Preparation method of self-repairing silver nanowire / carbon nanotube composite battery electrode

Abstract

The application discloses a kind of self-repairing type silver nanowire / carbon nanotube composite battery electrode preparation methods, belong to battery electrode material technical field.The method includes: first, silver nanowire surface is coated protective layer, and carbon nanotube surface is loaded nano catalyst;Subsequently, the silver nanowire-carbon nanotube hybrid structure is constructed by combining the two;Finally, by layer-by-layer assembly process, silver nanowire conductive bottom layer, the above-mentioned hybrid structure middle layer and microencapsulated active material surface layer are sequentially formed on the current collector, and the composite electrode is prepared.The electrode prepared by the method can effectively inhibit the formation and expansion of microcracks in the conductive network, relieve the volume change stress during charging and discharging, thereby endowing the electrode with excellent self-repairing ability and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of battery electrode technology, and particularly relates to a method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode. Background Technology

[0002] With the rapid development of new energy vehicles and large-scale energy storage, the demand for high-performance batteries is becoming increasingly urgent. Electrode materials, as a core component of batteries, directly affect their energy density, cycle life, and safety reliability. Currently, to achieve higher energy density, silicon-based, tin-based, and other alloy-type anode materials, as well as high-capacity cathode materials, are widely studied. However, these materials typically undergo drastic volume changes during charge and discharge, leading to the formation and propagation of microcracks within the electrode, disrupting the integrity of the conductive network. This results in problems such as active material shedding and increased interfacial impedance, ultimately causing rapid capacity decay and shortened cycle life. Therefore, effectively suppressing structural damage to electrode materials during cycling and maintaining the long-term stability of the conductive network has become a key challenge for improving battery performance.

[0003] However, this often comes at the cost of electrode compaction density and volumetric energy density, and the pore walls are prone to fracture during long-term cycling, resulting in insufficient structural stability. Therefore, current technologies still struggle to achieve self-repair and long-term stability of the electrode structure during cycling while ensuring high energy density, thus hindering the development and application of next-generation high-energy-density batteries.

[0004] To improve the conductivity and structural stability of electrode materials, conventional methods mainly involve adding conductive agents such as carbon black, carbon nanotubes, and graphite to construct electronic conduction pathways. However, these conductive agents are mostly discrete particles or short-range conductive networks, offering limited buffering capacity against volumetric deformation during cycling and failing to prevent the generation and propagation of microcracks. On the other hand, techniques such as template methods and foaming methods for constructing three-dimensional porous electrode structures can buffer volumetric expansion stress through pores, but this often sacrifices the electrode's compaction density and volumetric energy density. Furthermore, the pore walls are prone to fracture during long-term cycling, resulting in insufficient structural stability. Therefore, current technologies still struggle to achieve self-repair and long-term stability of the electrode structure during cycling while maintaining high energy density, hindering the development and application of next-generation high-energy-density batteries. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode, aiming to solve the technical problem that high-energy-density electrodes develop microcracks due to volume changes during cycling, leading to the destruction of the conductive network and a decrease in cycling stability.

[0006] The objective of this invention can be achieved through the following technical solutions: The specific technical solution is as follows: (1) Disperse silver nanowires in an aqueous solvent to form a dispersion, and then add 0.001-1.5 mol / L of conductive polymer monomer, dopant and interface modifier to the dispersion to form a mixed system, wherein the molar ratio of dopant and interface modifier is 1-100:1. Finally, place the mixed solution in a constant temperature water bath at 30-95℃ and stir to polymerize for 0.02-72 h. Through polymerization, dispersion and coupling, the mixed system undergoes in-situ polymerization reaction to obtain silver nanowires with a protective layer. (2) Carbon nanotubes were placed in an acidic solution with a mass fraction of 0.1-70% and refluxed at 80-100℃ for 0.1-72h. After cooling, they were washed with deionized water until neutral and vacuum dried for 0.1-100h to obtain activated carbon nanotubes. Subsequently, the activated carbon nanotube support was immersed in a solution containing a transition metal precursor with a concentration of 0.0001-1mol / L and ultrasonically treated for 0.02h-100h to adsorb the transition metal precursor onto the surface of the support. Finally, the support with the adsorbed transition metal precursor was transferred to a tube furnace for heat treatment reduction under a hydrogen atmosphere for 0.1h-100h. After cooling, it was washed and dried to obtain a carbon nanotube composite material with transition metal nanocatalytic active components loaded on the surface. (3) The silver nanowires with protective layer obtained in step (1) and the carbon nanotubes loaded with transition metal nanocatalyst obtained in step (2) are mixed at a preset mass ratio and dispersed in an organic solution to form a uniform suspension. The suspension is then placed in a microwave reactor for microwave reaction. The microwave frequency is set to 0.1-100 GHz, the power to 50-3000 W, and the reaction temperature to 60-300 °C. The reaction is continued for 0.01-100 h to obtain a silver nanowire-carbon nanotube hybrid structure.

[0007] (4) The silver nanowires with a protective layer are coated on the surface of the current collector by solution scraping and then subjected to ultraviolet curing treatment. The wavelength of the ultraviolet curing treatment is 254-365nm, the power is 30-300W, and the irradiation time is 0.1-300min. After the bottom layer is cured, the silver nanowire-carbon nanotube hybrid structure is uniformly deposited on the bottom layer surface by spray deposition. The spray pressure of the spray deposition is 0.01-10MPa and the nozzle moving speed is 1-100mm / s. The surface microencapsulated active material is prepared on the middle layer surface by sol-gel method. After drying, a self-healing silver nanowire / carbon nanotube composite battery electrode is obtained.

