A pitch-based hard carbon anode material, its preparation method and application

Abstract

This application belongs to the field of battery material preparation technology, and more specifically, relates to an asphalt-based hard carbon anode material, its preparation method, and its application. This application involves placing asphalt powder in a reaction chamber, then sequentially introducing inert gas and ozone in a cyclical manner. Atomic vapor deposition is used to oxidize the asphalt, with ozone directly cross-linking to form a cross-linked structure between the asphalt particles. This ensures uniform oxidation of the asphalt, inhibits rearrangement during subsequent carbonization, and yields disordered hard carbon, thereby improving the sodium storage capacity and electrochemical performance of the asphalt-based hard carbon anode material. Compared with existing preparation methods, this application achieves rapid and uniform oxidation of asphalt without introducing other heteroatoms and without requiring additional elution and impurity removal processes. It has advantages such as simple process, easy operation, and low cost, facilitating industrial production and widespread application, while also providing convenience for understanding the structure-property relationship of asphalt-based hard carbon anode materials.

Description

Technical Field

[0001] This application belongs to the field of battery material preparation technology, and more specifically, relates to an asphalt-based hard carbon anode material, its preparation method and application. Background Technology

[0002] Hard carbon materials are widely used in sodium-ion or lithium-ion batteries due to their advantages such as high capacity, low sodium intercalation potential, and good cycle stability. Many types of precursors can be used to prepare hard carbon, including biomass, resins, polymers, pitch, and anthracite. Among these, pitch is an ideal precursor for hard carbon materials because of its high carbon yield, abundant raw material sources, and low cost. However, pitch is highly susceptible to graphitization during high-temperature carbonization, resulting in soft carbon materials with small interlayer spacing, few defects, and low sodium storage capacity. Pre-oxidation and cross-linking of pitch are effective methods to inhibit graphitization during high-temperature carbonization, but traditional oxidation methods cannot achieve rapid and uniform oxidation of pitch. The oxidized pitch obtained after carbonization cannot meet the requirements for high-capacity sodium storage.

[0003] Furthermore, the preparation processes of most asphalt-based hard carbon anode materials are currently complex. For example, the preparation process in patent document CN117776148A requires the addition of a template agent to reduce the size of the asphalt carbon skeleton, shorten the oxidation path of the asphalt, shorten the oxidation crosslinking time, and improve the oxidation crosslinking effect. It also involves processes such as acid washing, drying, pulverizing, and sieving. Patent document CN118289737A involves dispersing oxidized asphalt, functional additives, and hard carbon precursors in a solvent, removing the solvent to regulate the pore structure and cycle stability of the hard carbon. Its preparation process is complex, making industrial-scale production difficult, and it also requires the addition of a certain amount of hard carbon precursor, which increases preparation costs and hinders widespread application. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide an asphalt-based hard carbon anode material, its preparation method and application, which aims to solve the problems that traditional oxidation methods cannot quickly and uniformly oxidize asphalt, and the asphalt-based hard carbon anode material prepared has low sodium storage capacity.

[0005] To achieve the above objectives, this application provides a method for preparing a pitch-based hard carbon anode material, comprising the following steps:

[0006] S1. Place asphalt powder in a reaction chamber, then sequentially introduce inert gas and ozone and repeat the cycle. Oxidize the asphalt powder by atomic vapor deposition to obtain an oxidation precursor.

[0007] S2. The above-mentioned oxidized precursor is carbonized in a protective atmosphere to obtain pitch-based hard carbon anode material.

[0008] Preferably, the aforementioned oxidation precursor is a heteroatom-doped oxidation precursor, wherein the heteroatom includes nitrogen atoms.

[0009] Preferably, the heteroatom further includes at least one of sulfur and phosphorus atoms.

[0010] Preferably, the method for preparing the above-mentioned heteroatom-doped oxide precursor includes the following steps:

[0011] S11. Inert gas is introduced to clean the reaction environment;

[0012] S12, introduce ozone;

[0013] S13. Introduce an inert gas carrying heteroatom compounds;

[0014] S14. Repeat steps S11, S12 and S13 in sequence to achieve uniform oxidation and heteroatom doping of asphalt powder, and obtain a heteroatom-doped oxidation precursor, wherein the mass percentage of nitrogen atoms is 0.1% to 0.5%.

