Silicon-based negative electrode material with three-dimensional conductive network and preparation method and application thereof

Abstract

The application belongs to the technical field of lithium ion batteries, and particularly relates to a silicon-based negative electrode material with a three-dimensional conductive network and a preparation method and application thereof. Firstly, a physical vapor deposition is used to form an ultrathin metal catalytic layer on the surface of silicon-based particles, and then carbon nanotubes are in-situ grown on the metal layer by a chemical vapor deposition method in an atmosphere containing hydrogen. The outermost carbon nanotubes are connected to each other to form a three-dimensional conductive network penetrating through the whole material, and the intermediate metal layer has the functions of catalytic growth and buffer support. The method innovatively realizes the construction of a stable multi-level structure of "silicon core-metal layer-carbon nanotube network" on the surface of nanosilicon particles, and effectively solves the problems of poor conductivity and large volume expansion of silicon-based materials. The prepared negative electrode material has high specific capacity, excellent initial coulomb efficiency and stable long cycle life, and is suitable for high-energy-density lithium ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a silicon-based anode material with a three-dimensional conductive network, its preparation method, and its application. Background Technology

[0002] As the core of modern high-performance energy storage systems, lithium-ion batteries urgently require the maturation and application of next-generation anode materials to further improve their energy density. Silicon-based materials are considered the most promising alternative to graphite due to their extremely high theoretical specific capacity. However, their inherent low conductivity and the problems caused by particle pulverization and repeated rupture of the solid electrolyte interface film due to the huge volume expansion during charging and discharging severely restrict their commercialization. Especially in applications requiring high rate capability and long cycle life, how to construct an electrode material that can simultaneously achieve efficient electron conduction, adapt to volume changes, and maintain structural stability has become a key technological bottleneck driving silicon-based anodes towards large-scale market application.

[0003] To address these challenges, current technologies primarily focus on improving the conductivity and structural integrity of silicon through carbon material composites. Common strategies include physically-mechanically mixing silicon particles with conductive agents such as carbon nanotubes and graphene, or using organic precursor coating followed by carbonization to construct conductive networks or protective layers. These methods improve electrode conductivity and buffer some volumetric stress to a certain extent. However, physical mixing methods struggle to achieve uniform and robust coating of conductive agents on the silicon particle surface, making phase separation highly likely during electrode fabrication and cycling, leading to localized conductive network failure and active material detachment. Organic precursor coating and carbonization processes often introduce large amounts of oxygen, reducing the material's tap density and triggering irreversible side reactions, significantly impairing initial coulombic efficiency and reversible capacity. More critically, the carbon-silicon interface bonding formed by external additions or simple coatings is typically weak, unable to withstand the drastic volumetric deformation of silicon during long-term cycling, ultimately leading to protective layer rupture, conductive network collapse, and permanent loss of electrical contact between the active material and the current collector. Existing composite strategies have failed to fundamentally solve the structural pulverization and interface stability problems of silicon-based anodes during repeated lithiation / delithiation processes. The "islanding" phenomenon that occurs in electrode materials after cycling, i.e., the failure of active silicon particles due to loss of electrical connection, remains the main cause of rapid capacity decay.

[0004] Developing a novel composite structure that enables a robust chemical / physical bond between the conductive network and silicon particles, and that can adapt to volume expansion while maintaining unobstructed electron conduction pathways, is crucial for achieving high performance and practical application of silicon-based anodes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a silicon-based anode material with a three-dimensional conductive network, its preparation method, and its applications. This invention provides an innovative solution for achieving high conductivity, structural stability, and long cycle life in silicon-based anode materials through an in-situ construction process combining physical vapor deposition and chemical vapor deposition.

[0006] The first objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a silicon-based anode material with a three-dimensional conductive network includes the following steps:

[0008] (1) A metal coating layer is formed on the surface of silicon-based particles by physical vapor deposition to obtain silicon-based particles coated with a metal layer;

[0009] (2) The silicon-based particles coated with metal layer obtained in step (1) are placed in a reactor, and a mixed gas containing acetylene, hydrogen and nitrogen is introduced. Chemical vapor deposition is carried out at a temperature of 600-800℃ to catalyze the growth of carbon nanotubes in situ on the surface of the metal coating layer, thereby constructing a three-dimensional conductive network of the coated particles and obtaining a silicon-based anode material with a three-dimensional conductive network.

[0010] Preferably, in step (1), the median diameter D of the silicon-based particles is... 50 The range is 20-600 nm.

[0011] More preferably, the median diameter D of the silicon-based particles 50 The wavelength is 50-300 nm.