[0008] The conductive polymer monomer mentioned in step 1 includes at least one of thiophene monomers, pyrrole monomers, or aniline monomers. The molar ratio of the conductive polymer monomer to the dopant is 0.001:1-20.

[0009] The dopant mentioned in step 1 includes at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), poly(2-acrylamide-2-methylpropanesulfonic acid) (PAMPS), polyvinyl sulfonate (PVS), sodium polystyrene sulfonate (PSS), polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), polystyrene sulfonic acid-maleic acid copolymer, and dodecylbenzene sulfonic acid (DBSA).

[0010] The interface modifier mentioned in step 1 includes at least one selected from silane coupling agents, titanate coupling agents, aluminate coupling agents, hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), fatty acid substances, and aliphatic amine substances. The amount of interface modifier added is 0.0001-15 wt% of the total mass of the conductive polymer monomer and dopant.

[0011] The transition metal precursor solution in step 2 is a soluble transition metal salt or an organometallic transition metal compound. The soluble transition metal salt is selected from at least one of nitrates, chlorides, acetates, sulfates, or ammonium complexes. The organometallic transition metal compound includes at least one of metal acetylacetonates, organometallic acid salts, or metal carbonyl compounds.

[0012] The silver nanowire-carbon nanotube composite process in step 3 involves combining silver nanowires and carbon nanotubes at a predetermined mass ratio. The mass ratio of silver nanowires to carbon nanotubes is 0.01:1-1000.

[0013] In step 4, the preparation of surface microencapsulated active material on the middle layer surface using the sol-gel method, followed by drying, yields a self-healing silver nanowire / carbon nanotube composite battery electrode. This process includes: mixing tetraethyl orthosilicate, dopamine, and deionized water to form a capsule wall precursor solution; adding silicon-based anode material and carbon black conductive additive, with a mass ratio of silicon-based anode material to carbon black conductive additive of 5-50:1, and the carbon black conductive additive accounting for 0.05-15 wt% of the total mass of the capsule core; ultrasonically dispersing the solution and then dropping it onto the middle layer surface; reacting for 0.02-100 h to form microencapsulated active material with a particle size of 1-5 μm; and drying the entire structure in a drying oven for 0.1-100 h, allowing the layers to naturally bond through hydrogen bonds and π-π stacking forces, thus obtaining the self-healing silver nanowire / carbon nanotube composite battery electrode.

[0014] This invention constructs a three-dimensional conductive network of "spring-shaped silver nanowires-carbon nanotubes" and combines it with microencapsulated active materials. This enables the electrode to adaptively suppress microcrack propagation and rebuild conductive pathways during cycling, thereby significantly improving the structural stability and cycle life of the electrode while maintaining high energy density. Furthermore, the fabrication method is process-controllable and highly adaptable, providing an effective electrode solution for developing high-energy-density, long-life batteries.

[0015] Compared with the prior art, the present invention has the following advantages: 1. Strong self-healing ability: The spring-like hybrid structure and microencapsulation design enable the electrode to spontaneously repair microcracks when its volume changes, maintaining the integrity of the conductive network.

[0016] 2. Balancing energy density and stability: The three-dimensional continuous conductive network buffers volume expansion while avoiding the sacrifice of electrode compaction density in traditional porous structures.

[0017] 3. Stable multi-level conductive pathways: The hierarchical conductive system constructed by silver nanowires, carbon nanotubes and SuperP significantly enhances electron / ion transport efficiency and interface stability.

[0018] 4. Mature and scalable technology: The processes used (such as blade coating, spray deposition, and sol-gel method) are all suitable for large-scale production and have good industrialization prospects. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the steps of a method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to the present invention.

[0020] Figure 2 This is a high-magnification scanning electron microscope image of carbon nanotubes after dispersion treatment in this invention.

[0021] Figure 3 This is a high-magnification scanning electron microscope image of the silver nanowires in this invention.

[0022] Figure 4 This is a high-magnification scanning electron microscope image of the silver nanowires in this invention.

[0023] Figure 5 This is a high-magnification scanning electron microscope image of the mixture of silver nanowires and carbon nanotubes in this invention.

[0024] Figure 6 This is a low-magnification scanning electron microscope image of the self-healing silver nanowire / carbon nanotube composite battery electrode of the present invention.

[0025] Figure 7 This is a comparison chart of the specific capacity of the self-healing silver nanowire / carbon nanotube composite battery obtained under different silver-carbon ratios in this invention.

[0026] Figure 8 This is a comparison chart of the rate performance of the self-healing silver nanowire / carbon nanotube composite battery obtained under different silver-carbon ratios in this invention. Detailed Implementation

[0027] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the technical solutions of the present invention, but should not be used to limit the scope of protection of the present invention.

