Silicon oxide composite anode materials based on photothermal synergistic modification and their preparation methods in lithium-ion batteries

Abstract

This invention provides a silicon oxide composite anode material based on photothermal synergistic modification, its preparation method, and a lithium-ion battery. The preparation method includes: dissolving a metal precursor and a reducing carbon source in water to obtain a precursor solution; dispersing carbon nanotubes in water to obtain a carbon nanotube dispersion; and adding the precursor solution and the carbon nanotube dispersion to a SiO₂ battery. x The material is subjected to photo-irradiation and then freeze-dried to obtain powder; the powder is then heat-treated to obtain a silicon oxide composite anode material. The silicon oxide composite anode material provided by this invention can effectively alleviate internal stress caused by volume changes, while simultaneously improving electronic conductivity and Li-ion conductivity during cycling. + The diffusion rate is increased, thus exhibiting significantly enhanced long-term cycling stability, which is beneficial for SiO₂. x The practical application of materials in lithium-ion batteries provides new solutions.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery preparation technology, specifically relating to a silicon oxide composite anode material based on photothermal synergistic modification, its preparation method, and a lithium-ion battery. Background Technology

[0002] Currently, commercial lithium-ion battery systems primarily use graphite as the anode material. However, limited by the relatively low theoretical capacity of graphite (approximately 372 mAh / g), its energy density cannot meet the ever-increasing demand for higher energy density. Therefore, developing novel anode materials with higher specific capacity has become an important research direction. Silicon oxide (SiO2) x Due to its high theoretical specific capacity and suitable lithium intercalation potential, SiO₂ is considered a potential alternative to graphite. x Significant volume expansion is often observed during cycling, which can lead to material pulverization and cracking, and trigger contact failure between the electrode and the current collector, thereby accelerating rapid capacity decay. Furthermore, SiO₂... x The low initial coulombic efficiency and poor intrinsic conductivity of anode materials further hinder their large-scale industrial application.

[0003] To address the above issues, current research on SiO x Material modification research mainly focuses on particle refinement, porous design, pre-lithiation, and composite with other materials. Among these, composite with carbon materials is considered a direct and effective method. Carbon materials not only possess excellent electrical conductivity but can also act as a protective layer, isolating the active silicon core from the electrolyte and reducing the formation of unstable solid electrolyte interphase (SEI) films. However, carbon coating alone cannot completely solve the problems inherent in silicon-based materials because silicon itself has high rigidity and significant volume expansion characteristics, causing the carbon layer to easily fracture due to mechanical stress during cycling, thus losing its protective effect.

[0004] Therefore, how to combine other components with excellent properties to construct a composite coating layer and further improve SiO₂ performance is a key challenge. x The electrochemical properties of materials have become a key research direction. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a silicon oxide composite anode material based on photothermal synergistic modification, its preparation method, and a lithium-ion battery. The silicon oxide composite anode material prepared by this invention can significantly suppress SiO₂ oxidation. x The volume expansion optimizes electron transport paths, resulting in superior cycle performance when used in lithium-ion batteries.

[0006] To achieve the above objectives, the present invention provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, wherein the preparation method includes:

[0007] A metal precursor and a reducing carbon source are dissolved in water and mixed to obtain a precursor solution. Carbon nanotubes are then dispersed in water to obtain a carbon nanotube dispersion. The precursor solution and the carbon nanotube dispersion are then added to SiO₂. x The material is subjected to light irradiation and then freeze-dried to obtain powder; the powder is then heat-treated to obtain a silicon oxide composite anode material.

[0008] Among them, SiO x In the material, the value of x is 0 < x ≤ 2; the molar ratio of the metal precursor to the reducing carbon source is 1 : (1-100); the metal precursor and SiO x The molar ratio of the materials is 1:(1-500); the carbon nanotubes and SiO x The molar ratio of the materials is 1 : (1-300).

[0009] According to a specific embodiment of the present invention, preferably, the metal precursor includes one or more of the following: copper chloride, copper sulfate, copper nitrate, magnesium chloride, magnesium sulfate, magnesium nitrate, aluminum chloride, aluminum sulfate, and aluminum nitrate.

[0010] According to a specific embodiment of the present invention, preferably, the reducing carbon source includes one or a combination of two or more of glucose, citric acid, oxalic acid, ascorbic acid, glucosamine, and triethanolamine. The reducing carbon source selected in this invention has significant advantages: its reducing properties are mild and controllable; in the absence of external conditions, the reduction rate of metal ions is relatively slow; after treatment with light of a specific wavelength, its reducing properties are enhanced, accelerating the reduction of metal ions; however, the enhanced reducing properties are still significantly weaker than strong reducing agents such as sodium borohydride, avoiding the formation of excessively large and unevenly distributed metal particles due to excessive reducing properties; moreover, in subsequent heat treatment processes, a carbon coating layer can be directly generated in situ on the material surface, eliminating the need for additional carbon precursors and simplifying the process.