[0015] Preferably, in step S13, the heteroatom compound includes one or more of urea, ammonium citrate, dopamine, amino acids, cyanamide, dicyanamide, melamine, and cyanuric acid.

[0016] Preferably, in step S14, the mass percentage of nitrogen atoms in the heteroatom-doped oxide precursor is 0.1% to 0.4%.

[0017] Preferably, in step S1, the particle size of the asphalt powder is 5μm to 20μm.

[0018] Preferably, in step S1, the temperature of the oxidation treatment is 200℃~400℃.

[0019] Preferably, in step S2, the protective atmosphere gas is one or more of nitrogen, argon, neon, helium, xenon, or krypton.

[0020] Preferably, in step S1, the temperature of the carbonization treatment is 1100℃~1700℃, and the carbonization time is 1h~5h.

[0021] On the other hand, this application also provides an asphalt-based hard carbon anode material, which is prepared by the above-described preparation method.

[0022] This application also provides the application of the above-mentioned pitch-based hard carbon anode material in the preparation of sodium-ion battery anode materials.

[0023] This application also provides a battery comprising a positive electrode and a negative electrode, wherein the negative electrode comprises the aforementioned pitch-based hard carbon negative electrode material.

[0024] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0025] (1) The preparation method of the asphalt-based hard carbon anode material provided in this application involves placing asphalt powder in a reaction chamber, then sequentially introducing inert gas and ozone in a cyclical manner, and oxidizing the asphalt powder using atomic vapor deposition. Ozone directly crosslinks the asphalt, forming a crosslinked structure between the asphalt particles. This ensures uniform oxidation of the asphalt, inhibits rearrangement of the asphalt during subsequent carbonization, and yields disordered hard carbon, thereby improving the sodium storage capacity and electrochemical performance of the asphalt-based hard carbon anode material. Compared with existing preparation methods, this application achieves rapid and uniform oxidation of asphalt without introducing other heteroatoms and without requiring additional elution and impurity removal processes. It has advantages such as simple process, easy operation, and low cost, facilitating industrial production and widespread application, while also providing convenience for understanding the structure-property relationship of asphalt-based hard carbon anode materials.

[0026] (2) In a preferred embodiment, this application employs atomic vapor deposition to oxidize asphalt while simultaneously doping it with heteroatoms, resulting in a more complex network structure in the oxidation precursor. This effectively inhibits the rearrangement of asphalt during carbonization, thereby significantly enhancing the sodium storage capacity of the asphalt-based hard carbon anode material. When the above-mentioned asphalt-based hard carbon anode material is applied to sodium-ion batteries, it can significantly improve the reversible capacity of the battery, exhibiting advantages such as high plateau capacity and stable cycle performance. Attached Figure Description

[0027] Figure 1 This is a flowchart of the preparation method of the pitch-based hard carbon anode material provided in this application;

[0028] Figure 2 This is the charge / discharge curve of the battery assembled in Embodiment 1 of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0030] This application provides a method for preparing an asphalt-based hard carbon anode material, such as... Figure 1 As shown, it includes the following steps:

[0031] S1. Place asphalt powder in a reaction chamber, then sequentially introduce inert gas and ozone and repeat the cycle. Oxidize the asphalt powder by atomic vapor deposition to obtain an oxidation precursor.

[0032] S2. The above-mentioned oxidized precursor is carbonized in a protective atmosphere to obtain pitch-based hard carbon anode material.

[0033] In some embodiments, step S1, the method for preparing the above-mentioned oxidized precursor includes the following steps:

[0034] S11. Inert gas is introduced to clean the reaction environment;

[0035] S12, introduce ozone;

[0036] S13. Repeat steps S11 and S12 in sequence to achieve uniform oxidation of asphalt powder and obtain an oxidation precursor.

[0037] It is understood that those skilled in the art can reasonably select the inert gas introduction time in step S11, the ozone introduction time in step S12, and the number of times to repeat steps S11 and S12 according to the actual situation, such as the capacity of the cavity of the atomic layer deposition equipment and the amount of asphalt powder to be processed. As long as uniform oxidation of the asphalt powder can be achieved, it is within the scope of protection of this application.