[0028] Example:

[0029] A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode comprises the following steps: (1) Silver nanowires are dispersed in an aqueous solvent to form a dispersion. Then, 0.001-1.5 mol / L of conductive polymer monomer, dopant, and interface modifier are added to the dispersion to form a mixed system. The conductive polymer monomer includes at least one of thiophene monomers, pyrrole monomers, or aniline monomers. The dopant includes at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), poly(2-acrylamide-2-methylpropanesulfonic acid) (PAMPS), polyvinyl sulfonate (PVS), sodium polystyrene sulfonate (PSS), polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), polystyrene sulfonic acid-maleic acid copolymer, and dodecylbenzene sulfonic acid (DBSA). The interface modifier includes at least one of silane coupling agents, titanate coupling agents, aluminate coupling agents, hexadecyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), fatty acid substances, and aliphatic amine substances. The molar ratio of the dopant to the interface modifier is 1-100:1. The amount of interface modifier added is 0.0001-15 wt% of the total mass of the conductive polymer monomer and the dopant. Finally, the mixed solution is placed in a constant temperature water bath at 30-95℃ and stirred for 0.02-72 h. Through polymerization, dispersion and coupling, the mixed system undergoes an in-situ polymerization reaction to obtain silver nanowires with a protective layer. (2) Carbon nanotubes are placed in an acidic solution with a mass fraction of 0.1-70% and refluxed at 80-100℃ for 0.1-72 h. After cooling, they are washed with deionized water until neutral and then vacuum dried at 60-80℃ for 0.1-100 h to obtain activated carbon nanotubes. Subsequently, the activated carbon nanotube carrier is immersed in a solution containing a transition metal precursor. The transition metal precursor solution is a soluble transition metal salt or an organometallic transition metal compound. The soluble transition metal salt is selected from at least one of nitrates, chlorides, acetates, sulfates, or ammonium complexes. The organometallic transition metal compound includes at least one of metal acetylacetonates, organometallic acid salts, or metal carbonyl compounds. The concentration of the transition metal precursor solution is 0.001-1 mol / L. The substrate was subjected to ultrasonic treatment for 0.02h-100h at an ultrasonic temperature of 25-35℃ to adsorb the transition metal precursor onto the surface of the support. Finally, the support with the adsorbed transition metal precursor was transferred to a tube furnace for heat treatment reduction in a hydrogen atmosphere for 0.1h-100h. After cooling, the substrate was washed and dried to obtain a carbon nanotube composite material with transition metal nanocatalytic active components loaded on its surface. (3) The silver nanowires with a protective layer obtained in step (1) and the carbon nanotubes loaded with transition metal nanocatalysts obtained in step (2) are mixed at a preset mass ratio of 0.01:1-1000. The mixture is then dispersed in an organic solution to form a uniform suspension. The suspension is then placed in a microwave reactor for microwave reaction. The microwave frequency is set to 0.1-100 GHz, the power to 50-3000 W, and the reaction temperature to 60-300 °C. The reaction is continued for 0.01-100 h to obtain a silver nanowire-carbon nanotube hybrid structure.

[0030] (4) The silver nanowires with a protective layer are coated on the surface of the current collector by solution scraping and then subjected to ultraviolet curing treatment. The wavelength of the ultraviolet curing treatment is 254-365nm, the power is 30-300W, and the irradiation time is 0.1-300min. After the bottom layer is cured, the silver nanowire-carbon nanotube hybrid structure is uniformly deposited on the bottom layer surface by spray deposition. The spray pressure of the spray deposition is 0.01-10MPa and the nozzle moving speed is 1-100mm / s. The surface microencapsulated active material is prepared on the middle layer surface by sol-gel method. The method involves preparing a surface microencapsulated active material on the middle layer surface using a sol-gel method, followed by drying to obtain a self-healing silver nanowire / carbon nanotube composite battery electrode. This process includes: mixing tetraethyl orthosilicate, dopamine, and deionized water to form a capsule wall precursor solution; adding silicon-based anode material and carbon black conductive additive, with a mass ratio of silicon-based anode material to carbon black conductive additive of 5-50:1, and the carbon black conductive additive accounting for 0.05-15 wt% of the total mass of the capsule core; ultrasonically dispersing the mixture and then dropping it onto the middle layer surface; reacting for 0.02-100 h to form microencapsulated active material with a particle size of 1-5 μm; and drying the entire structure in a drying oven for 0.1-100 h, allowing the layers to naturally bond through hydrogen bonds and π-π stacking forces to obtain the self-healing silver nanowire / carbon nanotube composite battery electrode.

[0031] Example:

[0032] The following is a detailed description of an embodiment of the preparation method of a self-healing silver nanowire / carbon nanotube composite battery electrode according to the present invention.

[0033] [Example 1] A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode (1) Protective coating on the surface of silver nanowires: Silver nanowires were dispersed in an aqueous solvent to form a dispersion. Then, PEDOT monomer with a concentration of 0.001-1.5 mol / L was slowly added dropwise to the dispersion while stirring at a medium speed with a magnetic stirrer to ensure that the PEDOT monomer was uniformly dispersed in the dispersion. PSS was added at a molar ratio of 0.0001:1-100 to PEDOT, with PSS acting as a dopant. The addition was also carried out while stirring to ensure that the PSS and PEDOT monomer were fully mixed. Finally, add 0.0001-15 wt% of a silane coupling agent based on the total mass of PEDOT:PSS. The silane coupling agent can be γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane. Add slowly dropwise and continue stirring for a period of time to allow the silane coupling agent to be uniformly dispersed in the mixture. Its function is to enhance the bonding force between the silver nanowires and PEDOT:PSS by binding the functional groups in its molecular structure to the hydroxyl groups on the surface of the silver nanowires and the sulfonic acid groups of PEDOT:PSS, respectively. This also improves the compatibility of the subsequently formed protective layer with other components. After all components have been added, continue stirring and polymerization for 0.02-72 hours. Through polymerization, dispersion, and coupling, the mixture undergoes an in-situ polymerization reaction, thereby forming a PEDOT:PSS composite protective layer on the surface of the silver nanowires.

