Graphdiyne-coated sulfur-doped modified carbon negative electrode material, and preparation method and application thereof

Abstract

The present application relates to graphdiyne coated sulfur-doped modified carbon negative electrode material and its preparation method and application. The preparation method of the carbon negative electrode material: glucose solution is hydrothermally treated to obtain black powder, the black powder and sulfur powder are mixed, and carbonization is carried out under inert atmosphere to obtain C-S material; the obtained C-S material is dispersed in a solvent, heated and reacted to obtain a reaction liquid; then HEB graphdiyne monomer solution is added to the reaction liquid to obtain a reaction mixture; the obtained reaction mixture is heated and reacted in an inert atmosphere under light shielding conditions to obtain the carbon negative electrode material. The present application provides a carbon negative electrode material which is synergistically modified by sulfur doping and graphdiyne coating and has stable structure and excellent electrochemical performance. The graphdiyne coating layer can inhibit the volume expansion during charging and discharging, enhance the structural stability, and provide additional lithium storage sites, realizing long-life cycle under fast-charging conditions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to graphdiyne-coated sulfur-doped modified carbon anode materials, their preparation methods, and applications. Background Technology

[0002] In recent years, the explosive growth of electric vehicles and smart electronic devices has placed higher demands on high-performance energy storage systems. As the current mainstream energy storage solution, lithium-ion batteries (LIBs) dominate the power battery and consumer electronics fields due to their excellent energy density (up to 250-300 Wh / kg), outstanding cycle stability, and relatively environmentally friendly characteristics. However, with the increasing demands of end-use applications for energy density (greater than 400 Wh / kg) and fast-charging capabilities (charging to 80% battery capacity within 15 minutes), the limited theoretical capacity of traditional carbon materials can no longer meet these needs. Furthermore, carbon anodes are prone to lithium dendrite growth, interfacial side reactions, and low-temperature performance degradation during fast charging, severely restricting battery safety and application scope. Therefore, the development of novel high-performance anode materials has become a current research hotspot.

[0003] To overcome the performance bottlenecks of carbon materials, researchers have proposed various modification methods, including structural modulation (such as porous carbon, carbon nanotubes, and graphene), surface modification (such as coating and functionalization), and heteroatom doping (N, S, P, B, etc.). Among these, the introduction of heteroatoms can alter the electronic structure, interlayer spacing, and surface chemistry of carbon materials, thereby improving lithium storage capacity, conductivity, and interfacial stability. Based on this, this application innovatively proposes a sulfur doping modification strategy, introducing sulfur atoms through high-temperature calcination to enhance the energy density of carbon anode materials. The introduction of sulfur atoms can effectively modulate the electronic structure of carbon materials, improve conductivity, and promote lithium-ion adsorption and diffusion. However, sulfur-doped carbon materials still face problems such as volume expansion and interfacial instability during cycling, leading to capacity decay and reduced cycle life.

[0004] To address this challenge, researchers have proposed various optimization strategies, including interface engineering, structural design, and composite modification. While these methods can partially improve the electrochemical performance of sulfur-doped carbon materials, studies have found that sulfur atoms are easily lost during long-term cycling, leading to structural collapse and significant volume expansion. Simultaneously, the unstable SEI film formed at the electrode / electrolyte interface during charge and discharge continuously consumes the active lithium source, severely impacting the battery's coulombic efficiency. To address these issues, carbon material surface modification technology has gradually become a research focus. By constructing functional layers such as graphene, carbon nanotubes, or conductive polymers on the carbon matrix surface, a synergistic effect of physical confinement and chemical bonding is achieved. However, existing coating materials still face two key challenges: first, the uniformity and structural stability of the coating layer are difficult to precisely control; second, the hysteresis problem of lithium-ion transport kinetics at the interface has not yet been effectively solved. Summary of the Invention

[0005] To address the technical problems of low specific capacity, poor cycle stability, and unsatisfactory fast-charging performance of carbon-based anode materials in existing lithium-ion batteries, this invention provides a graphyne-coated sulfur-doped modified carbon anode material, its preparation method, and its applications. The purpose of this invention is to provide a simple-to-prepare, structurally stable, and electrochemically superior sulfur-doped and graphyne-coated synergistically modified carbon anode material. Sulfur doping effectively improves the electronic conductivity and lithium-ion diffusion rate of carbon materials, while introducing abundant active sites, thus increasing the energy density of the carbon anode material. The graphyne coating layer can suppress volume expansion during charge and discharge, enhance structural stability, and provide additional lithium storage sites, achieving long-life cycling under fast-charging conditions. Compared to traditional carbon anode materials, this synergistically modified material significantly improves the specific capacity, long cycle life, and fast-charge / discharge performance of lithium-ion batteries, while also possessing feasibility for industrial production.

