Graphite-induced auxiliary carbonized hard carbon material as well as preparation method and application thereof

Abstract

The invention provides a graphite-induced auxiliary carbonized hard carbon material and a preparation method and application thereof, and belongs to the field of battery negative electrode material manufacturing, and the preparation method comprises the following steps: pretreating raw materials to obtain a hard carbon intermediate; 3%-8% of microcrystalline graphite powder is added into the hard carbon intermediate, mechanical ball milling is carried out for uniform mixing, and composite intermediate powder is obtained; placing the composite intermediate powder in a graphite crucible, covering the graphite crucible with a graphite plate, pressurizing, and performing high-temperature carbonization in an inert atmosphere to obtain a hard carbon material; the invention also discloses an application of the prepared hard carbon material as a negative electrode material in a sodium-ion battery. According to the invention, microcrystalline graphite is adopted as a graphitization seed crystal to carry out induction regulation and control on a hard carbon forming process, development and growth of graphite-like microcrystals and directional conversion of closed pores are realized, kilogram-level preparation verification is realized depending on an industrial production line, and an innovative path is provided for low-cost and large-scale production of high-performance hard carbon materials.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing negative electrode materials for batteries, and particularly to a hard carbon material induced by graphite for auxiliary carbonization, its preparation method and application. Background Art

[0002] In recent years, problems such as environmental pollution caused by traditional fossil energy have become increasingly serious, and it is urgent to develop sustainable and low-cost energy storage technologies. Sodium-ion batteries, with their advantages of rich resources and low cost, can alleviate the supply-demand contradiction of secondary batteries caused by the shortage of lithium resources to a certain extent. They are a beneficial supplement to lithium-ion batteries and are expected to show their unique advantages in the energy storage field, with broad development prospects. Currently, developing new high-performance negative electrode materials is the core to promote the commercialization process of sodium-ion batteries. Hard carbon materials have a high sodium storage capacity, low cost, a suitable carbon layer spacing, and a disordered microcrystalline structure, making them suitable for constructing sodium-ion batteries with excellent performance and showing potential for large-scale application. However, a large number of defects and micropores in the disordered structure of hard carbon lead to the formation of a large number of irreversible sodium storage sites, seriously affecting the first-cycle Coulombic efficiency and cycle stability of the negative electrode.

[0003] Currently, to address the above problems, researchers have regulated the degree of defects and layer spacing of hard carbon through various strategies. For example, increasing the carbonization temperature (>1600 °C) can improve the order degree of hard carbon and reduce the number of defects. However, excessive graphitization often causes the carbon layer spacing of graphite domains to shrink and the number of sodium storage active sites to decrease, resulting in a decline in sodium storage capacity and rate performance. Moreover, the hard carbon modification methods disclosed in the prior art, such as heteroatom doping and surface coating, are complex in process and difficult to carry out large-scale production and commercial application. Pressure-assisted carbonization with a graphite plate can reduce defects, increase graphite-like microcrystals, and at the same time improve ICE and reversible capacity. However, pressure-assisted carbonization often requires a self-supporting precursor to achieve, which limits the application of traditional powder materials as hard carbon precursors. Although specific precursors can be induced by introducing graphite microspheres, there is very little research on the universality of this method, lacking verification of large-scale preparation in industry, and it is difficult to achieve the synergistic improvement of ICE, reversible capacity, and rate performance.

[0004] Therefore, developing a general modification strategy with simple process and low cost for the graphitization regulation of hard carbon, and significantly improving the first-cycle Coulombic efficiency and rate performance of the material without affecting the sodium storage capacity, is of great significance for the development of high-performance negative electrode materials and the large-scale application of sodium-ion batteries. Summary of the Invention

[0005] In view of the deficiencies in the background art, a hard carbon material prepared by graphite-induced assisted carbonization, its preparation method and application, by introducing microcrystalline graphite, regulate the carbonization process of hard carbon precursors (such as starch, starch-phenolic copolymer, pitch, microcrystalline cellulose, etc.), realize the orderly growth of carbon layers and the evolution of closed pore structures, and have carried out universal exploration of various precursors and verification of kilogram-scale preparation in industry.