[0034] (2) Loading transition metal nanocatalysts onto the surface of carbon nanotubes: First, carbon nanotubes were placed in a 0.1-70% (w / w) nitric acid solution and refluxed at 80-100℃ for 0.1-72 h. After cooling, they were washed with deionized water until neutral and vacuum dried at 60-80℃ for 0.1-100 h to obtain activated carbon nanotubes. Subsequently, the activated carbon nanotube support was immersed in a 0.0001-1 mol / L Ni(NO3)2 solution and ultrasonically treated for 0.02 h-100 h to allow Ni to precipitate. 2+ Adsorbed onto the carrier surface; finally, the adsorbed Ni 2+ The carrier was transferred to a tube furnace for heat treatment reduction. The reduction was carried out in a hydrogen atmosphere for 0.1 h to 100 h. After cooling, the carrier was washed and dried to obtain carbon nanotubes with Ni nanocatalysts supported on the surface.

[0035] (3) Preparation of silver nanowire-carbon nanotube hybrid structure: The silver nanowires with protective layer obtained in step (1) and the carbon nanotubes with transition metal nanocatalysts obtained in step (2) are mixed at a mass ratio of 0.01:1-1000 and dispersed in ethylene glycol solution. The mixture is placed on a magnetic stirrer and stirred at medium speed for 0.01-100h to form a uniform suspension. The suspension is then placed in a microwave reactor for microwave reaction. The microwave frequency is set to 0.1-100GHz, the power to 50-3000W, and the reaction temperature to 60-300℃. The reaction is continued for 0.01-100h. The mixture is then transferred to a centrifuge tube and the precipitate obtained by centrifugation is gently washed with anhydrous ethanol. The precipitate is then transferred to a vacuum drying oven and dried for 0.1-100h to finally obtain the silver nanowire-carbon nanotube hybrid structure.

[0036] (4) Layer-by-layer assembly of electrodes: Silver nanowires coated with PEDOT:PSS protective layer were coated onto the surface of the current collector by solution scraping and UV curing treatment. The UV curing treatment wavelength was 254-365nm, the power was 30-300W, and the irradiation time was 0.1-300min. After the bottom layer was cured, the silver nanowire-carbon nanotube hybrid structure was uniformly deposited on the bottom layer surface by spray deposition. The spray pressure of spray deposition was 0.01-10MPa and the nozzle moving speed was 1-100mm / s. The surface microencapsulated active material was prepared on the middle layer surface by sol-gel method. After drying, the self-healing silver nanowire / carbon nanotube composite battery electrode was obtained.

[0037] [Example 2] A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode (1) Protective coating on the surface of silver nanowires: Silver nanowires were dispersed in deionized water to form a dispersion with a mass fraction of 0.5%. Pyrrole monomer with a concentration of 0.5 mol / L was added to the dispersion, followed by the dopant poly(2-acrylamide-2-methylpropanesulfonic acid) (PAMPS), with a molar ratio of pyrrole monomer to PAMPS of 1:1. Then, hexadecyltrimethylammonium bromide (CTAB) was added as an interface modifier, with an addition amount of 5% of the total mass of pyrrole monomer and PAMPS. The mixed solution was placed in a constant temperature water bath at 50°C and stirred at a speed of 300 rpm for 12 hours to allow pyrrole to polymerize in situ, forming a polypyrrole (PPy) / PAMPS composite protective layer on the surface of the silver nanowires.

[0038] (2) Loading transition metal nanocatalysts onto the surface of carbon nanotubes: Multi-walled carbon nanotubes were placed in a 30% sulfuric acid solution and refluxed at 90°C for 5 hours. After cooling, they were repeatedly washed with deionized water until the pH value reached 7, and then dried in a vacuum drying oven at 70°C for 12 hours to obtain activated carbon nanotubes. The activated carbon nanotubes were immersed in a 0.05 mol / L chloroplatinic acid (H2PtCl6) solution and sonicated at 30°C for 2 hours to allow platinum ions to be fully adsorbed onto the surface of the carbon nanotubes. Subsequently, the carbon nanotubes adsorbed with platinum ions were transferred to a tube furnace and reduced at 300°C for 3 hours in a hydrogen / argon mixed atmosphere (hydrogen integral 10%). After cooling, they were washed three times with deionized water and vacuum dried at 60°C to obtain a carbon nanotube composite material with platinum (Pt) nanoparticles loaded on the surface.

[0039] (3) Preparation of silver nanowire-carbon nanotube hybrid structure: The silver nanowires coated with PPy / PAMPS protective layer obtained in step (1) and the carbon nanotubes supported with Pt nanocatalyst obtained in step (2) were mixed at a mass ratio of 5:1 and dispersed in anhydrous ethanol. The suspension was placed in a microwave reactor, the microwave frequency was set to 2.45 GHz, the power to 800 W, the reaction temperature to 120℃, and the reaction was continued for 0.5 hours. After the reaction was completed, the product was centrifuged, washed three times with ethanol, and dried under vacuum at 60℃ for 6 hours to obtain the silver nanowire-carbon nanotube hybrid structure.