[0006] The first objective of this invention is to provide a method for preparing a graphdiyne-coated sulfur-doped modified carbon anode material, comprising the following steps:

[0007] A glucose solution was hydrothermally treated to obtain a black powder. The black powder was then mixed with sulfur powder and heated and carbonized in an inert atmosphere to obtain CS material.

[0008] The obtained CS material was dispersed in a solvent and heated to react, yielding a reaction solution; then, a HEB graphyne monomer solution was added to the reaction solution to obtain a reaction mixture.

[0009] Under light-protected conditions, the resulting reaction mixture was heated in an inert atmosphere to obtain the carbon anode material CS@GDY.

[0010] In some embodiments of the present invention, the concentration of the glucose solution is 1.5-3 mol / L.

[0011] In some embodiments of the present invention, the heating temperature of the hydrothermal treatment is 150-200 °C, and the time is 3-6 h.

[0012] In some embodiments of the present invention, the conditions for heating and carbonization are as follows: heating to 400-600 °C at a heating rate of 1-3 °C / min, and maintaining at this temperature for high-temperature calcination for 1-3 h; the inert atmosphere contains inactive gases including nitrogen and / or argon.

[0013] In some embodiments of the present invention, the mass ratio of black powder to sulfur powder is (1:4) to (1:2).

[0014] In some embodiments of the present invention, the solvent includes one or more of acetone, pyridine, and tetramethylethylenediamine (TMEDA); the volume ratio of acetone, pyridine, and tetramethylethylenediamine (TMEDA) is 100:(5~20):1; the present invention utilizes different mixing ratios of solvents to produce different morphologies of graphyne grown on carbon spheres; when pure pyridine is used, a sheet-like graphyne coating layer is grown; when a mixed solvent is used, a three-dimensional nanowall structure graphyne coating layer is formed, which is more conducive to the rapid transport of lithium ions and improves fast charging performance.

[0015] The heating reaction is carried out at a temperature of 50-80 ℃ for 24-48 h.

[0016] In some embodiments of the present invention, the concentration of the HEB graphyne monomer solution is 1~4 mg / mL.

[0017] The second objective of this invention is to provide a graphdiyne-coated sulfur-doped modified carbon anode material, prepared by the aforementioned preparation method; with a sulfur-doped carbon material as the core and a three-dimensional nanowalled network of graphdiyne carbon layers as the shell.

[0018] A third objective of this invention is to provide a negative electrode sheet comprising the aforementioned graphdiyne-coated sulfur-doped modified carbon negative electrode material.

[0019] A fourth objective of the present invention is to provide a lithium-ion battery including the negative electrode.

[0020] This invention innovatively proposes a strategy of synergistic modification using sulfur doping and graphyne coating, enhancing the electrochemical performance of carbon materials by precisely controlling their microstructure and interfacial properties. This synergistic modification strategy retains the capacity-enhancing advantages of sulfur doping while addressing stability issues through graphyne coating, providing a new technical path for achieving high-performance lithium-ion battery anode materials. Furthermore, this invention innovatively introduces a graphyne coating layer to construct a composite anode material with a multi-level structure. The unique porous structure of graphyne not only effectively suppresses sulfur loss but also provides a rapid channel for lithium-ion transport. More importantly, the excellent mechanical flexibility and chemical stability of graphyne can buffer volume changes during charge and discharge processes, maintaining the integrity of the electrode structure.

[0021] The technical solution of the present invention has the following advantages compared with the prior art:

[0022] This invention provides a simple, efficient, and scalable method for preparing graphdiyne-coated / sulfur-doped synergistically modified carbon anode materials, which can be achieved through a one-step solvothermal reaction and controllable carbonization process. The method is simple and uses readily available raw materials.