[0006] On the one hand, the present invention provides a preparation method of a hard carbon material prepared by graphite-induced assisted carbonization, and the preparation method includes the following steps: S1, pretreat the raw materials to obtain a hard carbon intermediate; the raw materials are one or more of corn starch, microcrystalline cellulose, pitch, and phenolic resin; S2, add 3%-8% of microcrystalline graphite powder to the hard carbon intermediate, and mechanically ball-mill to make it evenly mixed to obtain a composite intermediate powder; S3, place the composite intermediate powder obtained in S2 in a graphite crucible, cover the upper part of the composite intermediate powder with a graphite plate for pressurization, and perform high-temperature carbonization in an inert gas atmosphere to obtain a hard carbon material.

[0007] Preferably, in step S1, the pretreatment includes one or more of pre-oxidation treatment, pre-carbonization treatment, and steam activation treatment.

[0008] Preferably, when the raw material is corn starch, pre-oxidation treatment is carried out; when the raw materials are corn starch and phenolic resin, pre-oxidation treatment and pre-carbonization treatment are carried out; when the raw material is pitch, pre-oxidation treatment and steam activation treatment are carried out; when the raw material is microcrystalline cellulose, no pretreatment is carried out.

[0009] Preferably, when the raw materials are corn starch and phenolic resin, the mixing mass ratio of corn starch to phenolic resin is 5:1.

[0010] Preferably, during the pre-oxidation treatment, the pre-oxidation temperature of pitch is 300°C, the pre-oxidation temperature of other raw materials is 220-240°C, the heat preservation time is 5-6h, and the heating rate is 1-2°C / min; during the pre-carbonization treatment, the pre-carbonization temperature is 600°C, the heat preservation time is 2h, and the heating rate is 5°C / min; during the steam activation treatment, the heating rate is 5°C / min, the activation temperature is 900-950°C, the heat preservation time is 2h, and the steam flow rate is 200μL / min.

[0011] Preferably, during the mechanical ball-milling process in S2, the ball-milling speed is 500-800r / min, and the ball-milling time is 1-5h.

[0012] Preferably, during the high-temperature carbonization process in S3, the carbonization temperature is 1300-1500°C, the heat preservation time is 1-5h, and the heating rate is 1-10°C / min; the inert gas used is argon.

[0013] Preferably, during the pressure application in S3, the pressure applied above the composite intermediate powder is 100 - 500 Pa.

[0014] The present invention also provides a hard carbon material prepared by the above method.

[0015] The present invention also provides an application of the above hard carbon material in a sodium-ion battery, and the hard carbon material serves as a negative electrode material in the sodium-ion battery.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses corn starch, microcrystalline cellulose, asphalt, phenolic resin, etc. as precursors, which have a wide source, high consistency, and the potential for batch industrial preparation. By adjusting the pyrolysis path of precursors such as starch through graphite seeds, the carbon layers are guided to stack orderly along the graphite basal plane, significantly reducing the sp³ hybridization defect density; at the same time, it can catalyze the growth of carbon layers, promote the transformation of open-pore structures into closed pores, and form high-density sodium storage sites. Compared with the existing methods, the method provided by the present invention can maintain the high sodium storage capacity, high cycle stability and good rate performance of the hard carbon material, has a simple process flow and universality, low production cost, environmental friendliness, is suitable for large-scale batch preparation and commercial application, and has realized kilogram-level preparation verification relying on an industrial production line. Description of the Drawings

[0017] Figure 1 is the scanning electron microscope micrograph of the hard carbon material provided in Example 1 of the present invention.

[0018] Figure 2 is the X-ray diffraction pattern of the hard carbon material provided in Example 1 of the present invention.

[0019] Figure 3 is the small-angle X-ray scattering pattern of the hard carbon material provided in Example 1 of the present invention.

[0020] Figure 4 is the charge-discharge performance graph of the hard carbon materials provided in Example 1 and Comparative Example 1 of the present invention at a current density of 0.02 A / g.

[0021] Figure 5 is the rate performance graph of the hard carbon materials provided in Example 1 and Comparative Example 1 of the present invention at different current densities from 0.02 A / g to 1 A / g. Specific Embodiment Methods

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of the present disclosure without creative efforts also fall within the scope of protection of the present disclosure.

