SiO-coated HACDs lithium ion battery negative electrode material and preparation method thereof

Abstract

The invention relates to the technical field of electrochemical energy storage materials, and particularly discloses a SiO-coated HACDs lithium ion battery negative electrode material and a preparation method thereof.According to the material, micron-sized SiO serves as an inner core, the surface of the inner core is coated with humic acid derived carbon dots through firm amido bond chemical bonding, and a core-shell structure is formed. The preparation method comprises the following steps: carrying out surface amination modification on SiO particles by using a silane coupling agent, catalyzing amino groups on the surfaces of the SiO particles and carboxyl groups on the surfaces of the HACDs to carry out amidation reaction by using a condensation activator to form a chemically bonded precursor, and finally carrying out high-temperature carbonization treatment in an inert atmosphere to obtain a final product. By strengthening a chemical bonding strategy, the interface bonding strength of an HACDs coating layer and a SiO substrate is effectively improved, the overall conductivity of the material is improved, meanwhile, volume expansion of SiO in the charging and discharging process is remarkably buffered, and formation of a stable solid electrolyte interface film is promoted. The composite material is used as a lithium ion battery negative electrode active material, shows high initial coulombic efficiency, excellent rate capability and long cycle stability, is simple in preparation process, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials technology, specifically relating to the research and preparation of electrode materials for lithium-ion batteries. More specifically, this invention relates to a silicon-carbon composite anode material, particularly to a novel composite material (SiO@HACDs) formed by chemically coating silicon monoxide (SiO) with humic acid-derived carbon dots (HACDs), as well as the preparation method of this material and its application in high-energy-density, long-cycle-life lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries, with their outstanding advantages such as high energy density, long cycle life, and no memory effect, have become the core power technology for portable electronic devices, new energy vehicles, and stationary energy storage systems. The performance of the anode material is one of the key factors determining the energy density, power density, and cycle stability of lithium-ion batteries. Currently, commercial lithium-ion batteries commonly use graphite as the anode material, but its theoretical specific capacity is relatively low (only 372 mAh·g⁻¹), which is gradually failing to meet the urgent demand for continuously improving energy density in next-generation high-energy-density energy storage devices (such as electric vehicles and large-scale energy storage).

[0003] Against this backdrop, silicon-based materials, such as elemental silicon (Si) and its oxide (SiO2), are becoming increasingly important. x Due to its extremely high theoretical specific capacity (Si: approximately 4200 mAh·g⁻¹; SiO: approximately 2400 mAh·g⁻¹), silicon monoxide (SiO) has become the most promising candidate for next-generation anode materials. Among them, silicon monoxide (SiO) has attracted widespread attention because it can generate inert phases of Li₂O and Li₄SiO₄ that can buffer volume stress during the first charge-discharge process, and its cycle stability is better than that of Si. However, SiO still has the following inherent defects as an anode material, which seriously restricts its commercial application: (1) Huge volume expansion: During the lithium ion insertion / extraction process, SiO will still undergo significant volume changes (>200%), which will cause the active material particles to break and pulverize, as well as the electrical contact failure between the active material and the conductive network and current collector, resulting in rapid capacity decay.

[0004] (2) Poor intrinsic conductivity: SiO is a semiconductor material with low electronic conductivity, which limits the rate performance of the battery and the utilization rate of active materials.

[0005] (3) Low initial coulombic efficiency (ICE): During the first discharge, SiO reacts irreversibly with lithium ions to form a solid electrolyte interphase (SEI) film and an inert phase, consuming a large amount of active lithium source, resulting in low initial charge and discharge efficiency and reducing the energy density of the whole battery.

