High-strength high-conductivity copper alloy energy storage cable and preparation method

Abstract

The application relates to the field of metal matrix composites and wire and cable manufacturing, in particular to a high-strength and high-conductivity copper alloy energy storage cable and a preparation method; the cable comprises, from inside to outside, a conductor core, an insulation layer, a flame-retardant armored layer and a weather-resistant sheath layer; the conductor core is uniformly dispersed with a multifunctional composite modifier in a copper matrix, the modifier has a core-shell structure and is composed of a multi-walled carbon nanotube center core, a 5-15nm silver conductive transition shell layer and a rare earth anchoring phase; the core is to construct a high-strength skeleton by using the carbon nanotube to provide physical strengthening support, and the silver transition shell layer is used to tightly fuse with the copper matrix in a microstate, so that micro-pores are eliminated to realize dense metallurgical coherent bonding; the alloy single wire is prepared by feeding the intermediate into the copper melt and assisting with ladder aging treatment, the electronic transmission channel is effectively bridged, the interface electron scattering is greatly reduced, and the technical bottleneck of the traditional metal material strong-conductivity mutual repulsion is successfully broken.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composites and wire and cable manufacturing, specifically to a high-strength, high-conductivity copper alloy energy storage cable and its preparation method. Background Technology

[0002] In the current operating environment of energy storage power stations and high-power transmission, energy storage cables, as the core energy transmission carriers, face the harsh working conditions of high current cyclic impact and complex load fluctuations for a long time. In order to ensure the safe and efficient operation of the system, the copper alloy conductors in the cable need to have excellent mechanical load-bearing capacity, high power transmission efficiency and structural stability at high temperature.

[0003] To meet the aforementioned application requirements, existing conductor modification schemes generally employ traditional copper alloying processes or simple physical mixing of nanomaterials to improve overall performance. While these schemes can improve the initial tensile strength of materials to some extent, the traditional metal alloying mechanism inevitably increases the sources of electron scattering within and at grain boundaries, leading to a significant decrease in conductivity and making it difficult to overcome the technical bottleneck of the contradiction between strong and weak conductivity in metallic materials. In addition, conventionally added nano-reinforcers are prone to secondary agglomeration in high-temperature molten metals, and nanoscale micropores are commonly present between them and the copper matrix, exhibiting a typical mechanical debonding state. This interface defect not only fails to provide effective high-strength skeleton support for the metal but also further induces severe interface electron scattering, making the cable prone to stress relaxation and creep fracture under long-term stress and thermal cycling conditions, making it difficult to meet the comprehensive requirements of dense deployment and high-temperature operation of modern energy storage devices.

[0004] Therefore, how to effectively eliminate the microscopic defects at the interface between the reinforcement and the metal matrix and solve the problem of easy agglomeration of nanoparticles, so as to significantly improve the tensile strength and heat resistance of copper alloy cables without sacrificing conductivity, and achieve a synergistic combination of high strength, high conductivity and excellent stress relaxation resistance, has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength, high-conductivity copper alloy energy storage cable and its preparation method, so as to solve the problems mentioned in the background art. Specifically, the technical solution of this invention is as follows:

[0006] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0007] The conductor core, insulation layer, flame-retardant armor layer, and weather-resistant sheath layer are arranged sequentially from the inside out.

[0008] The conductor core is made of multiple copper alloy single wires twisted together, and the copper alloy single wire includes a copper matrix and a multifunctional composite modifier uniformly dispersed inside the copper matrix.

[0009] The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a silver conductive transition shell layer covering the surface of the multi-walled carbon nanotube central core, and a rare earth anchoring phase distributed on the outside of the silver conductive transition shell layer and at the grain boundaries of the copper matrix.

[0010] The thickness of the silver conductive transition shell is 5-15 nm; the rare earth anchoring phase contains lanthanum or cerium.

[0011] The multifunctional composite modifier is obtained by combining multifunctional composite modified intermediate particles with copper melt and then molding the mixture. The multifunctional composite modified intermediate particles are obtained by the following steps:

[0012] A1. Multi-walled carbon nanotubes are added to a mixture of concentrated nitric acid and concentrated sulfuric acid, and refluxed at 80°C for 4-6 hours. After centrifugation and washing until neutral, the nanotubes are dried under vacuum to obtain activated nanonuclei. The volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:3.

[0013] A2. The activated nanonuclei are ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone, and a silver ammonia solution with a concentration of 0.1-0.5 mol / L is added dropwise, followed by an ascorbic acid solution with a concentration of 0.1-0.5 mol / L. The mass ratio of the activated nanonuclei, silver ammonia solution and ascorbic acid solution is 1:(10-20):(5-15). The mixture is reacted at room temperature for 2 hours, filtered, washed and vacuum dried to obtain the composite powder.

[0014] A3. The composite powder is mixed with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), and stearic acid accounting for 1%-3% of the total mass of the mixture is added. The mixture is then subjected to high-energy ball milling under argon protection to obtain the multifunctional composite modified intermediate particles.

[0015] Preferably, the mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%.

[0016] Preferably, in step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%.

[0017] Preferably, the insulating layer is a cross-linked polyethylene insulating layer.

[0018] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0019] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared.

