Method for preparing graphite negative electrode by recycling and utilizing fine coke powder

Abstract

The application discloses a method for preparing a graphite negative electrode by recycling and utilizing coke fine powder with high value, comprising the following steps: grading coke fine powder generated in a grinding process and removing superfine particles; pre-carbonizing the graded material; graphitizing the pre-carbonized material; after the graphitized fine powder is compounded with a binder and a solvent, spray granulation is carried out; finally, the granulated graphite is mixed with a surface coating modification system, high-temperature carbonization is carried out, and a graphite negative electrode material is obtained. The method has the following advantages: 1) through a series of processes such as grading, pre-carbonization, graphitization, spray granulation and high-temperature carbonization, the coke fine powder which needs to be discarded is reused, and the recycling and utilization of the fine powder coke with high value are realized; 2) the secondary particle graphite is prepared by using the spray granulation method, which is beneficial to improving the fast charging and discharging performance; and 3) the surface coating modification system can produce significant synergistic effect, which can significantly improve the specific surface area, the rate performance and the cycle stability.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery anode materials, specifically to a method for preparing graphite anodes by recycling coke fine powder, and more particularly to a preparation method for high-value recycling of coke fine powder through classification, pre-carbonization, graphitization, spray granulation and surface coating modification. Background Technology

[0002] Graphite is currently the most widely used anode material for lithium-ion batteries due to its advantages such as high capacity, low voltage plateau, and low cost. However, the layered structure of graphite results in a long diffusion path for lithium ions and a low diffusion coefficient, leading to poor rate performance of graphite anodes. Shortening the lithium-ion diffusion path is one of the effective ways to improve the fast charging and discharging performance of anode materials.

[0003] In the processing of graphite anode materials, the crushing process of coke raw materials generates a large amount of fine powder. Statistics show that this process produces 15-25% fine coke powder with a volume average particle size (D50) ≤ 7 μm. These small particles, when used as anode materials, can shorten the diffusion path of lithium ions in the solid phase, which is beneficial for improving fast discharge performance. However, the excessively small particle size also brings a series of problems: a larger specific surface area and lower tap density, resulting in lower initial battery efficiency and energy density; simultaneously, the presence of ultrafine particles (particle size < 1.5 μm) in the fine powder increases the difficulty of anode slurry preparation, affecting slurry properties and subsequent electrode coating performance. Discarding the fine powder directly would result in resource waste.

[0004] Several attempts have been made in the existing technology for the recycling of fine coke powder. For example, one method involves mixing the fine powder with a binder, briquetting, crushing, and then graphitizing it. However, the secondary particles obtained from briquetting and granulation are irregular in shape and have many sharp edges, which is not conducive to improving the tap density and rate performance. Another example is the use of spray granulation technology to granulate coke powder. However, existing spray granulation technology usually involves directly spray granulating raw coke powder that has not undergone pre-carbonization and graphitization treatment, followed by heat treatment. The ultrafine particles in the fine powder are not effectively removed, and the specific surface area of ​​the final product is still relatively large.

[0005] In terms of surface coating modification, pitch coating is one of the most commonly used modification methods for graphite anode materials. It reduces the specific surface area and repairs surface defects by forming an amorphous carbon layer on the graphite surface, thereby improving initial efficiency and cycle life. However, the improvement in rate performance by using pitch coating alone is limited.

[0006] Therefore, there is an urgent need in this field for a method to prepare graphite anodes that can recycle coke fines at high value and obtain excellent electrochemical performance. Summary of the Invention

[0007] To address the technical problems of large specific surface area, low tap density, and poor initial efficiency and rate performance in the recycling of coke fine powder in existing technologies, this invention provides a method for preparing graphite anodes by high-value recycling of coke fine powder.

[0008] To address the aforementioned technical problems, this invention, through in-depth research and process optimization, proposes the following technical solution:

[0009] A method for preparing graphite anodes by high-value recycling of coke fine powder includes the following steps:

[0010] S1. The coke fine powder produced in the grinding process is classified to remove ultrafine particles with a particle size <1.5μm, and the classified material is obtained.

[0011] S2. The graded material obtained in step S1 is pre-carbonized to obtain pre-carbonized material;

[0012] S3. Graphitize the pre-carbonized material obtained in step S2 to obtain graphitized fine powder;

[0013] S4. The graphitized fine powder obtained in step S3 is compounded with binder and solvent, and then spray-granulated to obtain granulated graphite.

[0014] S5. The granulated graphite obtained in step S4 is mixed with the surface coating modification system and carbonized at high temperature to obtain a graphite anode material; the surface coating modification system includes asphalt.

[0015] In step S1, the grading process is used to remove ultrafine particles with a particle size <1.5μm from the coke powder. The inventors discovered that these ultrafine particles are the main factor causing excessive specific surface area and difficulty in pulping. After removing ultrafine particles through grading, the particle size distribution of the material is more uniform, which is beneficial for the uniformity of subsequent granulation and coating processes. If these ultrafine particles are not removed, it is difficult to control the specific surface area of ​​the final product below 2m² / g, and the viscosity of the slurry is not easy to control.

[0016] In step S2, the purpose of pre-carbonization is to remove volatiles from the material and improve its thermal stability. If the pre-carbonization temperature is too low or the time is insufficient, the residual volatiles in the material will be released rapidly during the subsequent graphitization process, affecting the structure and properties of the graphitized product.

[0017] In step S3, graphitization rearranges carbon atoms in the material to form an ordered graphite layer structure, giving the material good electronic conductivity and lithium intercalation capability.

[0018] In step S4, spray granulation agglomerates the fine primary graphite particles into secondary particles with good sphericity, which is beneficial for improving tap density and processing performance. The binder plays a binding and dispersing role in the spray granulation process, on the one hand helping the particles to disperse uniformly, and on the other hand binding the primary particles into secondary particles during the drying process.