[0006] To overcome the above defects, existing technologies mainly adopt the following strategies to modify SiO: (1) Nanostructuring: SiO is prepared into nanoparticles, nanowires or nanofilms to shorten the ion / electron transport path and relieve stress. However, the preparation process of nanomaterials is complicated, the yield is low, the tap density is small, and the surface side reactions are more intense. (2) Composite / coating: SiO is composited with carbon materials (such as amorphous carbon, graphene, carbon nanotubes) to utilize the excellent conductivity and flexibility of carbon materials to construct a conductive network and buffer volume changes. However, these carbon coating layers are usually prepared by physical mixing, mechanical grinding or simple liquid phase deposition, and the bonding force between them and the SiO matrix is ​​often weak, mostly physical adsorption or weak interaction. During long-term and intense volume expansion / contraction cycles, the coating layer is prone to peeling or damage, resulting in a decrease in the modification effect. (3) Structural design: Hollow, porous or core-shell structures are constructed to reserve expansion space. These methods are usually more complex and the structural stability control is difficult. (4) Pre-lithiation: The electrode is pre-lithiated to compensate for the first irreversible capacity loss, but this technology is complex and has safety hazards.

[0007] In recent years, carbon dots (CDs), as a novel type of zero-dimensional carbon nanomaterial, have shown great potential in optoelectronics, catalysis, and biology due to their small size (typically <10 nm), large specific surface area, abundant surface functional groups, good dispersibility, and tunable conductivity. Recently, researchers have begun exploring the application of CDs in electrochemical energy storage, such as using them as electrode materials for supercapacitors or conductive additives for lithium-ion battery electrodes. For example, Qu et al. (Adv. Mater. 2013) first reported the application of CDs in supercapacitors. However, in current technology, research on how to systematically and synergistically solve multiple problems of SiO anodes, such as poor conductivity, large volume expansion, and SEI film instability, by tightly binding CDs, especially those with specific origins and abundant surface functional groups (such as CDs derived from humic acid), with micron-sized SiO through strong chemical bonding strategies remains lacking. Meanwhile, there is a lack of in-depth and effective technical solutions regarding the preparation methods, bonding mechanisms, and long-cycle stability and mechanism of action of such composite materials in lithium-ion batteries, especially at high current densities.

[0008] Therefore, developing a novel composite material and preparation method that combines strong interfacial chemical bonding, simple processing, and comprehensive improvement of the electrochemical performance of SiO anode materials is of great significance for promoting the development of high-energy-density lithium-ion batteries. Summary of the Invention

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A SiO@HACDs lithium-ion battery anode material, wherein the SiO@HACDs lithium-ion battery anode material uses SiO as the core matrix and HACDs are chemically bonded to its surface, wherein the HACDs and SiO are chemically connected through amide bonds, and the particle size of SiO is 3-7μm.

[0010] Preferably, based on the total mass of the SiO@HACDs lithium-ion battery anode material, the mass fraction of HACDs is 10%-20%.

[0011] Preferably, the SiO@HACDs lithium-ion battery anode material is obtained by high-temperature carbonization treatment, the temperature of which is 800-950℃ and the carbonization time is 3-6 hours, and the carbonization treatment is carried out in an inert atmosphere.

[0012] The above-mentioned method for preparing a SiO@HACDs lithium-ion battery anode material includes the following steps: S1: Perform a silane alkylation reaction, disperse SiO particles in an organic solvent, add a silane coupling agent, perform ultrasonic dispersion and constant temperature stirring reaction, so that amino functional groups are grafted onto the surface of SiO particles. S2: Perform amide bonding reaction. Add HACDs and condensation activator to the reaction system of step S1, and continue the constant temperature stirring reaction to allow the abundant carboxyl groups on the surface of HACDs to undergo amidation condensation reaction with the amino groups grafted on the surface of SiO to form strong amide bonds, thereby obtaining the SiO@HACDs precursor. S3: Perform drying treatment, separate and dry the reaction product obtained in step S2 to obtain solid SiO@HACDs precursor powder; S4: High-temperature carbonization treatment is carried out. Under the protection of an inert atmosphere, the solid precursor powder obtained in step S3 is subjected to programmed high-temperature carbonization treatment, and then naturally cooled to room temperature. After grinding, the SiO@HACDs lithium-ion battery anode material is obtained.

[0013] Preferably, in step S1, the silane alkylation reaction is carried out at room temperature for 48 hours, the organic solvent is preferably anhydrous ethanol, and the silane coupling agent is 3-aminopropyltriethoxysilane.

