A method for granulating coal-based needle coke for high-energy-density energy storage anode materials

Abstract

This invention relates to a method for granulating coal-based needle coke into a high-energy-density energy storage negative electrode material, belonging to the field of energy storage battery technology. Modified Fe3O4@SiO2 magnetic microspheres are obtained by modifying Fe3O4@SiO2 magnetic microspheres. The modified Fe3O4@SiO2 magnetic microspheres of this invention have a pyridine structure on their surface, which can specifically adsorb quinoline insolubles with fused ring structures using π-π stacking and coordination effects, effectively improving the removal efficiency of quinoline insolubles. Furthermore, the modified Fe3O4@SiO2 magnetic microspheres of this invention also have a quaternary ammonium salt structure on their surface, which can not only generate electrostatic attraction with the negatively charged groups in quinoline insolubles and disrupt the hydrogen bond network between quinoline insolubles, further improving the adsorption efficiency of quinoline insolubles, but also effectively enhance the magnetic separation effect of the magnetic separation step, promote magnetic aggregation, accelerate separation, and effectively enhance the adsorption capacity of Fe3O4@SiO2 magnetic microspheres.

Description

Technical Field

[0001] This invention belongs to the field of energy storage battery technology, specifically, it relates to a method for granulating coal-based needle coke into a high-energy-density energy storage negative electrode material. Background Technology

[0002] As high-performance energy storage devices, lithium-ion batteries rely heavily on their anode materials, which are crucial in determining energy density, cycle life, and rate performance. Ideal anode materials require high reversible capacity, excellent electronic / ionic conductivity, good structural stability, and low expansion rate. While traditional graphite anodes are widely used, their theoretical capacity is nearing its limit, making it difficult to meet the ever-increasing demand for high energy density. Therefore, developing higher-performance carbon-based anode materials has become a research hotspot. Needle coke is a special type of coke with a highly oriented, streamlined fibrous structure. After graphitization, it exhibits a highly ordered layered structure, low resistivity, and low coefficient of thermal expansion. Based on the source of raw materials, needle coke is classified into oil-based needle coke and coal-based needle coke. Among them, coal-based needle coke, made from coal tar pitch, has shown great potential in the field of high-end anode materials due to its unique performance advantages. After high-temperature graphitization, coal-based needle coke forms a highly developed graphite-like microcrystalline structure with interlayer spacing close to that of ideal graphite, giving it high electronic conductivity and fast lithium-ion diffusion channels, significantly improving battery rate performance, and exhibiting extremely low volume expansion rate, which can effectively avoid electrode structure pulverization and ensure long-cycle stability.

[0003] Despite the significant advantages of coal-based needle coke, the residual quinoline insolubles in its preparation process severely restrict the electrochemical performance of anode materials. These insolubles consist of high-molecular-weight polycyclic aromatic hydrocarbons, carbon black, and inorganic ash impurities in coal tar pitch that are difficult to dissolve in quinoline solvents. In the raw material pretreatment stage of needle coke preparation (such as solvent refining and centrifugation), if the quinoline insolubles are not completely removed, they will remain in the intermediate products. During coking, these quinoline insoluble particles hinder the coalescence and growth of mesophase spheres, leading to localized structural distortions and microcracks in the final coke, reducing graphitization. The heteroatoms (O, S, N) and edge defects in the quinoline insolubles become active sites for electrolyte decomposition, exacerbating the uneven growth of the solid electrolyte interfacial film and consuming active lithium ions. Traditional quinoline insoluble removal processes have limited efficiency in removing submicron-sized quinoline insoluble particles, while excessive refining increases raw material loss and cost. Therefore, how to achieve deep removal of quinoline insolubles while ensuring the rheological properties of needle coke raw materials is the core challenge facing the current industrialization of coal-based needle coke anode materials. To solve the above technical defects, this invention provides a coal-based needle coke proportioning and granulation method for high energy density energy storage anode materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for granulating coal-based needle coke in a high-energy-density energy storage anode material, in order to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for granulating coal-based needle coke into a high-energy-density energy storage anode material includes the following steps:

[0007] The first step is to heat-modify kerosene pitch and then extract it with a mixed hydrocarbon solvent. After that, the pitch is left to stand in a water bath and the solvent is removed by distillation to obtain refined pitch for later use.

[0008] The second step involves using modified Fe3O4@SiO2 magnetic microspheres (silica-coated magnetic iron tetroxide microspheres) to perform magnetic separation on refined asphalt to obtain ultra-clean asphalt. Then, coking heavy oil is added to the ultra-clean asphalt for coking, followed by calcination to obtain raw coke powder.

[0009] The third step involves mixing the needle coke powder with the binder to obtain a shaped wet material. The wet material is then extruded through an extruder equipped with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke.

[0010] Furthermore, the adhesive is a phenolic resin.

[0011] Furthermore, the thermal modification is performed at a temperature of 380–420°C for 60–120 minutes.

[0012] Furthermore, the mixed hydrocarbon solvent is obtained by mixing an aliphatic hydrocarbon solvent and an aromatic hydrocarbon solvent at a mass ratio of 0.8 to 1:1, and the mass ratio of kerosene pitch to solvent is 1 to 1.2:1.

[0013] Furthermore, the water bath settling conditions are settling at a temperature of 40–60°C for 2–4 hours.

[0014] Furthermore, the magnetic field conditions for the magnetic separation are: magnetic field strength of 0.5–1.0T, magnetic field direction parallel to the flow axis of the reactants, temperature of 480–520℃, pressure of 0.3–0.5MPa, and time of 3–5h.

[0015] Furthermore, the mass ratio of ultra-clean pitch to coking heavy oil during coking is 1:4 to 5, the coking temperature is 520 to 580°C, and the coking time is 24 hours.