[0038] In some embodiments, in step S1, typically without limitation, the parameters for preparing the oxide precursor by atomic vapor deposition can be:

[0039] S11. Inert gas is introduced for 40 to 80 seconds to clean the reaction environment;

[0040] S12. Introduce ozone for 100-150 seconds;

[0041] S13. Repeat steps S11 and S12 10 to 100 times in sequence to achieve uniform oxidation of asphalt powder and obtain an oxidation precursor.

[0042] In some embodiments, in step S1, the aforementioned oxide precursor is a heteroatom-doped oxide precursor, and the heteroatom includes nitrogen atoms.

[0043] In some embodiments, the heteroatom further includes at least one of sulfur and phosphorus atoms.

[0044] In some embodiments, step S1, the method for preparing the heteroatom-doped oxide precursor, includes the following steps:

[0045] S11. Inert gas is introduced to clean the reaction environment;

[0046] S12, introduce ozone;

[0047] S13. Introduce an inert gas carrying heteroatom compounds;

[0048] S14. Repeat steps S11, S12 and S13 in sequence to achieve uniform oxidation and heteroatom doping of asphalt powder, and obtain a heteroatom-doped oxidation precursor, wherein the mass percentage of nitrogen atoms is 0.1% to 0.5%.

[0049] In some embodiments, in step S1, typically without limitation, the parameters for preparing the heteroatom-doped oxide precursor by atomic vapor deposition can be:

[0050] S11. Inert gas is introduced for 40 to 80 seconds to clean the reaction environment;

[0051] S12. Introduce ozone for 100-150 seconds;

[0052] S13. Introduce an inert gas carrying heteroatoms for 2 to 20 seconds;

[0053] S14. Repeat steps S11, S12, and S13 10 to 100 times in sequence to achieve uniform oxidation and heteroatom doping of the asphalt powder, and obtain a heteroatom-doped oxidation precursor.

[0054] This application utilizes an inert gas flow to guide the aforementioned heteroatom compounds into a reaction chamber and deposit them onto the surface of oxidized asphalt for heteroatom doping. During the experiment, it was unexpectedly discovered that when asphalt powder was uniformly oxidized and nitrogen-doped using atomic vapor deposition (APV), the reversible capacity of the asphalt-based hard carbon anode material used as a sodium-ion battery initially increased and then decreased with increasing nitrogen doping concentration. The highest reversible capacity was observed when the nitrogen doping concentration was 0.2% by mass. This may be because increasing the nitrogen doping concentration leads to the formation of a more complex network structure in the oxidation precursor, effectively suppressing rearrangement of the asphalt during carbonization, thereby significantly improving the sodium storage capacity of the asphalt-based hard carbon anode material and its electrochemical performance as a sodium-ion battery anode material. However, simultaneously, with increasing nitrogen doping concentration, the material structure becomes distorted, weakening the sodium storage capacity of the asphalt-based hard carbon anode material to some extent. On the other hand, as the amount of nitrogen atom doping increases, the initial efficiency of the battery shows an upward trend. This may be because the increase in nitrogen atom doping can provide more active sites for lithium-ion batteries, increase the contact area between the electrode and the electrolyte, which is conducive to the insertion and extraction of ions, thereby improving the initial efficiency of the battery.

[0055] In a preferred embodiment, the mass percentage of nitrogen atoms in the heteroatom-doped oxide precursor is 0.1% to 0.4%.

[0056] In a preferred embodiment, the mass percentage of nitrogen atoms in the heteroatom-doped oxide precursor is 0.1% to 0.3%.

[0057] The heteroatom compounds mentioned in this application include compounds capable of nitrogen atom doping. These compounds possess amino or cyano groups, which can serve as nitrogen sources for in-situ nitrogen atom doping, adjusting the structure and active sites of asphalt materials. Simultaneously, these groups can generate volatile gases such as ammonia during the carbonization process, which is beneficial for forming porous structures and acts as a pore-forming agent, comprehensively enhancing the sodium storage capacity of the asphalt-based hard carbon anode material and improving its electrochemical performance. It should be understood that the compounds capable of nitrogen atom doping can be, but are not limited to, one or more of urea, ammonium citrate, dopamine, amino acids, cyanamide, dicyanamide, melamine, and cyanuric acid.

[0058] In some embodiments, the heteroatom compounds described above also include at least one of compounds capable of phosphorus atom doping and compounds capable of sulfur atom doping. Examples include, but are not limited to, one or more of phospholipids, thiophene, sulfur, thiourea, thiosulfates, and thiols.