[0011] In some specific embodiments, preferably, the molar ratio of the metal precursor to the reducing carbon source is 1:(1-50), more preferably 1:(5-20).

[0012] In some specific embodiments, preferably, the metal precursor and SiO x The molar ratio of the materials is 1:(1-200), more preferably 1:(100-150).

[0013] In some specific embodiments, preferably, the carbon nanotubes (CNTs) are combined with SiO2. x The molar ratio of the materials is 1:(1-150), more preferably 1:(50-90).

[0014] In some specific implementations, preferably, the SiO x The material is silicon suboxide, where 0 < x < 2.

[0015] According to a specific embodiment of the present invention, preferably, the concentration of the metal precursor in the precursor solution is 0.01-50 mol / L (more preferably 0.1-25 mol / L, and even more preferably 0.5-1 mol / L) based on the volume of the precursor solution.

[0016] According to a specific embodiment of the present invention, preferably, the mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.1%-50% (more preferably 0.5%-20%, and even more preferably 1%-2%), based on the mass of the carbon nanotube dispersion. Before use, the precursor solution and the carbon nanotube dispersion can be ultrasonically dispersed separately.

[0017] According to a specific embodiment of the present invention, preferably, the volume ratio of the precursor solution to the carbon nanotube dispersion is 1:(0.9-50), more preferably 1:(0.9-10), and even more preferably 1:(0.9-2).

[0018] According to a specific embodiment of the present invention, preferably, the molar ratio of the metal precursor to the carbon nanotube is 1:(1-20), more preferably 1:(1-5).

[0019] According to a specific embodiment of the present invention, preferably, the wavelength of the light source for the light treatment is 200-400 nm, more preferably 275-394 nm; further preferably, the wavelength λ of the light source is one or a combination of two or more of 275 nm, 280 nm, 340 nm, 355 nm, 365 nm, 380 nm, 390 nm, and 394 nm. The present invention can achieve the desired wavelength by using a filter. In the present invention, a reducing carbon source (e.g., ascorbic acid) generates strongly reducing dehydroascorbic acid free radicals under ultraviolet light irradiation at the aforementioned wavelengths, which can significantly increase the reduction rate of metals. Simultaneously, due to the presence of ultraviolet light, the CNT surface can be effectively activated, generating oxygen-containing groups such as hydroxyl groups, thereby making it easier to react with SiO₂. x The active sites on the surface react, which effectively enhances the interfacial bonding strength.

[0020] According to a specific embodiment of the present invention, preferably, the sum of the light treatment times is 1-20 hours, more preferably 1-5 hours.

[0021] In some specific embodiments, preferably, the optical power density of the illumination treatment is 0.59-2.36 W / cm². 2 In this invention, a xenon lamp with a light source power of 100-400W can be used for illumination treatment.

[0022] According to a specific embodiment of the present invention, preferably, the precursor solution and the carbon nanotube dispersion are added to SiO₂. x The method of phototreatment in the material can be selected from any of the following:

[0023] Method 1: First, add the precursor solution to SiO2. x The material is light-treated for 0.5-10 hours (more preferably 1-2 hours), and then the carbon nanotube dispersion is added, and the light treatment continues for another 0.5-10 hours (more preferably 1-2 hours).

[0024] Method 2: Add the precursor solution and the carbon nanotube dispersion to SiO2. x After the material is processed, it is then subjected to light treatment for 1-20 hours (more preferably 1-5 hours).

[0025] Method 3: First add the carbon nanotube dispersion to SiO x The material is light-treated for 0.5-10 hours (more preferably 1-2 hours), and then the precursor solution is added, and the light treatment continues for another 0.5-10 hours (more preferably 1-2 hours).

[0026] According to a specific embodiment of the present invention, preferably, the precursor solution and the carbon nanotube dispersion are added to SiO₂. x Method two involves phototreatment of the material. By adding the precursor solution and carbon nanotube dispersion first, and then performing phototreatment simultaneously, the synchronicity and uniformity of metal ion reduction, functional group activation, and bonding interface formation processes can be ensured. This optimizes the structure of the three-dimensional conductive network, maximizes battery cycle performance, and effectively avoids the interaction between metal and CNTs on SiO2 during stepwise feeding. x Competition among surface active sites promotes uniform dispersion of the phases, overcoming the drawbacks of traditional methods such as complex processes and poor interfacial bonding. More preferably, method two involves simultaneously adding the precursor solution and the carbon nanotube dispersion to SiO₂. x The material is subjected to light treatment for 1-20 hours (more preferably 1-5 hours).