[0019] In step S5, the surface coating modification system includes asphalt. The asphalt melts during high-temperature carbonization and uniformly coats the surface of granulated graphite. It then pyrolyzes to form an amorphous carbon layer, which seals surface defects and openings, thereby reducing the specific surface area.

[0020] As a further improvement of the present invention, in step S1, the coke fine powder is selected from petroleum coke fine powder or needle coke fine powder; the particle size Dv50 of the graded material is 5-7 μm. Both petroleum coke and needle coke are commonly used raw materials for preparing graphite anodes, and their fine powders are suitable for the method of the present invention. Controlling the Dv50 after grading within the range of 5-7 μm ensures a sufficient proportion of fine powder to utilize its fast-charging advantage, while avoiding the problems of excessive specific surface area and difficulties in pulping caused by too many ultrafine particles.

[0021] As a further improvement of the present invention, in step S2, the maximum temperature of pre-carbonization is 1000–1250°C, and the volatile matter content of the material after pre-carbonization is less than 1%, with a tap density of 0.6–0.8 g / cm³. The inventors have found through experiments that a pre-carbonization temperature of 1000–1250°C can effectively remove volatile matter, reducing the volatile matter content to below 1%, while simultaneously achieving preliminary densification of the material, with a tap density reaching 0.6–0.8 g / cm³. If the pre-carbonization temperature is too low, volatile matter removal will be insufficient; if the temperature is too high, energy consumption will increase and may cause premature graphitization of the material, affecting the bonding force between particles during subsequent spray granulation.

[0022] As a further improvement of the present invention, in step S3, the graphitization is carried out using an Acheson furnace; the tap density of the graphitized material is 0.7–0.9 g / cm³, and the specific surface area is 2.5–4 m² / g. The Acheson furnace is currently the most commonly used graphitization equipment in the industrial production of graphite anode materials, with mature technology and large capacity. The tap density increased to 0.7–0.9 g / cm³ after graphitization, indicating that the internal structure of the particles tends to be denser after high-temperature graphitization. The specific surface area is 2.5–4 m² / g, which is lower than that of ungraphitized coke powder, but still relatively high, and needs to be further reduced in the subsequent coating process.

[0023] As a further improvement of the present invention, in step S4, the binder is carboxymethyl cellulose, and the solvent is water; the mass ratio of graphitized fine powder, binder, and solvent is 15-25 : 0.5-5 : 75-80; the air inlet velocity for spray granulation is 2-5 m³ / min, the air inlet temperature is 200-250℃, and the feed rate is 15-25 mL / min. Carboxymethyl cellulose (CMC) is a water-soluble cellulose derivative with good binding and dispersibility, making it an ideal binder in the spray granulation process. The inventors optimized the slurry ratio and spray granulation process parameters through numerous experiments. The solid content (graphitized fine powder + CMC) in the slurry is 20-30%, of which CMC accounts for 0.5-5%. This ratio ensures that the slurry has good flowability and atomization performance, while also providing sufficient binding force to keep the secondary particles intact. Within the parameter range of 2-5 m³ / min air inlet velocity, 200-250℃ air inlet temperature, and 15-25 mL / min feed rate, the secondary particles obtained by spray granulation have the best sphericity and the most concentrated particle size distribution.

[0024] As a further improvement of the present invention, in step S5, the surface coating modification system is composed of asphalt, nano-titanium dioxide and polyfurfuryl alcohol resin; the mass ratio of the asphalt, nano-titanium dioxide and polyfurfuryl alcohol resin is 9:2-4:3-7.

[0025] As will be readily understood by those skilled in the art, the asphalt refers to a mixture of thermoplastic hydrocarbons with a high softening point, obtained from petroleum or coal tar through processes such as distillation, oxidation, or blending. During the high-temperature carbonization process (1000–1150°C), asphalt pyrolyzes to form a soft carbon layer with a low degree of disorder. This carbon layer has a high degree of graphitization and good electronic conductivity.

[0026] In this invention, the nano-titanium dioxide refers to titanium dioxide particles with a grain size at the nanometer level, preferably rutile or anatase type, with rutile nano-titanium dioxide being more preferred. Rutile nano-titanium dioxide has advantages such as high thermodynamic stability, good chemical inertness, and good compatibility with carbon matrix.

[0027] In this invention, the polyfurfuryl alcohol resin (PFA) refers to a furan-based thermosetting resin prepared by polycondensation of furfuryl alcohol (molecular formula C5H6O2, CAS: 98-00-0) as a monomer under the action of an acidic catalyst. Those skilled in the art can purchase furfuryl alcohol commercially and prepare it themselves using existing polycondensation techniques, for example, by referring to the preparation method provided in the detailed embodiments section.

[0028] When asphalt is used alone for coating, the pyrolysis of asphalt forms a dense amorphous carbon layer, which can effectively seal defects and openings on the graphite surface, significantly reducing the specific surface area and improving the initial efficiency. However, it also increases the resistance of lithium ions crossing the interface, resulting in limited improvement in rate performance. Through extensive experiments, the inventors discovered that using asphalt, nano-titanium dioxide, and polyfurfuryl alcohol resin in the proportions described in this scheme can produce a significant synergistic effect.

[0029] As a further improvement of the present invention, the softening point of the asphalt is 180-200℃; the average particle size of the nano-titanium dioxide is 20-50nm; and the number-average molecular weight of the polyfurfuryl alcohol resin is 500-2000. Asphalt with a softening point of 180-200℃ exhibits suitable melt viscosity and fluidity during high-temperature carbonization, enabling the formation of a uniform coating layer on the graphite surface. If the softening point is too low, the asphalt melts and is lost prematurely during heating, resulting in an uneven coating layer; if the softening point is too high, the asphalt melting temperature is too high, and carbonization may begin before sufficient wetting of the graphite surface. A nano-titanium dioxide particle size of 20-50nm facilitates uniform dispersion in the carbon layer; excessively large particle sizes make it difficult to form a uniform composite structure, while excessively small particle sizes lead to agglomeration. A polyfurfuryl alcohol resin with a number-average molecular weight of 500-2000 exhibits suitable solubility and carbonization behavior; excessively low molecular weight results in insufficient char residue, while excessively high molecular weight makes dissolution difficult and hinders uniform mixing with the asphalt.