[0040] (4) Layer-by-layer assembly of electrodes: The silver nanowires with protective coating obtained in step (1) were coated onto the surface of the copper foil current collector using a solution-coated method, with the coating thickness controlled at 5 μm. Subsequently, ultraviolet curing was performed with an ultraviolet wavelength of 365 nm, a power of 100 W, and an irradiation time of 5 minutes. After the bottom layer was cured, the silver nanowire-carbon nanotube hybrid structure obtained in step (3) was dispersed in N-methylpyrrolidone (NMP) to prepare a dispersion with a concentration of 2 mg / mL. The dispersion was uniformly deposited onto the bottom layer surface by a spray deposition method with a spray pressure of 0.5 MPa and a nozzle moving speed of 20 mm / s. Microencapsulated active materials for the middle layer were prepared using a sol-gel method: Tetraethyl orthosilicate, dopamine, and deionized water were mixed at a volume ratio of 2:1:10 to form a precursor solution for the capsule wall. Silicon-based anode material (nano-silicon) and carbon black conductive additive were added, with a nano-silicon to carbon black mass ratio of 20:1, and carbon black comprising 1 wt% of the total capsule core mass. After ultrasonic dispersion for 30 minutes, the mixture was dropwise added to the middle layer surface and allowed to react for 2 hours, forming microencapsulated active materials with a particle size of 2-4 μm. The entire structure was placed in a vacuum drying oven and dried at 60°C for 12 hours. The layers naturally bonded through hydrogen bonds and π-π stacking forces, yielding a self-healing silver nanowire / carbon nanotube composite battery electrode.

[0041] [Example 3] A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode (1) Protective coating on the surface of silver nanowires: Silver nanowires were dispersed in isopropanol to form a dispersion with a mass fraction of 1%. Aniline monomer with a concentration of 0.8 mol / L was added to the dispersion, followed by dopant dodecylbenzenesulfonic acid (DBSA) and interface modifier titanate coupling agent (isopropyltris(dioctylpyrophosphoryloxy)titanate). The molar ratio of aniline monomer to DBSA was 1:0.5, and the amount of titanate coupling agent added was 0.5% of the total mass of aniline monomer and DBSA. The mixture was placed in an ice-water bath (0-5℃), and ammonium persulfate solution was slowly added dropwise as an initiator. After the addition was completed, the mixture was stirred and polymerized for 8 hours to allow aniline to polymerize in situ, forming a polyaniline (PANI) / DBSA composite protective layer on the surface of the silver nanowires.

[0042] (2) Loading transition metal nanocatalysts on the surface of carbon nanotubes: Single-walled carbon nanotubes were placed in a 10% hydrogen peroxide solution and refluxed at 60°C for 24 hours to introduce oxygen-containing functional groups. After cooling, they were washed with deionized water until neutral and vacuum dried at 80°C for 6 hours to obtain activated carbon nanotubes. The activated carbon nanotubes were immersed in an ethanol solution of 0.01 mol / L acetylacetone iron (Fe(acac)3) and ultrasonically treated at 25°C for 12 hours to adsorb the iron precursor onto the surface of the carbon nanotubes. Subsequently, the carbon nanotubes with adsorbed iron precursors were transferred to a tube furnace and heat-treated at 500°C for 2 hours under an argon atmosphere to decompose and reduce the acetylacetone iron, obtaining a carbon nanotube composite material with iron (Fe) nanoparticles loaded on the surface.

[0043] (3) Preparation of silver nanowire-carbon nanotube hybrid structure: The silver nanowires coated with PANI / DBSA protective layer obtained in step (1) and the carbon nanotubes loaded with Fe nanocatalyst obtained in step (2) were mixed at a mass ratio of 1:10 and dispersed in ethylene glycol. The suspension was placed in a microwave reactor, and the microwave frequency was set to 5.8 GHz, the power to 1500 W, and the reaction temperature to 180℃. The reaction was continued for 1 hour. After the reaction was completed, the product was centrifuged, washed three times with ethanol, and then vacuum dried at 80℃ for 4 hours to obtain the silver nanowire-carbon nanotube hybrid structure.

[0044] (4) Layer-by-layer assembly of electrodes: The silver nanowires with protective coating obtained in step (1) were coated onto the surface of the aluminum foil current collector using a solution coating method, with the coating thickness controlled at 3 μm. Subsequently, ultraviolet curing was performed with an ultraviolet wavelength of 254 nm, a power of 200 W, and an irradiation time of 2 minutes. After the bottom layer was cured, the silver nanowire-carbon nanotube hybrid structure obtained in step (3) was dispersed in deionized water to prepare a dispersion with a concentration of 1 mg / mL. The dispersion was uniformly deposited onto the bottom layer surface by spray deposition with a spray pressure of 0.2 MPa and a nozzle moving speed of 50 mm / s. Microencapsulated active materials for the middle layer were prepared using a sol-gel method: Tetraethyl orthosilicate, dopamine, and deionized water were mixed at a volume ratio of 1:1:20 to form a precursor solution for the capsule wall. A silicon-based anode material (silicon suboxide) and a carbon nanotube conductive agent were added, with a silicon suboxide to carbon nanotube mass ratio of 30:1, and carbon nanotubes comprising 3 wt% of the total capsule core mass. After ultrasonic dispersion for 1 hour, the mixture was dropwise added to the middle layer surface and reacted for 0.5 hours to form microencapsulated active materials with a particle size of 3-5 μm. The entire structure was placed in a forced-air drying oven and dried at 80°C for 6 hours. The layers naturally bonded through hydrogen bonds and π-π stacking forces, yielding a self-healing silver nanowire / carbon nanotube composite battery electrode.