[0059] This application does not limit the source of the asphalt powder. The asphalt powder can be a commercially available product or obtained by crushing asphalt. The crushing method can be mechanical bead milling, impact, shearing, and other conventional crushing methods. This application has no special requirements for the asphalt; asphalt known in the art can be used, such as, but not limited to, high softening point asphalt, medium softening point asphalt, and low softening point asphalt. In some embodiments, the particle size of the asphalt powder is 5μm to 20μm, which allows for rapid, uniform, and complete oxidation of the asphalt powder by atomic vapor deposition.

[0060] In some embodiments, the oxidation treatment temperature in step S1 is 200°C to 400°C.

[0061] In some embodiments, in step S2, the protective atmosphere is an inert gas, and the gas in the protective atmosphere is at least one of nitrogen, argon, neon, helium, xenon or krypton.

[0062] In some embodiments, in step S2, the carbonization temperature is 1100℃~1700℃, and the carbonization time is 1h~5h. It is understood that before the carbonization treatment, the above-mentioned oxidation precursor can also be pre-carbonized, wherein the pre-carbonization temperature can be, but is not limited to, 700℃~900℃, and the time can be, but is not limited to, 10min~30min.

[0063] Based on this, this application provides an asphalt-based hard carbon anode material, which is prepared by the above-described preparation method.

[0064] This application also provides the application of the above-mentioned pitch-based hard carbon anode material in the preparation of sodium-ion battery anode materials.

[0065] On the other hand, this application also provides a battery comprising a positive electrode and a negative electrode, wherein the negative electrode comprises the aforementioned pitch-based hard carbon negative electrode material.

[0066] In some embodiments, the battery described above is a sodium-ion battery.

[0067] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0068] The following is an example:

[0069] Example 1

[0070] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0071] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 8 μm.

[0072] (2) Place 30g of asphalt powder in the cavity of an atomic layer deposition (ALD) device and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, repeat steps S21 and S22 30 times in sequence; uniformly oxidize the asphalt powder at a temperature of 280℃ to obtain an oxidized precursor.

[0073] (3) The above-mentioned oxidized precursor was placed in a nitrogen atmosphere and kept at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain asphalt-based hard carbon anode material.

[0074] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble coin cells. The specific assembly method is as follows: The above-mentioned pitch-based hard carbon material was mixed with conductive carbon black and binder to form a slurry, which was uniformly coated on aluminum foil and dried to form an electrode. A sodium sheet was used as the counter electrode, and a glass fiber membrane was used as the separator. A mixed solution of 1 mol / L NaPF6 and ethylene carbonate (EC): dimethyl carbonate (DEC) = 1:1 vol.% was used as the electrolyte to form a coin cell. The first charge-discharge test was performed by discharging to 0V at 0.1C (nominal capacity 200mA / g) and then charging to 2.5V to obtain the first discharge capacity and the first charge capacity. Constant current charge-discharge test was performed at 0.1C, with a charge-discharge voltage range of 0V to 2.5V, and cycle performance test was performed under constant temperature conditions of 25℃. The first charge reversible capacity and first efficiency of the above battery are shown in Table 1, and the charge-discharge curves are shown in Table 2. Figure 2 As shown.

[0075] Comparative Example 1

[0076] The preparation of the pitch-based hard carbon anode material provided in this comparative example includes the following steps:

[0077] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 13 μm.

[0078] (2) Place 30g of asphalt powder in a crucible and oxidize it in a muffle furnace at 280℃ for 6h in an air atmosphere. After cooling to room temperature, the oxidized precursor is obtained.

[0079] (3) The above-mentioned oxidized precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain asphalt-based hard carbon anode material.

[0080] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0081] Example 2

[0082] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0083] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 5 μm.

[0084] (2) Place 30g of the above asphalt powder in the cavity of the atomic layer deposition equipment, and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, introduce nitrogen carrying urea, and introduce urea into the reaction chamber through fluidization, with a reaction time of 5 seconds; S24, repeat steps S21, S22, and S33 30 times in sequence; while uniformly oxidizing the asphalt powder, nitrogen atoms are doped at the same time. The oxidation treatment temperature is 280℃, and a nitrogen-doped oxidation precursor with a nitrogen atom mass percentage of 0.1% is obtained.