[0030] As a further improvement of the present invention, in step S5, the amount of the surface coating modification system added is 2-8% of the mass of the granulated graphite; the maximum temperature of the high-temperature carbonization is 1000-1150℃. The inventors have found through experiments that when the amount of the surface coating modification system added is in the range of 2-8%, a complete and uniform coating layer can be formed on the graphite surface. If the amount added is too low (<2%), the coating layer is incomplete and cannot effectively cover graphite surface defects, resulting in limited reduction of specific surface area; if the amount added is too high (>8%), the coating layer is too thick, which may hinder lithium-ion transport and reduce rate performance. The high-temperature carbonization temperature of 1000-1150℃ allows for sufficient carbonization of asphalt and polyfurfuryl alcohol resin, forming a dense carbon coating layer. If the temperature is too low, carbonization is incomplete, resulting in insufficient density and conductivity of the coating layer; if the temperature is too high, energy consumption increases and may cause unnecessary structural changes in the graphite lattice.

[0031] This invention also provides a graphite anode material prepared by the above-described method. The graphite anode material exhibits high initial efficiency, excellent rate performance, and good cycle stability.

[0032] This invention also provides the application of the graphite anode material in the preparation of lithium-ion battery anodes. The graphite anode material prepared by this invention is particularly suitable for applications requiring rapid charge and discharge performance, such as drones and start-stop power supplies.

[0033] Compared with the prior art, the beneficial effects of the present invention include:

[0034] 1) This invention reuses coke fine powder that would otherwise be discarded through a series of processes such as grading, pre-carbonization, graphitization, spray granulation and high-temperature carbonization, realizing the high-value recycling of fine coke powder and creating new revenue growth points for enterprises.

[0035] 2) This invention uses spray granulation to prepare secondary granular graphite. Compared with traditional briquetting or batch granulation, the prepared secondary granules are closer to spherical and have fewer edges and corners, which improves the tap density and reduces the OI value, thus improving fast charging and fast discharging performance.

[0036] 3) The surface coating modification system of the present invention can produce a significant synergistic effect, significantly improving rate performance and cycle stability while reducing specific surface area.

[0037] 4) The preparation method of the present invention has a clear process route and is controllable, making it suitable for large-scale industrial production. Attached Figure Description

[0038] Figure 1 This is a process flow diagram of Example 1 of the specific implementation method.

[0039] Figure 2 This is a SEM image of the graphite anode material in Example 1 of the specific implementation method. Detailed Implementation

[0040] To enable those skilled in the art to better implement the present invention, the present invention will be further described below with reference to embodiments. However, it should be understood that the present invention is not limited to the following embodiments.

[0041] For ease of comparison, the raw materials used in the following examples and comparative examples are all from the same batch, and the specific parameters of the raw materials are as follows:

[0042] Fine coke powder: needle-shaped fine coke powder (volatile matter 5.06%, ash content 0.01%, sulfur content 0.366%) or petroleum coke fine powder (volatile matter 10.25%, ash content 0.34%, sulfur content 0.386%), selected according to the specific examples;

[0043] Carboxymethyl cellulose (CMC): analytical grade, 2% aqueous solution (25℃) viscosity ≥300mPa·s, degree of substitution ≥0.9;

[0044] Deionized water: prepared in the laboratory, resistivity ≥18.2 MΩ·cm;

[0045] Asphalt: High softening point asphalt, softening point 187℃, ash content ≤0.3%;

[0046] Nano titanium dioxide: rutile type, average particle size 32nm, purity ≥99.8%;

[0047] Furfuryl alcohol: analytical grade, purity ≥98%, CAS: 98-00-0;

[0048] Oxalic acid: analytical grade, purity ≥99.5%;

[0049] Nitrogen: High-purity nitrogen, purity ≥ 99.999%.

[0050] Preparation method of polyfurfuryl alcohol resin:

[0051] The polyfurfuryl alcohol (PFA) resin used in the following examples and comparative examples was prepared according to the following method:

[0052] 100 g of furfuryl alcohol (CAS: 98-00-0, purity ≥98%) was added to a 500 mL three-necked flask and heated to 60 °C under nitrogen protection. 0.5 g of oxalic acid (purity ≥99.5%) was added as a catalyst, and the reaction was carried out at 60 °C and 300 r / min for 4 h with stirring. During the reaction, furfuryl alcohol underwent a condensation reaction, and the viscosity of the system gradually increased. After the reaction was completed, the product was cooled to room temperature, repeatedly washed with deionized water until neutral, and dried in a vacuum drying oven at 80 °C for 12 h to obtain polyfurfuryl alcohol resin. Gel permeation chromatography (GPC) determined that the number average molecular weight of the obtained polyfurfuryl alcohol resin ranged from 800 to 1200.

[0053] Example 1:

[0054] A method for preparing graphite anodes by high-value recycling of coke fine powder includes the following steps:

[0055] S1. Grading: Needle-shaped coke powder (volatile matter 5.06%, ash 0.01%, sulfur 0.366%) was selected as raw material and graded using an air classifier to remove ultrafine particles with a particle size <1.5μm, resulting in graded material. The particle size Dv50 of the graded material was measured to be 5.197μm using a laser particle size analyzer.

[0056] S2. Pre-carbonization: The graded material obtained in step S1 is loaded into a graphite crucible and placed in a tunnel kiln for pre-carbonization. The temperature is raised to 1250℃ at a heating rate of 5℃ / min and held for 4 hours, followed by natural cooling to room temperature. Nitrogen gas is introduced as a protective atmosphere during the pre-carbonization process at a flow rate of 2L / min. After pre-carbonization, the volatile matter content of the material is reduced to 0.36%, and the tap density is 0.792 g / cm³.