[0027] According to a specific embodiment of the present invention, preferably, the heat treatment is performed under a protective atmosphere, the heat treatment temperature is 300-1000℃, the heat treatment time is 3-12h, and the heating rate is 2-10℃ / min; more preferably, the heat treatment temperature is 300-800℃, the heat treatment time is 3-8h, and the heating rate is 2-5℃ / min; even more preferably, the heat treatment temperature is 400-500℃, and the heat treatment time is 3-5h; even more preferably, the protective atmosphere includes an argon atmosphere and / or a nitrogen atmosphere. In the present invention, the heat treatment enables the SiO2 in the sample to be removed. x The interfacial bonding ability with metal particles and CNTs is significantly enhanced, forming stronger chemical bonds; more importantly, the reducing carbon source can undergo pyrolysis and carbonization in this process, generating a carbon coating layer that uniformly coats the metal-supported SiO. x The particle surface can not only improve the conductivity of the material, but also effectively suppress SiO2. x The problem of particle volume expansion during the recycling process.

[0028] In some specific embodiments, preferably, the freeze-drying process involves pre-freezing the light-treated solution at a temperature of -20°C to -30°C for 12-60 hours, and then vacuum freeze-drying at -40°C to -60°C for 12-60 hours; more preferably, the pre-freezing time is 12-24 hours, and the vacuum freeze-drying time is 36-60 hours.

[0029] The preparation method provided by this invention first applies a specific wavelength of light to the metal salt / CNT dispersion, thereby achieving directional and accelerated reduction of metal ions, improving reduction efficiency, and simultaneously activating SiO₂. x The surface functional groups of CNTs promote the interaction between metal particles, CNTs, and SiO. x A stable chemical bonding interface is formed between the metal particles to construct a highly uniform and tightly interwoven three-dimensional conductive network, thereby optimizing the interface electron transport path and structural stability, improving the kinetic performance and bonding strength at the material interface, and achieving in-situ generation of metal particles and interface bonding in one step. Subsequently, the material is heat-treated to induce controlled pyrolysis of the reducing carbon source, which then bonds to the metal-supported SiO₂. x A continuous carbon coating layer is formed in situ on the particle surface. This carbon coating layer enhances local conductivity and provides mechanical constraint to suppress volume expansion during charging and discharging. Simultaneously, the carbon coating layer can form a composite buffer structure with the CNT conductive network, creating an amorphous carbon composite layer to exert a synergistic protection mechanism, thereby significantly suppressing SiO₂ formation. x Volume expansion.

[0030] The present invention also provides a silicon oxide composite anode material, which is prepared by the above-mentioned method for preparing silicon oxide composite anode materials based on photothermal synergistic modification.

[0031] According to a specific embodiment of the present invention, preferably, the silicon oxide composite anode material has SiO₂ particles loaded with metal particles. x The structure has an amorphous carbon composite layer coated on its surface. This amorphous carbon composite layer includes a buffer layer formed by carbon nanotubes and a carbon coating layer formed by a reducing carbon source. In this invention, the carbon coating layer formed by the reducing carbon source is not entirely on the outer side; a portion of the carbon coating layer formed by the reducing carbon source may also exist between the metal particle layer and the CNT buffer layer.

[0032] According to a specific embodiment of the present invention, preferably, with SiO as 100% by mass, the loading of the metal particles is 0.3%-3%, and the mass of the metal particles is measured in atomic mass.

[0033] According to a specific embodiment of the present invention, preferably, the thickness of the buffer layer is 5-20 nm and the thickness of the carbon coating layer is 5-25 nm.

[0034] In some specific embodiments, preferably, the size of the metal particles is 1-10 nm.

[0035] The present invention also provides a lithium-ion battery, wherein the lithium-ion battery includes a negative electrode, a counter electrode, a separator and an electrolyte, and the negative electrode contains the above-mentioned silicon oxide composite negative electrode material.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) The method for preparing silicon oxide composite anode material based on photothermal synergistic modification provided by the present invention does not adopt the traditional stepwise modification or strong reducing agent synthesis route, but innovatively introduces the strategy of photoirradiation treatment and photoirradiation treatment after all materials are added, forming a unique three-dimensional conductive network and synergistically optimized composite buffer system, which is manifested in: ① the metal particles generated in situ by photoirradiation can promote the formation of uniform and stable chemical bonding interfaces and optimize electron transport; ② the uniformly dispersed CNTs and the carbon coating layer generated in situ by heat treatment can effectively suppress SiO x The volume expansion of the material is a concern; therefore, the three-dimensional conductive network and the synergistically optimized composite buffer system can significantly improve the structural stability and cycling performance of the material.

[0038] (2) The method for preparing silicon oxide composite anode material based on photothermal synergistic modification provided by the present invention can realize SiO2 by simultaneously optimizing the electron transport path and volume expansion constraint mechanism. xThe material's superior cycle performance, while also ensuring safety, facilitates large-scale application.