[0020] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. The multifunctional composite modified intermediate particles are added to the copper melt by cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0021] S3. Cable forming: Multiple copper alloy single wires are stranded to form a conductor core, and then an insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to obtain a high-strength, high-conductivity copper alloy energy storage cable.

[0022] Preferably, in step S2, the protective gas is a vacuum or high-purity argon.

[0023] Preferably, in step S2, the step of the stepped aging treatment is as follows: keep at 350°C for 2 hours, then raise the temperature to 450°C and keep at that temperature for 1 hour.

[0024] Compared with existing technologies, the high-strength, high-conductivity copper alloy energy storage cable of the present invention has a core-shell structure in its multifunctional composite modifier, which consists of a multi-walled carbon nanotube central core and a 5-15nm thick silver conductive transition shell. The multi-walled carbon nanotube central core provides strong physical reinforcement support inside the copper matrix, effectively hindering dislocation movement and overcoming the defects of insufficient strength in traditional pure copper and conventional alloying mechanisms. At the same time, the 5-15nm thick silver conductive transition shell can form a good bond with the copper matrix, wrapping around the surface of the central core and improving the microscopic interface state between the multi-walled carbon nanotube and the metal matrix. This structure effectively bridges the electron transport channel and reduces interfacial electron scattering, thereby significantly increasing the tensile strength of the material without sacrificing conductivity, successfully breaking through the technical bottleneck of strong conduction repulsion in traditional metal materials.

[0025] 2. Addressing the technical drawback of traditional nano-reinforcements easily undergoing secondary agglomeration in molten metal, this invention achieves uniform dispersion of the modifier through a unique process design. In preparing the multifunctional composite modified intermediate particles, a high-energy ball milling process incorporating stearic acid and copper-rare earth intermediate alloy powder is introduced. Utilizing the surface activity and steric hindrance effect of stearic acid, the agglomeration of nanomaterials is successfully broken, achieving uniform refinement of the composite powder. Under a protective gas atmosphere, the modifier is added to high-purity oxygen-free copper heated to molten 1150-1200℃ using either a cored wire feeding method or a carrier gas deep-layer blowing method. This deep-layer wetting composite method not only avoids localized thermal stress concentration and high-temperature burn-off and floating of the modifier but also ensures uniform dispersion of the multifunctional composite particles within the copper matrix, guaranteeing a high degree of consistency in the macroscopic mechanical and electrical properties of long cables. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0027] Example 1:

[0028] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0029] The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt. The multifunctional composite modified intermediate particles are prepared through the following steps:

[0030] A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei.

[0031] A2. The activated nanonuclei were ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone. Silver ammonia solution and ascorbic acid solution, both with a concentration of 0.1-0.5 mol / L, were added dropwise. The mass ratio of activated nanonuclei, silver ammonia solution and ascorbic acid solution was 1:(10-20):(5-15). The mixture was reacted at room temperature for 2 hours. The mixture was then filtered, washed and vacuum dried to obtain the composite powder.

[0032] A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain multifunctional composite modified intermediate particles.

[0033] In this embodiment, a preferred embodiment of a high-strength, high-conductivity copper alloy energy storage cable is provided. The multifunctional composite modifier is not a conventional single physical mixture reinforcement, but a composite structure integrating a high-strength skeleton, an electron transport bridging layer, and grain boundary segregation phases. For the silver conductive transition shell, its thickness is specifically selected as 5nm. This specific thickness is at a low level, which can provide a basic electron tunneling effect, eliminate interfacial micropores, achieve metallurgical coherent bonding, and thus significantly reduce interfacial electron scattering.

[0034] During the processing of step A1, the time for reflux treatment of multi-walled carbon nanotubes in the mixed solution is precisely controlled to 4 hours. This operation aims to moderately activate the surface of multi-walled carbon nanotubes, introducing oxygen-containing functional groups while preserving the integrity of their core structure. The volume ratio of concentrated nitric acid to concentrated sulfuric acid is fixed at 1:3 and the reflux temperature is set at 80°C. This specific combination of acid ratio and temperature can precisely control the oxidation potential of the mixed acid, which can fully etch active anchor points such as carboxyl and hydroxyl groups on the surface of carbon nanotubes, while effectively avoiding excessive cutting and amorphization of the tube wall structure, thus ensuring its mechanical properties as a high-strength framework.

[0035] In the reaction system of step A2, the concentrations of both the silver ammonia solution and the ascorbic acid solution are set to 0.1 mol / L. The 0.1 mol / L silver ammonia solution is prepared on-site. The specific preparation steps are as follows: take a 0.1 mol / L silver nitrate aqueous solution, add 3% dilute ammonia water dropwise under stirring until the initially formed brown precipitate is just completely dissolved, and transfer it to a volumetric flask and make up to volume to obtain a silver ammonia solution with a concentration of 0.1 mol / L based on silver ions.

[0036] Furthermore, the preferred mass ratio of activated nanonuclei, silver ammonia solution, and ascorbic acid solution is 1:10:5. By constructing a low-concentration reduction system and controlling the reaction time to 2 hours at room temperature, this fixed room temperature reaction time of 2 hours effectively matches the reaction kinetics of the reduction system, inducing slow nucleation and two-dimensional epitaxial growth of silver atoms at the active sites on the surface of carbon nanotubes. This avoids incomplete coverage due to insufficient time or three-dimensional island-like aggregation of silver particles caused by excessive time, ensuring that the in-situ constructed silver shell is uniform, dense, and free of aggregation defects.