[0057] S3. Graphitization: The pre-carbonized material obtained in step S2 is placed in an Atchison graphitization furnace for graphitization treatment. The power supply curve of the graphitization furnace is as follows: heating to 1200℃ in 0-4h, heating to 2400℃ in 4-10h, heating to 3000℃ in 10-16h, holding at this temperature for 4h, and then naturally cooling. After graphitization, the tap density of the material is 0.881g / cm³, and the specific surface area is 2.84m² / g.

[0058] S4. Spray granulation: The graphitized fine powder obtained in step S3 is compounded with carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 24:1:75. First, CMC is dissolved in deionized water and stirred until completely dissolved. Then, the graphitized fine powder is added, and the mixture is stirred and dispersed at 500 r / min for 2 h to obtain a uniform slurry. Spray granulation is performed using a spray dryer with an inlet air velocity of 3.5 m³ / min, an inlet air temperature of 220℃, and a feed rate of 18 mL / min. Granulated graphite is collected after spray granulation.

[0059] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with asphalt (softening point 187℃) at a mass ratio of 100:2.5. The mixture is then mixed at 500 r / min for 30 min using a VC mixer to ensure that the asphalt is uniformly adhered to the surface of the granulated graphite. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is increased to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0060] The particle size of the graphite anode material obtained in this embodiment was measured to be Dv10=6.13μm, Dv50=12.28μm, tap density was 1.16g / cm³, and specific surface area was 1.57m² / g.

[0061] Example 2:

[0062] A method for preparing graphite anodes by high-value recycling of coke fine powder includes the following steps:

[0063] S1. Grading: Petroleum coke fine powder (volatile matter 10.25%, ash 0.34%, sulfur 0.386%) was selected as raw material and graded using an air classifier to remove ultrafine particles with a particle size <1.5μm, resulting in graded material. The particle size Dv50 of the graded material was measured to be 5.246μm.

[0064] S2. Pre-carbonization: The graded material obtained in step S1 is loaded into a graphite crucible and placed in a tunnel kiln for pre-carbonization. The temperature is raised to 1250℃ at a heating rate of 5℃ / min and held for 4 hours, followed by natural cooling to room temperature. Nitrogen gas is introduced as a protective atmosphere during the pre-carbonization process at a flow rate of 2L / min. After pre-carbonization, the volatile matter content of the material is reduced to 0.30%, and the tap density is 0.745 g / cm³.

[0065] S3. Graphitization: The pre-carbonized material obtained in step S2 is placed in an Atchison graphitization furnace for graphitization treatment. The power supply curve of the graphitization furnace is as follows: heating to 1200℃ in 0-4h, heating to 2400℃ in 4-10h, heating to 3000℃ in 10-16h, holding at this temperature for 4h, and then naturally cooling. After graphitization, the tap density of the material is 0.876 g / cm³, and the specific surface area is 3.05 m² / g.

[0066] S4. Spray granulation: The graphitized fine powder obtained in step S3 is compounded with carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 24:1:75. First, CMC is dissolved in deionized water and stirred until completely dissolved. Then, the graphitized fine powder is added, and the mixture is stirred and dispersed at 500 r / min for 2 h to obtain a uniform slurry. Spray granulation is performed using a spray dryer with an inlet air velocity of 3.5 m³ / min, an inlet air temperature of 220℃, and a feed rate of 18 mL / min. Granulated graphite is collected after spray granulation.

[0067] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with asphalt (softening point 187℃) at a mass ratio of 100:2.8. The mixture is then mixed at 500 r / min for 30 min using a VC mixer to ensure that the asphalt is uniformly adhered to the surface of the granulated graphite. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0068] The particle size of the graphite anode material obtained in this embodiment was measured to be Dv10=6.83μm, Dv50=12.74μm, tap density was 1.09g / cm³, and specific surface area was 1.72m² / g.

[0069] Example 3:

[0070] A method for preparing graphite anodes by high-value recycling of coke fine powder includes the following steps:

[0071] S1. Grading: Needle-shaped coke powder (volatile matter 5.06%, ash 0.01%, sulfur 0.366%) was selected as raw material and graded using an air classifier to remove ultrafine particles with a particle size <1.5μm, resulting in graded material. The particle size Dv50 of the graded material was measured to be 5.197μm.

[0072] S2. Pre-carbonization: The graded material obtained in step S1 is loaded into a graphite crucible and placed in a tunnel kiln for pre-carbonization. The temperature is raised to 1250℃ at a heating rate of 5℃ / min and held for 4 hours, followed by natural cooling to room temperature. Nitrogen gas is introduced as a protective atmosphere during the pre-carbonization process at a flow rate of 2L / min. After pre-carbonization, the volatile matter content of the material is reduced to 0.36%, and the tap density is 0.792 g / cm³.

[0073] S3. Graphitization: The pre-carbonized material obtained in step S2 is placed in an Atchison graphitization furnace for graphitization treatment. The power supply curve of the graphitization furnace is as follows: heating to 1200℃ in 0-4h, heating to 2400℃ in 4-10h, heating to 3000℃ in 10-16h, holding at this temperature for 4h, and then naturally cooling. After graphitization, the tap density of the material is 0.881g / cm³, and the specific surface area is 2.84m² / g.

[0074] S4. Spray granulation: The graphitized fine powder obtained in step S3 is compounded with carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 20:2:78. First, CMC is dissolved in deionized water and stirred until completely dissolved. Then, the graphitized fine powder is added, and the mixture is stirred and dispersed at 500 r / min for 2 h to obtain a uniform slurry. Spray granulation is performed using a spray dryer with an inlet air velocity of 4.0 m³ / min, an inlet air temperature of 250℃, and a feed rate of 15 mL / min. Granulated graphite is collected after spray granulation.