[0039] (3) The silicon oxide composite anode material provided by this invention can effectively alleviate the internal stress caused by volume changes, while improving the electronic conductivity and Li during cycling. + The diffusion rate is increased, thus exhibiting significantly enhanced long-term cycling stability, which is beneficial for SiO₂. x The practical application of materials in lithium-ion batteries provides new solutions. Attached Figure Description

[0040] Figure 1 Cycle performance diagrams of batteries made from the negative electrode materials provided in Examples 1-13 and Comparative Examples 1-5.

[0041] Figure 2 Scanning electron microscope (SEM) images of the negative electrode materials prepared in Comparative Example 1, Example 1, Example 6, and Example 10.

[0042] Figure 3 Transmission electron microscope (TEM) images of the negative electrode material prepared in Example 1 at different magnifications.

[0043] Figure 4 Transmission electron microscope (TEM) image of the negative electrode material prepared in Example 1 and corresponding energy dispersive spectral distribution diagrams of C, Cu, O, and Si elements.

[0044] Figure 5 AC impedance spectra of batteries made from the negative electrode materials provided in Examples 1, 6, 10 and Comparative Example 1.

[0045] Figure 6 The first charge-discharge curves of batteries made from the negative electrode materials provided in Examples 1-13 and Comparative Example 1. Detailed Implementation

[0046] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0047] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0048] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0049] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0050] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0051] Example 1:

[0052] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0053] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0054] (2) The precursor solution and carbon nanotube dispersion were simultaneously added to SiO at a volume ratio of 1:1.8. x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 2 hours using a 300W xenon lamp, during which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials is 1:150, and the CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0055] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0056] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0057] Example 2:

[0058] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0059] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0060] (2) The precursor solution and carbon nanotube dispersion were simultaneously added to SiO at a volume ratio of 1:1. x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 1 hour using a 300W xenon lamp, in which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials is 1:150, and the CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:90. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0061] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 3h.

[0062] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0063] Example 3:

[0064] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0065] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 1 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 2% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0066] (2) The precursor solution and carbon nanotube dispersion were simultaneously added to SiO at a volume ratio of 1:1. x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 2 hours using a 300W xenon lamp, during which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the bulk materials is 1:100, and the CNTs and SiO2 in the carbon nanotube dispersion are... x The molar ratio of the materials was 1:60. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0067] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 500℃, and the heat treatment time is 5h.

[0068] In the silicon suboxide composite anode material prepared in this embodiment, the metal particle loading is 1.44% based on the mass of SiO being 100%, and the mass of the metal particles is measured in atomic mass.

[0069] Example 4:

[0070] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0071] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0072] (2) The precursor solution and carbon nanotube dispersion were simultaneously added to SiO at a volume ratio of 1:1.8. xIn the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 3 hours using a 300W xenon lamp, during which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials is 1:150, and the CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0073] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 500℃, and the heat treatment time is 3h.

[0074] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0075] Example 5:

[0076] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0077] (1) AlCl3 and oxalic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of AlCl3 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0078] (2) The precursor solution and carbon nanotube dispersion were simultaneously added to SiO at a volume ratio of 1:1.8. x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 2 hours using a 300W xenon lamp, in which AlCl3 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials is 1:150, and the CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0079] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0080] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.41%, and the mass of the metal particles is in atomic mass.

[0081] Example 6:

[0082] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0083] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0084] (2) Add the carbon nanotube dispersion to SiO x In the material (x=1), CNTs and SiO in the carbon nanotube dispersion x The molar ratio of the materials was 1:50, and then light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) was used. 2 The system was irradiated for 1 hour using a 300W xenon lamp; then, a precursor solution was added, and the reaction system was irradiated again for 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The precursor solution contained CuSO4 and SiO2. x The molar ratio of the materials was 1:150. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0085] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0086] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0087] Example 7:

[0088] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0089] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0090] (2) Add the carbon nanotube dispersion to SiO x In the material (x=1), CNTs and SiO in the carbon nanotube dispersion x The molar ratio of the materials was 1:50, and then light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) was used. 2 The system was irradiated for 2 hours using a 300W xenon lamp; then, a precursor solution was added, and the reaction system was irradiated again for 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The precursor solution contained CuSO4 and SiO2. x The molar ratio of the materials was 1:150. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0091] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 3h.

[0092] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0093] Example 8:

[0094] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0095] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0096] (2) Add the carbon nanotube dispersion to SiO x In the material (x=1), CNTs and SiO in the carbon nanotube dispersion x The molar ratio of the materials was 1:50, and then light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) was used. 2 The system was irradiated for 2 hours using a 300W xenon lamp; then, a precursor solution was added, and the reaction system was irradiated again for 2 hours using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The precursor solution contained CuSO4 and SiO2. x The molar ratio of the materials was 1:150. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0097] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 500℃, and the heat treatment time is 3h.