[0037] In the composite stage of step A3, the mass ratio of composite powder to copper-rare earth intermediate alloy powder is selected as 1:5, and stearic acid accounting for 1% of the total mass of the mixture is added; the high-energy ball milling process utilizes the surface activity and steric hindrance effect of stearic acid to effectively prevent the secondary agglomeration of nanoparticles and realize the potential for uniform dispersion of multifunctional composite modified intermediate particles in the subsequent melt.

[0038] The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%;

[0039] In this embodiment, the rare earth anchoring phase specifically uses lanthanum, and its mass percentage in the copper alloy single wire is strictly controlled to be 0.01%. This low content design ensures that the matrix is ​​purified by reacting with the rare earth elements and impurities, while minimizing the interference of the precipitated phase on the electron transport channel, thereby enabling the energy storage cable to maintain a high conductivity in conventional charging and discharging scenarios.

[0040] In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%;

[0041] In this embodiment, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is set to 1%; an appropriate amount of rare earth elements are segregated around the grain boundaries of the copper matrix and the nanonuclei, providing a basic dislocation pinning effect during the solidification stage, thereby improving the initial tensile strength and structural stiffness of the conductor core.

[0042] The insulation layer is a cross-linked polyethylene insulation layer;

[0043] In this embodiment, cross-linked polyethylene is used as the insulation layer, which has excellent electrical insulation properties and heat aging resistance. It can work synergistically with the high-strength and high-conductivity conductor core to alleviate fatigue damage caused by thermal expansion and contraction stress and ensure the safe operation of the energy storage cable under long-term thermal cycling conditions.

[0044] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0045] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared according to the above method.

[0046] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. Multifunctional composite modified intermediate particles are added to the copper melt through cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0047] S3. Cable forming: Multiple copper alloy single wires are twisted together to form a conductor core. An insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to produce a high-strength, high-conductivity copper alloy energy storage cable.

[0048] In the preparation method of this embodiment, for the smelting process in step S2, the heating temperature is precisely controlled at 1150°C, and the multifunctional composite modified intermediate particles are added to the copper melt by the cored wire feeding method. The lower melting temperature combined with the cored wire feeding method can effectively avoid the burning and floating of the multifunctional composite modified intermediate particles in the high-temperature melt, ensuring that they are fully wetted and uniformly captured by the copper melt, thereby forming an oriented array and coherent interface inside the metal matrix, completing the phase transformation process from physical mixing to metallurgical bonding.

[0049] In step S2, the protective gas is a vacuum or high-purity argon.

[0050] In this embodiment, the protective environment for step S2 is selected as vacuum conditions; the vacuum environment can isolate oxygen and water vapor, prevent secondary oxidation of high-purity oxygen-free copper during the smelting process, and promote the escape of tiny bubbles inside the melt, further improving the density and purity of the composite melt.

[0051] In step S2, the steps of the stepped aging treatment are as follows: hold at 350℃ for 2 hours, raise the temperature to 450℃, and hold for 1 hour.

[0052] In this embodiment, the stepped aging treatment strictly follows the above temperature and time parameters; holding at 350°C for 2 hours utilizes the thermal hysteresis effect to induce the release of micro-stress and the annihilation of point defects inside the copper matrix; rapidly heating to 450°C and holding for 1 hour promotes sufficient segregation and precipitation of rare earth anchoring phases at grain boundaries; this cascade mechanism not only enhances the dislocation pinning effect but also significantly repairs the lattice distortion introduced by cold drawing, ultimately exhibiting good conductivity and basic tensile strength in the conventional charging and discharging scenarios of energy storage power stations.

[0053] Example 2:

[0054] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0055] The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt. The multifunctional composite modified intermediate particles are prepared through the following steps:

[0056] A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei.

[0057] A2. The activated nanonuclei were ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone. Silver ammonia solution and ascorbic acid solution, both with a concentration of 0.1-0.5 mol / L, were added dropwise. The mass ratio of activated nanonuclei, silver ammonia solution and ascorbic acid solution was 1:(10-20):(5-15). The mixture was reacted at room temperature for 2 hours. The mixture was then filtered, washed and vacuum dried to obtain the composite powder.

[0058] A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain multifunctional composite modified intermediate particles.

[0059] In this embodiment, the thickness of the silver conductive transition shell is specifically selected as 10 nm. This moderate thickness forms a stable metallurgical coherent bond with the multi-walled carbon nanotube core and the copper matrix, significantly reducing interfacial micro-defects. During the processing of step A1, the reflow treatment time is controlled to be 5 h, which provides richer surface bonding sites for the carbon nanotube surface.

[0060] In the reaction system of step A2, the concentrations of both the silver ammonia solution and the ascorbic acid solution are set to 0.3 mol / L. The 0.3 mol / L silver ammonia solution is prepared on-site. The specific preparation steps are as follows: take a 0.3 mol / L silver nitrate aqueous solution, add 4% dilute ammonia water dropwise under stirring until the initially formed brown precipitate is just completely dissolved, and transfer it to a volumetric flask and make up to volume to obtain a silver ammonia solution with a concentration of 0.3 mol / L based on silver ions.

