid-phase carbon source dipping-high-temperature pyrolysis method; s4, the composite wire is subjected to controlled cooling by applying axial tension in an inert atmosphere, and the composite wire with a stable structure is obtained; and S5, guiding and twisting the composite wire with the stable structure to obtain the high-conductivity graphene / copper composite cable. The high-conductivity graphene / copper composite cable has excellent conductivity.

Description

Technical Field

[0001] This invention belongs to the field of graphene composite material preparation technology, specifically relating to a highly conductive graphene / copper composite cable and its preparation method. Background Technology

[0002] Composite cables can be applied in power transmission, new energy equipment, rail transportation, aerospace, and other fields. With the rapid development of high-end fields such as power transmission, new energy equipment (e.g., drive motors for new energy vehicles), rail transportation, and aerospace, the industry has placed higher demands on the conductivity, mechanical properties, high-temperature stability, and reliability of core conductive materials. Traditional pure copper conductors are currently the mainstream conductive material, but their inherent defects, such as low conductivity, low mechanical strength, susceptibility to softening and deformation at high temperatures, and significant power loss during transmission, make them unsuitable for meeting the application requirements of next-generation high-efficiency energy-saving equipment for extremely low resistance, high current carrying capacity, and high reliability. This makes them a key material restricting technological upgrades in these high-end fields.

[0003] Therefore, there is an urgent need to develop a completely new composite cable. Summary of the Invention

[0004] The purpose of this invention is to provide a highly conductive graphene / copper composite cable and its preparation method, which effectively solves the problems of low precision in graphene growth control, poor product performance consistency, and poor interface bonding effect in the prior art, and realizes high-quality and large-scale preparation of graphene-copper composite cables, which is conducive to meeting the application needs of high-end fields.

[0005] The first aspect of this invention is to provide a method for preparing a highly conductive graphene / copper composite cable, comprising the following steps: S1: cleaning the surface of a copper wire substrate using an argon ion beam at a predetermined grazing incidence angle to obtain a clean copper wire substrate; S2: performing surface step reconstruction on the clean copper wire substrate to obtain a surface-reconstructed copper wire substrate; S3: arranging the surface-reconstructed copper wire substrate in a predetermined crystal orientation and performing graphene directional growth treatment to obtain a composite filament, wherein the graphene directional growth treatment is performed using a pulsed chemical vapor deposition method or a liquid-phase carbon source impregnation-high-temperature pyrolysis method; S4: subjecting the composite filament to controlled cooling under axial tension in an inert atmosphere to obtain a structurally stable composite filament; S5: guiding and stranding the structurally stable composite filament to obtain a highly conductive graphene / copper composite cable.

[0006] In some embodiments of this application, in S3, the pulsed chemical vapor deposition method includes: depositing graphene on a surface-reconstructed copper wire substrate using a carbon source precursor gas; optionally, the pulsed chemical vapor deposition method satisfies at least one of the following conditions: the carbon source precursor gas is methane or ethylene; the pulse frequency is 0.1Hz~1Hz; the duration of a single pulse is 5s~20s; the gas flow rate is 10sccm~50sccm; the temperature of the deposition zone is 900℃~1050℃; the pressure is 100Pa~1000Pa; and the in-situ monitoring results collected by Raman spectroscopy or optical microscopy show that the intensity ratio of the G peak to the 2D peak of graphene reaches a preset threshold or the number of graphene deposition layers is 1 to 3 layers.

[0007] In some embodiments of this application, in S3, the liquid-phase carbon source impregnation-high-temperature pyrolysis method includes: impregnating the surface-reconstructed copper wire substrate with a carbon source precursor solution, drying in stages, and forming a solid precursor film on the surface-reconstructed copper wire substrate; optionally, the impregnation meets at least one of the following conditions: the carbon source precursor solution is a graphene oxide dispersion or a polymeric carbon source solution; the concentration is 0.5 mg / mL to 5 mg / mL; the solvent includes one or more combinations of deionized water, ethanol, or dimethylformamide; the impregnation time is 10 s to 60 s; optionally, the staged drying meets at least one of the following conditions: the drying temperature is a gradient increase of 80℃ to 150℃; the drying time is 5 min to 20 min.

[0008] In some embodiments of this application, the surface-reconstructed copper wire substrate for forming the solid precursor film is subjected to high-temperature pyrolysis; optionally, the high-temperature pyrolysis meets at least one of the following conditions: the atmosphere is an inert protective gas or a reducing mixed gas; the gas flow rate is 50 sccm to 200 sccm; the pressure is atmospheric pressure or slightly positive pressure; the heating rate is 5℃ / min to 20℃ / min; and the temperature is raised to 600℃ to 800℃ and held for 10 min to 60 min.

[0009] In some embodiments of this application, in S3, the predetermined crystal orientation is

[100] or

[111] .

[0010] In some embodiments of this application, in S1, the energy range of the argon ion beam is 100 eV to 500 eV, the predetermined grazing incidence angle is 5° to 30°, the surface cleaning time is 10 min to 30 min, and the vacuum degree of surface cleaning is less than or equal to 1 × 10⁻⁶. -5 Pa.

[0011] In some embodiments of this application, in S2, the method for surface step reconstruction includes: treating a clean copper wire substrate with a hydrogen-argon mixed atmosphere containing 5% to 20% hydrogen gas, at a treatment temperature of 500°C to 800°C, at a treatment pressure of 100Pa to 500Pa, and at a treatment time of 30 to 60 minutes.

[0012] In some embodiments of this application, in step S4, the inert atmosphere is argon gas with a purity of ≥99.999% or nitrogen gas with a purity of ≥99.999%, the axial tension is 0.1N~1N, the cooling rate is 1℃ / min~5℃ / min, and the gas is cooled to room temperature.

[0013] In some embodiments of this application, in S5, the guide angle of the guide twisting is 15°~45°, and the rotation speed is 10rpm~30rpm.

[0014] The second aspect of the present invention is to provide a highly conductive graphene / copper composite cable, which is a highly conductive graphene / copper composite cable prepared using the preparation method of the highly conductive graphene / copper composite cable provided in the first aspect, wherein the outer diameter of the highly conductive graphene / copper composite cable is 0.1 mm to 10 mm.

[0015] The beneficial effects of the present invention include at least one of the following: Compared with the prior art, the method for preparing highly conductive graphene / copper composite cables provided in this application processes the copper wire substrate to obtain an atomically clean, stepped, reconstructed copper wire substrate with consistent crystal orientation. Carbon atoms preferentially adsorb and nucleate at the low-index crystal plane steps of the copper wire and grow epitaxially along the crystal orientation, so that the graphene lattice orientation is highly matched with the copper wire substrate. This significantly reduces interface defects caused by lattice mismatch and disordered nucleation, strengthens the interfacial bonding between graphene and the copper substrate, and reduces interfacial resistance.

[0016] The preparation method provided in this application employs either pulsed chemical vapor deposition (PCCVD) or liquid-phase carbon source impregnation-high-temperature pyrolysis for the directional growth of graphene. This method, coordinated with subsequent process steps, promotes the continuity and uniformity of the formed graphene layer. It is suitable for the large-scale, continuous fabrication needs of composite cables, balancing process efficiency and product quality.

[0017] The high-conductivity graphene / copper composite cable provided in this application has a thin, continuous, low-defect graphene layer, which can fully utilize its ultra-high intrinsic electron mobility to form a synergistic conductive structure with the copper wire substrate. Electrons can be efficiently transferred between the graphene layer and the copper substrate. Compared with pure copper wire and graphene / copper composite wire prepared by traditional processes, the intrinsic conductivity of the composite wire is greatly improved, and it has high conductivity. Attached Figure Description

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This invention provides a method for preparing a highly conductive graphene / copper composite cable according to one embodiment of the present invention. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] To overcome the performance limitations of pure copper conductors, graphene-copper composites, which combine graphene with a copper wire matrix and possess ultra-high intrinsic electron mobility, excellent mechanical strength, and thermal conductivity, are widely recognized as the most promising pathway for developing next-generation high-performance conductive materials. Effective compositing of graphene with a copper wire matrix can significantly improve the composite material's overall electrical, thermal, and mechanical properties.

[0024] Currently, chemical vapor deposition (CVD) is the mainstream process for preparing graphene-copper composite materials. However, existing CVD processes still have many technical defects in practical applications: First, the carbon source supply often adopts continuous gas flow or simple pulse mode, which lacks precise control over the dynamic adsorption and diffusion process of carbon atoms. This easily leads to multi-layer disordered stacking or island-like growth of graphene on the copper wire substrate surface, making it difficult to form a continuous and uniform graphene coating layer. Second, there is a lack of in-situ, real-time, and precise means to determine the graphene growth endpoint. Existing technologies mostly rely on electron beam post-processing and other methods to improve interface performance, which cannot terminate the deposition in time during the growth process, easily causing the number of graphene layers to run out of control. The above problems directly lead to large fluctuations in the number and quality of graphene layers in the prepared graphene-copper composite cables between batches and in different sections of the same wire. This results in poor conductivity stability and low reliability of the composite cables, failing to meet the stringent requirements of high-end electrical equipment for the uniformity of conductive material performance.