[0012] More preferably, the median diameter D of the silicon-based particles 50 The wavelength is 80-120 nm.

[0013] Preferably, in step (1), the silicon-based particles are any one or more of pure silicon, silicon oxide, silicon-carbon anode and silicon alloy.

[0014] More preferably, the silicon-based particles are pure silicon or silicon alloy.

[0015] Preferably, in step (1), the silicon-based particles are spherical, polyhedral, conical, or other irregularly shaped.

[0016] More preferably, the silicon-based particles are spherical or polyhedral in shape.

[0017] Preferably, in step (1), the physical vapor deposition is any one or more of magnetron sputtering, evaporation deposition and ion plating.

[0018] More preferably, the physical vapor deposition is magnetron sputtering.

[0019] Preferably, in step (1), the material of the metal cladding layer is any one or more of copper, iron, cobalt, nickel, gold, silver, zinc, chromium, manganese, aluminum and indium.

[0020] More preferably, the metal cladding layer is made of any one or more of copper, iron, nickel, or cobalt.

[0021] Preferably, in step (1), the thickness of the metal cladding layer is 0.1-5 nm.

[0022] More preferably, the thickness of the metal cladding layer is 0.5-3 nm.

[0023] Preferably, in step (1), the physical vapor deposition process takes 60-720 min.

[0024] More preferably, the physical vapor deposition process takes 120-360 minutes.

[0025] Preferably, after obtaining silicon-based particles coated with a metal layer in step (1), a post-processing step is further included, which includes sieving or gas-phase classification.

[0026] Further preferred, in step (1), the silicon-based particles coated with a metal layer obtained in the post-processing step have a particle size greater than 20 nm and less than 600 nm.

[0027] Preferably, in step (2), the acetylene gas flow rate is 0.2-1.5 L / min, the hydrogen gas flow rate is 0.2-1.5 L / min, and the nitrogen gas flow rate is 0.5-2.0 L / min.

[0028] More preferably, the acetylene gas flow rate is 0.3-0.8 L / min, the hydrogen gas flow rate is 0.3-0.8 L / min, and the nitrogen gas flow rate is 0.6-1.0 L / min.

[0029] Preferably, in step (2), the reaction time of the chemical vapor deposition is 30-360 min.

[0030] More preferably, the reaction time is 100-120 min.

[0031] Preferably, in step (2), the heating rate of the chemical vapor deposition is 2-10 °C / min.

[0032] Preferably, in step (2), the mass of carbon nanotubes accounts for 10-50 wt% of the total mass of the silicon-based anode material with a three-dimensional conductive network.

[0033] More preferably, the carbon nanotubes account for 15-28 wt% of the total mass.

[0034] Preferably, in step (2), the diameter of the carbon nanotubes is 10-150 nm.

[0035] More preferably, the diameter of the carbon nanotubes is 60-120 nm.

[0036] Preferably, in step (2), the length of the carbon nanotube is 1-20 μm.

[0037] More preferably, the length of the carbon nanotube is 1-15 μm.

[0038] More preferably, the length of the carbon nanotubes is 10-15 μm.

[0039] This scheme employs a combined physical vapor deposition (PVD) and chemical vapor deposition (CVD) technique. First, a uniform, ultrathin, and firmly bonded metal layer is constructed on the surface of nano-silicon particles using PVD. This metal layer has multiple functions: firstly, it is an excellent electronic conductor, directly improving the electronic conductivity of the silicon-based particle surface; secondly, it serves as a catalyst active site for subsequent CVD, its specific crystal structure and surface energy effectively catalyzing the cracking and carbon atom recombination of carbon source gases such as acetylene; thirdly, the metal layer, with its certain ductility, acts as a buffer layer, partially absorbing the volume expansion stress of the silicon nuclei during charging and discharging, reducing damage to the surface structure. Then, through CVD, a mixture of acetylene, hydrogen, and nitrogen is introduced at a suitable temperature of 600-800℃. Acetylene serves as the carbon source, hydrogen plays a crucial role in reducing metal surface oxides and etching amorphous carbon to promote graphitization growth, and nitrogen serves as the carrier and protective gas. By utilizing the catalytic effect of the metal layer on the surface of silicon-based particles, carbon atoms generated from the cracking of the carbon source dissolve, diffuse, and precipitate on the metal layer surface, directionally growing carbon nanotubes. The grown carbon nanotubes radiate outwards from the silicon-based particles, overlapping and entangled with carbon nanotubes grown on adjacent particles, ultimately forming a continuous, interconnected three-dimensional network structure. This three-dimensional network provides a highway for the rapid transport of electrons and lithium ions. Its excellent mechanical strength and toughness can bind the silicon-based particles, inhibiting their displacement and pulverization during cycling, while the gaps between the networks facilitate electrolyte wetting. Through these principles, this scheme achieves the goal of precisely constructing an integrated structure of "silicon core-metal buffer / catalytic layer-carbon nanotube conductive network" at the nanoscale, thereby simultaneously and significantly improving the conductivity, structural stability, and cycle life of silicon-based anode materials.