[0014] Preferably, in step S2, the amide bonding reaction is carried out at room temperature, the stirring time is 24 hours, and the condensation activator is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0015] Preferably, in step S3, the drying temperature is 60°C.

[0016] Preferably, in step S4, the rate of temperature increase is 15°C / min.

[0017] The application of the aforementioned SiO@HACDs lithium-ion battery anode material in lithium-ion batteries specifically includes using SiO@HACDs lithium-ion battery anode material as an active material, mixing it with a conductive agent and a binder in a certain mass ratio of 90:5:5 to form an electrode slurry, coating it onto a current collector, and then drying and rolling it to form a negative electrode sheet for assembling lithium-ion batteries.

[0018] Preferably, the conductive agent is acetylene black or carbon nanotubes, the binder is LA132, the current collector is preferably copper foil, and the lithium-ion battery includes a half-cell or a full-cell battery.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention creatively constructs amide bonds between micron-sized SiO particles and nano-sized HACDs through a two-step chemical reaction of "silicon-based alkylation-amidation". This strong chemical bond ensures that the carbon dot coating layer is tightly bonded to the SiO matrix during long-term charge-discharge cycles and is not easily peeled off, fundamentally solving the problem of easy detachment of physical coating layers. The strong interfacial bonding provides excellent structural stability for the composite material.

[0020] 2. The HACDs of this invention possess excellent electrical conductivity, and their graphitization degree is significantly improved after high-temperature carbonization. The HACDs uniformly bonded to the SiO surface are interconnected, constructing a highly efficient three-dimensional electronic conductive network on and between the SiO particles, greatly improving the overall electronic conductivity of the composite material, thereby significantly enhancing the rate performance and active material utilization of the battery.

[0021] 3. This invention features a dual buffering mechanism, resulting in excellent volume expansion suppression. First, the coating layer and its strong bond with SiO constrain the volume expansion of SiO. Second, during high-temperature carbonization, SiO undergoes a thermal disproportionation reaction, generating nano-Si crystals dispersed within the SiO2 matrix. This internal microstructure effectively buffers the stress during lithiation / delithiation. The synergistic effect of these two mechanisms enables the composite material to exhibit an extremely low volume expansion rate.

[0022] 4. The uniform and robust HACDs coating layer of this invention can act as a barrier, reducing direct contact between SiO and the electrolyte and promoting the formation of a thinner and more stable SEI film. More importantly, the nano-sized HACDs can be embedded inside the SEI film, producing a "rivet" or "nail" effect, which significantly enhances the mechanical strength and chemical stability of the SEI film, effectively preventing it from repeatedly breaking and regenerating during cycling, greatly reducing the continuous consumption of active lithium and electrolyte, thereby achieving excellent long-term cycling stability.

[0023] 5. The embodiments of this invention demonstrate that the SiO@20%HACDs-900 composite material prepared by this invention achieves an initial discharge specific capacity of 1961.7 mAh·g⁻¹ at a current density of 0.1 A·g⁻¹, with an initial coulombic efficiency as high as 75.11%; after 100 cycles at a current density of 0.5 A·g⁻¹, the capacity retention rate is as high as 92.22%, and the average coulombic efficiency exceeds 99.8%. Its performance is significantly superior to unmodified SiO and most carbon-coated SiO composite materials in the prior art.