[0023] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the subject matter of the present disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless expressly so defined herein.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase "embodiments" appearing in various places in the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0025] A method for preparing a hard carbon material assisted by graphite induction carbonization provided by the present invention specifically includes the following steps: S1. Pretreat the raw materials to obtain a hard carbon intermediate; The raw materials are one or more of corn starch, microcrystalline cellulose, pitch, and phenolic resin; when the raw material is corn starch, pre-oxidation treatment is carried out; when the raw materials are corn starch and phenolic resin, pre-oxidation treatment and pre-carbonization treatment are carried out; when the raw material is pitch, pre-oxidation treatment and steam activation treatment are carried out; when the raw material is microcrystalline cellulose, no pretreatment is carried out. S2. Add 3%-8% of microcrystalline graphite powder to the hard carbon intermediate, for example, it can be 3%, 5%, 7%, 8%, and mechanically ball-mill to mix evenly to obtain a composite intermediate powder; S3. Place the composite intermediate powder obtained in S2 in a graphite crucible, cover the upper part of the composite intermediate powder with a graphite plate for pressurization, the average pressure applied to the powder is 100-500 Pa, for example, it can be 100 Pa, 150 Pa, 250 Pa, 450 Pa, 500 Pa, and carry out high-temperature carbonization in an argon atmosphere to obtain a hard carbon material.

[0026] In some embodiments of the present invention, the carbonization temperature for high-temperature carbonization is 1100 - 1500 °C, for example, it can be 1100 °C, 1300 °C, 1500 °C; the heat preservation time is 1 - 5 h, for example, it can be 1 h, 2 h, 3 h, 4 h, 5 h; the heating rate is 1 - 10 °C / min, for example, it can be 1 °C / min, 3 °C / min, 5 °C / min, 7 °C / min, 10 °C / min.

[0027] The present invention will be further described below through specific embodiments.

[0028] Example 1 S1. Place the alumina crucible filled with corn starch in a tube furnace, pump air into the tube with an air pump, and heat it to 240 °C at a heating rate of 1 °C / min. After heat preservation for 6 h, naturally cool it to room temperature; S2. Add microcrystalline graphite powder to the obtained pre-oxidized starch. The mass ratio of the added microcrystalline graphite to the pre-oxidized starch is 0.05, and mechanically ball mill for 2 h to make it evenly mixed. The rotational speed of the ball mill is 600 r / min; S3. Place the intermediate powder obtained in S2 in a graphite crucible, cover the powder with a graphite plate for pressurization, the pressure applied to the powder is 150 Pa, heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, after heat preservation for 3 h, cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0029] The scanning electron microscope micrograph of the prepared hard carbon material is as Figure 1 shown. It can be observed that the prepared hard carbon material presents an interlaced and stacked sheet structure, which is beneficial to ion conduction and can obtain a relatively high compaction density; the X-ray diffraction pattern of the hard carbon material is as Figure 2 shown. The two obvious diffraction peaks near 24° and 43° respectively correspond to the (002) and (100) crystal planes, which conform to the typical amorphous structure characteristics of hard carbon. In addition, the diffraction peak near 26° comes from the doped microcrystalline graphite phase structure; the small-angle X-ray scattering pattern of the hard carbon material is as Figure 3 shown. There is an obvious plateau near q = 0.1 Å−1 in the SAXS curve, corresponding to the existence of micropores and nanoscale voids between sp2 carbon planes, which provides space for sodium ion insertion and helps the hard carbon material obtain excellent sodium storage capacity.

[0030] Example 2 S1. Uniformly mix corn starch and phenolic resin at a mass ratio of 5:1. Place the alumina crucible filled with corn starch and phenolic resin in a tube furnace, pump air into the tube with an air pump, and heat it to 240 °C at a heating rate of 1 °C / min. After heat preservation for 6 h, naturally cool it to room temperature; S2. Place the graphite crucible containing the pre-oxidized mixed raw materials in a tube furnace, heat it to 600 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 2 h, and then cool it naturally to room temperature; S3. Add microcrystalline graphite powder to the pre-carbonized product obtained in S2. The mass ratio of the added microcrystalline graphite to the pre-carbonized product is 0.05, and mechanically ball-mill for 2 h to make it evenly mixed. The rotation speed of the ball mill is 600 r / min; S4. Place the intermediate powder obtained in S3 in a graphite crucible, cover the powder with a graphite plate for pressure application. The pressure applied to the powder is 150 Pa. Heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally cool it naturally to room temperature to obtain the hard carbon material.