[0025] Based on this, to address the problems of low precision in graphene growth control, poor interfacial bonding, and inconsistent product performance in existing technologies, and to achieve high-quality, large-scale fabrication of graphene-copper composite cables to meet the application needs of high-end fields, this application provides a highly conductive graphene / copper composite cable and its preparation method, significantly improving the electrical conductivity, thermal conductivity, and overall mechanical properties of the composite material.

[0026] The first aspect of this invention is to provide a method for preparing a highly conductive graphene / copper composite cable, comprising the following steps: S1: Cleaning the surface of a copper wire substrate using an argon ion beam at a predetermined grazing incidence angle to obtain a clean copper wire substrate. S2: Performing surface step reconstruction on the clean copper wire substrate to obtain a surface-reconstructed copper wire substrate. S3: Aligning the surface-reconstructed copper wire substrate with a predetermined crystal orientation and performing graphene directional growth treatment to obtain a composite filament. The graphene directional growth treatment is performed using a pulsed chemical vapor deposition (CVD) method or a liquid-phase carbon source impregnation-high-temperature pyrolysis method. S4: Applying axial tension to the composite filament in an inert atmosphere for controlled cooling to obtain a structurally stable composite filament. S5: Guide-stranding the structurally stable composite filament to obtain a highly conductive graphene / copper composite cable. This preparation process, through the organic connection and synergistic optimization of each step, systematically solves key problems in the preparation of traditional graphene-copper composite materials, such as substrate impurity, disordered graphene growth, poor interfacial bonding, and unstable product performance, from the microscopic interface to the macroscopic molding. The resulting highly conductive graphene / copper composite cable possesses excellent electrical and mechanical properties and industrial application value. In some embodiments of this application, step S1 of the preparation method utilizes the physical sputtering effect of an argon ion beam to achieve atomic-level cleaning of the copper wire surface at a predetermined grazing incidence angle. The kinetic energy of the argon ion beam can strip away the oxide layer, organic contaminants, and adsorbed impurities from the copper wire surface. The grazing incidence angle design ensures that the ion momentum is mainly transferred tangentially along the copper wire surface, achieving efficient impurity removal while avoiding the introduction of bulk phase dislocations or deep defects into the copper crystal body, thus providing an impurity-free, lattice-complete active substrate for subsequent graphene growth.

[0027] In some embodiments of this application, in S1, for example, the energy range of the argon ion beam is 100 eV to 500 eV, the predetermined grazing incidence angle is 5° to 30°, the surface cleaning time is 10 min to 30 min, and the vacuum degree of surface cleaning is less than or equal to 1 × 10⁻⁶. - 5 Pa. The aforementioned parameters work together to control the physical sputtering process, reducing damage to the copper wire substrate, achieving precise impurity removal, and ultimately obtaining an atomically clean, lattice-complete, oxidation-free, and residue-free copper wire surface.

[0028] In some embodiments of this application, for example, the energy range of the argon ion beam in S1 is 100eV~500eV. This low-energy sputtering range is a suitable energy range, which can provide sufficient kinetic energy to strip the oxide layer (Cu2O, CuO), hydrocarbon organic matter and adsorbed water molecules on the copper surface, without causing argon ions to be injected into the copper substrate due to excessive energy, thus preventing bulk phase faults, lattice distortions or deep defects, and only acting on the surface atomic layer.

[0029] It should be noted that in some embodiments, the energy of the argon ion beam can be, for example, 100 eV, 150 eV, 200 eV, 250 eV, 300 eV, 350 eV, 400 eV, 450 eV, 500 eV or a range of any two of these values, or other values ​​selected from the above range.

[0030] In some embodiments of this application, for example, in S1, the predetermined grazing incidence angle is 5°~30°. The grazing incidence angle is the angle between the ion beam and the normal to the surface of the copper wire. This angle design allows the momentum of argon ions to be mainly transferred tangentially along the surface of the copper wire, rather than bombarding the surface perpendicularly. Tangential momentum can more efficiently strip away contaminants adsorbed on the surface, while significantly reducing problems such as surface roughening and amorphous damage caused by perpendicular bombardment, thus ensuring the flatness of the copper surface.

[0031] It should be noted that in some embodiments, the predetermined grazing incidence angle can be, for example, 5°, 10°, 15°, 20°, 25°, 30° or a range of any two of these values, or other values ​​selected from the above range.

[0032] In some embodiments of this application, for example, the surface cleaning time in S1 is 10 min to 30 min. This time range is beneficial for balancing thorough cleaning and processing efficiency. Sufficient sputtering time allows the argon ion beam to achieve uniform treatment in the axial and circumferential directions of the copper wire, thoroughly removing contaminants from each area; at the same time, it avoids excessive sputtering caused by excessive time, preventing a large number of copper surface atoms from being stripped off and damaging the surface integrity of the copper lattice.

[0033] It should be noted that in some embodiments, the surface cleaning time may be, for example, 10 min, 15 min, 20 min, 25 min, 30 min, or a range of any two of these values, or other values ​​selected from the above range.

[0034] In some embodiments of this application, for example, the vacuum degree of surface cleaning in S1 is less than or equal to 1 × 10⁻⁶. -5 Pa. The ultra-high vacuum environment can completely suppress the secondary adsorption of gaseous molecules on the copper surface, and prevent molecules such as oxygen, water and organic matter in the air from re-attaching to the copper wire surface during the cleaning process; at the same time, it ensures that the transmission path of the argon ion beam is undisturbed, so that the ion beam spot is uniform and the momentum is stable, thus achieving uniform cleaning of the copper surface.

[0035] In some embodiments of this application, step S2 of the preparation method involves reconstructing the surface of a clean copper wire substrate to obtain a reconstructed copper wire substrate. Under a high-temperature hydrogen-containing atmosphere, the copper wire surface reconstruction is achieved through the synergistic effect of hydrogen reduction and copper atom surface migration. Hydrogen reduces the trace oxygen atoms remaining on the copper wire surface, further purifying the surface; the high temperature enhances the diffusion ability of copper surface atoms, causing surface atoms to rearrange orderly along low-index crystal planes, forming an atomically flat step-like structure. This optimizes the copper lattice arrangement and increases surface energy, providing uniform nucleation sites and diffusion paths for the directional epitaxial growth of graphene.

[0036] In some embodiments of this application, in S2, the surface step reconstruction method includes: treating a clean copper wire substrate with a hydrogen-argon mixed atmosphere containing 5% to 20% hydrogen gas, at a treatment temperature of 500°C to 800°C, a treatment pressure of 100 Pa to 500 Pa, and a treatment time of 30 to 60 minutes. Through the synergistic effect of these parameters, the copper wire surface spontaneously evolves into a regular structure dominated by low-index crystal planes, with step heights approaching those of single atoms / few atomic layers in the copper lattice, and mesa surfaces that are atomically flat.

[0037] In some embodiments of this application, the surface step reconstruction method in S2 employs a hydrogen-argon mixed atmosphere with a hydrogen gas fraction of 5% to 20% to treat the cleaned copper wire substrate. Argon serves as an inert protective gas to prevent the highly reactive surface of the cleaned copper wire from re-oxidizing at high temperatures. Hydrogen is the core functional gas, which, on the one hand, removes the trace amounts of surface oxygen atoms remaining from step S1 through a reduction reaction, further purifying the chemical state of the copper surface and eliminating impurities that interfere with graphene growth. On the other hand, the weak etching effect of hydrogen can help adjust the energy distribution of the copper surface, guiding copper atoms to migrate to low free energy regions and promoting the formation of a regular step structure. A hydrogen gas fraction of 5% to 20% is a suitable range for reduction purification and avoiding excessive hydrogen etching that damages the copper surface. If the proportion is too low, the reduction will be insufficient; if it is too high, it will cause the copper surface atoms to peel off, destroying the lattice integrity.

[0038] It should be noted that in some embodiments, the hydrogen gas fraction may be, for example, 5%, 7%, 10%, 12%, 15%, 18%, 20%, or a range of any two of these values, or other values ​​selected from the above range.

[0039] In some embodiments of this application, the processing temperature of the surface step reconstruction method in S2 is 500℃~800℃. This temperature range is the high diffusion activity range of copper surface atoms, which can provide sufficient thermodynamic kinetic energy for the surface migration of copper atoms, allowing atoms in the microscopic protrusion regions with higher surface free energy to rearrange to the low-index crystal planes (100) and (111) regions with lower free energy, without causing grain growth and bulk softening of the copper wire due to excessive temperature, thus avoiding structural distortion of the copper substrate itself. When the temperature is below 500℃, the diffusion ability of copper atoms is insufficient, and a regular step structure cannot be formed. Above 800℃, the copper wire is prone to thermal deformation and loses the structural stability of the substrate.

[0040] It should be noted that in some embodiments, the processing temperature may be, for example, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C or a range of any two of these values, or other values ​​selected from the above range.

[0041] In some embodiments of this application, the processing pressure of the surface step reconstruction method in S2 is 100 Pa to 500 Pa. This pressure range can balance the collision frequency of atmosphere molecules and the atomic migration efficiency of the copper surface. If the pressure is too high, the frequent collisions between atmosphere molecules and copper surface atoms will hinder the directional migration of copper atoms, making it difficult to form a continuous step structure. If the pressure is too low, the hydrogen molecule concentration is insufficient, which cannot achieve sufficient reduction and purification, and copper surface atoms are prone to random desorption, resulting in an uneven surface structure. A pressure of 100 Pa to 500 Pa can ensure that the hydrogen-argon mixed atmosphere uniformly coats the copper wire, while providing a stable environment for copper atom migration.