[0075] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with asphalt (softening point 187℃) at a mass ratio of 100:3.2. The mixture is then mixed at 500 r / min for 30 min using a VC mixer to ensure that the asphalt is uniformly adhered to the surface of the granulated graphite. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0076] The particle size of the graphite anode material obtained in this embodiment was measured to be Dv10=6.96μm, Dv50=13.17μm, tap density was 1.04g / cm³, and specific surface area was 1.89m² / g.

[0077] Example 4:

[0078] A method for preparing graphite anodes by high-value recycling of coke fine powder includes the following steps:

[0079] S1. Grading: Needle-shaped coke powder (volatile matter 5.06%, ash 0.01%, sulfur 0.366%) was selected as raw material and graded using an air classifier to remove ultrafine particles with a particle size <1.5μm, resulting in graded material. The particle size Dv50 of the graded material was measured to be 5.197μm.

[0080] S2. Pre-carbonization: The graded material obtained in step S1 is loaded into a graphite crucible and placed in a tunnel kiln for pre-carbonization. The temperature is raised to 1250℃ at a heating rate of 5℃ / min and held for 4 hours, followed by natural cooling to room temperature. Nitrogen gas is introduced as a protective atmosphere during the pre-carbonization process at a flow rate of 2L / min. After pre-carbonization, the volatile matter content of the material is reduced to 0.36%, and the tap density is 0.792 g / cm³.

[0081] S3. Graphitization: The pre-carbonized material obtained in step S2 is placed in an Atchison graphitization furnace for graphitization treatment. The power supply curve of the graphitization furnace is as follows: heating to 1200℃ in 0-4h, heating to 2400℃ in 4-10h, heating to 3000℃ in 10-16h, holding at this temperature for 4h, and then naturally cooling. After graphitization, the tap density of the material is 0.881g / cm³, and the specific surface area is 2.84m² / g.

[0082] S4. Spray granulation: The graphitized fine powder obtained in step S3 is compounded with carboxymethyl cellulose (CMC) and deionized water at a mass ratio of 24:1:75. First, CMC is dissolved in deionized water and stirred until completely dissolved. Then, the graphitized fine powder is added, and the mixture is stirred and dispersed at 500 r / min for 2 h to obtain a uniform slurry. Spray granulation is performed using a spray dryer with an inlet air velocity of 3.5 m³ / min, an inlet air temperature of 220℃, and a feed rate of 18 mL / min. Granulated graphite is collected after spray granulation.

[0083] S5. Preparation of the surface-coating modified system: Weigh each component according to the mass ratio of asphalt: nano-titanium dioxide: polyfurfuryl alcohol resin = 9:3:5. Add nano-titanium dioxide (average particle size 32nm) and polyfurfuryl alcohol resin (number average molecular weight 800-1200) to asphalt (softening point 187℃), and mix in a VC mixer at 500r / min for 40min to obtain a uniform surface-coating modified system powder.

[0084] S6. Coating and Carbonization: The granulated graphite obtained in step S4 and the surface coating modification system prepared in step S5 are mixed at a mass ratio of 100:4. The mixture is stirred at 500 r / min for 40 min using a VC mixer to ensure that the surface coating modification system is uniformly adhered to the surface of the granulated graphite. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0085] The particle size of the graphite anode material obtained in this embodiment was measured to be Dv10=6.58μm, Dv50=12.56μm, tap density was 1.21g / cm³, and specific surface area was 1.42m² / g.

[0086] Comparative Example 1:

[0087] This comparative example serves as a control experiment for Example 1, and is conducted according to the same steps as Example 1, except that: in step S1, no grading process is performed; ungraded needle-shaped coke powder raw material (particle size Dv1=0.883μm, Dv50=4.381μm) is directly used for subsequent processes. The specific scheme is as follows:

[0088] S1. Select needle-shaped coke powder as raw material (volatile matter 5.06%, ash content 0.01%, sulfur content 0.366%), without classification, and use directly. Raw material particle size Dv1=0.883μm, Dv50=4.381μm.

[0089] S2 to S5 are the same as in Example 1.

[0090] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=2.28μm, Dv50=5.083μm, tap density was 0.80g / cm³, and specific surface area was 3.27m² / g.

[0091] Comparative Example 2:

[0092] This comparative example serves as a control experiment for Example 2, and is conducted according to the same steps as Example 2, except that: in step S1, no grading is performed; ungraded petroleum coke fine powder raw material (particle size Dv1=0.374μm, Dv50=4.03μm) is directly used for subsequent processes. The specific scheme is as follows:

[0093] S1. Select petroleum coke fine powder as raw material (volatile matter 10.25%, ash content 0.34%, sulfur content 0.386%), without classification, and use directly. Raw material particle size Dv1=0.374μm, Dv50=4.03μm.

[0094] S2 to S5 are the same as in Example 2.

[0095] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=2.47μm, Dv50=5.134μm, tap density was 0.72g / cm³, and specific surface area was 4.07m² / g.

[0096] Comparative Example 3:

[0097] This comparative example serves as a control experiment for Example 1, and is conducted according to the same steps as Example 1, except that: in step S4, spray granulation is not performed; instead, the graphitized fine powder is directly coated and carbonized. The specific scheme is as follows:

[0098] S1 to S3 are the same as in Example 1.

[0099] S4. No spray granulation: The graphitized fine powder obtained in step S3 (without granulation) is directly coated and carbonized.

[0100] S5, Coating and carbonization are the same as in Example 1.

[0101] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=1.63μm, Dv50=5.661μm, tap density was 0.88g / cm³, and specific surface area was 3.52m² / g.

[0102] Comparative Example 4:

[0103] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that in step S5, only asphalt is used as the coating agent (i.e., the surface coating modification system does not contain nano-titanium dioxide or polyfurfuryl alcohol resin), and the amount of coating agent added is maintained at 4%. The specific scheme is as follows:

[0104] S1 to S4 are the same as in Example 4.

[0105] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with pitch (softening point 187℃) at a mass ratio of 100:4 using a VC mixer at 500 r / min for 40 min. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0106] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.47μm, Dv50=12.38μm, tap density was 1.15g / cm³, and specific surface area was 1.55m² / g.