[0031] Example 3 S1. Place the alumina crucible containing pitch in a tube furnace, pump air into the tube with an air pump, heat it to 300 °C at a heating rate of 2 °C / min, keep it for 5 h, and then cool it naturally to room temperature; S2. Place the alumina crucible containing pre-oxidized pitch in a tube furnace, heat it to 900 °C at a heating rate of 5 °C / min, and introduce a mixed gas of steam and nitrogen into the tube using a steam generating device. The steam flow rate is 200 μL / min. Keep it for 2 h and then cool it naturally to room temperature; S3. Add microcrystalline graphite powder to the activated product obtained in S2. The mass ratio of the added microcrystalline graphite to the activated product is 0.05, and mechanically ball-mill for 2 h to make it evenly mixed. The rotation speed of the ball mill is 600 r / min; S4. Place the intermediate powder in a graphite crucible, cover the powder with a graphite plate for pressure application. The pressure applied to the powder is 150 Pa. Heat it to 1500 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally cool it naturally to room temperature to obtain the hard carbon material.

[0032] Example 4 S1. Add microcrystalline graphite powder to microcrystalline cellulose. The mass ratio of the added microcrystalline graphite to microcrystalline cellulose is 0.05, and mechanically ball-mill for 2 h to make it evenly mixed. The rotation speed of the ball mill is 600 r / min; S2. Place the mixture obtained in S1 in a graphite crucible, cover the powder with a graphite plate for pressure application. The pressure applied to the powder is 150 Pa. Heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally cool it naturally to room temperature to obtain the hard carbon material.

[0033] Example 5 In this example, a kilogram-scale carbonization process verification was carried out relying on industrial pusher kiln equipment.

[0034] S1. Add microcrystalline graphite powder to microcrystalline cellulose. The mass ratio of the added microcrystalline graphite to microcrystalline cellulose is 0.05, and mix it in a mixer for 1 h to make it evenly mixed. S2. Place the mixture obtained in S1 in an alumina crucible. Place thin graphite plates below and above the powder, cover it with an alumina plate for pressurization. The pressure applied to the powder is 300 Pa. The crucible is wrapped with graphite paper, heat-insulating cotton and semi-coke, and placed at the pusher kiln inlet. The pusher rate is 1 m / h, and it lasts for 14 h, 6 h, and 6 h in the heating zone, heat-insulating zone, and cooling zone respectively. The temperature in the heat-insulating zone is 1100 - 1200 °C, and finally it is naturally cooled to room temperature to obtain a hard carbon material.

[0035] Example 6 In this example, a kilogram-scale carbonization process verification was carried out relying on industrial pusher kiln equipment.