[0042] It should be noted that in some embodiments, the processing pressure may be, for example, 100 Pa, 150 Pa, 200 Pa, 250 Pa, 300 Pa, 350 Pa, 400 Pa, 450 Pa, 500 Pa, or a range of any two of these values, or other values ​​selected from the above range.

[0043] In some embodiments of this application, the processing time for the surface step reconstruction method in S2 is 30-60 minutes. This time range is the necessary period for copper surface atoms to complete migration, rearrangement, and shaping. 30 minutes is the minimum time for copper surface atoms to achieve ordered rearrangement and form the initial step structure; if this time is insufficient, the step structure will be discontinuous and the crystal orientation will be disordered. Within 60 minutes, the copper surface step structure can be completely shaped, forming atomically flat mesa and regular step edges. Exceeding this time will not have a significant structural optimization effect, only increasing process time and reducing production efficiency.

[0044] It should be noted that in some embodiments, the processing time may be, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or a range of any two of these values, or other values ​​selected from the above range.

[0045] In some embodiments of this application, step S3 of the preparation method involves: arranging the surface-reconstructed copper wire substrate in a predetermined crystal orientation and performing graphene directional growth treatment to obtain a composite wire. The graphene directional growth treatment is performed using a vapor-phase pulsed chemical vapor deposition method or a liquid-phase carbon source impregnation-high-temperature pyrolysis method.

[0046] In some embodiments of this application, in S3, the predetermined crystal orientation is

[100] or

[111] . Copper has a face-centered cubic crystal structure, and

[100] (cubic crystal orientation) and

[111] (close-packed crystal orientation) are its most important low-index crystal planes. Compared with high-index crystal planes, the two have the core structure and energy characteristics suitable for the directional epitaxial growth of graphene, and are highly consistent with the process results of the step reconstruction in S2, making them the optimal crystal orientation selection for the preparation of graphene copper composite cables.

[0047] In some embodiments of this application, step S3 of the preparation method can employ either pulsed chemical vapor deposition (CVD) or liquid-phase carbon source impregnation-high-temperature pyrolysis. Pulsed CVD achieves controlled adsorption and layer-by-layer epitaxial growth of carbon atoms through pulsed introduction of carbon source gas. The pulse intervals provide time for carbon atom diffusion rearrangement and lattice coalescence, suppressing disordered multilayer stacking and island-like growth of graphene. Simultaneously, the predetermined crystal orientation of the copper wire ensures high lattice matching between graphene and the copper substrate, achieving directional growth of graphene. Liquid-phase impregnation-high-temperature pyrolysis utilizes the uniformity of solution wetting to uniformly adsorb carbon source molecules onto the copper wire surface. After drying to form a solid precursor film, high-temperature pyrolysis decomposes the carbon source into active carbon atoms, which, under the catalysis of the copper substrate, recombine in situ along the copper lattice direction to form graphene. By controlling the carbon source concentration and impregnation time, the number of graphene layers can be precisely adjusted, achieving directional growth.

[0048] The two methods of preparation method S3 are described below. The first method uses pulsed chemical vapor deposition, as detailed below.

[0049] In some embodiments of this application, such as Figure 1 As shown, in S3, the pulsed chemical vapor deposition method includes: using carbon source precursor gas to deposit graphene on the reconstructed copper wire substrate. In S3, pulsed CVD is based on the precise alignment of the

[100] or

[111] crystal orientation of the copper wire. Through the selection of carbon source, precise limitation of pulse process parameters, and determination of the growth endpoint by in-situ optical monitoring, the controllable, directional, and precisely layered epitaxial growth of graphene on the surface of the copper wire is achieved. This method is beneficial to reduce the inherent defects of traditional continuous ventilation CVD, and to precisely control the supply, diffusion, nucleation and growth of carbon atoms throughout the entire process. At the same time, combined with in-situ monitoring, it achieves result-oriented growth control. The various process conditions and monitoring requirements are coordinated with each other, and finally, 1 to 3 layers of continuous low-defect graphene layers with high lattice matching with the copper substrate are formed on the surface of the copper wire, providing a core mesoscopic structure guarantee for the preparation of high-performance graphene copper composite wires.

[0050] In some embodiments of this application, in S3, the gas-phase pulsed chemical vapor deposition method satisfies at least one of the following conditions: the carbon source precursor gas is methane or ethylene; the pulse frequency is 0.1Hz to 1Hz; the duration of a single pulse is 5s to 20s; the gas flow rate is 10sccm to 50sccm; the temperature of the deposition zone is 900℃ to 1050℃; the pressure is 100Pa to 1000Pa; and the in-situ monitoring results collected by Raman spectroscopy or optical microscopy show that the intensity ratio of the G peak to the 2D peak of graphene reaches a preset threshold or the number of graphene deposition layers is 1 to 3 layers.

[0051] In some embodiments of this application, in S3, the carbon source precursor gas in the pulsed chemical vapor deposition method is methane or ethylene. Methane and ethylene are efficient low-carbon hydrocarbon carbon sources for graphene CVD growth. Both have moderate carbon-hydrogen bond energies and can undergo mild and sufficient thermal decomposition on the copper substrate surface at deposition temperatures of 900℃~1050℃, generating single active carbon atoms without excessive heteroatoms (such as nitrogen and oxygen) residue, thus avoiding the introduction of heteroatom defects during graphene growth. Simultaneously, their carbon source molecular structures are simple, and the carbon atom supply rate after decomposition is easily controlled by pulse parameters to meet the requirements of layer-by-layer growth. Compared to other carbon sources (such as acetone and benzene), methane and ethylene leave no organic solvent residue, ensuring the cleanliness of the graphene / copper interface and improving interfacial adhesion.

[0052] In some embodiments of this application, in S3, during pulsed chemical vapor deposition, the pulse frequency is 0.1Hz to 1Hz. This corresponds to a pulse period of 10s to 100s, providing a sufficient time window for carbon atom adsorption, diffusion, and nucleation. A frequency that is too high (>1Hz) will result in excessively rapid carbon source supply, causing carbon atoms to nucleate in large quantities before they can diffuse, leading to multilayer stacking and island-like growth. A frequency that is too low (<0.1Hz) will result in insufficient carbon atom supply, slow graphene growth rate, reduced process efficiency, and a tendency to form discontinuous graphene layers.

[0053] It should be noted that in some embodiments, the pulse frequency may be, for example, 0.1Hz, 0.2Hz, 0.3Hz, 0.4Hz, 0.5Hz, 0.6Hz, 0.7Hz, 0.8Hz, 0.9Hz, 1Hz or a range of any two of these values, or other values ​​selected from the above range.

[0054] In some embodiments of this application, in step S3, during pulsed chemical vapor deposition, the duration of a single pulse is 5 to 20 seconds. This duration ensures that the amount of carbon atoms provided by each pulse is just sufficient for the nucleation and initial expansion of monolayer graphene, without excessive carbon atom accumulation. If the duration is too short, the amount of carbon atoms will be insufficient, resulting in discontinuous expansion of the graphene crystal planes. If the duration is too long, there will be an excess of carbon atoms, which can easily lead to further nucleation on the already formed graphene layer, resulting in a bilayer or multilayer disordered structure.

[0055] It should be noted that in some embodiments, the duration of a single pulse can be, for example, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, or a range of any two of these values, or other values ​​selected from the above range.

[0056] In some embodiments of this application, in step S3, during pulsed chemical vapor deposition, the gas flow rate is 10 sccm to 50 sccm. This flow rate range ensures uniform distribution of the carbon source gas within the deposition zone, providing a uniform supply of carbon atoms to the surface of the multi-oriented copper wires. If the flow rate is too low, the carbon source gas concentration is insufficient, resulting in uneven graphene growth. If the flow rate is too high, turbulence is generated in the carbon source gas within the deposition zone, leading to an excess of carbon atoms in certain areas of the copper wires and causing graphene growth defects.

[0057] It should be noted that in some embodiments, the gas flow rate may be, for example, 10 sccm, 15 sccm, 20 sccm, 25 sccm, 30 sccm, 35 sccm, 40 sccm, 45 sccm, 50 sccm or a range of any two of these values, or other values ​​selected from the above range.

[0058] In some embodiments of this application, in S3, during the pulsed chemical vapor deposition method, the temperature of the deposition zone is 900℃~1050℃. This temperature is a suitable temperature range for the epitaxial growth of graphene catalyzed by a copper substrate. On the one hand, it can ensure sufficient thermal decomposition of methane / ethylene to generate highly active carbon atoms; on the other hand, it can provide sufficient thermodynamic kinetic energy for the two-dimensional diffusion of carbon atoms on the copper

[100] /

[111] crystal plane, so that carbon atoms can expand in an orderly manner along the lattice direction to form a continuous graphene layer; at the same time, this temperature maintains a safe distance from the melting point of copper (1083℃) to avoid softening and deformation of the copper wire and ensure the stability of the substrate structure. If the temperature is below 900℃, the carbon source decomposition is insufficient, the carbon atom activity is low, the graphene growth is slow and amorphous carbon is easily formed; if the temperature is above 1050℃, the copper atom diffusion is too strong, which can easily lead to distortion of the copper substrate crystal plane and destroy the lattice matching degree between graphene and copper.