[0107] Comparative Example 5:

[0108] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that in step S5, only nano-titanium dioxide is used as the coating agent (i.e., the surface coating modification system does not contain asphalt or polyfurfuryl alcohol resin), and the amount of coating agent added is maintained at 4%. The specific scheme is as follows:

[0109] S1 to S4 are the same as in Example 4.

[0110] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with nano-titanium dioxide (average particle size 32nm) at a mass ratio of 100:4, and mixed at 500r / min for 40min using a VC mixer. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0111] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.21μm, Dv50=12.05μm, tap density was 1.08g / cm³, and specific surface area was 2.84m² / g.

[0112] Comparative Example 6:

[0113] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that in step S5, only polyfurfuryl alcohol resin is used as the coating agent (i.e., the surface coating modification system does not contain asphalt or nano-titanium dioxide), and the amount of coating agent added is maintained at 4%. The specific scheme is as follows:

[0114] S1 to S4 are the same as in Example 4.

[0115] S5. Coating and Carbonization: The granulated graphite obtained in step S4 is mixed with polyfurfuryl alcohol resin (number average molecular weight 800-1200) at a mass ratio of 100:4, and mixed at 500 r / min for 40 min using a VC mixer. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0116] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.33μm, Dv50=12.19μm, tap density was 1.05g / cm³, and specific surface area was 2.61m² / g.

[0117] Comparative Example 7:

[0118] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that: in step S5, the surface coating modification system consists of asphalt and nano-titanium dioxide (excluding polyfurfuryl alcohol resin), the mass ratio of asphalt to nano-titanium dioxide is 9:3 (consistent with Example 4), and the amount of coating agent added remains at 4%. The specific scheme is as follows:

[0119] S1 to S4 are the same as in Example 4.

[0120] S5. Preparation of binary coating system: Weigh each component according to the mass ratio of asphalt: nano titanium dioxide = 9:3, and mix them for 40 min at 500 r / min using a VC mixer to obtain the binary coating system.

[0121] S6. Coating and Carbonization: The granulated graphite obtained in step S4 and the binary coating system prepared in step S5 are mixed at a mass ratio of 100:4 using a VC mixer at 500 r / min for 40 min. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0122] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.52μm, Dv50=12.47μm, tap density was 1.18g / cm³, and specific surface area was 1.48m² / g.

[0123] Comparative Example 8:

[0124] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that: in step S5, the surface coating modification system consists of asphalt and polyfurfuryl alcohol resin (excluding nano-titanium dioxide), the mass ratio of asphalt to polyfurfuryl alcohol resin is 9:5 (consistent with Example 4), and the amount of coating agent added remains at 4%. The specific scheme is as follows:

[0125] S1 to S4 are the same as in Example 4.

[0126] S5. Preparation of binary coating system: Weigh each component according to the mass ratio of asphalt:polyfurfuryl alcohol resin = 9:5, and mix them for 40 minutes at 500 r / min using a VC mixer to obtain the binary coating system.

[0127] S6. Coating and Carbonization: The granulated graphite obtained in step S4 and the binary coating system prepared in step S5 are mixed at a mass ratio of 100:4 using a VC mixer at 500 r / min for 40 min. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0128] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.49μm, Dv50=12.42μm, tap density was 1.12g / cm³, and specific surface area was 1.62m² / g.

[0129] Comparative Example 9:

[0130] This comparative example serves as a control experiment for Example 4, and is conducted according to the same steps as Example 4, except that: in step S5, the surface coating modification system consists of nano-titanium dioxide and polyfurfuryl alcohol resin (excluding asphalt), with a mass ratio of nano-titanium dioxide to polyfurfuryl alcohol resin of 3:5 (consistent with Example 4), and the amount of coating agent added remains at 4%. The specific scheme is as follows:

[0131] S1 to S4 are the same as in Example 4.

[0132] S5. Preparation of binary coating system: Weigh each component according to the mass ratio of nano titanium dioxide: polyfurfuryl alcohol resin = 3: 5, and mix them with a VC mixer at 500 r / min for 40 min to obtain the binary coating system.

[0133] S6. Coating and Carbonization: The granulated graphite obtained in step S4 and the binary coating system prepared in step S5 are mixed at a mass ratio of 100:4 using a VC mixer at 500 r / min for 40 min. The mixture is then placed in a graphite crucible and placed in a high-temperature carbonization furnace. Under a nitrogen atmosphere, the temperature is raised to 1100℃ at a heating rate of 3℃ / min and held for 3 h. Subsequently, it is naturally cooled to room temperature to obtain the graphite anode material.

[0134] The particle size of the graphite anode material obtained in this comparative example was measured to be Dv10=6.28μm, Dv50=12.11μm, tap density was 1.02g / cm³, and specific surface area was 2.43m² / g.

[0135] Performance verification experiment:

[0136] The graphite anode materials obtained in Examples 1 to 4 and Comparative Examples 1 to 9 were subjected to the following performance tests:

[0137] 1. Half-cell assembly

[0138] The graphite anode materials obtained in each embodiment and comparative example were uniformly mixed with styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC-Na), and carbon black (Super-P) at a mass ratio of 96.6:1.4:1.0:1.0 to form a slurry. The slurry was coated onto a 6μm copper current collector, transferred to an 80℃ forced-air drying oven for 2 hours, and then dried overnight in a 90℃ vacuum drying oven. Finally, it was compacted by a roller mill and sliced.

[0139] CR2032 button half-cells were assembled in an argon-filled glove box. The counter electrode was a lithium sheet (1 mm thick), the electrolyte was 1.0 M LiPF6 / (EC:DEC:DMC=1:1:1, V:V:V), and the separator was a 20 μm microporous polyethylene membrane.