[0045] [Example 4] A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode (1) Protective coating on the surface of silver nanowires: Silver nanowires were dispersed in ethylene glycol to form a dispersion with a mass fraction of 2%. 3,4-ethylenedioxythiophene (EDOT) monomer with a concentration of 1.2 mol / L was added to the dispersion, followed by the dopant sodium polystyrene sulfonate (PSS) and the interface modifier γ-glycidyl etheroxypropyltrimethoxysilane. The molar ratio of EDOT monomer to PSS was 1:2, and the amount of interface modifier added was 10% of the total mass of EDOT and PSS. The mixed solution was placed in a constant temperature water bath at 85℃ and stirred for 2 hours to allow EDOT to polymerize in situ, forming a PEDOT:PSS composite protective layer on the surface of the silver nanowires.

[0046] (2) Loading transition metal nanocatalysts on the surface of carbon nanotubes: Carboxylated carbon nanotubes (without additional activation) were immersed in a 0.1 mol / L aqueous solution of cobalt acetate (Co(Ac)2) and ultrasonically treated at 35°C for 0.5 hours to adsorb cobalt ions onto the surface of the carbon nanotubes. Subsequently, the carbon nanotubes adsorbed with cobalt ions were transferred to a tube furnace and reduced at 400°C for 2 hours under a hydrogen atmosphere. After cooling, they were washed with deionized water and vacuum dried at 60°C to obtain a carbon nanotube composite material with cobalt (Co) nanoparticles loaded on the surface.

[0047] (3) Preparation of silver nanowire-carbon nanotube hybrid structure: The silver nanowires coated with PEDOT:PSS protective layer obtained in step (1) and the carbon nanotubes supported with Co nanocatalyst obtained in step (2) were mixed at a mass ratio of 100:1 and dispersed in NMP. The suspension was placed in a microwave reactor, and the microwave frequency was set to 0.5 GHz, the power to 500 W, and the reaction temperature to 80℃. The reaction was continued for 3 hours. After the reaction was completed, the product was separated by centrifugation, washed with ethanol, and then vacuum dried at 50℃ for 12 hours to obtain the silver nanowire-carbon nanotube hybrid structure.

[0048] (4) Layer-by-layer assembly of electrodes: The silver nanowires with protective coating obtained in step (1) were coated onto the surface of the titanium foil current collector using a solution-coating method, with the coating thickness controlled at 10 μm. Subsequently, ultraviolet curing was performed with an ultraviolet wavelength of 310 nm, a power of 50 W, and an irradiation time of 10 minutes. After the bottom layer was cured, the silver nanowire-carbon nanotube hybrid structure obtained in step (3) was dispersed in acetone to prepare a dispersion with a concentration of 5 mg / mL. The dispersion was then uniformly deposited onto the bottom layer surface using a spray deposition method with a spray pressure of 5 MPa and a nozzle moving speed of 5 mm / s. Microencapsulated active materials for the middle layer were prepared using a sol-gel method: Tetraethyl orthosilicate, dopamine, and deionized water were mixed at a volume ratio of 3:2:50 to form a precursor solution for the capsule wall. A silicon-based anode material (silicon-carbon composite material) and graphene conductive additive were added, with a mass ratio of silicon-carbon composite material to graphene of 10:1, and graphene accounting for 0.5 wt% of the total core mass. After ultrasonic dispersion for 15 minutes, the mixture was dropwise added to the middle layer surface and reacted for 5 hours to form microencapsulated active materials with a particle size of 1-3 μm. The entire structure was placed in a vacuum drying oven and dried at 40°C for 24 hours. The layers naturally bonded through hydrogen bonds and π-π stacking forces, yielding a self-healing silver nanowire / carbon nanotube composite battery electrode.

[0049] In the above embodiments, the coating solution was prepared by adding a predetermined amount of silver nanowires coated with a PEDOT:PSS protective layer to a mixed solvent of ethylene glycol and deionized water, and then ultrasonicating the mixture in an ultrasonic disperser to ensure that the silver nanowires were uniformly dispersed in the solvent without significant agglomeration. The current collector was fixed on a fixture on a horizontal worktable, and its surface was wiped with alcohol to remove oil and impurities. After the alcohol had completely evaporated, the prepared coating solution was poured onto one end of the current collector. An adjustable-thickness scraper was selected, and the distance between the scraper and the surface of the current collector was set. The scraper was moved at a constant speed along the length of the current collector to form a continuous and uniform wet film on the surface of the current collector, avoiding local areas that were too thick or too thin. After coating was completed, The current collector with a wet film is transferred to the UV curing machine. The distance between the UV lamp and the surface of the current collector is adjusted, and the UV curing parameters are set to wavelength 254-365nm and power 30-300W. The equipment is turned on for UV curing treatment, and the irradiation time is controlled between 0.1-300min. UV irradiation can promote the evaporation of residual solvent in the coating solution and further cross-link the PEDOT:PSS molecular chains, enhancing the adhesion between the bottom layer and the current collector and preventing the bottom layer from falling off in subsequent operations. The bottom layer formed after curing serves as the conductive substrate of the electrode, providing stable support for the subsequent middle and top layers. At the same time, relying on the synergistic effect of silver nanowires and PEDOT:PSS, the initial conductive path is constructed.