[0059] It should be noted that in some embodiments, the temperature of the deposition zone may be, for example, 900°C, 950°C, 1000°C, 1050°C, or a range of any two of these values, or other values ​​selected from the above range.

[0060] In some embodiments of this application, in S3, during pulsed chemical vapor deposition, the pressure is 100 Pa to 1000 Pa. This low to medium vacuum pressure range balances the residence time and diffusion efficiency of carbon source molecules. If the pressure is too high, carbon source molecules collide frequently in the deposition zone, resulting in excessive residence time and a local excess of carbon atoms. If the pressure is too low, the residence time of carbon source molecules is too short, leading to insufficient carbon atom adsorption and discontinuous graphene growth. Simultaneously, this pressure range ensures the precision of the pulsed carbon source supply, ensuring that the amount of carbon source delivered in each pulse reaches the copper wire surface stably, achieving quantifiable control of carbon atom supply.

[0061] It should be noted that in some embodiments, the pressure may be, for example, 100Pa, 200Pa, 300Pa, 400Pa, 500Pa, 600Pa, 700Pa, 800Pa, 900Pa, 1000Pa or a range of any two of these values, or other values ​​selected from the above range.

[0062] In some embodiments of this application, in S3, during the pulsed chemical vapor deposition (PVD) method, the in-situ monitoring results acquired by Raman spectroscopy or optical microscopy indicate that the intensity ratio of the G peak to the 2D peak of graphene reaches a preset threshold or that the number of graphene deposition layers is 1 to 3. The in-situ monitoring results are directly used as the growth termination signal, rather than solely relying on time parameters, achieving a leap from process control to result control and effectively avoiding layer number deviations caused by equipment fluctuations and changes in carbon source concentration.

[0063] In some embodiments of this application, Raman spectroscopy is used as a characteristic characterization method for the number and quality of graphene layers, and the G peak of graphene (~1580 cm⁻¹) is used. -1 ) Corresponding to sp 2 In-plane vibrations of carbon, 2D peak (~2700 cm⁻¹) -1 The peaks IG and I2D are characteristic peaks of graphene, and the intensity ratio (IG / I2D) has a clear correlation with the number of graphene layers: IG / I2D ≈ 0.3 for monolayer graphene, about 0.7 for bilayer, about 1.0 for trilayer, and the ratio continues to increase beyond three layers. By monitoring this ratio to reach a preset threshold, the number of graphene layers can be accurately determined, avoiding layer deviations caused by relying on experience to control the time.

[0064] In some embodiments of this application, optical microscopy monitoring can intuitively determine the coverage and layer evolution of graphene by collecting the reflection contrast and image texture of the copper wire surface. The surface reflection characteristics of 1-3 layer graphene are significantly different from those of copper substrate and multilayer graphene. Image analysis can quickly pinpoint the target layer number, which is suitable for the rapid monitoring needs in large-scale production.

[0065] In summary, if the gas-phase pulsed chemical vapor deposition method is used in the preparation method, the high-quality copper substrate formed by the synergistic control of various process conditions and the precise layer control by in-situ monitoring can be perfectly matched with the previous S1 atomic-level cleaning, S2 step reconstruction, and S3 crystal orientation alignment. This fundamentally solves the problems of disordered graphene growth, large layer number fluctuations, and uneven quality in traditional CVD processes. It provides a graphene-copper composite filament with excellent structure for the subsequent S4 controlled cooling and S5 stranding into cables, while improving the overall stability and scalability of the process.

[0066] The second scheme of preparation method S3 (liquid phase carbon source impregnation-high temperature pyrolysis method) is described below.

[0067] In some embodiments of this application, in S3, the liquid-phase carbon source impregnation-high-temperature pyrolysis method includes: impregnating the surface-reconstructed copper wire substrate with a carbon source precursor solution, drying in stages, and forming a solid precursor film on the surface-reconstructed copper wire substrate; optionally, the impregnation meets at least one of the following conditions: the carbon source precursor solution is a graphene oxide dispersion or a polymeric carbon source solution; the concentration is 0.5 mg / mL to 5 mg / mL; the solvent includes one or more combinations of deionized water, ethanol, or dimethylformamide; the impregnation time is 10 s to 60 s; optionally, the staged drying meets at least one of the following conditions: the drying temperature is a gradient increase of 80℃ to 150℃; the drying time is 5 min to 20 min.

[0068] The liquid-phase carbon source impregnation-high-temperature pyrolysis method in S3 is a core pre-process for graphene preparation via impregnation and segmented drying. Utilizing a high-quality copper substrate formed through atomic-level cleaning in S1, step-like reconstruction in S2, and crystal orientation alignment in S3, precise control over the carbon source precursor solution, impregnation parameters, and segmented drying process enables uniform adsorption and controllable film formation of carbon source molecules on the copper wire surface. This results in a uniform, agglomerated, and tightly bonded solid precursor film, laying the mesoscopic structural foundation for the subsequent high-temperature pyrolysis stage of graphene's directional nucleation and layered growth. This step overcomes the random film formation defects of traditional liquid-phase impregnation, leveraging the uniformity of solution wetting to meet the demands of large-scale processing of fine-diameter copper wires. The synergistic interaction of various process conditions ensures precise and controllable carbon source film formation.

[0069] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the type, concentration, solvent selection of the carbon source precursor solution, as well as the impregnation time and temperature and time parameters of segmented drying, are conducive to uniform adsorption of carbon source, dense and defect-free film formation, and tight bonding with copper substrate. The value range of each condition is conducive to improving the balance of solution wettability, film formation controllability, and process adaptability, and is highly synergistic with the previous copper substrate treatment process.

[0070] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the carbon source precursor solution is a graphene oxide dispersion or a polymeric carbon source solution. In the graphene oxide dispersion, the graphene oxide sheets have abundant oxygen-containing functional groups, which can form hydrogen bonds / coordinate bonds with the active copper atoms on the copper wire surface, achieving a tight bond with the copper substrate. Furthermore, the sheet structure can be directly converted into graphene sheets after pyrolysis and reduction, without the need for complex carbon chain reconstruction, resulting in high grapheneization efficiency. In the polymeric carbon source solution (such as PVP or phenolic resin), the molecular chains are flexible and can fully fill the atomic-level gaps on the copper wire surface through solution wetting. During pyrolysis, the carbon chains gradually break down and aromatize, ultimately recombinating into graphene under the catalysis of the copper substrate, making it suitable for large-scale, continuous impregnation processes. Both types of carbon sources are free of heteroatoms such as sulfur, nitrogen, and phosphorus. After pyrolysis, they only produce carbon and small molecule gases, leaving no heteroatom impurities on the copper surface. This avoids introducing defects during graphene growth and ensures the cleanliness of the graphene / copper interface.

[0071] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the concentration of the carbon source precursor solution is 0.5 mg / mL to 5 mg / mL. This concentration range is beneficial for controllable film thickness, prevention of agglomeration and precipitation, and control over the number of graphene layers after subsequent pyrolysis. A concentration ≥ 0.5 mg / mL ensures sufficient carbon source molecules in the solution to form a continuous and dense monolayer / thin adsorption layer on the copper wire surface, avoiding discontinuous film layers due to excessively low concentrations, which would prevent the formation of a complete graphene layer after pyrolysis. A concentration ≤ 5 mg / mL prevents carbon source molecules from agglomerating in the solution, while ensuring that the carbon source molecules adsorbed on the copper surface are monodisperse, preventing excessively thick film layers due to excessive carbon source, which would lead to the formation of multilayer graphene or amorphous carbon after pyrolysis, precisely matching the requirement of "directional growth of monolayer graphene".

[0072] It should be noted that in some embodiments, the concentration of the carbon source precursor solution may be, for example, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, or a range of any two of these values, or other values ​​selected from the above range.

[0073] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the solvent of the carbon source precursor solution includes one or more combinations of deionized water, ethanol, or dimethylformamide. The selected solvents are beneficial in balancing solution dispersibility, copper surface wettability, and easy solvent removal, and none of them chemically react with the copper substrate, ensuring the stability of the copper surface structure and carbon source adsorption. Deionized water is suitable for dispersing graphene oxide, has moderate surface tension, can achieve sufficient wetting on atomically clean copper surfaces, and is non-toxic, low-cost, and suitable for large-scale production. Ethanol has low surface tension, better wettability than water, can spread rapidly on the copper wire surface, and has a low boiling point (78°C), making it easy to remove during drying, suitable for rapid impregnation film formation of fine-diameter copper wires. Dimethylformamide (DMF) is a polar aprotic solvent, suitable for the dissolution and dispersion of polymeric carbon sources, and has good compatibility with the copper surface, allowing polymeric carbon source molecules to be tightly adsorbed on the copper surface without desorption before pyrolysis. If the aforementioned solvents are used for mixing, the surface tension, dispersibility, and evaporation rate of the solution can be controlled by adjusting the ratio, adapting to the processing needs of different carbon sources (graphene oxide / polymer) and copper wires of different specifications (fine diameter / coarse diameter), thereby improving process flexibility.