[0061] Furthermore, the mass ratio of activated nanonuclei, silver ammonia solution, and ascorbic acid solution was 1:15:10; by increasing the precursor concentration, the deposition rate of silver atoms was accelerated, forming a continuous and dense transition shell; in the composite stage of step A3, the mass ratio of composite powder to copper-rare earth intermediate alloy powder was selected as 1:7.5, and stearic acid accounting for 2% of the total mass of the mixture was added; the appropriate increase of stearic acid provided the best steric hindrance balance during the ball milling process, ensuring the uniform refinement of the powder;

[0062] The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%;

[0063] In this embodiment, the rare earth anchoring phase specifically uses cerium, and its mass percentage in the copper alloy single wire is controlled at 0.08%; this moderate content forms uniform dislocation pinning points inside the matrix, effectively improving the overall yield strength of the material.

[0064] In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%;

[0065] In this embodiment, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is set to 2%; this ratio ensures sufficient segregation driving force during the crystallization process, enabling rare earth elements to be precisely anchored at the grain boundaries.

[0066] The insulation layer is a cross-linked polyethylene insulation layer;

[0067] In this embodiment, cross-linked polyethylene is used as the insulation layer, utilizing its stable molecular chain structure to provide durable electrical and mechanical protection for the conductor core;

[0068] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0069] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared according to the above method.

[0070] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. Multifunctional composite modified intermediate particles are added to the copper melt through cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0071] S3. Cable forming: Multiple copper alloy single wires are twisted together to form a conductor core. An insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to produce a high-strength, high-conductivity copper alloy energy storage cable.

[0072] In the preparation method of this embodiment, for the melting process in step S2, the heating temperature is controlled at 1175°C, and the multifunctional composite modified intermediate particles are added to the copper melt by carrier gas deep blowing method; the higher temperature combined with the deep blowing method effectively depolymerizes potential agglomerates by using the kinetic energy of carrier gas, thereby achieving deep wetting and three-dimensional dispersion distribution of the modifier in the copper melt.

[0073] In step S2, the protective gas is a vacuum or high-purity argon.

[0074] In this embodiment, the protective environment for step S2 is selected as high-purity argon gas; the inert gas atmosphere effectively avoids the burning loss of alloying elements during the melting process and maintains the precise stability of the melt composition.

[0075] In step S2, the steps of the stepped aging treatment are as follows: hold at 350℃ for 2 hours, raise the temperature to 450℃, and hold for 1 hour.

[0076] In this embodiment, the stepped aging treatment strictly follows the above temperature and time parameters; through the appropriate silver layer thickness and the introduction of cerium, this embodiment enables the high-strength, high-conductivity copper alloy energy storage cable to maintain high conductivity while providing excellent tensile strength and stress relaxation resistance in the high-current cyclic impact scenario of energy storage power station, thus verifying the robustness of this technical solution under different formulations.

[0077] Example 3:

[0078] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0079] The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt. The multifunctional composite modified intermediate particles are prepared through the following steps:

[0080] A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei.

[0081] A2. The activated nanonuclei were ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone. Silver ammonia solution and ascorbic acid solution, both with a concentration of 0.1-0.5 mol / L, were added dropwise. The mass ratio of activated nanonuclei, silver ammonia solution and ascorbic acid solution was 1:(10-20):(5-15). The mixture was reacted at room temperature for 2 hours. The mixture was then filtered, washed and vacuum dried to obtain the composite powder.

[0082] A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain multifunctional composite modified intermediate particles.

[0083] In this embodiment, the thickness of the silver conductive transition shell is specifically selected to be 15 nm; the thicker shell provides sufficient interfacial wettability and eliminates interfacial electron scattering sources; during the processing of step A1, the reflow treatment time is extended to 6 h, which aims to deeply activate the carbon nanotubes.

[0084] In the reaction system of step A2, the concentrations of both the silver ammonia solution and the ascorbic acid solution were set to 0.5 mol / L. The 0.5 mol / L silver ammonia solution was prepared on-site. The specific preparation steps were as follows: Take a 0.5 mol / L silver nitrate aqueous solution, and add 5% (w / w) dilute ammonia solution dropwise while stirring until the initially formed brown precipitate is completely dissolved. Transfer the solution to a volumetric flask and dilute to volume to obtain a silver ammonia solution with a concentration of 0.5 mol / L based on silver ions. The mass ratio of activated nanonuclei, silver ammonia solution, and ascorbic acid solution was 1:20:15. The high concentration of precursors promoted rapid nucleation of silver atoms and the growth of a thicker coating layer.

[0085] In the composite stage of step A3, the mass ratio of the composite powder to the copper-rare earth intermediate alloy powder is selected as 1:10, and stearic acid accounting for 3% of the total mass of the mixture is added; the high proportion of stearic acid is specifically used to deal with the agglomeration tendency of high-concentration powder systems and ensure the ball milling effect.

[0086] The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%;

[0087] In this embodiment, the rare earth anchoring phase specifically uses lanthanum, and its mass percentage in the copper alloy single wire is controlled at 0.15%. The high content of lanthanum brings about a strong grain boundary segregation effect, which greatly enhances the anti-slip ability of the grain boundaries.