[0050] After the substrate has solidified, the silver nanowire-carbon nanotube hybrid structure is uniformly deposited onto the substrate surface via spray deposition. Specific procedures include: preparing a spray suspension; adding the silver nanowire-carbon nanotube hybrid structure to an ethylene glycol solution and ultrasonically dispersing it for 0.1-10 hours to ensure uniform dispersion and no sedimentation; fixing the current collector with the solidified substrate on the worktable of the spray deposition equipment; adjusting the vertical distance between the spray nozzle and the substrate surface; setting the spray parameters: spray pressure 0.01-10 MPa, nozzle moving speed 1-100 mm / s; and setting the nozzle moving path. It is a reciprocating system; the spraying equipment is turned on, and the suspension is atomized through the nozzle and sprayed evenly on the bottom surface. The atomized micro-droplets ensure that the hybrid structure is evenly distributed on the bottom surface and avoid local accumulation. After spraying, it is left to stand naturally for a period of time to allow the surface solvent to evaporate initially and form a middle layer attached to the bottom surface. This middle layer relies on the elastic deformation capability of the hybrid structure to buffer the internal stress caused by the volume change of the active material during subsequent electrode charging and discharging. At the same time, the silver nanowires and carbon nanotubes in the hybrid structure can be connected with the conductive network of the bottom layer to further enhance the overall conductivity of the electrode.

[0051] The sol-gel method was used to prepare surface microencapsulated active materials on the middle layer surface. The specific steps included: first, preparing a capsule wall precursor solution; adding tetraethyl orthosilicate, dopamine, and deionized water to a beaker according to a predetermined ratio; adjusting the pH of the solution to weakly acidic using hydrochloric acid or ammonia; and stirring in a magnetic stirrer to ensure thorough mixing of all components, forming a homogeneous capsule wall precursor solution; weighing the two materials at a mass ratio of silicon-based anode material to carbon black conductive additive of 5-50:1, with the carbon black conductive additive accounting for 0.05-15 wt% of the total capsule core mass; adding the two materials to the capsule wall precursor solution; and transferring the mixture to an ultrasonic disperser for ultrasonication to break up the agglomeration of the silicon-based material, ensuring uniform dispersion of the silicon-based material and carbon black in the capsule wall precursor solution, forming capsules. Core-capsule wall mixture: The current collector with the middle layer is transferred to the support of a constant temperature water bath. The water bath temperature is set to 30-400℃. The core-capsule wall mixture is dripped onto the surface of the middle layer at a constant flow rate using a peristaltic pump. The water bath temperature is kept stable during the dripping process. After the dripping is completed, the reaction continues at this temperature for 0.02-100h. During the reaction, tetraethyl orthosilicate undergoes a hydrolysis-condensation reaction to form a siloxane network, and dopamine undergoes a simultaneous oxidative polymerization reaction. The two work together to form a continuous capsule wall on the surface of the silicon-based material and carbon black, ultimately forming microencapsulated active material with a particle size of 1-5μm. The capsule wall has suitable mechanical strength and can stably encapsulate the internal silicon-based anode material and carbon black conductive additive, preventing the active material from falling off or agglomerating in subsequent operations.

[0052] After the surface layer preparation is completed, the entire structure is transferred to a vacuum drying oven. After closing the oven door, the vacuum system is turned on. Once the vacuum level inside the oven reaches the preset value, the drying temperature is set to 40-200℃ and the drying is continued for 0.1-100 hours. During the drying process, residual solvents and moisture in each layer can be removed, while promoting the formation of molecular forces between the layers: the sulfonic acid groups of PEDOT:PSS in the bottom layer form hydrogen bonds with the hydroxyl groups on the surface of the middle carbon nanotubes, and the conjugated structure of the middle carbon nanotubes forms π-π stacking forces with the dopamine conjugated structure of the surface microcapsule wall. This allows the layers to be tightly bonded through these natural forces, without the need to add a large amount of binder. After drying, the entire structure is removed to obtain a self-healing silver nanowire / carbon nanotube composite battery electrode.

[0053] In this battery electrode, the capsule walls of the microencapsulated active material are formed by the reaction of tetraethyl orthosilicate and dopamine. When microcracks develop in the electrode due to volume changes in the active material during long-term cycling, the mechanical force generated during crack propagation breaks down the microcapsule walls, releasing the internal silicon-based anode material and carbon black conductive additive. The silicon-based material fills the cracks, restoring the continuity of the electrode material, while the carbon black conductive additive connects with the surrounding silver nanowires and carbon nanotubes at the crack, reconstructing the conductive pathway and preventing conductivity interruption caused by cracks. This self-healing mechanism requires no external intervention and can respond to and repair microcracks in real time, preventing further cracking. This method continuously expands the overall performance of the electrode, improving its long-term cycle stability and solving the problem of rapid capacity decay caused by the inability of traditional electrodes to heal cracks. Simultaneously, each layer of the electrode is prepared layer by layer through solution coating, spray deposition, and sol-gel methods. The layers are naturally bonded by hydrogen bonds and π-π stacking forces, eliminating the need for large amounts of additional insulating binders or the need to deliberately construct low-density porous structures to buffer volume changes. This effectively avoids the decrease in conductivity caused by binders and the reduction in energy density caused by porous designs, enabling the electrode to possess both high conductivity and high energy density, meeting the requirements for high-energy-density batteries.