[0074] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the impregnation time is 10s~60s. This time range is conducive to balancing sufficient carbon source adsorption with avoiding over-adsorption, taking into account both film uniformity and process efficiency. A time ≥10s allows carbon source molecules to achieve sufficient and uniform adsorption in the axial, circumferential, and atomic-level gaps of the copper wire through a diffusion-adsorption process, forming an adsorption layer without dead corners, and avoiding local film loss caused by excessively short impregnation time. A time ≤60s can prevent carbon source molecules from undergoing multilayer adsorption / agglomeration on the copper surface, forming only a monolayer or thin adsorption layer, while avoiding excessively long process time, improving the processing efficiency of continuous impregnation, and adapting to the pace of large-scale production.

[0075] It should be noted that in some embodiments, the immersion time may be, for example, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, or a range of any two of these values, or other values ​​selected from the above range.

[0076] In some embodiments of this application, in the S3 liquid-phase carbon source impregnation-high-temperature pyrolysis method, the segmented drying must meet at least one of the following conditions: the drying temperature is a gradient increase from 80°C to 150°C; the drying time is 5 min to 20 min. Segmented drying is a key quality control step in liquid-phase film formation. Gradient heating and limited drying time enable gradual solvent removal, guide the orderly formation of the carbon source film, and avoid the defects of traditional isothermal rapid drying.

[0077] In some embodiments of this application, the temperature is gradually increased from 80°C to 150°C. In the low-temperature stage (around 80°C), the free solvent on the copper surface is removed first to prevent the carbon source molecules from agglomerating due to the airflow impact caused by rapid solvent evaporation. In the medium-high temperature stage (gradually increasing to 150°C), the bound solvent between the carbon source molecules and the copper surface is removed. Simultaneously, a gentle thermal effect guides the carbon source molecules to arrange themselves orderly and closely adhere to the copper surface, forming a dense solid film. The upper temperature limit is controlled at 150°C to prevent premature pyrolysis or oxidation of the carbon source molecules due to excessively high temperatures, thus ensuring the structural integrity of the precursor film.

[0078] It should be noted that in some embodiments, the temperature for gradient heating can be, for example, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or a range of any two of these values, or other values ​​selected from the above range.

[0079] In some embodiments of this application, a drying time of 5 to 20 minutes ensures complete solvent removal while allowing sufficient time for carbon source molecules to complete their ordered rearrangement. If the time is too short, solvent removal will be incomplete, and rapid solvent evaporation during pyrolysis will cause the film to crack. If the time is too long, there is no additional film-forming optimization effect; it only increases process time and reduces production efficiency.

[0080] It should be noted that in some embodiments, the drying time may be, for example, 5 min, 10 min, 15 min, 20 min, or a range of any two of these values, or other values ​​selected from the above range.

[0081] In some embodiments of this application, during the impregnation and segmented drying process, the structural characteristics of the copper substrate are perfectly adapted to the synergistic control of various process conditions, which solves the problems of uneven film layer, agglomeration, cracking and poor bonding with the substrate in traditional liquid phase impregnation film formation. This provides a uniform, dense and clean solid carbon source substrate for high-quality graphene growth in the subsequent high-temperature pyrolysis stage, while giving full play to the process advantages of liquid phase method for large-scale, continuous production and adaptation to fine-diameter copper wires.

[0082] In some embodiments of this application, the surface-reconstructed copper wire substrate forming the solid precursor film is subjected to high-temperature pyrolysis. The high-temperature pyrolysis meets at least one of the following conditions: the atmosphere is an inert protective gas or a reducing mixed gas; the gas flow rate is 50 sccm to 200 sccm; the pressure is atmospheric pressure or slightly positive pressure; the heating rate is 5℃ / min to 20℃ / min; the temperature is raised to 600℃ to 800℃ and held for 10 min to 60 min. This stage is based on the controlled pyrolysis of carbon source catalyzed by copper

[100] or

[111] crystal orientation - graphene directional epitaxial growth process. Under an inert / reducing protective atmosphere, by slowly controlling the heating rate and holding at a constant temperature, the carbon source molecules in the solid precursor film gradually undergo thermal decomposition (removal of functional groups and small molecule gases). The remaining active carbon atoms diffuse, nucleate and recombine in an orderly manner along the lattice direction of the copper

[100] or

[111] crystal plane under the catalysis of the copper substrate, and finally form a single layer of graphene that matches the lattice of the copper substrate. The controlled atmosphere, pressure, and flow rate throughout the process provide a stable environment for the directional recombination of carbon atoms, preventing carbon source oxidation, uneven carbonization, or damage to the graphene layer. The thin, dense solid precursor film with precise carbon content formed by the initial impregnation and segmented drying provides a quantitative and uniform carbon source for pyrolysis, avoiding excessive carbon source leading to multilayer graphene / amorphous carbon. The atomic-level cleaning, step reconstruction, and crystal orientation unification of the copper substrate after S1-S3 treatment endow it with excellent catalytic activity and directional guiding effect, serving as a lattice template for the recombination of carbon atoms into graphene.

[0083] In some embodiments of this application, the atmosphere for high-temperature pyrolysis is an inert protective gas or a reducing mixed gas. This atmosphere protects the carbon source and copper substrate throughout the process, preventing oxidation and carbon source failure. The inert gas isolates the copper wire surface from oxygen in the air, preventing re-oxidation during pyrolysis (damaging the graphene growth template) and oxidation of the solid carbon source to CO / CO2, leading to carbon source loss. It also prevents defects in the graphene layer from being oxidized. The reducing mixed gas (e.g., 5% H2 + 95% Ar), in addition to preventing oxidation, can remove residual oxygen-containing functional groups (such as hydroxyl and carboxyl groups) from the carbon source molecules through the weak reducing effect of hydrogen, further purifying the carbon source. Simultaneously, it slightly etches the copper surface, enhancing its catalytic activity and promoting the orderly recombination of carbon atoms. Both atmospheres are free of heteroatoms and will not react with the carbon source or copper substrate, ensuring the purity and interface cleanliness of the graphene growth.

[0084] In some embodiments of this application, the gas flow rate for high-temperature pyrolysis is 50 sccm to 200 sccm. This flow rate range is conducive to balancing uniform atmosphere coverage and timely removal of small molecules from the pyrolysis process. A flow rate ≥ 50 sccm helps ensure rapid and uniform distribution of the protective gas within the pyrolysis furnace, completely covering multiple copper wires and forming a protective atmosphere without dead zones, thus preventing oxidation caused by localized contact with air. A flow rate ≤ 200 sccm helps to promptly remove small molecule gases (such as H2O and CH4) generated during carbon source pyrolysis, preventing small molecules from accumulating and adsorbing onto the copper surface within the furnace, interfering with the directional diffusion and nucleation of carbon atoms; at the same time, it avoids excessive flow forming a strong airflow that impacts the active carbon atoms on the copper surface, leading to discontinuous graphene growth.

[0085] It should be noted that, in some embodiments, the gas flow rate for high-temperature pyrolysis can be, for example, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm, 150 sccm, 160 sccm, 170 sccm, 180 sccm, 190 sccm, 200 sccm, or a range of any two of these values, or other values ​​selected from the above range.

[0086] In some embodiments of this application, the pressure for high-temperature pyrolysis is atmospheric pressure or slightly positive pressure. This pressure design is suitable for the characteristics of liquid-phase methods without vacuum equipment and for large-scale production, while ensuring the stability of the pyrolysis environment. Atmospheric pressure is the conventional pressure for industrial production, eliminating the need for additional vacuum equipment, reducing equipment investment and operational complexity, and adapting to continuous production lines, seamlessly integrating with the impregnation + segmented drying process rhythm. Slightly positive pressure further prevents external air from seeping into the pyrolysis furnace, improving the reliability of atmosphere protection and avoiding carbon source oxidation or copper substrate re-oxidation caused by trace oxygen entry, making it particularly suitable for large-scale, long-term continuous pyrolysis processing. At a suitable high-temperature pyrolysis pressure, the thermal decomposition rate of carbon source molecules and the diffusion rate of carbon atoms are in equilibrium, preventing carbon atom desorption due to excessively low pressure and the accumulation of small molecule gases due to excessively high pressure.

[0087] In some embodiments of this application, the heating rate of high-temperature pyrolysis is 5°C / min to 20°C / min. Slow, controlled heating is key to achieving ordered pyrolysis of the carbon source and avoiding defects in graphene growth. A rate ≤20°C / min allows the carbon source molecules to undergo a gradual process of defunctionalization, carbon chain aromatization, and release of active carbon atoms, avoiding rapid heating that could cause instantaneous and violent decomposition of the carbon source molecules, generating a large amount of amorphous carbon or carbon particles. It also prevents thermal stress between the copper wire and the carbon source film due to a sudden temperature rise, which could lead to film cracking and detachment. A rate ≥5°C / min helps ensure process efficiency, avoiding excessively slow heating that could result in a long production cycle. It also provides sufficient thermodynamic kinetic energy for carbon atoms to diffuse along the copper lattice direction, preventing the formation of amorphous carbon due to slow pyrolysis, thus adapting to the pace of large-scale production.

[0088] It should be noted that, in some embodiments, the heating rate of high-temperature pyrolysis can be, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min, 20°C / min, or a range of any two of these values, or other values ​​selected from the above range.