[0088] In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%;

[0089] In this embodiment, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is set to 3%; the high concentration of rare earth source provides a sufficient material basis for subsequent phase transformation and segregation.

[0090] The insulation layer is a cross-linked polyethylene insulation layer;

[0091] In this embodiment, cross-linked polyethylene is used as the insulation layer to meet the insulation requirements under high-temperature operating conditions;

[0092] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0093] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared according to the above method.

[0094] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. Multifunctional composite modified intermediate particles are added to the copper melt through cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0095] S3. Cable forming: Multiple copper alloy single wires are twisted together to form a conductor core. An insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to produce a high-strength, high-conductivity copper alloy energy storage cable.

[0096] In the preparation method of this embodiment, for the melting process in step S2, the heating temperature is controlled at 1200℃, and the multifunctional composite modified intermediate particles are added to the copper melt by the cored wire feeding method; the high temperature of 1200℃ gives the melt extremely low viscosity, accelerates the interfacial diffusion and coherent bonding of atoms, and the cored wire feeding method ensures the precise addition of high concentration of modifier.

[0097] In step S2, the protective gas is a vacuum or high-purity argon.

[0098] In this embodiment, the protective environment for step S2 is selected as a vacuum condition to minimize the interference of impurity gases.

[0099] In step S2, the steps of the stepped aging treatment are as follows: hold at 350℃ for 2 hours, raise the temperature to 450℃, and hold for 1 hour.

[0100] In this embodiment, the stepped aging treatment strictly follows the above temperature and time parameters; this embodiment adopts a high raw material ratio and process parameters, which is particularly suitable for dense wiring and high-temperature operation conditions of energy storage power stations, exhibiting outstanding yield strength and heat resistance stability, and effectively preventing creep fracture under long-term stress.

[0101] Example 4:

[0102] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0103] The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt. The multifunctional composite modified intermediate particles are prepared through the following steps:

[0104] A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei.

[0105] A2. The activated nanonuclei were ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone. Silver ammonia solution and ascorbic acid solution, both with a concentration of 0.1-0.5 mol / L, were added dropwise. The mass ratio of activated nanonuclei, silver ammonia solution and ascorbic acid solution was 1:(10-20):(5-15). The mixture was reacted at room temperature for 2 hours. The mixture was then filtered, washed and vacuum dried to obtain the composite powder.

[0106] A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain multifunctional composite modified intermediate particles.

[0107] In this embodiment, the thickness of the silver conductive transition shell is specifically selected as 7 nm; this thickness achieves a good balance between microstructure and electrical performance while ensuring the electron tunneling effect; during the processing in step A1, the reflow treatment time is controlled at 4.5 h; in the reaction system of step A2, the concentrations of both silver ammonia solution and ascorbic acid solution are set to 0.2 mol / L, and the mass ratio of activated nanonuclei, silver ammonia solution, and ascorbic acid solution is 1:12:7; in the composite stage of step A3, the mass ratio of composite powder to copper-rare earth intermediate alloy powder is selected as 1:6, and stearic acid accounting for 1.5% of the total mass of the mixture is added; this ratio achieves a good balance between powder refinement and surface activity;

[0108] The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%;

[0109] In this embodiment, the rare earth anchoring phase specifically uses cerium, and its mass percentage in the copper alloy single wire is controlled at 0.04%; this trace addition not only purifies the matrix but also provides a moderate strengthening effect.

[0110] In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%;

[0111] In this embodiment, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is set to 1.5%;

[0112] The insulation layer is a cross-linked polyethylene insulation layer;

[0113] In this embodiment, cross-linked polyethylene is used as the insulation layer to maintain basic electrical insulation performance;

[0114] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0115] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared according to the above method.

[0116] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. Multifunctional composite modified intermediate particles are added to the copper melt through cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0117] S3. Cable forming: Multiple copper alloy single wires are twisted together to form a conductor core. An insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to produce a high-strength, high-conductivity copper alloy energy storage cable.

[0118] In the preparation method of this embodiment, for the melting process in step S2, the heating temperature is controlled at 1160°C, and the multifunctional composite modified intermediate particles are added to the copper melt by carrier gas deep blowing method; the mild melting conditions combined with carrier gas blowing effectively disperse the modified particles and avoid local thermal stress concentration.

[0119] In step S2, the protective gas is a vacuum or high-purity argon.

[0120] In this embodiment, the protective environment for step S2 is selected as high-purity argon gas.

[0121] In step S2, the steps of the stepped aging treatment are as follows: hold at 350℃ for 2 hours, raise the temperature to 450℃, and hold for 1 hour.

[0122] In this embodiment, the stepped aging treatment strictly follows the above temperature and time parameters; this embodiment demonstrates the process adaptability under the condition of fine adjustment of raw material ratio. The synergistic cooperation between the silver conductive transition shell and the rare earth anchoring phase enables the cable to achieve an excellent balance in terms of mechanical fatigue life and Joule heat loss control under normal environment.

[0123] Example 5:

[0124] A high-strength, high-conductivity copper alloy energy storage cable, comprising:

[0125] The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt. The multifunctional composite modified intermediate particles are prepared through the following steps:

[0126] A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei.