[0023] This invention provides a method for constructing carbon anode materials based on synergistic modification of graphdiyne coating and sulfur doping. The three-dimensional porous network structure of graphdiyne significantly enhances the lithium-ion transport rate, while the active sites introduced by sulfur doping effectively enhance the material's charge storage capacity. This dual modification strategy solves the key technical problems of low specific capacity, poor fast-charging performance, and insufficient long-life cycle life of traditional carbon anode materials.

[0024] This invention provides a high-performance lithium-ion battery anode material. Through the synergistic effect of a graphdiene coating and sulfur doping, this material significantly improves the battery's reversible capacity and fast-charging performance (at 10 A g). -1 At current density, it can achieve 468.5 mAh·g -1 In addition to its specific capacity, it also exhibits excellent cycle stability and rate performance (at 10 A·g). -1 (The capacity retention rate reaches 84% ​​after 700 cycles at the current density). The material's unique core-shell structure and chemical composition enable it to effectively mitigate the volume expansion problem during charge and discharge while maintaining high conductivity. Attached Figure Description

[0025] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0026] Figure 1 These are SEM images of the materials obtained in the embodiments and comparative examples of the present invention, wherein: (a) C, (b) CS, (c) CS@GDY.

[0027] Figure 2 These are SEM and mapping images of the materials obtained in the embodiments and comparative examples of the present invention; wherein, (a) is the SEM image of CS-GDY; (b) is the mapping image of the S element in CS@GDY; (c) is the mapping image of the C element in CS@GDY; (d) is the SEM image of CS; (e) is the mapping image of the S element in CS; and (f) is the mapping image of the C element in CS.

[0028] Figure 3 These are EDS diagrams of materials CS and CS@GDY obtained from the embodiments and comparative examples of this invention.

[0029] Figure 4 These are XRD patterns of materials C, CS, and CS@GDY obtained in the embodiments and comparative examples of this invention.

[0030] Figure 5 These are Raman diagrams of materials C, CS, and CS@GDY obtained in the embodiments and comparative examples of this invention.

[0031] Figure 6 These are electrochemical performance graphs of the materials obtained in the embodiments and comparative examples of the present invention; wherein: (a) C, (b) CS, (c) CS@GDY at 10 A·g -1 Charge-discharge curves under different cycles; (d) C, CS and CS@GDY at 10 A·g -1 Cyclic plot at current density.

[0032] Figure 7 These are electrochemical performance graphs of the materials obtained in the embodiments and comparative examples of the present invention; wherein: (a) rate performance graphs of C, CS and CS@GDY at different current densities; (b) C, (c) CS, (d) charge-discharge curves of CS@GDY at different current densities. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing CS@GDY nanocomposite materials, as detailed below:

[0036] (1) At room temperature, a 1.5 mol / L glucose aqueous solution was prepared and then injected into a stainless steel high-pressure reactor (filling rate 90%). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the above powder material and sulfur powder were placed in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain CS anode material. The specific parameters for carbonization were: heating to 500 °C at a heating rate of 2 °C / min and maintaining at this temperature for 2 h, and then cooling to room temperature.

[0037] (2) Add the CS powder obtained in step (1) to a mixed solution of acetone, pyridine and tetramethylethylenediamine (TMEDA) (volume ratio 100:5:1), and react at 50 °C for 2 h to obtain the reaction solution.

[0038] (3) Subsequently, 50 mg of HEB (graphyne monomer) was dissolved in 25 mL of acetone and slowly added dropwise to the reaction solution obtained in step (2) over approximately 2 h to obtain the reaction mixture. The reaction mixture was stirred at low speed for 24 h under an argon atmosphere at 50 °C (in the dark). After the reaction was completed, the CS@GDY powder material was obtained by centrifugation and washing. Unreacted monomers and oligomers were removed by washing with hot acetone and N,N-dimethylformamide (DMF), and the pure CS@GDY powder was obtained by vacuum drying.

[0039] Comparative Example 1

[0040] This comparative example provides a method for preparing a pure C anode material, as shown below:

[0041] A 1.5 mol / L glucose aqueous solution was prepared at room temperature and then injected into a stainless steel high-pressure reactor (90% filling rate). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. This powder was then carbonized in an argon atmosphere in a tube furnace to obtain pure C anode material. The specific carbonization parameters were: heating to 500 °C at a rate of 2 °C / min, maintaining this temperature for 2 h, and then cooling to room temperature.