[0036] S1. Add microcrystalline graphite powder to microcrystalline cellulose. The mass ratio of the added microcrystalline graphite to microcrystalline cellulose is 0.05, and mix it in a mixer for 1 h to make it evenly mixed. S2. Place the mixture obtained in S1 in an alumina crucible. Place thin graphite plates below and above the powder, cover it with an alumina plate for pressurization. The pressure applied to the powder is 300 Pa. The crucible is wrapped with graphite paper, heat-insulating cotton and semi-coke, and placed at the pusher kiln inlet. The pusher rate is 1 m / h, and it lasts for 14 h, 6 h, and 6 h in the heating zone, heat-insulating zone, and cooling zone respectively. The temperature in the heat-insulating zone is 1100 - 1200 °C, and it is naturally cooled to room temperature. S3. Place the carbonized product obtained in S2 in a graphite crucible, heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, hold it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0037] Comparative Example 1 S1. Place an alumina crucible containing corn starch in a tube furnace, pump air into the tube with an air pump, heat it to 240 °C at a heating rate of 1 °C / min, hold it for 6 h, and then naturally cool it to room temperature. S2. Place the pre-oxidized starch obtained in S1 in a graphite crucible, heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, hold it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0038] Comparative Example 2 S1. Uniformly mix corn starch and phenolic resin at a mass ratio of 5:1. Place the alumina crucible containing corn starch and phenolic resin in a tube furnace. Pump air into the tube with an air pump and heat it at a heating rate of 1 °C / min to 240 °C. After maintaining the temperature for 6 h, naturally cool it to room temperature; S2. Place the graphite crucible containing the pre-oxidized mixed raw materials in a tube furnace. Heat it to 600 °C at a heating rate of 5 °C / min under an argon atmosphere. After maintaining the temperature for 2 h, naturally cool it to room temperature; S3. Place the pre-carbonized product obtained in S2 in a graphite crucible. Heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere. After maintaining the temperature for 3 h, cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0039] Comparative Example 3 S1. Place the alumina crucible containing pitch in a tube furnace. Pump air into the tube with an air pump and heat it at a heating rate of 2 °C / min to 300 °C. After maintaining the temperature for 5 h, naturally cool it to room temperature; S2. Place the alumina crucible containing pre-oxidized pitch in a tube furnace. Heat it to 900 °C at a heating rate of 5 °C / min. Pass a mixture of water vapor and nitrogen into the tube using a water vapor generating device, with a water vapor flow rate of 200 μL / min. After maintaining the temperature for 2 h, naturally cool it to room temperature; S3. Place the activated product obtained in S2 in a graphite crucible. Heat it to 1500 °C at a heating rate of 5 °C / min under an argon atmosphere. After maintaining the temperature for 3 h, cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0040] Comparative Example 4 S1. Place the graphite crucible containing microcrystalline cellulose in a tube furnace. Heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere. After maintaining the temperature for 3 h, cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0041] Comparative Example 5 S1. Place microcrystalline cellulose in an alumina crucible, wrap the crucible with graphite paper, insulation cotton and semi-coke, and place it at the mouth of a pusher kiln; the pusher rate is 1 m / h, and it takes 14 h, 6 h, and 6 h in the heating zone, insulation zone, and cooling zone respectively, where the temperature in the insulation zone is 1100 - 1200 °C, and finally naturally cool it to room temperature to obtain a hard carbon material.

[0042] Comparative Example 6 S1. Place microcrystalline cellulose in an alumina crucible, which is wrapped with graphite paper, heat insulation cotton and semi-coke, and place it at the mouth of the pusher kiln. The pusher rate is 1 m / h, and it lasts for 14 h, 6 h, and 6 h in the heating zone, heat preservation zone, and cooling zone respectively. The temperature in the heat preservation zone is 1100 - 1200 °C, and finally it is naturally cooled to room temperature to obtain the hard carbon material.

[0043] S2. Place the carbonized product obtained in S1 in a graphite crucible, heat it to 1300 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 3 h, then cool it to 500 °C at a rate of 2 °C / min, and finally naturally cool it to room temperature to obtain the hard carbon material.

[0044] Assemble sodium-ion batteries and conduct electrochemical performance tests on Examples 1 - 6 and Comparative Examples 1 - 6: Mix the prepared hard carbon material with sodium alginate binder in a mass ratio of 0.95:0.05, add an appropriate amount of deionized water, grind it evenly and then coat it on copper foil, dry it in a vacuum drying oven at 80 °C for 12 h, and cut it into electrode sheets with a diameter of 10 mm. The separator used for assembling the battery is a glass fiber separator, the electrolyte is 1 M NaPF6 ether-based electrolyte, and the counter electrode is a sodium metal sheet. After the assembled battery is left standing for 8 h, constant current charge and discharge tests are carried out at different current densities.