[0040] The second objective of this invention is achieved through the following technical solution:

[0041] A silicon-based anode material with a three-dimensional conductive network is prepared by the method described above.

[0042] Preferably, the structure of the silicon-based anode material with a three-dimensional conductive network includes: silicon-based particles in the core, an ultrathin metal layer covering the surface of the silicon-based particles, and carbon nanotubes that grow outward from the surface of the metal layer and interweave to form a three-dimensional network.

[0043] The third objective of this invention is achieved through the following technical solution:

[0044] A lithium-ion battery comprising a silicon-based anode material having a three-dimensional conductive network as described above.

[0045] Preferably, the lithium-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0046] More preferably, the negative electrode comprises the silicon-based negative electrode material, a binder, and a conductive agent.

[0047] More preferably, the mass ratio of the silicon-based anode material, binder, and conductive agent is (90-96):(2-5):(1-4).

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. This invention creatively combines physical vapor deposition (PVD) and chemical vapor deposition (CVD) technologies, providing a novel approach to constructing silicon-based anode materials. The process first involves forming a uniform metal coating layer on the surface of silicon-based particles via PVD, and then using this metal layer as a catalytically active substrate to grow a three-dimensional network of carbon nanotubes in situ.

[0050] 2. The material prepared by this invention possesses a unique and highly efficient multi-level synergistic structure. The metal layer is not simply an additive, but simultaneously performs three key functions: enhancing electronic conductivity, catalyzing carbon nanotube growth, and buffering volume expansion stress. This metal layer is firmly bonded to the silicon-based particles and chemically connected in situ to the outer carbon nanotubes, thereby forming a stable and efficient electron transport and stress dissipation channel within the material.

[0051] 3. The three-dimensional carbon nanotube network formed in situ by this invention constitutes a macroscopic conductive framework encapsulating the active particles. This network exhibits high bonding strength with the active material, providing not only excellent electronic and ion conductivity, but also, due to its inherent mechanical toughness and network structure, effectively binding the silicon-based particles and adapting to their volume changes. This significantly suppresses the pulverization of the electrode material and ensures the structural integrity of the electrode during long-term cycling.

[0052] 4. The preparation method of this invention has relatively mild conditions, especially the physical vapor deposition process, which can achieve uniform construction of the metal layer without significantly damaging the electrochemical activity of the silicon material itself. This method is applicable to nanoscale silicon-based particles, achieving effective control over the thickness and coverage of the coating layer, laying a solid foundation for the subsequent catalytic growth of high-quality carbon nanotubes.

[0053] 5. Based on the aforementioned material and structural advantages, lithium-ion batteries made using the silicon-based anode material provided in this invention exhibit a significant improvement in overall performance. While maintaining high specific capacity, the battery's initial coulombic efficiency, rate performance, and long-cycle stability are all simultaneously optimized, effectively overcoming the bottleneck problems of rapid capacity decay and short lifespan of traditional silicon-based anodes, and possessing significant practical application value. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the preparation process of the present invention;

[0055] Figure 2 This is a scanning electron microscope (SEM) image of the silicon-based anode material with a three-dimensional conductive network in Example 1.

[0056] Figure 3 The image shows a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 1.

[0057] Figure 4 The image shows a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 2.

[0058] Figure 5 The image shows a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 4.

[0059] Figure 6 The image shows a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 5.

[0060] Figure 7 The image shows a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 6.

[0061] Figure 8 This is a scanning electron microscope (SEM) image of the silicon-based anode material in Comparative Example 7. Detailed Implementation

[0062] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0063] The materials used in the embodiments and comparative examples of this invention are described below:

[0064] Silicon-based materials: nano-silicon particles, whose D 50 The particle size is 100 nm; purchased from Ningbo Guangxin Nanomaterials Co., Ltd.

[0065] Single-walled carbon nanotubes: specific surface area ≥1200 m² 2 / g, purchased from Ausen Nanotechnology (Shenzhen) Co., Ltd.

[0066] Volume distribution particle size D 50 The median diameter of the cumulative volume distribution of particles, obtained by using a laser diffraction particle size analyzer (refer to standard GB / T 19077), is the diameter at which the volume of coarse and fine particles in the sample each accounts for 50%.