[0098] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0099] Example 9:

[0100] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0101] (1) AlCl3 and oxalic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of AlCl3 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0102] (2) Add the carbon nanotube dispersion to SiO x In the material (x=1), CNTs and SiO in the carbon nanotube dispersion x The molar ratio of the materials was 1:50, and then light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) was used. 2 The system was irradiated for 1 hour using a 300W xenon lamp; then, a precursor solution was added, and the reaction system was irradiated again for 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The AlCl3 and SiO2 in the precursor solution... x The molar ratio of the materials was 1:150. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0103] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0104] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.41%, and the mass of the metal particles is in atomic mass.

[0105] Example 10:

[0106] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0107] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0108] (2) Add the precursor solution to SiO x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 1 hour using a 300W xenon lamp, in which CuSO4 and SiO2 in the precursor solution were reacted. xThe molar ratio of the materials was 1:150; then, a carbon nanotube dispersion was added, and the reaction system was irradiated for another 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0109] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0110] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0111] Example 11:

[0112] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0113] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0114] (2) Add the precursor solution to SiO x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 2 hours using a 300W xenon lamp, during which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials was 1:150; then, a carbon nanotube dispersion was added, and the reaction system was irradiated for another 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The CNTs and SiO2 in the carbon nanotube dispersion... xThe molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0115] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 3h.

[0116] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0117] Example 12:

[0118] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0119] (1) CuSO4 and ascorbic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of CuSO4 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0120] (2) Add the precursor solution to SiO x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 2 hours using a 300W xenon lamp, during which CuSO4 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials was 1:150; then, a carbon nanotube dispersion was added, and the reaction system was further irradiated with light at a wavelength of λ=365nm for 2 hours. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The CNTs and SiO₂ in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0121] (3) After freeze-drying, the obtained powder is placed in a tube furnace for high-temperature pyrolysis and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 500℃, and the heat treatment time is 3h.

[0122] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.96%, and the mass of the metal particles is in atomic mass.

[0123] Example 13:

[0124] This embodiment provides a method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, including the following steps:

[0125] (1) AlCl3 and oxalic acid were dissolved in deionized water at a molar ratio of 1:10 and mixed to obtain a precursor solution. The concentration of AlCl3 in the precursor solution was 0.5 mol / L, and uniform dispersion was achieved by ultrasonic treatment. Next, deionized water and CNT were mixed to prepare a carbon nanotube dispersion with a CNT concentration of 1% by mass, and uniform dispersion was also achieved by ultrasonic treatment.

[0126] (2) Add the precursor solution to SiO x In the material (x=1), light with a wavelength λ = 365nm (optical power density of 1.77 W / cm²) is then used. 2 The sample was irradiated for 1 hour using a 300W xenon lamp, in which AlCl3 and SiO2 in the precursor solution were reacted. x The molar ratio of the materials was 1:150; then, a carbon nanotube dispersion was added, and the reaction system was irradiated for another 1 hour using light with a wavelength of λ=365nm. The volume ratio of the precursor solution to the carbon nanotube dispersion was 1:1.8. The CNTs and SiO2 in the carbon nanotube dispersion... x The molar ratio of the materials was 1:50. After the photo-reaction was completed, the resulting solution was placed in a -20℃ freezer for 24 hours for pre-freezing, and then placed in a vacuum freeze dryer for drying at -40℃ for 48 hours.

[0127] (3) After freeze-drying, the obtained powder is placed in a tube furnace and heated for high-temperature pyrolysis, and then cooled to obtain silicon suboxide composite anode material. Argon gas is continuously introduced for protection during the heating, high-temperature pyrolysis and cooling process in the tube furnace. The heating rate is 5 ℃ / min, the heat treatment temperature is 400℃, and the heat treatment time is 4h.

[0128] In the silicon suboxide composite anode material prepared in this embodiment, the mass of SiO is 100%, the loading of metal particles is 0.41%, and the mass of the metal particles is in atomic mass.

[0129] Comparative Example 1:

[0130] This comparative example uses silicon suboxide products commercially available from Xinno Chemical (Shenzhen) Co., Ltd., and is named Comparative Example 1.

[0131] The scanning electron microscope image of the silicon suboxide product in this comparative example is as follows: Figure 2 As shown in (a) of the diagram.

[0132] Comparative Example 2:

[0133] This comparative example provides a method for preparing a negative electrode material, which is carried out in accordance with the steps of Example 1, except that no metal precursor is added to the precursor solution, and the concentration of ascorbic acid in the precursor solution is kept at 5 mol / L. The remaining steps and proportions remain unchanged to obtain the negative electrode material.

[0134] Comparative Example 3:

[0135] This comparative example provides a method for preparing a negative electrode material, which is carried out in accordance with the steps of Example 1, except that the carbon nanotube dispersion is replaced with pure deionized water and CNTs are not introduced. The remaining steps and proportions remain unchanged to obtain the negative electrode material.

[0136] Comparative Example 4:

[0137] This comparative example provides a method for preparing a negative electrode material, which is carried out in accordance with the steps of Example 1, except that the wavelength of the light source during the light treatment is changed and a filter with λ=520nm is used to treat the material with light. The other steps and the proportions remain unchanged to obtain the negative electrode material.