[0089] In some embodiments of this application, the high-temperature pyrolysis heating to 600℃~800℃ and holding for 10min~60min is beneficial for copper substrate catalytic graphene growth, achieving complete grapheneization and directional recombination of the carbon source. Among them, the temperature range of 600℃~800℃ is the highly efficient active range for copper

[100] /

[111] crystal orientation substrate to catalyze the conversion of carbon source into graphene. It can ensure that the carbon source molecules are completely thermally decomposed into active carbon atoms, and can provide sufficient kinetic energy for the two-dimensional diffusion and nucleation of carbon atoms. At the same time, it avoids the growth of copper wire grains and crystal plane distortion caused by excessively high temperature (>800℃), which would destroy the lattice template for graphene growth, and can also prevent the graphene layer from thermally detaching due to excessive temperature. If the temperature is below 600℃, the carbon source will not be decomposed sufficiently and will not form active carbon atoms, only amorphous carbon will be generated. The holding time of 10min~60min provides sufficient time for the directional diffusion of carbon atoms, lattice recombination, and graphene shaping. A time of ≥10 min ensures that active carbon atoms diffuse and nucleate fully along the copper lattice direction, forming a continuous graphene layer; a time of ≤60 min avoids excessive heat preservation, which would cause carbon atoms to continue to nucleate on the already formed graphene layer, forming multilayer graphene. At the same time, it prevents the copper wire from softening and deforming due to prolonged high temperature, ensuring the mechanical properties of the composite wire. The amount of carbon source conversion in a single heat preservation is exactly matched with the carbon content of the precursor film, achieving precise growth of single-layer graphene.

[0090] It should be noted that in some embodiments, the temperature rise caused by high-temperature pyrolysis can be, for example, 600°C, 650°C, 700°C, 750°C, 800°C or a range of any two of these values, or other values ​​selected from the above range.

[0091] It should be noted that in some embodiments, the duration of heat preservation can be, for example, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, or a range of any two of these values, or other values ​​selected from the above range.

[0092] In some embodiments of this application, in the preparation method S4: the composite filament is subjected to controlled cooling under axial tension in an inert atmosphere to obtain a structurally stable composite filament. The synergistic effect of the inert atmosphere preventing oxidation, the axial tension stress regulation, and the slow cooling thermal stress release solves the interface problem caused by the difference in thermal expansion coefficients between graphene and copper. The inert atmosphere prevents oxidation of the composite filament during cooling; the axial tension forms a uniform tensile stress field, guiding the orderly release of interfacial thermal strain along the axial direction, avoiding stress concentration in the radial direction or at local interfaces; the slow cooling rate effectively inhibits wrinkling, cracking, or peeling of the graphene layer from the copper substrate, maintaining the structural integrity of the graphene layer and the tightness of the interfacial bonding.

[0093] In some embodiments of this application, in step S4, the inert atmosphere is argon gas with a purity of ≥99.999% or nitrogen gas with a purity of ≥99.999%, the axial tension is 0.1N~1N, the cooling rate is 1℃ / min~5℃ / min, and the temperature is cooled to room temperature. The purity and type of the inert atmosphere, the value of the axial tension, and the limitation of the cooling rate in step S4 are beneficial for efficiently releasing interfacial thermal stress, maintaining the integrity of the graphene / copper interface, and ensuring the stability of the composite filament structure. The value range of each condition is beneficial for balancing stress control effect, process feasibility, and composite filament performance, and is suitable for the cooling requirements of both gas-phase and liquid-phase precursor processes.

[0094] A high-purity inert atmosphere provides an ultra-clean, oxygen-free, and water-free cooling environment for the composite filaments, completely preventing oxidation damage and adapting to the high-temperature cooling process. A purity of ≥99.999% thoroughly removes impurities such as oxygen, water, and carbon dioxide from the atmosphere, preventing oxidation of the high-temperature composite filaments (especially the atomically clean graphene / copper interface) during cooling. Oxidation of the copper substrate forms a new oxide layer, disrupting the lattice matching and interfacial bonding between graphene and copper. Graphene oxidation generates oxygen-containing functional groups, introducing structural defects, significantly reducing its electron mobility, and ultimately causing a sharp drop in the conductivity of the composite filaments.

[0095] Argon and nitrogen are both chemically inert industrial protective gases, suitable for various process requirements. For example, argon has a larger atomic weight, providing stronger atmosphere sealing and making it suitable for higher initial cooling temperatures of 900℃ to 1050℃ in gas-phase processes, preventing trace oxygen permeation at high temperatures. Nitrogen is cheaper and more readily available, suitable for initial cooling temperatures of 600℃ to 800℃ in liquid-phase processes, balancing process effectiveness with the cost requirements of large-scale production. Furthermore, neither reacts chemically with graphene or copper, ensuring interface cleanliness during the cooling process.

[0096] In some embodiments of this application, the axial tension is 0.1N~1N. Axial tension is beneficial for balancing effective stress guidance with avoiding plastic deformation of the wire, and for the orderly release of thermal stress. Tension ≥0.1N can form a uniform axial tensile stress field inside the composite wire. This stress field can provide directional constraint on the thermal shrinkage of the copper substrate, guiding the interfacial thermal stress caused by the difference in thermal shrinkage between copper and graphene to be released orderly only along the axial direction. This completely avoids stress concentration caused by local accumulation of stress in the radial direction and at the interface, and fundamentally prevents the graphene layer from wrinkling, cracking, and peeling due to excessive local stress. Tension ≤1N strictly controls the tension within the elastic deformation range of the copper wire, avoiding plastic tensile deformation of the copper wire due to excessive tension, which would damage the lattice structure of the copper substrate and the geometry of the composite wire. At the same time, it prevents irreversible structural damage to the graphene layer due to excessive stretching, ensuring the integrity, continuity, and electron transport performance of the graphene layer. Maintaining constant tension throughout the cooling process ensures a uniform and stable stress field, preventing disordered stress release caused by tension fluctuations, guaranteeing consistent stress release across all axial sections of the composite filament, and improving the uniformity of the filament's performance after cooling.

[0097] It should be noted that in some embodiments, the axial tension can be, for example, 0.1N, 0.2N, 0.3N, 0.4N, 0.5N, 0.6N, 0.7N, 0.8N, 0.9N, 1N, or a range of any two of these values, or other values ​​selected from the above range.

[0098] In some embodiments of this application, the cooling rate is 1℃ / min to 5℃ / min. The cooling rate is adapted to the initial temperature difference between the gas phase and the liquid phase. A rate ≤ 5℃ / min provides sufficient time for the release of interfacial thermal stress, allowing the copper substrate and the graphene layer to undergo synchronous and slow thermal contraction, significantly reducing the shrinkage difference between the two. This avoids the instantaneous generation of stress due to excessively rapid cooling, which cannot be released in time, thus preventing microcracks in the graphene layer and interfacial debonding. For the higher initial temperature of 900℃ to 1050℃ in the gas phase method, a rate of 5℃ / min can ensure the gradual release of stress from high temperature to medium temperature, while a slower rate of 1℃ / min is suitable for high-end preparation scenarios with higher requirements for interfacial performance. A cooling rate ≥1℃ / min ensures effective stress release while maintaining process efficiency, avoiding excessively slow cooling that could lead to long production cycles (e.g., cooling from 1000℃ to room temperature requires approximately 16.5 hours at 1℃ / min and approximately 3.3 hours at 5℃ / min). This aligns with the pace of large-scale continuous production and prevents slow grain growth caused by prolonged exposure of copper wires to the mid-temperature range, maintaining the fine-grained structure and mechanical properties of the copper substrate. Cooling to room temperature achieves complete structural stabilization of the composite filament, minimizing and stabilizing residual thermal stress at the interface. This prevents structural deformation and graphene layer detachment caused by continued stress release during subsequent room temperature storage or stranding into cables due to incomplete cooling, ensuring the long-term structural stability of the composite filament.

[0099] It should be noted that in some embodiments, the cooling rate may be, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min or a range of any two of these values, or other values ​​selected from the above range.

[0100] In some embodiments of this application, step S5 of the preparation method involves guiding and stranding structurally stable composite filaments to obtain a highly conductive graphene / copper composite cable. Through the geometric constraints of a fixed-angle guiding mold and the micro-tension control during the stranding process, multiple composite filaments form a regular, dense spiral stranded structure. Maintaining a constant strand pitch and micro-tension during the stranding process ensures close contact between the filaments. The graphene layer forms a continuous conductive path in the contact area, and the copper substrate forms axially parallel metal conductive channels, achieving a dense and continuous conductive network in the macroscopic cable.

[0101] In some embodiments of this application, in step S5, the guiding angle of the guided stranding is 15°~45°, and the rotation speed is 10rpm~30rpm. Multiple graphene-copper composite filaments treated in step S4 are fed parallel into a fixed-angle rotating mold. The mold rotates around the cable axis at a set speed, while a traction mechanism drives the filaments forward continuously along the axial direction. The 15°~45° guiding angle provides a fixed spiral forming trajectory for the filaments. The rotation speed of 10rpm~30rpm is linked with the traction speed to control the constant strand pitch, allowing multiple composite filaments to form a high-density, regularly spirally arranged overall cable under the combined action of geometric constraints and micro-tension. The composite filaments prepared in step S4 have the characteristics of tight interface, good flexibility, and excellent mechanical strength, providing a structural basis for resisting mechanical stress during the stranding process. Furthermore, the precise limitation of stranding parameters avoids mechanical tension / bending stress damaging the interface between the graphene layer and the copper substrate, ultimately achieving a complete transfer of microscopic interface properties to macroscopic cable properties.