[0067] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited thereto.

[0068] Example 1

[0069] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 1 includes the following steps:

[0070] (1) Install a circular copper target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% onto the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the magnetron sputtering vacuum chamber, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a sputtering frequency of 200 kHz for 240 min. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform copper coating.

[0071] The particle was removed and cut perpendicularly along the plane containing the center of the particle using focused ion beam (FIB) technology. The thickness of the outer copper layer was then observed using a transmission electron microscope. The thickness of the copper layer was 2.00 nm.

[0072] (2) The silicon-based particles coated with copper layer obtained in step (1) are processed by gas phase fractionation technology to obtain silicon-based particles coated with copper layer with a particle size distribution between 102-152 nm.

[0073] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction, wherein the acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and 650 ℃ conditions, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 1.

[0074] In silicon-based anode materials with a three-dimensional conductive network, carbon nanotubes account for 25.77 wt% of the total mass.

[0075] The silicon-based anode material with a three-dimensional conductive network prepared in Example 1 was observed by scanning electron microscopy, and the results were obtained. Figure 2 The scanning electron microscope image shown shows that carbon nanotubes grow densely and uniformly outwards using the copper layer on the surface of silicon-based particles as growth sites. The carbon nanotubes interweave with each other to form a complete three-dimensional network structure, and the carbon nanotubes are of uniform thickness.

[0076] Example 2

[0077] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 2 includes the following steps:

[0078] (1) Install a circular copper target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% onto the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the magnetron sputtering vacuum chamber, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a frequency of 200 kHz for 60 minutes. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform copper coating.

[0079] The particle was removed and cut perpendicularly along the face where the center of the particle is located using focused ion beam (FIB) technology. The thickness of the outer copper layer was then observed using a transmission electron microscope. The thickness of the copper layer was 0.51 nm.

[0080] (2-3) Same as step (2-3) in Example 1.

[0081] Example 3

[0082] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 3 includes the following steps:

[0083] (1) Install a circular copper target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% onto the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the magnetron sputtering vacuum chamber, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a sputtering frequency of 200 kHz for 480 min. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform copper coating.

[0084] The particle was removed and cut perpendicularly along the face where the center of the particle is located using focused ion beam (FIB) technology. The thickness of the outer copper layer was then observed using a transmission electron microscope, and the thickness of the copper layer was 3.87 nm.

[0085] (2-3) Same as step (2-3) in Example 1.

[0086] Example 4

[0087] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 4 includes the following steps:

[0088] (1-2) Same as steps (1-2) in Example 1.

[0089] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tube, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and 650 ℃ conditions, the reaction continues for 60 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 4.

[0090] Example 5

[0091] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 5 includes the following steps:

[0092] (1-2) Same as steps (1-2) in Example 1.

[0093] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and at 650 ℃, the reaction continues for 240 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 4.

[0094] Example 6

[0095] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 6 includes the following steps:

[0096] (1-2) Same as steps (1-2) in Example 1.

[0097] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction, wherein the acetylene gas flow rate is set to 0.2 L / min, the hydrogen gas flow rate is set to 0.2 L / min, and the nitrogen gas flow rate is maintained at 0.5 L / min. Under this mixed atmosphere and at 650 ℃, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 6.

[0098] Example 7

[0099] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 7 includes the following steps:

[0100] (1-2) Same as steps (1-2) in Example 1.

[0101] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 1.5 L / min, the hydrogen gas flow rate is set to 1.5 L / min, and the nitrogen gas flow rate is maintained at 2.0 L / min. Under this mixed atmosphere and 650 ℃ conditions, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 7.

[0102] Example 8

[0103] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 8 includes the following steps:

[0104] (1) Install a circular iron target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% on the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the vacuum chamber of the magnetron sputtering equipment, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a sputtering frequency of 200 kHz for 240 min. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform iron layer on their surface.

[0105] (2-3) Same as step (2-3) in Example 1.

[0106] Example 9

[0107] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 9 includes the following steps:

[0108] (1-2) Same as steps (1-2) in Example 1.

[0109] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 600 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 600 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and at 600 ℃, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 9.

[0110] Example 10

[0111] The preparation method of the silicon-based anode material with a three-dimensional conductive network in Example 10 includes the following steps:

[0112] (1-2) Same as steps (1-2) in Example 1.

[0113] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 800 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 800 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and 800 ℃ conditions, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material with a three-dimensional conductive network as described in Example 10.