[0138] Comparative Example 5:

[0139] This comparative example provides a method for preparing a negative electrode material, which is carried out in accordance with the steps of Example 1, except that: no heat treatment process is performed in step (3), and the remaining steps and dosage ratios remain unchanged to obtain the negative electrode material.

[0140] The negative electrode materials of Examples 1-13 and Comparative Examples 1-5 were used to fabricate electrodes, and 2032 coin cells were assembled for electrochemical testing. The electrochemical testing was carried out according to the following steps:

[0141] The negative electrode material to be tested was mixed evenly in a mass ratio of negative electrode material: conductive agent (Super P): binder (SBR): CMC = 80:10:7:3. Water was used as a solvent to form a slurry, which was then coated onto copper foil with a coating thickness of 100 μm. The coating was then placed in a vacuum oven and dried at 80 °C for 12 h to obtain the negative electrode sheet.

[0142] CR2032 coin cells were assembled in a glove box (water and oxygen levels were both less than 0.01 ppm). The cells used lithium foil as the counter electrode, polyethylene as the separator, and LiF6 as the electrolyte, which was a mixed solution of DMC (dimethyl carbonate), DEC (diethyl carbonate), and EC (ethylene carbonate) (DMC:DEC:EC volume ratio of 1:1:1). The concentration of LiF6 was 1 mol / L.

[0143] The assembled button cells were subjected to charge-discharge cycle tests at a 1C current density on a Landian system (manufacturer: Wuhan Landian Electronics Co., Ltd., model CT3002A). The test results are shown in Table 1. Figure 1 , Figure 6 As shown.

[0144] Using a CHI660E electrochemical workstation (manufactured by Shanghai Chenhua Instruments Co., Ltd.), the negative electrode materials provided in Examples 1, 6, 10, and Comparative Example 1 were subjected to AC impedance spectroscopy tests under standard testing conditions. The obtained AC impedance spectra are shown below. Figure 5 As shown.

[0145] Table 1. Comparison of electrochemical performance between Examples 1-13 and Comparative Examples 1-5

[0146]

[0147] As shown in Table 1, although the first-cycle charge specific capacity of the batteries prepared in Examples 1-13 and Comparative Examples 2-5 was lower than that of the battery prepared in Comparative Example 1, this is because CNTs, reducing carbon sources, and other substances were introduced during the modification and coating process, reducing the content of active materials in the negative electrode, which is unavoidable in the material optimization process. However, the first-cycle coulombic efficiency of the batteries prepared in Examples 1-13 was higher than that of Comparative Examples 1-5. It is also noteworthy that the batteries prepared with the modified silicon suboxide negative electrode material of Examples 1-13 showed a significant improvement in capacity retention after 200 cycles. Figure 1 The cycle performance graphs of batteries made from the negative electrode materials provided in Examples 1-13 and Comparative Example 1 are shown (triangles represent coulombic efficiency, and spheres represent reversible capacity). Figure 1 It can be seen that the modified batteries prepared in Examples 1-13 showed significantly improved cycle performance after 200 cycles, confirming the results in Table 1.

[0148] The improved long-cycle performance of the above embodiments is mainly due to the synergistically optimized structural design of the present invention:

[0149] (1) Uniformly dispersed CNTs can be used in SiO x Long-range electronic pathways are established between particles. At the same time, the inherent excellent elasticity and mechanical strength of CNTs can effectively buffer SiO2. x Volume deformation during charging and discharging, thereby suppressing particle pulverization;

[0150] (2) Using a carbon source with mild reducing properties can avoid the formation of metal particles that are too large and unevenly distributed due to excessive reducing properties. Furthermore, by introducing light treatment of a specific wavelength, this invention can directionally accelerate the reduction process of metal ions and simultaneously activate the surface functional groups of the material, promoting the formation of metal particles, CNTs, and SiO. x A stable chemical bonding interface is formed between them, thereby optimizing the interface electron transport path and structural stability, and solving the problem that the reduction rate of metal ions by a mildly reducing carbon source is slow under conditions without external field intervention.

[0151] (3) During the inert atmosphere heat treatment process, the reducing carbon source undergoes controlled pyrolysis, resulting in SiO₂. x A continuous carbon coating layer is generated in situ on the particle surface; this carbon coating layer has the functions of enhancing local conductivity, providing mechanical constraints to suppress particle expansion during charging and discharging, and constructing a composite buffer system with the CNT conductive network, thereby forming a synergistic protection mechanism.