[0024] 6. The preparation method of this invention has a clear process, mild reaction conditions, readily available raw materials, no need for complex and expensive equipment, and is easy to scale up, thus having high practical value and industrialization prospects. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0026] Figure 1 SEM image of SiO; Figure 2 (a) SEM image of SiO@20%HACDs-900; EDS mapping of (b) C, (c) O, (d) Si elements collected in the rectangular area of ​​Figure a and (e) EDS spectral analysis of the corresponding elements; Figure 3 (ac) TEM image of SiO@20%HACDs-900; (d) EDS mapping of C, (e) O, and (f) Si elements; (g) EDS spectral analysis of the corresponding elements collected in the rectangular region of Figure c. (The inset of Figure a is a high-resolution TEM image of HACDs, and the inset of Figure b is a particle size distribution map of HACDs in TEM). Figure 4 TGA curves for the selected samples; Figure 5 (a) XRD diffraction pattern and (b) Raman spectrum of the selected sample; Figure 6 (a) FT-IR spectrum and (b) XPS full spectrum of the selected sample; XPS high-resolution elemental spectra of SiO@20%HACDs-25: (c) C1s, (d) N1s, (e) O1s and (f) Si2p. Figure 7 High-resolution elemental spectra of SiO@20%HACDs-900: (a) C1s, (b) N1s, (c) O1s and (d) Si2p; Figure 8(a) Discharge and (b) Charge Cycling Performance and Coulombic Efficiency Curves for the Selected Samples. (0%: SiO-900; 10%: SiO@10%HACDs-900; 20%: SiO@20%HACDs-900; 30%: SiO@30%HACDs-900); Figure 9 Charge-discharge cycle performance and coulombic efficiency curves of (a) SiO@20%HACDs-25 and (b) HACDs-900; Figure 10 (a) Discharge and (b) Charge rate performance curves at different current densities; Figure 11 Cyclic voltammetry curves of (a) SiO-900 and (b) SiO@20%HACDs-900; Figure 12 Nyquist plots of the selected samples. (The inset in the upper right corner is a magnified view of the high-frequency region; the inset in the middle is the fitted equivalent circuit). Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] Example 1 Preparation of humic acid-derived carbon dots (HACDs): HACDs were prepared using a hydrothermal method: 1.0 g of coal-based humic acid powder was accurately weighed and dispersed in 50 mL of deionized water. The mixture was sonicated for 30 minutes to form a uniform brown suspension. The suspension was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), sealed, and placed in an oven at 210 °C for 10 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting brownish-black liquid product was filtered through a 0.22 μm microporous membrane to remove large particulate impurities. The filtrate was placed in a dialysis bag with a molecular weight cutoff of 500 Da and dialyzed in deionized water for 48 hours to remove unreacted small organic molecules and ionic impurities. Finally, the dialyzed solution was freeze-dried to obtain a brownish-black, fluffy solid, which was the HACDs.

[0029] Example 2 Preparation of SiO@20%HACDs-900 lithium-ion battery anode material: S1: Weigh 5.0g of silicon monoxide (SiO) powder with a particle size of 3-7μm and place it in a 200mL beaker. Add 50mL of anhydrous ethanol and ultrasonically disperse for 5 minutes.

[0030] S2: Add 50 μL of 3-aminopropyltriethoxysilane (APTES) to the above dispersion. Seal the mouth of the beaker with aluminum foil and magnetically stir at 300 rpm for 48 hours at room temperature to carry out the silanization reaction.

[0031] S3: Add 1.25g of the HACDs prepared in Example 1 (equivalent to 25% of the initial SiO mass, which, after subsequent carbonization and weight loss, will have a target mass fraction of approximately 20% in the final composite material) and 2μL of the condensation activator EDC to the reaction system of step S2. Continue the amidation reaction by magnetic stirring at 300rpm for 24 hours at room temperature.

[0032] S4: The mixture obtained in step S3 is dried in an oven at 60°C for 12 hours to obtain a dried solid precursor, denoted as SiO@20%HACDs-25.

[0033] S5: After thoroughly grinding the dried precursor in a mortar, transfer it to a quartz boat. Place the quartz boat in the center of a tube furnace and purge it with high-purity nitrogen (99.999%) as a protective gas at a flow rate of 50 sccm for 30 minutes to purge all air.

[0034] S6: Under a nitrogen atmosphere, the tubular furnace is heated from room temperature to 900°C at a heating rate of 15°C / min, and carbonized at this temperature for 5 hours.

[0035] S7: After carbonization, turn off the heating power and allow the tube furnace to cool naturally to room temperature under nitrogen protection. Remove the product from the quartz boat, grind it again, and obtain a black powdery final product, denoted as SiO@20%HACDs-900.