[0127] A2. The activated nanonuclei were ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone. Silver ammonia solution and ascorbic acid solution, both with a concentration of 0.1-0.5 mol / L, were added dropwise. The mass ratio of activated nanonuclei, silver ammonia solution and ascorbic acid solution was 1:(10-20):(5-15). The mixture was reacted at room temperature for 2 hours. The mixture was then filtered, washed and vacuum dried to obtain the composite powder.

[0128] A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain multifunctional composite modified intermediate particles.

[0129] In this embodiment, the thickness of the silver conductive transition shell is specifically selected to be 13 nm; this relatively thick shell structure further enhances the connectivity of the electron transport bridging layer; during the processing of step A1, the reflux treatment time is controlled to be 5.5 h; in the reaction system of step A2, the concentrations of both the silver ammonia solution and the ascorbic acid solution are set to 0.4 mol / L, and the mass ratio of the activated nanonucleus, the silver ammonia solution, and the ascorbic acid solution is 1:18:13;

[0130] In the composite stage of step A3, the mass ratio of the composite powder to the copper-rare earth intermediate alloy powder was selected as 1:9, and stearic acid accounting for 2.5% of the total mass of the mixture was added; this parameter combination was intended to explore the encapsulation and dispersion effect under a high wall material ratio.

[0131] The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%;

[0132] In this embodiment, the rare earth anchoring phase specifically uses lanthanum, and its mass percentage in the copper alloy single wire is controlled at 0.12%; the high content of lanthanum forms a continuous segregated phase at the grain boundaries;

[0133] In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%;

[0134] In this embodiment, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is set to 2.5%;

[0135] The insulation layer is a cross-linked polyethylene insulation layer;

[0136] In this embodiment, cross-linked polyethylene is used as the insulation layer to provide reliable external protection;

[0137] A method for preparing a high-strength, high-conductivity copper alloy energy storage cable includes the following steps:

[0138] S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles were prepared according to the above method.

[0139] S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. Multifunctional composite modified intermediate particles are added to the copper melt through cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire.

[0140] S3. Cable forming: Multiple copper alloy single wires are twisted together to form a conductor core. An insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to produce a high-strength, high-conductivity copper alloy energy storage cable.

[0141] In the preparation method of this embodiment, for the melting process in step S2, the heating temperature is controlled at 1190°C, and the multifunctional composite modified intermediate particles are added to the copper melt by the cored wire feeding method; the higher melting temperature promotes the rapid interdiffusion of the thick shell layer and the matrix atoms.

[0142] In step S2, the protective gas is a vacuum or high-purity argon.

[0143] In this embodiment, the protective environment for step S2 is selected as a vacuum condition;

[0144] In step S2, the steps of the stepped aging treatment are as follows: hold at 350℃ for 2 hours, raise the temperature to 450℃, and hold for 1 hour.

[0145] In this embodiment, the stepped aging treatment strictly follows the above temperature and time parameters; this embodiment, with a higher silver layer thickness and a higher rare earth content, shows that the synergistic effect of multiple functional groups effectively prevents local agglomeration caused by excessive modifiers, and exhibits stable structural stiffness and low resistance characteristics when dealing with complex load fluctuations in energy storage power stations.

[0146] Comparative Example 1:

[0147] This comparative example uses the same raw material formulation and process parameters as Example 2, but the copper alloy single wire does not contain a multi-walled carbon nanotube central core and a silver conductive transition shell during the preparation process. It is prepared using only the traditional copper-rare earth alloy process. This represents the traditional copper alloy conductor processing method, which lacks the interfacial electron transport bridging and high-strength skeleton support process of the multifunctional composite modifier. It serves as a blank control to compare and verify the role of the core core-shell structure of this invention.

[0148] Comparative Example 2:

[0149] This comparative example uses the same raw material formulation and preparation steps as Example 2, the only difference being that the multifunctional composite modifier does not contain a silver conductive transition shell; specifically, acid-treated multi-walled carbon nanotubes are directly mixed with copper-rare earth intermediate alloy powder to prepare the product, without performing the in-situ construction of the silver shell in step A2; this comparative example aims to verify the necessity of the silver conductive transition shell in eliminating interfacial micropores and reducing electron scattering.

[0150] Comparative Example 3:

[0151] This comparative example uses the same raw material formulation as Example 2, but the multifunctional composite modifier does not contain rare earth anchoring phase during the manufacturing process; silver atoms are tightly fused with the copper matrix in the microscopic state; this comparative example is used to verify the role of rare earth anchoring phase in segregating at grain boundaries and providing dislocation pinning effect, as well as its contribution to thermal stability.

[0152] Comparative Example 4:

[0153] This comparative example uses the same raw material formulation and pretreatment process as Example 2, but omits the high-energy ball milling step in step A3. Instead, the composite powder and copper-rare earth intermediate alloy powder are simply physically mixed and then added to the copper melt. This comparative example is used to verify the indispensability of the high-energy ball milling process in overcoming the agglomeration defects of nanomaterials and achieving uniform dispersion of the modifier within the copper matrix. In addition, comparative examples 5 and 6 are set up to verify the boundaries of the core process parameters. Comparative example 5 uses the same raw material formulation and preparation steps as Example 2, except that in step A1, the reflux temperature is set to 95°C and the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:1. Comparative example 6 uses the same raw material formulation and preparation steps as Example 2, except that in step A2, the room temperature reaction time is shortened to 1 hour.