[0152] The synergistic effect of the above structural design effectively solves the SiO2 problem. x The core defects of the anode material, namely low electronic conductivity and significant volume effect, significantly improve its long-cycle stability. In contrast, Comparative Example 2, due to the lack of a metal precursor, suffers from the incompatibility between CNTs and SiO2. x The bonding between them is weak, making them prone to aggregation and unable to form a uniform conductive network, and the interface stability is insufficient. Comparative Example 3, due to the lack of CNTs, not only loses the long-range framework that maintains structural stability, but also, due to the lack of CNTs as a dispersion carrier, the metal is prone to aggregation, thereby reducing the SiO₂ content. x Surface ion transport channels; Comparative Example 4, due to the use of infrared light instead of ultraviolet light treatment, resulted in insufficient light energy, making it difficult to achieve directional accelerated reduction of metal ions and effectively activate SiO. x / CNT surface functional groups; Comparative Example 5, due to lack of calcination, resulted in the inability of the reducing carbon source to form a protective carbon layer to suppress volume expansion, and the lack of calcination also prevented the removal of the coating on SiO. xSurface impurities lead to the loss and coverage of surface active sites. Therefore, batteries made from the negative electrode materials of Comparative Examples 2-5 exhibit low capacity retention after 200 cycles and poor long-term cycle stability. In contrast, the negative electrode material of Comparative Example 1, although unmodified, retains intact SiO₂. x The original structure, without the more severe structural damage, ion transport obstruction and surface active site loss caused by the above-mentioned component deficiency or process defects, therefore the long cycle stability of the battery made thereis better than that of Comparative Examples 2-5, but still not as good as that of Examples 1-13.

[0153] This invention further explores the effect of the feeding sequence of the precursor solution and carbon nanotube dispersion on cycling performance. Test results show that the strategy of uniform phototreatment (Method 2) can significantly optimize the cycling performance of the material. Examples 1-5, using Method 2, showed specific capacities of 1054.09, 1049.92, 1092.58, 994.87, and 1062.88 mAh / g after 200 cycles, with a capacity retention of >82%. This is significantly better than Method 3 (capacity retention >75% in Examples 6-9), Method 1 (capacity retention >65% in Examples 10-13), and the unmodified Comparative Example 1 (capacity retention 55.19%), which involves adding CNTs first followed by the metal precursor. The performance differences stem from the regulatory effect of the feeding sequence on the microstructure: when Method 2 is used, with the precursor solution and carbon nanotube dispersion added first, followed by phototreatment, the metal ions and CNTs can work together on SiO₂. x The surface of the surface, thereby avoiding excessive occupation of active sites by a single component, promotes uniform dispersion of each phase, enhances interfacial bonding ability, and ultimately constructs a highly uniform, tightly interwoven three-dimensional conductive network, forming a co-modified interface. For example... Figure 2 (b) and Figure 3 As shown in (a) and (b) of Example 1, CNTs exhibit a uniform distribution in the modified material. Meanwhile, Figure 3 (c) and (d) in Example 1 show that, after heat treatment, an amorphous carbon composite layer coating structure can be formed in situ on the surface of the negative electrode material, including a buffer layer formed by CNTs and a carbon coating layer formed by a reducing carbon source. The thickness of the buffer layer is 5-10 nm, and the thickness of the carbon coating layer is 15-25 nm. Furthermore, Figure 4 The results confirmed the presence of copper, and that the element was evenly distributed; at the same time Figure 3 No metal particles were clearly observed at a magnification scale of 10 nm, therefore the metal particles loaded in Example 1 were small in size, ranging from 1 to 10 nm.

[0154] In contrast, when using method three—adding carbon nanotube dispersion first and then precursor solution—CNTs preferentially occupy some sites to establish initial connections, while the subsequently added metal mainly modifies the CNTs and the remaining SiO₂. x The surface area limits the promotion of CNT dispersion; therefore, the sample of Example 6 exhibits uneven CNT distribution and agglomeration (e.g., Figure 2 (as shown in (c)); when the method of adding the precursor solution first and then the carbon nanotube dispersion is adopted, the SiO2 will be passivated by the metal layer. x The surface makes it difficult for subsequent CNTs to anchor effectively, forming a loose external network (such as...). Figure 2 As shown in (d) in the figure, the long-range conductivity and mechanical support advantages of CNTs cannot be effectively transferred to the active material. Figure 5 The electrochemical impedance results further illustrate this structural difference: Example 1 exhibits the lowest impedance (R) (R0). 实施例1 < R 实施例6 < R 实施例10 < R 对比例1 This indicates that it has the strongest interfacial bonding ability. Therefore, this invention can optimize the structure of the three-dimensional conductive network by controlling the feeding sequence, thereby maximizing the improvement of battery cycle performance.

[0155] In addition, by Figure 6 The initial charge-discharge curves show that the voltage of each sample stabilizes at a plateau of approximately 0.2 V during discharge, and the voltage plateau appears at approximately 0.5 V during the charging phase, indicating that the charge-discharge plateau conforms to the SiO2 standard. x The charging and discharging behavior of the material is understood; therefore, the negative electrode material prepared using the method provided in this invention successfully retains SiO₂. x The inherent structural characteristics of active substances.