[0085] (3) The nitrogen-doped oxide precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain pitch-based hard carbon anode material.

[0086] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0087] Example 3

[0088] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0089] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 10 μm.

[0090] (2) Place 30g of the above asphalt powder in the cavity of an atomic layer deposition apparatus, and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, introduce an inert gas carrying ammonium citrate, and introduce ammonium citrate into the reaction chamber through fluidization, with a reaction time of 5 seconds; S24, repeat steps S21, S22, and S33 60 times in sequence; while uniformly oxidizing the asphalt powder, nitrogen atoms are doped, and the oxidation treatment temperature is 280℃, to obtain a nitrogen-doped oxidation precursor with a nitrogen atom mass percentage of 0.2%.

[0091] (3) The nitrogen-doped oxide precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain pitch-based hard carbon anode material.

[0092] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0093] Example 4

[0094] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0095] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 16 μm.

[0096] (2) Place 30g of the above asphalt powder in the cavity of an atomic layer deposition apparatus, and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, introduce an inert gas carrying melamine, and introduce melamine into the reaction chamber through fluidization, with a reaction time of 5 seconds; S24, repeat steps S21, S22, and S33 80 times in sequence; while uniformly oxidizing the asphalt powder, nitrogen atoms are doped, and the oxidation treatment temperature is 280℃, to obtain a nitrogen-doped oxidation precursor with a nitrogen atom mass percentage of 0.3%.

[0097] (3) The nitrogen-doped oxide precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain pitch-based hard carbon anode material.

[0098] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0099] Example 5

[0100] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0101] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 8 μm.

[0102] (2) Place 30g of the above asphalt powder in the cavity of an atomic layer deposition apparatus, and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, introduce an inert gas carrying cyanamide, and introduce cyanamide into the reaction chamber through fluidization, with a reaction time of 5 seconds; S24, repeat steps S21, S22, and S33 90 times in sequence; while uniformly oxidizing the asphalt powder, nitrogen atoms are doped at the same time. The oxidation treatment temperature is 280℃, and a nitrogen-doped oxidation precursor with a nitrogen atom mass percentage of 0.4% is obtained.

[0103] (3) The nitrogen-doped oxide precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain pitch-based hard carbon anode material.

[0104] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0105] Example 6

[0106] The preparation method of the pitch-based hard carbon anode material provided in this embodiment includes the following steps:

[0107] (1) The asphalt was crushed to obtain asphalt powder with an average particle size of 6μm.

[0108] (2) Place 30g of the above asphalt powder in the cavity of the atomic layer deposition equipment, and perform atomic vapor deposition according to the following steps: S21, purge with nitrogen for 60 seconds; S22, introduce ozone for 120 seconds; S23, introduce an inert gas carrying urea, and introduce urea into the reaction chamber through fluidization, with a reaction time of 5 seconds; S24, repeat steps S21, S22, and S33 100 times in sequence; while uniformly oxidizing the asphalt powder, nitrogen atoms are doped at the same time. The oxidation treatment temperature is 280℃, and a nitrogen-doped oxidation precursor with a nitrogen atom mass percentage of 0.5% is obtained.

[0109] (3) The nitrogen-doped oxide precursor was placed at 1300℃ for 2 hours for high-temperature carbonization treatment to obtain pitch-based hard carbon anode material.

[0110] The above-mentioned pitch-based hard carbon anode material was used as the anode material for sodium-ion batteries to assemble into button cells. The assembly method was the same as in Example 1. The reversible capacity and initial efficiency of the first charge were tested, and the results are shown in Table 1.

[0111] Table 1. Performance of the batteries assembled in Examples 1-6 and Comparative Example 1.

[0112] Reversible capacity during the first charge (mAh / g) First-time efficiency (%) Example 1 300.33 88.71 Comparative Example 1 283.68 86.62 Example 2 313.29 86.03 Example 3 321.72 87.46 Example 4 310.52 87.43 Example 5 302.83 88.32 Example 6 283.57 88.41

[0113] As shown in Table 1, comparing Example 1 and Comparative Example 1, it can be seen that, compared with traditional oxidation methods, this application uses atomic vapor deposition to oxidize asphalt, directly cross-linking it with ozone to form a cross-linked structure between the asphalt particles. This ensures uniform oxidation of the asphalt, inhibits rearrangement of the asphalt during subsequent carbonization, and yields disordered hard carbon, thereby improving the sodium storage function of the asphalt-based hard carbon anode material. When the asphalt-based hard carbon anode material prepared in the above examples is applied to sodium-ion batteries, it can improve the reversible capacity and initial efficiency of the battery. Figure 2 It has advantages such as high platform capacity and stable cycle performance.