[0102] In some embodiments of this application, in step S5, the guiding angle of the guide stranding is 15°~45°. This range is adapted to the forming angle of the graphene-copper composite wire, ensuring cable quality while avoiding performance damage caused by excessive stranding. An angle ≥15° provides sufficient helical forming constraint for multiple composite wires, enabling close surface contact between the wires. This ensures that the graphene layer on the wire surface forms a continuous conductive path in the contact area, and the copper substrate forms axially parallel metal conductive channels, significantly reducing the contact resistance between the wires. At the same time, a suitable helical angle enables the cable to form a stable spatial structure, improving the cable's tensile and bending mechanical properties and avoiding cable deformation and conductivity fluctuations caused by loose stranding. An angle of ≤45° limits the bending and torsional stresses on the composite wires during stranding to within the elastic range, preventing excessive bending of the wires due to excessive angle, which could cause micro-cracking of the graphene layer, peeling from the copper substrate, or plastic deformation of the copper wires. At the same time, a guide angle within 45° ensures that the cable strand pitch is appropriate, avoiding uneven cable outer diameter and surface unevenness caused by excessively small strand pitch, and facilitating subsequent processing such as insulation coating and end connection.

[0103] It should be noted that in some embodiments, the guide angle of the guide twist can be, for example, 15°, 20°, 25°, 30°, 35°, 40°, 45° or a range of any two of these values, or other values ​​selected from the above range.

[0104] In some embodiments of this application, in step S5, the rotational speed of the guide stranding is 10 rpm to 30 rpm. The rotational speed and traction speed are linked to determine the strand pitch of the cable, which is a key parameter for controlling the efficiency and structural uniformity of the cabling process. This range works in conjunction with a guide angle of 15° to 45° to achieve stable forming and efficient production. A rotational speed ≥ 10 rpm is beneficial to the cabling process efficiency, adapts to the rhythm of large-scale continuous production, avoids low cabling speed and long production cycle caused by too slow a rotational speed, and matches the continuous feed rate of the composite filament to achieve integrated continuous processing of filament preparation and stranding into cabling. The basic rotational speed of 10 rpm can ensure the stability of the mold rotation and avoid uneven stranding and local loosening of the filament caused by too low a rotational speed. A rotation speed of ≤30rpm allows the composite filaments to slowly and smoothly form a spiral structure along the guide angle during the stranding process. This provides time for micro-tension adjustment between the filaments, ensuring uniform force on each filament and avoiding excessive tension and inconsistent strand pitch caused by excessive rotation speed, which could lead to damage to the graphene layer and distortion of the cable structure. At the same time, a rotation speed of less than 30rpm can precisely control the constant strand pitch, ensuring consistent structure across all sections of the cable along the axial direction, guaranteeing uniform conductivity, and eliminating the problem of excessively high local contact resistance.

[0105] It should be noted that in some embodiments, the rotation speed may be, for example, 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, or a range of any two of these values, or other values ​​selected from the above range.

[0106] The twist pitch is controlled by the rotation speed and the guide angle. At a fixed traction speed, the rotation speed and the guide angle work together to determine the twist pitch (the higher the rotation speed / the larger the angle, the smaller the twist pitch). The combination of a rotation speed of 10rpm to 30rpm and an angle of 15° to 45° can form the optimal twist pitch range for graphene copper composite wire, which ensures a dense structure and avoids over-twisting, thus achieving a balance between structure and performance.

[0107] The second aspect of this invention is to provide a highly conductive graphene / copper composite cable, which is a highly conductive graphene / copper composite cable prepared using the preparation method of the highly conductive graphene / copper composite cable provided in the first aspect. The outer diameter of the highly conductive graphene / copper composite cable is 0.1 mm to 10 mm. Based on the excellent effects of the preparation method, this composite cable has achieved breakthrough optimization in terms of the structural characteristics of the graphene layer, the bonding state of the graphene-copper interface, and the conductive network of the macroscopic stranded structure. Compared with traditional pure copper cables and existing graphene-copper composite cables, it has far superior conductivity, mechanical properties, and batch stability, and its outer diameter specifications cover a wide range, making it suitable for engineering application needs in many fields such as high-end power transmission and new energy equipment.

[0108] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or through existing methods; unless otherwise specified, the amounts of experimental reagents used are the amounts used in conventional experimental operations; unless otherwise specified, the experimental methods are all conventional methods.

[0109] Example 1 In this embodiment, the aim is to prepare a highly conductive graphene / copper composite cable with superior conductivity and interface quality. The preparation method specifically includes the following steps: Surface cleaning A pure copper wire (purity >99.99%) with a diameter of 0.5 mm was continuously fed into the ultra-high vacuum chamber. The chamber was then evacuated to a vacuum level of 5 × 10⁻⁶. -6 Pa. The ion source is activated to generate an argon ion beam with an energy of 300 eV. The ion beam is adjusted to a grazing incidence angle of 15° relative to the normal of the copper wire surface for irradiation, and cleaning is continued for 20 minutes to obtain an atomically clean copper surface.

[0110] Surface step reconstruction The cleaned copper wire was transferred to a connected high-temperature processing chamber. A mixed gas consisting of 10% hydrogen and 90% argon was introduced to maintain the chamber pressure at 300 Pa. The copper wire was heated to 650 °C and processed under this condition for 45 min. After processing, an atomically flat

[111] crystal plane-dominated step structure was formed on the surface of the copper wire.

[0111] Crystal alignment and feed The axial crystal orientation of multiple reconstructed copper wires is corrected to the

[111] direction using an optical alignment system. The crystal orientation deviation angle θ of a single copper wire is controlled to be less than 2 degrees, and the crystal orientation dispersion index η of multiple copper wires is controlled to be less than 3 degrees. Multiple copper wires with consistent crystal orientation are fed into the deposition zone of the chemical vapor deposition (CVD) equipment in parallel and stably.

[0112] Pulse chemical vapor deposition of graphene The temperature in the deposition zone was raised to 1000℃, while the pressure was maintained at 500 Pa. Methane (CH4) was introduced in a pulsed manner. 4 The copper wire was used as the carbon source. The pulse frequency was 0.5 Hz, each pulse lasted 10 s, the gas flow rate during the pulse was 30 sccm, and only argon gas was introduced during the pulse interval. Under these conditions, carbon atoms were adsorbed at the copper wire steps and graphene was epitaxially grown.

[0113] In-situ monitoring and growth termination In-situ real-time monitoring was performed using a Raman spectrometer integrated within the deposition zone. When the intensity ratio (I_G / I_2D) of the graphene's G peak to 2D peak stabilized at around 0.3 and conformed to the characteristics of monolayer graphene, the methane gas source was immediately shut off to terminate the deposition.

[0114] Inert atmosphere tension cooling Heating was stopped, and a protective atmosphere of 99.999% pure argon gas was introduced into the deposition zone. A constant axial tension of 0.5 N was applied to the composite filament using a tension controller. The temperature was then slowly cooled to room temperature at a rate of 2 °C / min under programmed temperature control.

[0115] Stranded into a cable at a fixed angle Seven graphene-copper composite filaments prepared above were arranged in parallel and fed into a fixed-angle rotating mold. The guide angle of the mold was set to 30°, the rotation speed to 20 rpm, and the traction speed was matched with the rotation speed to maintain a constant strand pitch. During the stranding process, a slight tension was applied to each filament, and a composite cable with an outer diameter of approximately 1.5 mm was finally obtained.

[0116] The composite cable was tested using methods commonly used by those skilled in the art. Its volume conductivity was increased by about 8% compared to that of pure copper cable of the same specification. Moreover, the conductivity decay rate was less than 1% after repeated bending tests, demonstrating excellent conductivity and interface stability.

[0117] Example 2 This embodiment focuses on improving preparation efficiency and process stability while ensuring good performance, making it suitable for large-scale production.

[0118] Surface cleaning A batch processing method was adopted, placing multiple copper wires in a vacuum chamber. (The process is described in 1×10...) -5 Under a vacuum of Pa, an argon ion beam with an energy of 150 eV was used to clean for 15 minutes at a grazing incidence angle of 25°.

[0119] Surface step reconstruction In an atmosphere containing 15% hydrogen (with the remainder being argon), the copper wire was treated at a pressure of 200 Pa and a temperature of 550 °C for 35 min to form a stepped structure on the surface of the copper wire, which is dominated by the

[100] crystal plane.

[0120] Crystal alignment and feed The copper wire is aligned to the

[100] direction, and the crystal orientation deviation angle θ is controlled to be less than 3°. The multi-wire crystal orientation dispersion η is controlled to be less than 5° before it is sent into the deposition area.

[0121] Pulse chemical vapor deposition of graphene The temperature in the sedimentation zone was set at 950℃ and the pressure at 800Pa.

[0122] Ethylene (C2H4) was used as the carbon source, with a pulse frequency of 0.8 Hz, a single pulse duration of 8 s, and a pulse flow rate of 40 sccm.

[0123] In-situ monitoring and growth termination In-situ monitoring was performed using a high-temperature resistant optical microscope, and the graphene coverage was analyzed by image contrast. When the system determined that the surface was completely covered by uniform bilayer graphene (the image contrast reached a preset threshold), the carbon source supply was automatically terminated.

[0124] Inert atmosphere tension cooling Under a pure nitrogen atmosphere (99.999%), an axial tension of 0.2 N was applied, and the mixture was cooled at a rate of 4 °C / min.