[0036] Example 3 Preparation of SiO@10%HACDs-900 lithium-ion battery anode material: The preparation method is the same as in Example 2, except that the amount of HACDs added in step S3 is changed to 0.55g (equivalent to 11% of the initial mass of SiO, with a target mass fraction of approximately 10%). The final product is denoted as SiO@10%HACDs-900.

[0037] Comparative Example 1 Preparation of SiO@30%HACDs-900 lithium-ion battery anode material: The preparation method is the same as in Example 2, except that the amount of HACDs added in step S3 is changed to 2.15g (equivalent to 43% of the initial mass of SiO, with a target mass fraction of approximately 30%). The final product is denoted as SiO@30%HACDs-900.

[0038] Comparative Example 2 Preparation of pure SiO-900 material: Take 5.0g of SiO powder, place it in a quartz boat, and directly perform high-temperature carbonization treatment according to steps S5 to S7 in Example 2 (carbonizing at 900℃ for 5 hours under nitrogen at 15℃ / min), without any surface modification or carbon dot coating. The final product is denoted as SiO-900.

[0039] Comparative Example 3 Uncarbonized SiO@20%HACDs-25: Only step S4 of Example 2 was performed to obtain a dry solid precursor SiO@20%HACDs-25 without high-temperature carbonization treatment.

[0040] Comparative Example 4 Preparation of physically mixed sample SiO+HACDs-900: Take 4.0 g of SiO-900 (prepared from Comparative Example 2) and 1.0 g of HACDs-900 (obtained by treating HACDs prepared in Example 2 at 900℃ / 5h under the same carbonization conditions) and simply physically mix them in a mortar for 10 minutes. The product is denoted as (SiO+HACDs-900) physical mixture.

[0041] Material structure and morphology characterization 1. Scanning Electron Microscopy (SEM): Observation of SiO@20%HACDs-900 in Example 2 showed that it maintained the particle morphology of the SiO raw material (3-7 μm). The particle surface was rougher than that of SiO-900 in Comparative Example 2, but there were no obvious independent HACDs agglomerates, indicating that the HACDs were uniformly attached. Specifically, as follows... Figures 1-4 As shown.

[0042] 2. Transmission Electron Microscopy (TEM) and Elemental Distribution Analysis (EDS Mapping): TEM images show a layer of amorphous / fuzzy lattice fringes, approximately several nanometers thick, on the surface of SiO@20%HACDs-900 particles. High-resolution images show lattice fringes with a spacing of 0.21 nm, corresponding to the (100) crystal plane of graphitic carbon in HACDs. EDS surface scanning analysis of individual particle cross-sections shows that the C element signal is uniformly distributed throughout the particle cross-section (especially in the edge region), while the Si and O element signals are stronger in the core region, further confirming the uniform coating of HACDs. Specifically... Figure 2-3 As shown.

[0043] 3. X-ray Diffraction (XRD): The XRD pattern of the product in Example 2 shows that, in addition to the broad peak of amorphous SiO2, characteristic diffraction peaks of crystalline silicon (Si) appear at approximately 28°, 47°, and 56°, proving that SiO underwent a thermal disproportionation reaction (SiO→Si+SiO2) during carbonization at 900°C. Simultaneously, a weak, broad diffraction peak can be observed near approximately 25°, attributed to the (002) crystal plane of graphitized carbon in HACDs. Specifically... Figure 5 As shown in a.

[0044] 4. Raman Spectroscopy: The product of Example 2 showed distinct D and G peaks at 1345 cm⁻¹ and 1584 cm⁻¹, respectively, which originate from the disordered carbon structure and graphite sp² hybridization structure in HACDs. Its I D / I G The ratio (approximately 0.55) is lower than that of the precursor (SiO@20%HACDs-25, I D / I G (≈0.72), indicating that high-temperature carbonization increased the graphitization degree of HACDs. Specifically, as shown... Figure 5 As shown in b.