[0042] Comparative Example 2

[0043] This comparative example provides a method for preparing a CS anode material, as shown below:

[0044] A 1.5 mol / L glucose aqueous solution was prepared at room temperature and then injected into a stainless steel high-pressure reactor (90% filling rate). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the powder material was mixed with sulfur powder in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain the CS anode material. The specific carbonization parameters were: heating to 500 °C at a rate of 2 °C / min, maintaining this temperature for 2 h, and then cooling to room temperature.

[0045] Example 2

[0046] This comparative example provides a method for preparing CS@GDY nanocomposite materials, as detailed below:

[0047] (1) At room temperature, a 1.5 mol / L glucose aqueous solution was prepared and then injected into a stainless steel high-pressure reactor (filling rate 90%). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the above powder material and sulfur powder were placed in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain CS anode material. The specific parameters were: heating to 500 °C at a heating rate of 2 °C / min and maintaining at this temperature for 2 h, and then cooling to room temperature.

[0048] (2) Add the CS powder obtained in step (1) into the pyridine solution and react at 50 °C for 2 h to obtain the reaction solution.

[0049] (3) Subsequently, 50 mg of HEB was dissolved in 25 mL of acetone and slowly added dropwise to the above solution over 2 h to obtain the reaction mixture. The reaction mixture was stirred at low speed for 24 h under an argon atmosphere at 50 °C (in the dark). After the reaction was completed, the mixture was centrifuged and washed to obtain CS@GDY powder material. Unreacted monomers and oligomers were removed by washing with hot acetone and N,N-dimethylformamide (DMF), and the pure CS@GDY powder was obtained by vacuum drying.

[0050] Example 3

[0051] (The difference between this and Example 1 is that the ratio of the mixed solvent in step (2) is different.)

[0052] This embodiment provides a method for preparing CS@GDY nanocomposite materials, as detailed below:

[0053] (1) At room temperature, a 1.5 mol / L glucose aqueous solution was prepared and then injected into a stainless steel high-pressure reactor (filling rate 90%). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the above powder material and sulfur powder were placed in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain CS anode material. The specific parameters for carbonization were: heating to 500 °C at a heating rate of 2 °C / min and maintaining at this temperature for 2 h, and then cooling to room temperature.

[0054] (2) Add the CS powder obtained in step (1) to a mixed solution of acetone, pyridine and tetramethylethylenediamine (TMEDA) (volume ratio 100:20:1) and react at 50 °C for 2 h to obtain the reaction solution.

[0055] (3) Subsequently, 50 mg of HEB was dissolved in 25 mL of acetone and slowly added dropwise to the reaction solution obtained in step (2) over approximately 2 h to obtain the reaction mixture. The reaction mixture was stirred at low speed for 24 h under an argon atmosphere at 50 °C (the operation should be carried out in the dark). After the reaction was completed, the CS@GDY powder material was obtained by centrifugation and washing. Unreacted monomers and oligomers were removed by washing with hot acetone and N,N-dimethylformamide (DMF), and the pure CS@GDY powder was obtained by vacuum drying.

[0056] Example 4

[0057] This embodiment provides a method for preparing CS@GDY nanocomposite materials, as detailed below:

[0058] (1) At room temperature, a 1.5 mol / L glucose aqueous solution was prepared and then injected into a stainless steel high-pressure reactor (filling rate 90%). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the above powder material and sulfur powder were placed in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain CS anode material. The specific parameters for carbonization were: heating to 500 °C at a heating rate of 2 °C / min and maintaining at this temperature for 2 h, and then cooling to room temperature.

[0059] (2) Add the CS powder obtained in step (1) to a mixed solution of acetone, pyridine and tetramethylethylenediamine (TMEDA) (volume ratio 100:5:1), and react at 50 °C for 2 h to obtain the reaction solution.

[0060] (3) Subsequently, 25 mg of HEB was dissolved in 25 mL of acetone and slowly added dropwise to the above mixture (about 2 h). The final reaction mixture was stirred at low speed at 50 °C for 24 h under argon protection (the operation should be carried out in the dark). After the reaction was completed, the CS@GDY powder material was obtained by centrifugation and washing. Unreacted monomers and oligomers were removed by washing with hot acetone and N,N-dimethylformamide (DMF), and the pure CS@GDY powder was obtained by vacuum drying.