[0114] Comparative Example 1

[0115] The preparation method of the silicon-based anode material in Comparative Example 1 includes the following steps:

[0116] (1) Weigh 100g of silicon-based particles and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the system. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and 650 ℃ conditions, the reaction continues for 120 min. After the reaction is completed, shut off the acetylene and hydrogen gas lines, and cool the furnace temperature to room temperature at a rate of 4 ℃ / min in a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 1.

[0117] The silicon-based anode material prepared in Comparative Example 1 was observed by scanning electron microscopy, and the results were obtained. Figure 3The scanning electron microscope images shown indicate that no carbon nanotubes grew on the surface of the silicon-based particles or between the particles. The silicon nanoparticles still exhibit an individual particle state, with only a small amount of amorphous carbon adhering to them, and they failed to form an effective conductive network structure.

[0118] Comparative Example 2

[0119] The preparation method of the silicon-based anode material in Comparative Example 2 includes the following steps:

[0120] (1-2) Same as steps (1-2) in Example 1.

[0121] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tube, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the system. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce acetylene gas (flow rate 0.6 L / min) and nitrogen gas (flow rate 1.2 L / min), without introducing hydrogen gas, and continue the reaction for 120 min. After the reaction is completed, shut off the acetylene gas path, and cool the furnace temperature to room temperature at a rate of 4 ℃ / min under a pure nitrogen atmosphere. Collect the reaction products to obtain the silicon-based anode material of Comparative Example 2.

[0122] The silicon-based anode material prepared in Comparative Example 2 was observed by scanning electron microscopy, and the results were obtained. Figure 4 The scanning electron microscope image shown indicates that only a small number of short and sparse carbon nanotubes are generated on the surface of the silicon-based particles. The carbon nanotubes have uneven morphology and fail to cross-link with each other to form a continuous three-dimensional network.

[0123] Comparative Example 3

[0124] The preparation method of the silicon-based anode material in Comparative Example 3 includes the following steps:

[0125] Weigh out 74.23 g of silicon nanoparticles and 25.77 g of single-walled carbon nanotubes. Transfer the mixture to a vacuum ball mill jar, add an appropriate amount of zirconia grinding balls, and ball mill on a planetary ball mill at 200 rpm for 30 min to obtain the silicon-based anode material of Comparative Example 3.

[0126] Comparative Example 4

[0127] The preparation method of the silicon-based anode material in Comparative Example 4 includes the following steps:

[0128] (1-2) Same as steps (1-2) in Example 1.

[0129] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and at 650 ℃, the reaction continues for 10 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 4.

[0130] Scanning electron microscopy was used to observe the silicon-based anode material prepared in Comparative Example 4, and the results were obtained. Figure 5 The scanning electron microscope image shown only reveals a small number of fine carbon nanotubes, which cannot form an interwoven conductive network.

[0131] Comparative Example 5

[0132] The preparation method of the silicon-based anode material in Comparative Example 5 includes the following steps:

[0133] (1-2) Same as steps (1-2) in Example 1.

[0134] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and at 650 ℃, the reaction continues for 500 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 5.

[0135] Scanning electron microscopy was used to observe the silicon-based anode material prepared in Comparative Example 5, and the results were obtained. Figure 6 The scanning electron microscope image shown reveals a large number of carbon nanotube networks. However, the carbon nanotube networks are uneven in thickness, with some carbon nanotubes overgrown and others connected into blocks, greatly reducing the buffer space.

[0136] Comparative Example 6

[0137] The preparation method of the silicon-based anode material in Comparative Example 6 includes the following steps:

[0138] (1-2) Same as steps (1-2) in Example 1.

[0139] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tube, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction. The acetylene gas flow rate is set to 0.1 L / min, the hydrogen gas flow rate is set to 0.1 L / min, and the nitrogen gas flow rate is maintained at 0.2 L / min. Under this mixed atmosphere and at 650 ℃, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 6.

[0140] Scanning electron microscopy was used to observe the silicon-based anode material prepared in Comparative Example 6, and the results were obtained. Figure 7 The scanning electron microscope image shown shows carbon nanotubes, but the carbon nanotubes are thin and some areas have not yet grown enough carbon nanotubes, resulting in insufficient structural strength.

[0141] Comparative Example 7

[0142] The preparation method of the silicon-based anode material in Comparative Example 7 includes the following steps:

[0143] (1-2) Same as steps (1-2) in Example 1.

[0144] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen gas at a flow rate of 1.0 L / min for 10 min, then evacuate the furnace. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 650 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen gas at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 650 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction, wherein the acetylene gas flow rate is set to 3.0 L / min, the hydrogen gas flow rate is set to 3.0 L / min, and the nitrogen gas flow rate is maintained at 4.0 L / min. Under this mixed atmosphere and 650 ℃ conditions, the reaction continues for 120 min. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 7.