[0045] The relevant parameters and test results of the assembled batteries are shown in Table 1. Among them, the first-cycle charge and discharge curves of the hard carbon materials prepared in Example 1 and Comparative Example 1 at a current density of 0.02 A / g are as Figure 4 shown. The reversible specific capacity of the hard carbon material in Example 1 is 328.9 mAh g -1 , and the first Coulombic efficiency reaches 91.5%; the hard carbon material prepared in Comparative Example 1 was not doped with microcrystalline graphite, and its reversible specific capacity was only 302.6 mAh g -1 , and the first Coulombic efficiency was only 86.1%; the rate performance diagrams of the hard carbon materials prepared in Example 1 and Comparative Example 1 at different current densities from 0.02 A g -1 -1 to 1 A g -1 are as Figure 5 shown. The hard carbon material prepared in Example 1 has a reversible specific capacity of 144 mAh g -1 at a current density of 1 A g -1 , indicating that an appropriately increased degree of graphitization does not affect the adsorption and insertion rate of sodium ions, making the hard carbon material exhibit excellent rate performance.

[0046] Table 1 The following is the table of relevant parameters of the half-cells assembled in Comparative Examples 1 - 6 and Examples 1 - 6 in turn

[0047] The embodiments given above are the preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential addition or replacement made by those skilled in the art according to the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A preparation method of a hard carbon material assisted by graphite induction carbonization, characterized in that, the preparation method includes the following steps: S1, pretreat the raw materials to obtain a hard carbon intermediate; the raw materials are one or more of corn starch, microcrystalline cellulose, pitch, and phenolic resin; S2, add 3%-8% of microcrystalline graphite powder to the hard carbon intermediate, and mechanically ball mill to mix evenly to obtain a composite intermediate powder; S3, place the composite intermediate powder obtained in S2 in a graphite crucible, cover the upper part of the composite intermediate powder with a graphite plate for pressurization, and carry out high-temperature carbonization in an inert gas atmosphere to obtain a hard carbon material.

2. The preparation method of a hard carbon material assisted by graphite induction carbonization according to claim 1, characterized in that, In step S1, the pretreatment includes one or more of pre-oxidation treatment, pre-carbonization treatment, and steam activation treatment.

3. The preparation method of a hard carbon material assisted by graphite induction carbonization according to claim 2, wherein, When the raw material is corn starch, pre-oxidation treatment is carried out; when the raw materials are corn starch and phenolic resin, pre-oxidation treatment and pre-carbonization treatment are carried out; when the raw material is pitch, pre-oxidation treatment and steam activation treatment are carried out; when the raw material is microcrystalline cellulose, no pretreatment is carried out.

4. The preparation method of a hard carbon material assisted by graphite-induced carbonization according to claim 3, characterized in that, When the raw materials are corn starch and phenolic resin, the mixing mass ratio of corn starch and phenolic resin is 5:

1.

5. The preparation method of a hard carbon material assisted by graphite-induced carbonization according to claim 2, characterized in that, During pre-oxidation treatment, the pre-oxidation temperature of pitch is 300°C, the pre-oxidation temperature of other raw materials is 220-240°C, the holding time is 5-6h, and the heating rate is 1-2°C / min; during pre-carbonization treatment, the pre-carbonization temperature is 600°C, the holding time is 2h, and the heating rate is 5°C / min; during steam activation treatment, the heating rate is 5°C / min, the activation temperature is 900-950°C, the holding time is 2h, and the water vapor flow rate is 200μL / min.

6. The preparation method of a hard carbon material assisted by graphite induction carbonization according to claim 1, characterized in that, During the mechanical ball milling process in S2, the ball milling speed is 500-800r / min, and the ball milling time is 1-5h.

7. The preparation method of a hard carbon material assisted by graphite induction carbonization according to claim 1, characterized in that, During the high-temperature carbonization process in S3, the carbonization temperature is 1300-1500°C, the holding time is 1-5h, and the heating rate is 1-10°C / min; the inert gas used is argon.

8. The preparation method of a hard carbon material assisted by graphite induction carbonization according to claim 1, characterized in that, During the pressurization process in S3, the pressure applied above the composite intermediate powder is 100-500Pa.

9. A hard carbon material prepared by the preparation method of the graphite-induced assisted carbonization hard carbon material according to any one of claims 1-8.

10. Use of the hard carbon material according to claim 9 in a sodium ion battery, characterized in that, The hard carbon material is used as a negative electrode material in a sodium ion battery.

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