[0154] Verification experiment:

[0155] To further demonstrate the feasibility of the multifunctional composite modifier of this invention in eliminating interfacial micropores and reducing electron scattering, a verification experiment was set up to measure the interfacial bonding state and electron tunneling effect between the copper matrix and the central core of the multi-walled carbon nanotube. The experiment used high-resolution transmission electron microscopy to observe the single-line cross-sections prepared under different processes. In the comparative sample without the addition of a silver conductive transition shell, there were obvious nanoscale pores at the interface between the carbon nanotube and the copper matrix, and the interfacial wetting angle was greater than 120 degrees, indicating that the two exhibited a typical mechanical debonding state.

[0156] In the smelting system of this invention, after constructing a 5 to 15 nm silver conductive transition shell in situ in step A2, the silver atoms and the copper matrix are tightly fused in the microscopic state, and the microscopic pores at the interface are completely filled, forming a dense metallurgical coherent bond, and the interface wetting angle is reduced to close to 0 degrees. This fully demonstrates that the silver conductive transition shell successfully bridges the originally broken electron transport channel. Through the core-shell structure design, this invention successfully reduces the interface electron scattering cross section by about 40%, which is sufficient to support the high-strength and high-conductivity copper alloy energy storage cable to maintain extremely high conductivity under complex working conditions without sacrificing mechanical strength.

[0157] Testing standards:

[0158] Tensile strength was determined using a computer-controlled electronic universal testing machine at a tensile speed of 2 mm / min and room temperature, in accordance with standard GB / T228.1. Conductivity was determined using a four-probe resistivity meter at a constant temperature of 20℃, and the results were converted to the international standard percentage for annealed copper. Stress relaxation rate was determined using a high-temperature stress relaxation tester at 150℃ for 1000 hours, with the initial stress set at 80% of the yield strength. Each sample was tested in parallel five times, and the average value was taken after removing the maximum and minimum values ​​to eliminate data deviation caused by random errors.

[0159] Specific testing process:

[0160] Accurately cut 500mm length copper alloy single-wire samples from each group, ultrasonically clean the surface oil with anhydrous ethanol, and then dry. Fix both ends of the sample in the fixture of a universal testing machine, apply axial tensile load until fracture, record the maximum tensile force, and calculate the tensile strength. Cut 1000mm length samples and connect them to the test fixture of a four-probe resistivity meter, apply a constant DC current and measure the voltage drop, calculate the volume resistivity and convert it to conductivity. Place the samples in a 150℃ high-temperature environment chamber, apply an initial preload, continuously monitor the stress decay over 1000 hours, and calculate the stress relaxation rate. All data are acquired and statistically processed in real time through built-in software. The communication interface for data acquisition in the built-in software adopts the RS-485 industrial protocol, and the sampling frequency is fixed at 10Hz. Its statistical processing specifically includes a moving average filtering algorithm for high-frequency oscillation noise, and its discretization processing logic is as follows:

[0161]

[0162] in, For the first Output of smoothed stress data after filtering at each sampling point For the sensor to collect data in real time Input the original stress data of each sampling point. The set sliding window size, This is the discrete-time index of the current sampling point. For local summation index within the sliding window;

[0163] The subsequent calculation logic for the average value after removing the maximum and minimum values ​​is as follows:

[0164]

[0165] in, This is the final average value after removing extreme values. This represents the total number of parallel tests. For the first The specific data results of the parallel tests. For testing batch indexing, and These represent the maximum and minimum values ​​in the sample set, respectively. To ensure that the mass percentage of rare earth elements in the final copper alloy single wire is controlled within the range of 0.01% to 0.15%, the mass ratio of the multifunctional composite modified intermediate particles to the copper melt must be strictly controlled during the smelting and compounding process in step S2. This mass ratio must satisfy the following formula relationship:

[0166] Intermediate intermediate W RE =m 中间体 ×P RE中间体 +m Cu ×100%

[0167] Among them, W RE m represents the mass percentage of rare earth elements in the final copper alloy single wire. 中间体 P represents the total mass of the added multifunctional composite modified intermediate particles. RE m represents the mass fraction of rare earth elements in the intermediate particles. Cu This refers to the mass of the copper melt.

[0168] Table 1 Performance test data of Examples 1-5 and Comparative Examples 1-6

[0169]

[0170] As shown in Table 1, the high-strength, high-conductivity copper alloy energy storage cables prepared in Examples 1 to 5 all achieved an excellent balance between tensile strength and conductivity, and possessed outstanding heat resistance stability. With the change in the thickness of the silver conductive transition shell and the content of rare earth elements, the various performance indicators showed a regular evolution. Comparing Example 2 and Comparative Example 1, it can be seen that after introducing the multifunctional composite modifier, the tensile strength significantly increased from 450 MPa to 620 MPa. This indicates that the multi-walled carbon nanotube core constructs a high-strength skeleton inside the copper matrix, and its physical strengthening and support effectively hinders dislocation movement, solving the problem of insufficient strength in traditional copper alloys.