[0061] Example 5 This example provides a method for preparing CS@GDY nanocomposite materials, as detailed below:

[0062] (1) At room temperature, a 1.5 mol / L glucose aqueous solution was prepared and then injected into a stainless steel high-pressure reactor (filling rate 90%). After hydrothermal treatment at 190 °C for 5 h, a black powder was obtained. Subsequently, the above powder material and sulfur powder were placed in a corundum crucible at a mass ratio of 1:3 and carbonized in an argon atmosphere in a tube furnace to obtain CS anode material. The specific parameters for carbonization were: heating to 500 °C at a heating rate of 2 °C / min and maintaining at this temperature for 2 h, and then cooling to room temperature.

[0063] (2) Add the CS powder obtained in step (1) to a mixed solution of acetone, pyridine and tetramethylethylenediamine (TMEDA) (volume ratio 100:5:1), and react at 50 °C for 2 h to obtain the reaction solution.

[0064] (3) Subsequently, 100 mg of HEB was dissolved in 25 mL of acetone and slowly added dropwise to the reaction solution obtained in step (2) over approximately 2 h to obtain the reaction mixture. The final reaction mixture was stirred at low speed for 24 h under an argon atmosphere at 50 °C (in the dark). After the reaction was completed, the CS@GDY powder material was obtained by centrifugation and washing. Unreacted monomers and oligomers were removed by washing with hot acetone and N,N-dimethylformamide (DMF), and the pure CS@GDY powder was obtained by vacuum drying.

[0065] Characterization

[0066] The pure C and CS anode materials obtained in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1, were structurally characterized. The results are shown in […]. Figures 1-5 .

[0067] Figure 1To examine the microstructure and structure of the C and CS anode materials prepared in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1, a ZESSIS Sigma 300 field emission scanning electron microscope (SEM) was used. SEM images revealed that glucose self-assembled to form uniformly sized carbon nanospheres (C) during the hydrothermal reaction. The basic structure of the CS nanocomposite material obtained after sulfurization remained unchanged. After graphyne coating, a three-dimensional network structure of GDY was clearly observed growing on the surface of the CS material. This three-dimensional network structure helps increase the active sites of the electrode material, alleviates volume expansion, and improves structural stability, thereby enhancing the energy storage performance of the electrode material.

[0068] Figure 2 The elemental energy spectrum of the C and CS anode materials prepared in specific comparative examples 1 and 2 and the CS@GDY nanocomposite material obtained in Example 1 are shown. The experimental setup used was an energy dispersive spectrometer equipped with a Sigma 300 field emission scanning electron microscope manufactured by ZESSIS, Japan. The test results show that the CS and CS@GDY composite material contains C and S elements.

[0069] Figure 3 The images show the EDS spectra of the C and CS anode materials prepared in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1. The experimental setup used was an energy dispersive spectroscopy (EDS) spectrometer attached to a Sigma 300 field emission scanning electron microscope manufactured by ZESSIS, Japan. The test results show that the C and S contents in the CS composite material are 78.4% and 21.6%, respectively, and the contents in CS@GDY are 83.2% and 16.8%, respectively. The GDY coating increases the carbon content.

[0070] Figure 4 The XRD patterns of the C and CS anode materials prepared in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1 are shown. The testing apparatus used was a Bruker D8 Advance X-ray diffractometer (Cu target, λ=1.5406Å). Compared with pure C material, it can be found that due to the doping of large-radius sulfur atoms, the XRD patterns of the CS obtained in Comparative Example 2 and the CS@GDY composite material prepared in Example 1 shift to a lower angle, i.e., the lattice spacing increases, proving the successful doping of sulfur.

[0071] Figure 5 Raman spectra of the C and CS anode materials prepared in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1, were obtained using a LabRAM HR Evolution spectrometer. Compared to the pure C sample, after sulfurization treatment, I... D / I GThe ratio of sulfur doping to ion adsorption capacity increased significantly, indicating that sulfur doping increased structural defects in the material, potentially exposing more active sites and enhancing the ion adsorption capacity of the electrode material. After the introduction of GDY, the ion adsorption capacity at 2100 cm⁻¹ increased. -1 Small characteristic peaks were observed around the peak value, representing the stretching vibrations of the alkyne bonds, indicating that GDY was successfully coated onto the surface of CS. The self-expanding pore properties of GDY further enhance the rapid transport of lithium ions, improving fast-charging performance.