[0045] 5. Fourier Transform Infrared Spectroscopy (FT-IR): In the spectrum of the product of Example 2, a characteristic absorption peak at 1630 cm⁻¹ attributed to the C=O stretching vibration of the amide bond and a CN stretching vibration peak at 1401 cm⁻¹ were observed, confirming the presence of the amide bond. Specifically, as follows... Figure 6 As shown.

[0046] 6. X-ray photoelectron spectroscopy (XPS): XPS analysis of the product in Example 2 revealed high-resolution C1s spectra with peaks for C=C, CC, CO, CN, and C=O components. High-resolution N1s spectra showed peaks for CN bonds, which, together with the FT-IR results, confirms the successful construction of the amide bond. Specifically... Figure 7 As shown.

[0047] Electrochemical performance testing 1. Electrode Preparation: The materials obtained in Examples 2-3 and Comparative Examples 1-4 were used as active materials. The active material, acetylene black, carbon nanotubes, and aqueous binder (LA132) were weighed according to a mass ratio of 90:4:1:5. An appropriate amount of deionized water was added, and the mixture was stirred in a planetary ball mill at 400 rpm for 4 hours to obtain a uniform slurry. The slurry was uniformly coated onto a 10 μm thick copper foil, with a coating thickness of approximately 100 μm. The electrode was then dried in a vacuum oven at 100°C for 8 hours. After removal, it was rolled using a roller mill under a pressure of 10 MPa and then punched into circular pieces with a diameter of 12 mm as working electrodes. The active material loading of the electrode was approximately 1.0-1.2 mg cm⁻².

[0048] 2. Battery Assembly: All operations were performed in an argon-atmospheric glove box (H2O, O2 < 0.1 ppm). A lithium metal sheet (Φ16 mm) was used as both the counter and reference electrodes, a Celgard 2400 polypropylene membrane as the separator, and the electrolyte was a mixed solvent of EC / DMC / EMC (volume ratio 1:1:1) containing 1.0 M LiPF6, with 10 wt% fluoroethylene carbonate (FEC) added as a film-forming additive. A CR2032 coin cell was assembled.

[0049] 3. Electrochemical testing: (1) Constant current charge-discharge test: A Neware battery testing system was used, with a test voltage range of 0.005-1.5V (vs. Li⁺ / Li). Initial charge-discharge activation was performed at a current density of 0.1 Ag⁻¹, followed by long-cycle testing at a current density of 0.5 Ag⁻¹. Details are as follows... Figure 8 , Figure 9 As shown.

[0050] (2) Rate performance test: The system was cycled 5 times at different current densities (0.1, 0.2, 0.5, 1.0, 2.0, 3.2 Ag⁻¹), and finally tested at a current density of 0.1 Ag⁻¹ to assess its capacity recovery. (Specific details are as follows...) Figure 10 As shown.

[0051] (3) Cyclic voltammetry (CV): Using an electrochemical workstation, the first three CV curves were tested within a voltage range of 0.01-2.5V at a scan rate of 0.1mVs⁻¹. (Specific details are as follows...) Figure 11 As shown.

[0052] (4) Electrochemical Impedance Spectroscopy (EIS): At the cell's open-circuit potential, a sinusoidal wave perturbation with an amplitude of 5 mV is applied, with a frequency range of 100 kHz to 0.01 Hz. The EIS spectra of the cell before and after cycling are then measured. Specifically... Figure 12 As shown.