[0171] Compared with Comparative Example 2, the conductivity of the present invention, due to the presence of a silver conductive transition shell, jumped significantly from 85.2% to 97.5%. This confirms that the shell has a significant synergistic effect in eliminating interfacial micropores and reducing electron scattering, constructing a continuous electron tunneling channel at the molecular level and achieving efficient electron transport. Compared with Comparative Example 3, under long-term high-temperature conditions at 150°C, the stress relaxation rate of the sample with rare earth anchoring phase decreased significantly from 9.2% to 3.5%, highlighting the key contribution of rare earth element segregation and dislocation pinning at grain boundaries to thermal stability, effectively preventing grain boundary sliding and creep fracture under long-term stress.

[0172] Compared with Comparative Example 4, the sample using high-energy ball milling process showed better performance in all aspects, indicating that the kinetic processing method effectively solved the technical problem of easy agglomeration of nanomaterials in metal melt and ensured the uniform dispersion of the modifier in the copper matrix. In addition, compared with Comparative Example 5, it can be seen that when the reflux temperature in step A1 is too high and the proportion of nitric acid is too large, the tensile strength drops sharply from 620 MPa to 485 MPa. This verifies that deviating from the specific acid ratio and temperature will cause serious damage to the carbon nanotube skeleton, causing it to lose its mechanical load-bearing capacity as a high-strength skeleton.

[0173] Comparing Example 2 and Comparative Example 6, it can be seen that when the reaction time in step A2 is shortened to 1 hour, the conductivity drops significantly from 97.5% to 88.5%. This confirms that insufficient reaction time leads to incomplete coating of the silver conductive transition shell, and the exposed carbon matrix causes severe interfacial electron scattering, resulting in performance degradation. The above experimental data verifies the rationality of the core process parameter settings of the present invention. The various technical features of the present invention together break through the technical bottleneck of the contradiction between strong conductivity and high conductivity in traditional copper alloy conductors.

[0174] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-strength, high-conductivity copper alloy energy storage cable, characterized in that, include: The structure comprises, from the inside out, a conductor core, an insulating layer, a flame-retardant armor layer, and a weather-resistant sheath layer. The conductor core is composed of multiple stranded copper alloy wires, each wire comprising a copper matrix and a multifunctional composite modifier uniformly dispersed within the copper matrix. The multifunctional composite modifier has a core-shell structure, comprising a multi-walled carbon nanotube central core, a 5-15 nm thick silver conductive transition shell coating the surface of the central core, and a rare-earth anchoring phase containing lanthanum or cerium distributed on the outer side of the shell and at the grain boundaries of the copper matrix. The multifunctional composite modifier is obtained by compounding multifunctional composite modified intermediate particles with copper melt, and the multifunctional composite modified intermediate particles are prepared through the following steps: A1. Add multi-walled carbon nanotubes to a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, reflux at 80°C for 4-6 hours, centrifuge and wash until neutral, and vacuum dry to obtain activated nanonuclei. A2. The activated nanonuclei are ultrasonically dispersed in an aqueous solution containing polyvinylpyrrolidone, and silver ammonia solution and ascorbic acid solution with a concentration of 0.1-0.5 mol / L are added dropwise in sequence. The mass ratio of the activated nanonuclei, silver ammonia solution and ascorbic acid solution is 1:(10-20):(5-15). The reaction is carried out at room temperature for 2 hours, and the mixture is filtered, washed and vacuum dried to obtain composite powder. A3. Mix the composite powder with copper-rare earth intermediate alloy powder at a mass ratio of 1:(5-10), add 1%-3% stearic acid of the total mass of the mixture, and ball mill under argon protection to obtain the multifunctional composite modified intermediate particles.

2. The high-strength, high-conductivity copper alloy energy storage cable according to claim 1, characterized in that, The mass percentage of lanthanum or cerium in the rare earth anchoring phase in the copper alloy single wire is 0.01%-0.15%.

3. The high-strength, high-conductivity copper alloy energy storage cable according to claim 1, characterized in that, In step A3, the mass fraction of rare earth elements in the copper-rare earth master alloy powder is 1%-3%.

4. The high-strength, high-conductivity copper alloy energy storage cable according to claim 1, characterized in that, The insulation layer is a cross-linked polyethylene insulation layer.

5. A method for preparing a high-strength, high-conductivity copper alloy energy storage cable as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of multifunctional composite modified intermediate particles: Multifunctional composite modified intermediate particles are prepared according to the steps described in claim 1. S2. Preparation of copper alloy single wire: Under protective gas, high-purity oxygen-free copper is heated to 1150-1200℃ to obtain copper melt. The multifunctional composite modified intermediate particles are added to the copper melt by cored wire feeding or carrier gas deep blowing to obtain composite melt. The composite melt is then subjected to continuous casting and rolling, and multiple cold drawing to obtain drawn single wire. The drawn single wire is subjected to step aging treatment to obtain copper alloy single wire. S3. Cable forming: Multiple copper alloy single wires are stranded to form a conductor core, and then an insulation layer, a flame-retardant armor layer and a weather-resistant sheath layer are extruded sequentially on the outside of the conductor core to obtain a high-strength, high-conductivity copper alloy energy storage cable.

6. The preparation method according to claim 5, characterized in that, In step S2, the protective gas is high-purity argon.

7. The preparation method according to claim 5, characterized in that, In step S2, the step of the stepped aging treatment is as follows: keep at 350°C for 2 hours, then raise the temperature to 450°C and keep at that temperature for 1 hour.

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