[0156] In summary, this invention, through a photothermal synergistic modification strategy and an optimized feeding process, achieves SiO₂ modification. x A three-dimensional composite structure consisting of "in-situ reduced metal nanoparticles, uniformly dispersed CNT long-range conductive networks, and an in-situ generated carbon coating layer" was successfully constructed on the material surface. The preparation method provided by this invention innovatively achieves simultaneous regulation of directional reduction of metal ions and activation of functional groups, stable bonding of each phase interface, and in-situ controllable growth of the carbon coating layer, thereby synergistically optimizing the charge transport dynamics and structural stress regulation capability of the material, and thus significantly improving the long-cycle performance and stability of the battery.

Claims

1. A method for preparing a silicon oxide composite anode material based on photothermal synergistic modification, characterized in that, The preparation method includes: A metal precursor and a reducing carbon source are dissolved in water and mixed to obtain a precursor solution. Carbon nanotubes are then dispersed in water to obtain a carbon nanotube dispersion. The precursor solution and the carbon nanotube dispersion are then added to SiO₂. x The material is subjected to light irradiation and then freeze-dried to obtain powder; the powder is then heat-treated to obtain a silicon oxide composite anode material. Among them, SiO x In the material, the value of x is 0 < x ≤ 2; The molar ratio of the metal precursor to the reducing carbon source is 1:(1-100); The metal precursor and SiO x The molar ratio of the materials is 1:(1-500); the carbon nanotubes and SiO x The molar ratio of the materials is 1 : (1-300).

2. The preparation method according to claim 1, characterized in that, The metal precursor includes one or more of the following: copper chloride, copper sulfate, copper nitrate, magnesium chloride, magnesium sulfate, magnesium nitrate, aluminum chloride, aluminum sulfate, and aluminum nitrate.

3. The preparation method according to claim 1, characterized in that, The reducing carbon source includes one or more of glucose, citric acid, oxalic acid, ascorbic acid, glucosamine, and triethanolamine.

4. The preparation method according to claim 1, characterized in that, The concentration of the metal precursor in the precursor solution is 0.01-50 mol / L, based on the volume of the precursor solution. The mass fraction of carbon nanotubes in the carbon nanotube dispersion is 0.1%-50% based on the mass of the carbon nanotube dispersion.

5. The preparation method according to claim 4, characterized in that, The volume ratio of the precursor solution to the carbon nanotube dispersion is 1:(0.9-50).

6. The preparation method according to claim 1, 4, or 5, characterized in that, The molar ratio of the metal precursor to carbon nanotubes is 1:(1-20).

7. The preparation method according to claim 1, characterized in that, The wavelength of the light source used for the light treatment is 200-400nm.

8. The preparation method according to claim 7, characterized in that, The total duration of the light treatment is 1-20 hours.

9. The preparation method according to claim 1, 7, or 8, characterized in that, The precursor solution and the carbon nanotube dispersion were added to SiO₂. x The method of phototreatment in the material can be selected from any of the following: Method 1: First, add the precursor solution to SiO2. x The material is treated with light for 0.5-10 hours, and then the carbon nanotube dispersion is added, followed by another 0.5-10 hours of light treatment. Method 2: Add the precursor solution and the carbon nanotube dispersion to SiO2. x After the material is processed, it is then subjected to light treatment for 1-20 hours; Method 3: First add the carbon nanotube dispersion to SiO x The material is treated with light for 0.5-10 hours, and then the precursor solution is added, followed by another 0.5-10 hours of light treatment.

10. The preparation method according to claim 1, characterized in that, The heat treatment is carried out under a protective atmosphere, the temperature is 300-1000℃, the time is 3-12h, and the heating rate is 2-10℃ / min.

11. A silicon oxide composite anode material, characterized in that, It is prepared by the method for preparing silicon oxide composite anode material based on photothermal synergistic modification as described in any one of claims 1-10.

12. The silicon oxide composite anode material according to claim 11, characterized in that, This silicon oxide composite anode material has SiO₂ loaded with metal particles. x The structure has an amorphous carbon composite layer on its surface, the amorphous carbon composite layer comprising a buffer layer formed by carbon nanotubes and a carbon coating layer formed by a reducing carbon source.

13. The silicon oxide composite anode material according to claim 12, characterized in that, SiO x The mass of the metal particles is 100%, and the loading of the metal particles is 0.3%-3%, with the mass of the metal particles measured in atomic mass.

14. The silicon oxide composite anode material according to claim 12, characterized in that, The thickness of the buffer layer is 5-20 nm, and the thickness of the carbon coating layer is 5-25 nm.

15. A lithium-ion battery, characterized in that, The lithium-ion battery includes a negative electrode, a counter electrode, a separator, and an electrolyte, wherein the negative electrode contains the silicon oxide composite negative electrode material as described in any one of claims 11-14.

Images