[0140] 2. Electrochemical performance testing

[0141] After half-cell assembly, the cells were allowed to rest for 12 hours, then discharged at 0.05C to 5mV. After resting for 5 minutes, they were discharged at 0.05mA to 5mV, then rested for another 5 minutes before being discharged at 0.01mA to 5mV. After resting for 5 minutes, they were charged at 0.1C to 2.0V. The initial charge capacity and initial coulombic efficiency were recorded. Rate performance testing was conducted at current densities of 0.2C, 1C, 3C, and 5C, recording the discharge capacity at each rate. The capacity retention rate was calculated based on the 0.2C capacity. The tests were performed on the Blue Electric CT3002A battery testing system. Cycle performance testing was conducted at a 1C current density for 200 charge-discharge cycles, and the capacity retention rate was recorded.

[0142] The test results are shown in Tables 1 and 2.

[0143] Table 1. Physical properties and electrochemical performance of graphite anode materials in each embodiment and comparative example.

[0144] Example 1 Needle coke + grading + granulation + asphalt coating 352.2 92.74 Example 2 Petroleum coke + grading + granulation + asphalt coating 347.1 92.15 Example 3 Needle coke + grading + granulation + asphalt coating 351.4 91.51 Example 4 Needle coke + grading + granulation + ternary composite coating 356.8 93.62 Comparative Example 1 Ungraded + needle coke + bitumen coating 283.1 74.32 Comparative Example 2 Ungraded + petroleum coke + asphalt coating 320.6 85.88 Comparative Example 3 Ungranulated + needle coke + asphalt coating 274.8 72.29 Comparative Example 4 Asphalt coating only 351.5 92.58 Comparative Example 5 <![CDATA[Only nano TiO2 coating]]> 326.4 87.63 Comparative Example 6 Polyfurfuryl alcohol resin coating only 338.7 89.24 Comparative Example 7 <![CDATA[Binary coating of asphalt + nano TiO₂]]> 353.2 92.91 Comparative Example 8 Asphalt + polyfurfuryl alcohol binary coating 352.8 92.73 Comparative Example 9 <![CDATA[Nano TiO2 + polyfurfuryl alcohol binary coating]]> 332.5 88.56

[0145] Table 2. Rate performance and cycling performance of each embodiment and comparative example.

[0146] Example 1 Needle coke + grading + granulation + asphalt coating 352.1 271.3 77.1 92.8 Example 2 Petroleum coke + grading + granulation + asphalt coating 347.0 263.2 75.9 91.5 Example 3 Needle coke + grading + granulation + asphalt coating 351.3 265.7 75.6 91.2 Example 4 Needle coke + grading + granulation + ternary composite coating 356.7 296.7 83.2 96.4 Comparative Example 1 Ungraded + needle coke + bitumen coating 283.1 185.7 65.6 78.3 Comparative Example 2 Ungraded + Petroleum coke + Asphalt coating 320.6 220.8 68.9 82.7 Comparative Example 3 Ungranulated + needle coke + asphalt coating 274.8 172.6 62.8 75.9 Comparative Example 4 Asphalt coating only 351.4 269.8 76.8 92.5 Comparative Example 5 <![CDATA[Only nano TiO₂ coating]]> 326.3 243.2 74.5 88.9 Comparative Example 6 Polyfurfuryl alcohol resin coating only 338.6 257.1 75.9 90.6 Comparative Example 7 <![CDATA[Asphalt + nano-TiO₂ binary coating]]> 353.1 275.4 78.0 93.2 Comparative Example 8 Asphalt + polyfurfuryl alcohol binary coating 352.7 272.6 77.3 92.9 Comparative Example 9 <![CDATA[Nano-TiO₂ + polyfurfuryl alcohol binary coating]]><![CDATA[]]>< 332.4 248.3 74.7 89.7

[0147] The results in Tables 1 and 2 show that:

[0148] 1. Effect of the grading process: Comparing Example 1 (graded, Dv50 = 5.197 μm) and Comparative Example 1 (ungraded, Dv50 = 4.381 μm), the initial charge capacity of the product increased from 283.1 mAh / g to 352.2 mAh / g, the initial efficiency increased from 74.32% to 92.74%, and the 5C rate retention increased from 65.6% to 77.1% after grading. Similarly, comparing Example 2 (graded) and Comparative Example 2 (ungraded), the initial charge capacity increased from 320.6 mAh / g to 347.1 mAh / g, the initial efficiency increased from 85.88% to 92.15%, and the 5C rate retention increased from 68.9% to 75.9% after grading. This indicates that grading to remove ultrafine particles (particle size < 1.5 μm) is a key step in improving initial charge capacity, initial efficiency, and rate performance.

[0149] 2. Effect of spray granulation: Comparing Example 1 (spray granulation) and Comparative Example 3 (no granulation), the initial charge capacity of the product increased from 274.8 mAh / g to 352.2 mAh / g after spray granulation, the initial efficiency increased from 72.29% to 92.74%, and the 5C rate retention increased from 62.8% to 77.1%. This indicates that the spherical secondary particles formed by spray granulation effectively improve the tap density and electrochemical performance.

[0150] 3. Synergistic effect of the ternary composite coating system: Under the condition that the total amount of coating agent added is 4%, the following comparisons were made between Example 4 (asphalt + nano TiO2 + polyfurfuryl alcohol resin) and Comparative Example 4 (asphalt only), Comparative Example 5 (nano TiO2 only), and Comparative Example 6 (polyfurfuryl alcohol resin only):

[0151] Initial charge capacity: Example 4 shows 356.8 mAh / g, an improvement of 5.3–30.4 mAh / g compared to the single-coated system. Initial efficiency: Example 4 shows 93.62%, an improvement of 1.04–5.99 percentage points compared to the single-coated system. 5C rate retention: Example 4 shows 83.2%, an improvement of 6.4–8.7 percentage points compared to the single-coated system. 1C cycle retention after 200 cycles: Example 4 shows 96.4%, an improvement of 3.9–7.5 percentage points compared to the single-coated system.