[0114] Examples 2-6, based on Example 1, employed atomic vapor deposition to oxidize asphalt while simultaneously doping it with nitrogen atoms. The mass percentage of nitrogen doping ranged from 0.1% to 0.5%. Experiments revealed that nitrogen doping significantly improved the sodium storage capacity of the asphalt-based hard carbon anode material. With increasing nitrogen doping concentration, the reversible capacity of the battery initially increased and then decreased, reaching its highest point at a nitrogen doping mass percentage of 0.2%. This may be because the increased nitrogen doping concentration led to the formation of a more complex network structure in the oxidation precursor, effectively inhibiting rearrangement of the asphalt during carbonization, thus significantly enhancing the sodium storage capacity of the asphalt-based hard carbon anode material and its electrochemical performance as a sodium-ion battery anode material. However, with increasing nitrogen doping concentration, the material structure became distorted, weakening the sodium storage capacity of the asphalt-based hard carbon anode material to some extent. Nevertheless, its electrochemical performance, such as sodium storage capacity or initial efficiency, remained higher than that of asphalt-based hard carbon anode materials prepared by traditional oxidation methods.

[0115] In summary, compared with existing preparation methods, this application can achieve rapid and uniform oxidation of asphalt without introducing other heteroatoms and without requiring additional elution and impurity removal processes. It has the advantages of simple process, easy operation, and low cost, and provides convenience for the structure-property relationship of asphalt-based hard carbon anode materials.

[0116] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing an asphalt-based hard carbon anode material, characterized in that, Includes the following steps: S1. Place the asphalt powder in a reaction chamber and oxidize it using atomic vapor deposition to obtain an oxidation precursor. The method for preparing the oxidized precursor includes the following steps: S11. Inert gas is introduced for 40 to 80 seconds to clean the reaction environment; S12. Introduce ozone for 100-150 seconds; Repeat steps S11 and S12 10 to 100 times to achieve uniform oxidation of asphalt powder and obtain an oxidation precursor. S2. The oxidized precursor is carbonized in a protective atmosphere to obtain pitch-based hard carbon anode material.

2. The preparation method according to claim 1, characterized in that, The oxidation precursor is a heteroatom-doped oxidation precursor, and the heteroatom includes nitrogen atoms; The method for preparing the heteroatom-doped oxide precursor includes the following steps: S11. Inert gas is introduced for 40 to 80 seconds to clean the reaction environment; S12. Introduce ozone for 100-150 seconds; S13. Introduce an inert gas carrying heteroatoms for 2 to 20 seconds; S14. Repeat steps S11, S12, and S13 10 to 100 times in sequence to achieve uniform oxidation and heteroatom doping of asphalt powder, and obtain a heteroatom-doped oxidation precursor, wherein the mass percentage of nitrogen atoms is 0.1% to 0.4%.

3. The preparation method according to claim 2, characterized in that, In step S13, the heteroatom compound includes one or more of urea, ammonium citrate, dopamine, amino acids, cyanamide, dicyanamide, melamine, and cyanuric acid.

4. The preparation method according to claim 1, characterized in that, In step S1, the particle size of the asphalt powder is 5μm~20μm.

5. The preparation method according to claim 1, characterized in that, In step S1, the oxidation treatment temperature is 200℃~400℃.

6. The preparation method according to claim 1, characterized in that, In step S2, the protective atmosphere gas is one or more of nitrogen, argon, neon, helium, xenon, or krypton; And / or, the carbonization treatment is carried out at a temperature of 1100℃~1700℃ for a time of 1h~5h.

7. A pitch-based hard carbon anode material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the pitch-based hard carbon anode material as described in claim 7 in the preparation of sodium-ion battery anode materials.

9. A battery, characterized in that, It includes a positive electrode and a negative electrode, wherein the negative electrode includes the pitch-based hard carbon negative electrode material as described in claim 7.

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