[0054] The above-described 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 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode, characterized in that, The method includes the following steps: (1) Protective coating on the surface of silver nanowires: Silver nanowires are dispersed in an aqueous solvent to form a dispersion. Then, 0.001-1.5 mol / L of conductive polymer monomer, dopant and interface modifier are added to the dispersion to form a mixed system. The molar ratio of dopant and interface modifier is 1-100:

1. Finally, the mixed solution is placed in a constant temperature water bath at 30-95℃ and stirred for 0.02-72 h. Through polymerization, dispersion and coupling, the mixed system undergoes in-situ polymerization reaction, thereby forming a conductive polymer composite protective layer on the surface of silver nanowires. (2) Loading transition metal nanocatalysts on the surface of carbon nanotubes: First, carbon nanotubes are placed in an acidic solution with a mass fraction of 0.1-70% and refluxed at 80-100℃ for 0.1-72h. After cooling, they are washed with deionized water until neutral and dried for 0.1-100h to obtain activated carbon nanotubes. Then, the activated carbon nanotube support is immersed in a solution containing a transition metal precursor with a concentration of 0.0001-1mol / L and ultrasonically treated for 0.02h-100h to adsorb the transition metal precursor onto the surface of the support. Finally, the support with the adsorbed transition metal precursor is transferred to a tube furnace for heat treatment reduction. After cooling, it is washed and dried to obtain a carbon nanotube composite material with transition metal nanocatalytic active components loaded on the surface. (3) Preparation of silver nanowire-carbon nanotube hybrid structure: The silver nanowires with protective layer obtained in step (1) and the carbon nanotubes loaded with transition metal nanocatalyst obtained in step (2) are mixed at a preset mass ratio and dispersed in an organic solution to form a uniform suspension. The suspension is then placed in a microwave reactor for microwave reaction and the reaction is continued for 0.01~100h to obtain the silver nanowire-carbon nanotube hybrid structure. (4) Layer-by-layer assembly of electrodes: Silver nanowires with a protective layer are coated onto the surface of the current collector by solution scraping and photocuring treatment for 0.1-300 min. After the bottom layer is cured, the silver nanowire-carbon nanotube hybrid structure is uniformly deposited on the bottom layer surface. Microencapsulated active material is prepared on the surface of the middle layer by sol-gel method and dried to obtain a self-healing silver nanowire / carbon nanotube composite battery electrode.

2. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, The conductive polymer monomer includes at least one of thiophene monomers, pyrrole monomers, or aniline monomers.

3. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, The dopant includes at least one of polyvinylidene fluoride, polyacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, polyvinyl sulfonate, sodium polystyrene sulfonate, polyvinylpyrrolidone, polyethylene oxide, polystyrene sulfonic acid-maleic acid copolymer, and dodecylbenzene sulfonic acid, wherein the molar ratio of the conductive polymer monomer to the dopant is 0.001:1-20.

4. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, The interface modifier includes at least one of the following: silane coupling agent, titanate coupling agent, aluminate coupling agent, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, sodium dodecyl sulfate, fatty acid substances, and fatty amine substances.

5. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 4, characterized in that, The amount of the interface modifier added is 0.0001-15 wt% of the total mass of the conductive polymer monomer and dopant.

6. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, In step (2) above, the transition metal precursor solution is a soluble transition metal salt or an organic transition metal compound, wherein the soluble transition metal salt is selected from at least one of nitrate, chloride, acetate, sulfate or ammonium complex.

7. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 6, characterized in that, The transition metal organometallic compound includes at least one of metal acetylacetonate, organometallic acid salt, or metal carbonyl compound.

8. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, In step (3) above, the method includes the step of combining silver nanowires and carbon nanotubes at a preset mass ratio. The mass ratio of silver nanowires to carbon nanotubes is 0.01:1-1000.

9. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, In step (4) above, the preparation of surface microencapsulated active material on the middle layer surface using the sol-gel method and the subsequent drying to obtain a self-healing silver nanowire / carbon nanotube composite battery electrode includes: mixing tetraethyl orthosilicate, dopamine and deionized water to form a capsule wall precursor solution, adding silicon-based anode material and carbon black conductive additive, the mass ratio of silicon-based anode material to carbon black conductive additive being 5-50:1, the carbon black conductive additive accounting for 0.05-15wt% of the total mass of the capsule core, ultrasonically dispersing and then dropping it onto the middle layer surface, reacting for 0.02-100h to form microencapsulated active material; drying the overall structure for 0.1-100h, the layers naturally combining through hydrogen bonds and π-π stacking forces to obtain a self-healing silver nanowire / carbon nanotube composite battery electrode.

10. The method for preparing a self-healing silver nanowire / carbon nanotube composite battery electrode according to claim 1, characterized in that, The self-healing silver nanowire / carbon nanotube composite battery electrode prepared by combining silver nanowires and carbon nanotubes can significantly improve the conductivity of the electrode, inhibit the formation and propagation of microcracks in the conductive network, and effectively alleviate the structural damage caused by volume changes of the electrode material during charging and discharging, thereby endowing the battery electrode with excellent self-healing ability and cycle stability.

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