[0145] Scanning electron microscopy was used to observe the composite silicon-based anode material prepared in Comparative Example 7, and the results were obtained. Figure 8 The scanning electron microscope image shown reveals a large number of carbon nanotubes. However, the diameter of the carbon nanotubes is already quite large, and carbon particles have formed in some areas. Although there is a conductive network, the carbon content is too high, which may greatly reduce the product capacity.

[0146] Comparative Example 8

[0147] The preparation method of the silicon-based anode material in Comparative Example 8 includes the following steps:

[0148] (1) Install a circular copper target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% onto the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the magnetron sputtering vacuum chamber, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a sputtering frequency of 200 kHz for 10 minutes. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform copper coating.

[0149] The particle was removed and cut perpendicularly along the face where the center of the particle was located using focused ion beam (FIB) technology. The thickness of the outer copper coating was then observed using a transmission electron microscope. The thickness of the copper coating was 0.08 nm.

[0150] (2-3) Same as step (2-3) in Example 1.

[0151] Comparative Example 9

[0152] The preparation method of the silicon-based anode material in Comparative Example 8 includes the following steps:

[0153] (1) Install a circular copper target with a diameter of 100 mm, a thickness of 5 mm, and a purity ≥99.99% onto the cathode target position of the magnetron sputtering equipment. Take 100 g of nano-silicon particles and transfer them to the vibrating stirring container in the magnetron sputtering vacuum chamber, so that the particles are continuously in a tumbling motion during the deposition process. Evacuate the vacuum chamber to 5 × 10⁻⁶ m³ / h. -4 The pressure was increased to 2 Pa by introducing argon gas, and this process of evacuation and argon gas introduction was repeated three times. Argon gas was then continuously introduced, and the pressure inside the vacuum chamber was stabilized at 0.5 Pa by adjusting the solenoid valve. Magnetron sputtering was then initiated at a power of 500 W and a sputtering frequency of 200 kHz for 1080 min. The power was then turned off, and the sample was removed after the chamber cooled, yielding silicon-based particles with a uniform copper coating.

[0154] The particle was removed and cut perpendicularly along the face where the center of the particle was located using focused ion beam (FIB) technology. The thickness of the outer copper coating was then observed using a transmission electron microscope. The thickness of the copper coating was 8.00 nm.

[0155] (2-3) Same as step (2-3) in Example 1.

[0156] Comparative Example 10

[0157] The preparation method of the silicon-based anode material of Comparative Example 10 includes the following steps:

[0158] (1-2) Same as steps (1-2) in Example 1.

[0159] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen at a flow rate of 1.0 L / min for 10 minutes, then evacuate. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 550 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 550 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction, wherein the acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and 550 ℃ conditions, the reaction continues for 120 minutes. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 10.

[0160] Comparative Example 11

[0161] The preparation method of the silicon-based anode material of Comparative Example 11 includes the following steps:

[0162] (1-2) Same as steps (1-2) in Example 1.

[0163] (3) Weigh 100g of the copper-coated silicon-based particles from step (2) and place them in a horizontal rotary furnace. After sealing the furnace tubes, perform gas replacement: introduce nitrogen at a flow rate of 1.0 L / min for 10 minutes, then evacuate. Repeat this process three times to ensure that the reaction system is inert. Then, set the process parameters: heat the central temperature zone of the furnace to 850 ℃ at a heating rate of 4 ℃ / min, and continuously introduce nitrogen at a flow rate of 1.2 L / min as a protective gas during this process. After the temperature stabilizes at 850 ℃, introduce a mixed gas composed of acetylene, hydrogen and nitrogen to start the chemical vapor deposition reaction, wherein the acetylene gas flow rate is set to 0.6 L / min, the hydrogen gas flow rate is set to 0.6 L / min, and the nitrogen gas flow rate is maintained at 1.2 L / min. Under this mixed atmosphere and at 850 ℃, the reaction continues for 120 minutes. After the reaction was completed, the acetylene and hydrogen gas lines were shut off, and the furnace temperature was lowered to room temperature at a rate of 4 °C / min under a pure nitrogen atmosphere. The reaction products were collected to obtain the silicon-based anode material of Comparative Example 11.

[0164] The silicon-based anode materials prepared in Examples 1-10 and Comparative Examples 1-11 were subjected to physical characterization and electrochemical performance testing. The results are shown in Table 1. The testing methods and standards are as follows:

[0165] Powder resistivity testing: A four-probe powder resistivity tester was used to test the intrinsic electronic conductivity of the material under a constant pressure of 20 MPa.