[0152] The above results show that the performance indicators of the ternary composite coating system are significantly better than those of the single coating system, especially the improvement in rate performance and cycle performance.

[0153] 4. Comparison of binary and ternary coatings: Comparative Example 4 with Comparative Example 7 (asphalt + nano-TiO2 binary), Comparative Example 8 (asphalt + polyfurfuryl alcohol binary), and Comparative Example 9 (nano-TiO2 + polyfurfuryl alcohol binary):

[0154] The initial efficiency of Example 4 was 93.62%, compared to 92.91% for Comparative Example 7, 92.73% for Comparative Example 8, and 88.56% for Comparative Example 9. The ternary composite showed an improvement of 0.71 percentage points compared to the best-performing binary system (Comparative Example 7).

[0155] The 5C rate retention rate of Example 4 was 83.2%, compared to 78.0% for Comparative Example 7, 77.3% for Comparative Example 8, and 74.7% for Comparative Example 9. The ternary composite rate was 5.2 percentage points higher than that of Comparative Example 7, 5.9 percentage points higher than that of Comparative Example 8, and 8.5 percentage points higher than that of Comparative Example 9.

[0156] The retention rate after 200 cycles of 1C in Example 4 was 96.4%, compared to 93.2% in Comparative Example 7, 92.9% in Comparative Example 8, and 89.7% in Comparative Example 9. This represents an improvement of 3.2 percentage points compared to Comparative Example 7, 3.5 percentage points compared to Comparative Example 8, and 6.7 percentage points compared to Comparative Example 9.

[0157] The above results demonstrate that the rate performance and cycling performance of the ternary composite coating system are significantly superior to any binary coating system, fully proving the clear synergistic effect among asphalt, nano-titanium dioxide, and polyfurfuryl alcohol resin. The improvement in rate performance is particularly significant—the 5C retention rate of the ternary composite (83.2%) is more than 5 percentage points higher than the optimal binary system (Comparative Example 7, 78.0%). The inventors believe this is because the dense carbon layer formed by the pyrolysis of asphalt constructs a continuous closed barrier on the graphite surface. This barrier not only reduces the specific surface area and side reaction active sites but also provides a stable and compatible carbon-based anchoring environment for the uniform dispersion of nano-TiO2 particles, significantly amplifying its ion conduction efficiency. Simultaneously, the local conductive network established by the uniformly dispersed nano-TiO2 in the carbon layer, in turn, optimizes the electron transport path in the asphalt carbon layer, effectively reducing the interfacial impedance that might otherwise exist due to its dense structure. The interfacial coupling between polyfurfuryl alcohol resin-derived hard carbon and pitch soft carbon creates a dynamic relationship between the lithium-ion rapid insertion channel created by the appropriately increased interlayer spacing of the hard carbon, the dense shielding function of the pitch carbon, and the ion conduction function of TiO2, forming a closed-conductivity-buffering linkage system. In this system, the shielding layer creates a stable interface with low side reactions for the channel, the channel provides a path for lithium ions to quickly reach the active site, and the buffer layer absorbs volume expansion stress and, in turn, reinforces the structural integrity of the shielding layer. All three are indispensable, resulting in overall rate performance and cycle stability that are significantly better than any single or binary combination.

Claims

1. A method for preparing graphite anodes by high-value recycling of coke fine powder, characterized in that, Includes the following steps: S1. The coke fine powder produced in the grinding process is classified to remove ultrafine particles with a particle size <1.5μm to obtain classified material; S2. The graded material obtained in step S1 is pre-carbonized to obtain pre-carbonized material; S3. Graphitize the pre-carbonized material obtained in step S2 to obtain graphitized fine powder; S4. The graphitized fine powder obtained in step S3 is compounded with binder and solvent, and then spray-granulated to obtain granulated graphite. S5. The granulated graphite obtained in step S4 is mixed with the surface coating modification system and carbonized at high temperature to obtain a graphite anode material; the surface coating modification system includes asphalt.

2. The preparation method according to claim 1, characterized in that, In step S1, the coke fine powder is selected from petroleum coke fine powder or needle coke fine powder; the particle size Dv50 of the graded material is 5-7 μm.

3. The preparation method according to claim 1, characterized in that, In step S2, the maximum temperature of pre-carbonization is 1000-1250℃, the volatile matter content of the pre-carbonized material is less than 1%, and the tap density is 0.6-0.8 g / cm³.

4. The preparation method according to claim 1, characterized in that, In step S3, the graphitization is carried out using an Atchison furnace; the tap density of the graphitized material is 0.7-0.9 g / cm³, and the specific surface area is 2.5-4 m² / g.

5. The preparation method according to claim 1, characterized in that, In step S4, the binder is carboxymethyl cellulose, and the solvent is water; the mass ratio of graphitized fine powder, binder and solvent is 15-25 : 0.5-5 : 75-80; the air inlet velocity of spray granulation is 2-5 m³ / min, the air inlet temperature is 200-250℃, and the feed rate is 15-25 mL / min.

6. The preparation method according to claim 1, characterized in that, In step S5, the surface coating modification system is composed of asphalt, nano-titanium dioxide and polyfurfuryl alcohol resin; the mass ratio of asphalt, nano-titanium dioxide and polyfurfuryl alcohol resin is 9:2-4:3-7.

7. The preparation method according to claim 6, characterized in that, The softening point of the asphalt is 180-200℃; the average particle size of the nano-titanium dioxide is 20-50nm; and the number average molecular weight of the polyfurfuryl alcohol resin is 500-2000.

8. The preparation method according to claim 6, characterized in that, In step S5, the amount of the surface coating modification system added is 2 to 8% of the mass of granulated graphite; the maximum temperature of the high-temperature carbonization is 1000 to 1150°C.

9. A graphite anode material prepared by the method for preparing graphite anodes from high-value recycled coke fine powder as described in any one of claims 1 to 8.

10. The application of the graphite anode material according to claim 9 in the preparation of lithium-ion battery anodes.

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