[0072] Electrochemical performance testing

[0073] The cycling performance, rate performance, and charge-discharge curves of the C and CS anode materials prepared in Comparative Examples 1 and 2 and the CS@GDY nanocomposite material obtained in Example 1 were measured. The results are shown in the figure. Figures 6-7 .

[0074] Figure 6 When the C and CS anode materials prepared in Comparative Examples 1 and 2 and the CS@GDY nanocomposite material obtained in Example 1 are used as LIBs anode materials, the reaction temperature at 10 A g is measured. -1 Cyclic performance at current density and charge-discharge curves at different cycle numbers. Figure 6 From (a), (b), and (c), we can see that in 10 A g −1 At the specified current density, the C electrode exhibited a capacity of 104.4 mAh g⁻¹ after 500 cycles. In comparison, the CS and CS@GDY electrodes showed discharge capacities of 322.8 mA hg⁻¹ and 442.5 mA hg⁻¹, respectively, after 500 cycles. Figure 6 From (d), we can see that at 10 A g -1 At the specified current density, the CS@GDY electrode retained 84% of its capacity after 700 cycles. These results indicate that the CS@GDY electrode material prepared using the sulfur-doped synergistic GDY coating modification strategy exhibits excellent cycling performance in lithium storage. The high specific capacity and excellent cycling stability of the prepared CS@GDY electrode are attributed to the introduction of sulfur and the construction of the GDY and C heterostructure. The synergistic effect of the heterojunction and sulfur doping plays a crucial role in stabilizing the electrode structure, increasing active sites, and improving lithium-ion transport efficiency.

[0075] Figure 7 The figure shows the rate performance and charge-discharge curves of the C and CS anode materials prepared in Comparative Examples 1 and 2, and the CS@GDY nanocomposite material obtained in Example 1, when used as LIBs anode materials at different current densities. As can be seen from the figure, at 20 A g... -1 At high current densities, the specific capacity of the C electrode is only 24.3 mAh g⁻¹. -1The specific capacities of the CS and CS@GDY electrodes were 89.7 and 194.9 mAh g, respectively. -1 The synergistic modification of sulfur doping and GDY coating not only improves the specific capacity of traditional carbon materials, but also achieves long-term cycling stability under high current density.

[0076] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a graphdiyne-coated sulfur-doped modified carbon anode material, characterized in that, Includes the following steps: A glucose solution was hydrothermally treated to obtain a black powder. The black powder was then mixed with sulfur powder and heated and carbonized in an inert atmosphere to obtain CS material. The obtained CS material was dispersed in a solvent and heated at 50°C for 2 hours to obtain a reaction solution; then, the HEB graphyne monomer solution was added to the reaction solution to obtain a reaction mixture. Under light-protected conditions, the resulting reaction mixture was heated at 50-80 °C for 24-48 h in an inert atmosphere to obtain the carbon anode material. The solvent includes acetone, pyridine, and tetramethylethylenediamine; the volume ratio of acetone, pyridine, and tetramethylethylenediamine is 100:(5~20):

1.

2. The preparation method according to claim 1, characterized in that, The concentration of the glucose solution is 1.5-3 mol / L.

3. The preparation method according to claim 1, characterized in that, The hydrothermal treatment is carried out at a heating temperature of 150-200 ℃ for 3-6 h.

4. The preparation method according to claim 1, characterized in that, The conditions for heating and carbonization are as follows: heating to 400-600 ℃ at a heating rate of 1-3 ℃ / min, and carbonization time of 1-3 h; Inert gases in an inert atmosphere include nitrogen and / or argon.

5. The preparation method according to claim 1, characterized in that, The mass ratio of black powder to sulfur powder is (1:4) to (1:2).

6. The preparation method according to claim 1, characterized in that, The concentration of the HEB graphyne monomer solution is 1~4 mg / mL.

7. A graphdiyne-coated sulfur-doped modified carbon anode material, characterized in that, The carbon anode material is prepared by the preparation method described in any one of claims 1 to 6; the carbon anode material has a core-shell structure, with sulfur-doped carbon material as the core and a three-dimensional nanowalled network of graphdiyne carbon layers as the shell.

8. A negative electrode sheet, characterized in that, Including the graphdiyne-coated sulfur-doped modified carbon anode material as described in claim 7.

9. A lithium-ion battery, characterized in that, Includes the negative electrode sheet as described in claim 8.

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