[0125] Stranded into a cable at a fixed angle Nineteen composite wires are twisted together at a guide angle of 20° and a rotation speed of 25 rpm to produce a composite cable with an outer diameter of approximately 4.0 mm.

[0126] This embodiment offers a wider manufacturing process window, faster production speed, and a stable yield rate exceeding 98%. The resulting cable exhibits 5% higher conductivity than pure copper cable, good mechanical strength and flexibility, and high overall cost-effectiveness, making it suitable for use as a conductor in power transmission cables.

[0127] Example 3 This embodiment aims to prepare composite cables with better conductivity and interface quality through a liquid phase impregnation-high temperature pyrolysis process.

[0128] The steps of surface cleaning, surface step reconstruction, crystal orientation alignment and feeding, and fixed-angle stranding are the same as in Example 1. The difference compared to Example 1 is: Carbon source impregnation and drying An aqueous solution of graphene oxide with a concentration of 1.5 mg / mL was prepared, and a small amount of sodium dodecylbenzenesulfonate was added as a dispersant. Multiple reconstructed copper wires with aligned crystal orientations were continuously passed through an impregnation tank at a linear speed of 0.5 m / min for 30 s. Subsequently, they were placed in a three-stage drying oven, with the first stage drying at 80℃ for 5 min, the second stage drying at 120℃ for 5 min, and the third stage drying at 150℃ for 5 min, so that the graphene oxide was uniformly attached and reduced to a solid film.

[0129] High-temperature pyrolysis grapheneization The dried coated copper wire is fed into a tubular pyrolysis furnace and a mixture of high-purity argon and 5% hydrogen is introduced at a flow rate of 100 sccm. The temperature is increased to 750℃ at a rate of 10℃ / min and held for 30 min. During this process, graphene oxide is thermally reduced and recombined into continuous monolayer graphene.

[0130] Inert atmosphere tension cooling After the heat preservation is completed, heating is stopped, and pure argon gas protection is switched. An axial tension of 0.3N is applied, and the mixture is cooled to room temperature at a rate of 2℃ / min.

[0131] Tests showed that the conductivity of the cable prepared in this embodiment was about 7.5% higher than that of pure copper, the graphene coverage was uniform and there was no agglomeration, the interface was tightly bonded, and the resistance fluctuation between batches was less than 0.5%.

[0132] Example 4 This embodiment focuses on improving the processing efficiency of the liquid phase method and is suitable for large-scale continuous production.

[0133] The steps of surface cleaning, surface step reconstruction, crystal orientation alignment and feeding, and fixed-angle stranding are the same as in Example 2. The difference between Example 2 and Example 2 is as follows: Carbon source impregnation and drying A dimethylformamide solution of polyvinylpyrrolidone was used as the carbon source at a concentration of 2.0 mg / mL. The copper wire was immersed for 20 seconds, and the drying was carried out in two stages: drying at 100℃ for 4 minutes and drying at 140℃ for 4 minutes.

[0134] High-temperature pyrolysis grapheneization The pyrolysis temperature was 700℃, the holding time was 20 min, the heating rate was 15℃ / min, and the protective atmosphere was pure nitrogen.

[0135] Inert atmosphere tension cooling Apply 0.2N axial tension and cool at a rate of 3℃ / min.

[0136] The preparation efficiency of this embodiment is about 40% higher than that of Example 3, with a yield of over 97%. The conductivity of this composite cable is 6.2% higher than that of pure copper. The graphene layers are mainly single-layered, making it suitable for mid-to-high-end power transmission applications.

[0137] In summary, the highly conductive graphene / copper composite cable and its preparation method provided in this application achieve directional graphene growth through atomic-level cleaning with argon ion beams, step-like reconstruction of the copper wire surface, and precise crystal orientation alignment, combined with gas-phase pulsed CVD or liquid-phase carbon source impregnation-high-temperature pyrolysis. Furthermore, the optimized process, including inert atmosphere axial tension-controlled cooling and angle-guided stranding, solves the problems of disordered graphene growth, poor interfacial bonding, and lattice mismatch in traditional preparation methods at the microscopic level, enabling graphene and the copper substrate to form a highly matched synergistic conductive structure. This significantly reduces interface resistance; the composite cables produced macroscopically have an outer diameter ranging from 0.1mm to 10mm, and their conductivity is significantly improved compared to pure copper cables (up to about 8%). They also exhibit excellent mechanical properties, low conductivity decay rate after bending, small performance fluctuations between batches, and high yield. At the same time, the process is adapted for large-scale continuous production, balancing efficiency and quality. This effectively breaks through the performance bottleneck of traditional pure copper conductors and can meet the stringent requirements of high conductivity, high reliability, and high current carrying capacity of conductive materials in high-end fields such as power transmission, new energy equipment, rail transportation, and aerospace.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a highly conductive graphene / copper composite cable, characterized in that, Includes the following steps: S1: The copper wire substrate is cleaned by using an argon ion beam at a predetermined grazing incidence angle to obtain a clean copper wire substrate. S2: Perform surface step reconstruction on the clean copper wire substrate to obtain a surface-reconstructed copper wire substrate; S3: The surface-reconstructed copper wire substrate is arranged in a predetermined crystal orientation and graphene is oriented to grow to obtain a composite wire. The graphene oriented growth process is carried out by gas phase pulsed chemical vapor deposition or liquid phase carbon source impregnation-high temperature pyrolysis. S4: The composite filament is subjected to controlled cooling under axial tension in an inert atmosphere to obtain a structurally stable composite filament. S5: Guide and twist the structurally stable composite filaments to obtain the highly conductive graphene / copper composite cable.

2. The preparation method according to claim 1, characterized in that, In S3, the gas-phase pulsed chemical vapor deposition method includes: using a carbon source precursor gas to deposit graphene on the surface-reconstructed copper wire substrate; Optionally, the gas-phase pulsed chemical vapor deposition method shall at least meet one of the following conditions: the carbon source precursor gas is methane or ethylene; the pulse frequency is 0.1Hz~1Hz; the duration of a single pulse is 5s~20s; the gas flow rate is 10sccm~50sccm; the temperature of the deposition zone is 900℃~1050℃; the pressure is 100Pa~1000Pa; and the in-situ monitoring results acquired by the Raman spectrometer or optical microscope are that the intensity ratio of the G peak to the 2D peak of graphene reaches a preset threshold or the number of graphene deposition layers is 1 to 3 layers.

3. The preparation method according to claim 1, characterized in that, In S3, the liquid phase carbon source impregnation-high temperature pyrolysis method includes: impregnating the surface reconstructed copper wire substrate with a carbon source precursor solution, drying it in stages, and forming a solid precursor film on the surface reconstructed copper wire substrate; Optionally, the impregnation shall at least meet one of the following conditions: the carbon source precursor solution is a graphene oxide dispersion or a polymeric carbon source solution; the concentration is 0.5 mg / mL to 5 mg / mL; the solvent includes one or more combinations of deionized water, ethanol, or dimethylformamide; and the impregnation time is 10 s to 60 s. Optionally, the segmented drying shall at least meet one of the following conditions: the drying temperature is increased by a gradient from 80℃ to 150℃; the drying time is from 5 min to 20 min.

4. The preparation method according to claim 3, characterized in that, The surface-reconstructed copper wire substrate forming the solid precursor film is subjected to high-temperature pyrolysis. Optionally, the high-temperature pyrolysis shall at least meet one of the following conditions: the atmosphere is an inert protective gas or a reducing mixed gas; the gas flow rate is 50 sccm to 200 sccm; the pressure is atmospheric pressure or slightly positive pressure; the heating rate is 5℃ / min to 20℃ / min; and the temperature is raised to 600℃ to 800℃ and held for 10 min to 60 min.

5. The preparation method according to claim 1, characterized in that, In S3, the predetermined crystal orientation is [100] or [111].

6. The preparation method according to any one of claims 1 to 5, characterized in that, In S1, the energy range of the argon ion beam is 100 eV to 500 eV, the predetermined grazing incidence angle is 5° to 30°, the surface cleaning time is 10 min to 30 min, and the vacuum degree of surface cleaning is less than or equal to 1 × 10⁻⁶. -5 Pa.

7. The preparation method according to any one of claims 1 to 5, characterized in that, In S2, the surface step reconstruction method includes: treating the clean copper wire substrate with a hydrogen-argon mixed atmosphere with a hydrogen gas integral of 5% to 20%, the treatment temperature being 500℃ to 800℃, the treatment pressure being 100Pa to 500Pa, and the treatment time being 30min to 60min.

8. The preparation method according to any one of claims 1 to 5, characterized in that, In S4, the inert atmosphere is argon gas with a purity of ≥99.999% or nitrogen gas with a purity of ≥99.999%, the axial tension is 0.1N~1N, the cooling rate is 1℃ / min~5℃ / min, and the temperature is cooled to room temperature.

9. The preparation method according to any one of claims 1 to 5, characterized in that, In S5, the guide angle of the guide twist is 15°~45°, and the rotation speed is 10rpm~30rpm.

10. A highly conductive graphene / copper composite cable, characterized in that, The high-conductivity graphene / copper composite cable prepared using the preparation method of any one of claims 1 to 9 may optionally have an outer diameter of 0.1 mm to 10 mm.

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