[0166] The preparation of the coin cell includes: weighing 4.7275 g of silicon-based anode material, 0.1225 g of conductive agent (Super P), and 0.1500 g of binder (polyvinylidene fluoride, PVDF) and mixing them at a mass ratio of 94.55:2.45:3. First, PVDF is added to 20 ml of N-methylpyrrolidone (NMP) solvent and stirred at 600 rpm for 30 min in a planetary mixer. Then, the conductive agent is added and stirring is continued at 600 rpm for 30 min. Finally, the silicon-based anode material is added and stirred at 600 rpm for 60 min. After vacuuming, the stirring speed is increased to 1000 rpm and stirred for 120 min to obtain a uniform electrode slurry. The slurry is uniformly coated onto a copper foil current collector, dried under vacuum at 120℃ for 12 hours, and then cut into discs with a diameter of 14 mm as working electrodes. In an argon-protected glove box, a CR2032 coin cell was assembled using a lithium metal sheet as the counter electrode, Celgard 2400 as the separator, and 1 M LiPF6 in EC:DEC (volume ratio 1:1) as the electrolyte.

[0167] Charge / discharge test: Using the Wuhan Landian Battery testing system, the battery was placed in a 30℃ constant temperature chamber. First, it underwent three charge / discharge cycles at a current density of 0.1C (1C is calculated as 2000 mA / g) for activation. Subsequently, it was tested at 0.005-1.5 V (vs. Li). + Within the voltage range of / Li, constant current charge-discharge cycle tests were performed at a current density of 1C. The initial discharge specific capacity, initial coulombic efficiency, and capacity retention after 100 cycles were recorded.

[0168] Table 1. Performance test results of coin cells using silicon-based anode materials from the examples and comparative examples.

[0169]

[0170] As shown in Example 1, constructing a 2nm thick copper layer on the surface of silicon-based particles via physical vapor deposition, and then using this as a catalytic site for in-situ growth of carbon nanotubes via chemical vapor deposition, yields a material that combines a highly conductive network with structural stability. Its initial coulombic efficiency reaches 91%, and its capacity retention rate after 100 cycles reaches 95.5%, making it a preferred solution for achieving high capacity and long cycle life. Examples 2 and 3 demonstrate that this process has good tolerance for metal layer thickness, which is beneficial for stable production. Examples 4 and 5 show that within a chemical vapor deposition time range of 60 to 240 minutes, the materials exhibit a powder resistivity below 1.1 Ω·cm and a cycle retention rate above 92%, proving the wide process window. Examples 6 and 7 demonstrate that by adjusting the mixed gas flow rate, the growth status of carbon nanotubes can be controlled within a wide range, obtaining different combinations of specific capacity and cycle performance to meet diverse needs. Example 8 uses iron as the metal coating layer, and the resulting material also exhibits low resistivity and good cycle performance, indicating that this technical solution has universal applicability to the selection of catalytic metal types. Examples 9 and 10 further confirm that chemical vapor deposition temperatures in the range of 600 to 800°C can effectively catalyze the growth of carbon nanotube networks, ensuring the stability of material properties.