[0053] Table 1 summarizes the electrochemical performance data of the key samples (cycle 100, 0.5Ag⁻¹). Table 1 Table 2 Comparison of electrochemical performance of lithium-ion batteries based on carbon-modified SiO anode materials Table 2 In summary, comparing Example 2 with Comparative Example 2, it was found that the SiO@20%HACDs-900 composite material coated with HACDs through chemical bonding exhibited a capacity retention of 92.22% after 100 cycles at a current density of 0.5 A·g⁻¹, significantly higher than the uncoated SiO-900 (72.86%). This demonstrates that the chemically bonded HACDs coating effectively buffers volume expansion and improves cycle stability. Comparing Example 2 with Comparative Example 3, it was found that the sample carbonized at 900℃ showed significantly better performance than the uncarbonized precursor SiO@20%HACDs-25 (capacity retention of only 62.31%). This indicates that high-temperature carbonization not only increases the graphitization degree of HACDs but also promotes the disproportionation reaction of SiO to generate nano-Si grains, synergistically enhancing the material's conductivity and structural stability. By comparing Example 2 with Comparative Example 4, it was found that the coating layer constructed by chemical bonding has stronger interfacial bonding and better electrochemical performance than the simple physical mixing ((SiO+HACDs-900) physical mixing, with a capacity retention of about 80%). This shows that the amide bonding strategy is the key to constructing a stable core-shell structure and realizing a high-performance SiO-based anode.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A SiO@HACDs lithium-ion battery anode material, characterized in that, The SiO@HACDs lithium-ion battery anode material uses SiO as the core matrix and HACDs are chemically bonded to its surface. The HACDs and SiO are chemically connected through amide bonds, and the particle size of SiO is 3-7 μm.

2. The SiO@HACDs lithium-ion battery anode material according to claim 1, characterized in that, Based on the total mass of the SiO@HACDs lithium-ion battery anode material, the mass fraction of HACDs is 10%-20%.

3. The SiO@HACDs lithium-ion battery anode material according to claim 1, characterized in that, The SiO@HACDs lithium-ion battery anode material is obtained through high-temperature carbonization treatment, with the carbonization temperature being 800-950℃ and the carbonization time being 3-6 hours. The carbonization treatment is carried out under an inert atmosphere.

4. A method for preparing a SiO@HACDs lithium-ion battery anode material according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Perform a silane alkylation reaction, disperse SiO particles in an organic solvent, add a silane coupling agent, perform ultrasonic dispersion and constant temperature stirring reaction, so that amino functional groups are grafted onto the surface of SiO particles. S2: Perform amide bonding reaction. Add HACDs and condensation activator to the reaction system of step S1, and continue the constant temperature stirring reaction to allow the abundant carboxyl groups on the surface of HACDs to undergo amidation condensation reaction with the amino groups grafted on the surface of SiO to form strong amide bonds, thereby obtaining the SiO@HACDs precursor. S3: Perform drying treatment, separate and dry the reaction product obtained in step S2 to obtain solid SiO@HACDs precursor powder; S4: High-temperature carbonization treatment is carried out. Under the protection of an inert atmosphere, the solid precursor powder obtained in step S3 is subjected to programmed high-temperature carbonization treatment, and then naturally cooled to room temperature. After grinding, the SiO@HACDs lithium-ion battery anode material is obtained.

5. The method for preparing a SiO@HACDs lithium-ion battery anode material according to claim 4, characterized in that, In step S1, the silane alkylation reaction is carried out at room temperature for 48 hours with stirring. The organic solvent is preferably anhydrous ethanol, and the silane coupling agent is 3-aminopropyltriethoxysilane.

6. The method for preparing a SiO@HACDs lithium-ion battery anode material according to claim 4, characterized in that, In step S2, the amide bonding reaction is carried out at room temperature for 24 hours with stirring, and the condensation activator is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

7. The method for preparing a SiO@HACDs lithium-ion battery anode material according to claim 4, characterized in that, In step S3, the drying temperature is 60°C.

8. The method for preparing a SiO@HACDs lithium-ion battery anode material according to claim 4, characterized in that, In step S4, the programmed heating rate is 15°C / min.

9. The application of the SiO@HACDs lithium-ion battery anode material according to any one of claims 1-4 in lithium-ion batteries, characterized in that, Specifically, the process involves using SiO@HACDs lithium-ion battery anode material as the active material, mixing it with a conductive agent and a binder in a certain mass ratio of 90:5:5 to form an electrode slurry, coating it onto a current collector, and then drying and rolling it to form a negative electrode sheet for use in assembling lithium-ion batteries.

10. The application according to claim 9, characterized in that, The conductive agent is acetylene black or carbon nanotubes, the binder is LA132, the current collector is preferably copper foil, and the lithium-ion battery includes a half cell or a full cell.

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