[0171] Comparing Example 1 and Comparative Example 1, it can be seen that without a metal coating layer formed beforehand by physical vapor deposition, the silicon particle surface lacks catalytically active sites, and carbon nanotubes cannot be grown in situ during chemical vapor deposition, resulting in a material powder resistivity as high as 4.7 × 10⁻⁶. 4The carbon nanotubes exhibit extremely poor conductivity (Ω·cm), resulting in an initial battery efficiency of only 65.3% and a capacity retention rate plummeting to 10.3% after 100 cycles, failing to meet usage requirements. Comparison of Example 1 and Comparative Example 2 reveals that without the introduction of hydrogen gas during chemical vapor deposition, the reduction of the metal surface and the regulation of amorphous carbon by hydrogen cannot be achieved. This leads to sparse carbon nanotube growth, uneven morphology, and the inability to form a continuous, interconnected three-dimensional network, significantly reducing the material's cycle stability, with a capacity retention rate of only 80.5% after 100 cycles. Comparison of Example 1 and Comparative Example 3 shows that the simple physical mixing method used to introduce carbon nanotubes results in only mechanical contact with silicon particles, leading to weak bonding and a powder resistivity as high as 13.79 Ω·cm. Furthermore, the electrode structure is prone to collapse during cycling, resulting in a capacity retention rate of only 68.3%, far inferior to the integrated structure constructed through in-situ growth. Comparing Example 4 and Comparative Example 4, it is evident that when the chemical vapor deposition time is too short (only 10 min), the carbon nanotubes grow insufficiently, resulting in a fragmented network structure. This limits the binding of active materials and the improvement of conductivity, leading to decreased cycle performance and a capacity retention rate of only 82.6%. Comparing Example 5 and Comparative Example 5, it is evident that when the chemical vapor deposition time is too long (reaching 500 min), the carbon nanotubes overgrow, agglomerate, and even clog the pores. Although the resistivity is low and the cycle retention rate is high, the proportion of active materials is excessively compressed, resulting in an initial discharge specific capacity of only 787 mAh / g, severely sacrificing energy density. Comparing Example 6 and Comparative Example 6, it is evident that when the reactant gas flow rate is too low, the carbon source supply is insufficient, leading to weak carbon nanotube growth and insufficient network strength. This affects the structural stability and conductivity of the material, reducing the cycle retention rate to 86.5%. Comparing Example 7 with Comparative Example 7, it is evident that when the reactant gas flow rate is too high, the carbon nanotube diameter becomes excessively large, resulting in significant carbon deposition. Although a conductive network is constructed, this severely reduces the initial discharge specific capacity of the material to 1063 mAh / g. Comparing Example 2 with Comparative Example 8, it is evident that when the physical vapor deposition time is too short, and the metal coating thickness is only approximately 0.08 nm, the catalytic sites are insufficient and discontinuous, leading to low catalytic efficiency in subsequent carbon nanotube growth. The constructed three-dimensional network exhibits defects, resulting in poor material cycling stability and a capacity retention rate of only 76% after 100 cycles. Comparing Example 3 with Comparative Example 9, it is evident that when the physical vapor deposition time is too long, and the metal coating thickness increases to approximately 8 nm, the excessively thick inactive metal layer severely reduces the overall specific capacity of the material, with an initial discharge specific capacity of only 957 mAh / g, rendering it unsuitable for application. By comparing Examples 9 and 10 with Comparative Examples 10 and 11, it can be seen that the chemical vapor deposition temperature is crucial. If the temperature is too low, such as 550°C, the catalytic reaction cannot proceed effectively, and the performance deteriorates sharply. If the temperature is too high, such as 850°C, it may have an adverse effect on the microstructure of the material, and the overall performance is not optimal.In summary, this invention successfully constructs a robust three-dimensional conductive network with an ultrathin metal layer as a bridge and carbon nanotubes as a framework by precisely combining physical vapor deposition and chemical vapor deposition. This structure can simultaneously achieve high electronic conductivity, efficient ion transport, and effective buffering of volume expansion, thereby solving the core problems of rapid capacity decay and short cycle life of silicon-based anode materials.

[0172] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from its principles and spirit. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a silicon-based anode material with a three-dimensional conductive network, characterized in that, Includes the following steps: (1) A metal coating layer is formed on the surface of silicon-based particles by physical vapor deposition to obtain silicon-based particles coated with a metal layer; (2) The silicon-based particles coated with metal layer obtained in step (1) are placed in a reactor, and a mixed gas containing acetylene, hydrogen and nitrogen is introduced. Chemical vapor deposition is carried out at a temperature of 600-800℃. Carbon nanotubes are catalytically grown in situ on the surface of the metal coating layer to construct a three-dimensional conductive network of the coated particles and obtain a silicon-based anode material with a three-dimensional conductive network. The metal cladding layer is made of any one or more of copper, iron, cobalt, gold, silver, zinc, chromium, manganese, aluminum, and indium. The thickness of the metal cladding layer is 0.1-5 nm; In the mixture of acetylene, hydrogen, and nitrogen, the acetylene flow rate is 0.2-1.5 L / min, the hydrogen flow rate is 0.2-1.5 L / min, and the nitrogen flow rate is 0.5-2.0 L / min.

2. The preparation method according to claim 1, characterized in that, In step (1), the median diameter of the silicon-based particles is 20-600 nm.

3. The preparation method according to claim 1, characterized in that, In step (1), the silicon-based particles are any one or more of pure silicon, silicon oxide, silicon-carbon anode and silicon alloy.

4. The preparation method according to claim 1, characterized in that, In step (1), the physical vapor deposition is any one or more of magnetron sputtering, evaporation deposition and ion plating.

5. The preparation method according to claim 1, characterized in that, In step (1), the physical vapor deposition is magnetron sputtering.

6. The preparation method according to claim 1, characterized in that, In step (2), the reaction time for chemical vapor deposition is 30-360 min.

7. A silicon-based anode material having a three-dimensional conductive network, which is prepared by the preparation method according to any one of claims 1-6.

8. A lithium-ion battery, characterized in that, It includes the silicon-based anode material with a three-dimensional conductive network as described in claim 7.

Images