[0016] Furthermore, the calcination temperature is 1100–1250℃, and the calcination time is 3–12 hours.

[0017] Furthermore, the modified Fe3O4@SiO2 magnetic microspheres are prepared by the following steps:

[0018] Step 1: Magnetic Fe3O4@SiO2 microspheres coated with silica, silane coupling agent KH-560, and ethanol solution were mixed in a three-necked flask, a condenser and a thermometer were installed, and magnetic stirring was turned on. The reaction was carried out at 40-60℃ for 4-8 hours. After the reaction was completed, the solid was separated by filtration and washed with anhydrous ethanol and deionized water in sequence, and then dried to obtain epoxidized Fe3O4@SiO2 magnetic microspheres.

[0019] Step 2: Epoxidized Fe3O4@SiO2 magnetic microspheres, 4-aminopyridine, and anhydrous ethanol were mixed in a three-necked flask, fitted with a condenser and a thermometer, and magnetic stirring was turned on. The mixture was then reacted at 50-60℃ for 3-4 hours. After the reaction was completed, the solid was filtered to separate it and washed with anhydrous ethanol and deionized water in sequence before drying to obtain highly adsorbent Fe3O4@SiO2 magnetic microspheres.

[0020] Step 3: Mix highly adsorbent Fe3O4@SiO2 magnetic microspheres, 1-chlorobutane, and acetonitrile in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 30-40℃ for 24 hours. After the reaction is complete, filter to separate the solid, wash it with anhydrous ethanol and deionized water in sequence, and then dry to obtain modified Fe3O4@SiO2 magnetic microspheres.

[0021] Furthermore, the volume fraction of the ethanol solution used in step 1 is 40-60%.

[0022] Furthermore, in step 1, the ratio of silica-coated magnetic iron oxide microspheres, silane coupling agent KH-560, and ethanol solution used is 10g: 6-12g: 240-300mL.

[0023] Furthermore, in step 2, the ratio of epoxidized Fe3O4@SiO2 magnetic microspheres, 4-aminopyridine, and anhydrous ethanol is 12-14 g: 6-10 g: 240-300 mL.

[0024] Furthermore, in step 3, the ratio of highly adsorbent Fe3O4@SiO2 magnetic microspheres, 1-chlorobutane, and acetonitrile used is 13–16 g: 4–8 g: 240–300 mL.

[0025] The beneficial effects of this invention are:

[0026] 1) This invention modifies Fe3O4@SiO2 magnetic microspheres by grafting an epoxy-containing silane coupling agent onto the surface of the Fe3O4@SiO2 magnetic microspheres to obtain epoxidized Fe3O4@SiO2 magnetic microspheres. Then, the epoxy groups on the surface of the epoxidized Fe3O4@SiO2 magnetic microspheres undergo a ring-opening reaction with the amino group in 4-aminopyridine to obtain highly adsorbent Fe3O4@SiO2 magnetic microspheres with a pyridine structure. Subsequently, the chlorine atom of 1-chlorobutane reacts with the nitrogen atom of the highly adsorbent Fe3O4@SiO2 magnetic microspheres to undergo a quaternary ammonium salt reaction to obtain modified Fe3O4@SiO2 magnetic microspheres with a quaternary ammonium salt structure. The modified Fe3O4@SiO2 magnetic microspheres of this invention have a pyridine structure on their surface, which can specifically adsorb quinoline insolubles with fused ring structures by utilizing the π-π stacking effect and coordination effect, effectively improving the removal efficiency of quinoline insolubles.

[0027] 2) The modified Fe3O4@SiO2 magnetic microspheres of the present invention have a quaternary ammonium salt structure on their surface. The quaternary ammonium salt structure is positively charged and can generate electrostatic attraction with the negatively charged groups in quinoline insolubles, and destroy the hydrogen bond network between quinoline insolubles, thereby further improving the adsorption efficiency of quinoline insolubles. In addition, the electrostatic interaction of the quaternary ammonium salt structure can also effectively improve the magnetic separation effect of the magnetic separation step, promote magnetic separation aggregation, accelerate separation, and effectively enhance the adsorption capacity of Fe3O4@SiO2 magnetic microspheres. Detailed Implementation

[0028] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0029] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0030] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0031] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0032] Example 1

[0033] A method for granulating coal-based needle coke into a high-energy-density energy storage anode material includes the following steps:

[0034] The first step is to heat-modify the kerosene pitch at 380℃ for 120 minutes and then extract it with a mixed hydrocarbon solvent. The mixed hydrocarbon solvent is obtained by mixing aliphatic hydrocarbon solvent and aromatic hydrocarbon solvent at a mass ratio of 0.8:1. The mass ratio of kerosene pitch to solvent is 1:1. After that, the mixture is allowed to stand at 40℃ for 4 hours and the solvent is removed by distillation to obtain refined pitch for later use.

[0035] The second step involves using modified Fe3O4@SiO2 magnetic microspheres to perform magnetic separation on refined asphalt under the following conditions: magnetic field strength of 0.5T, magnetic field direction parallel to the flow axis of the reactants, temperature of 480℃, pressure of 0.3MPa, and time of 3h. This yields ultra-clean asphalt, which is then coked by adding coking heavy oil at a mass ratio of 1:4. The coking temperature is 520℃, and the coking time is 24h. The resulting raw coke powder is then calcined at 1100℃ for 12h.

[0036] The third step involves mixing the needle coke powder with the phenolic resin binder to obtain a shaped wet material. The wet material is then extruded through an extruder equipped with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke.

[0037] The modified Fe3O4@SiO2 magnetic microspheres are prepared by the following steps:

[0038] Step 1: Mix 10g of silica-coated magnetic iron oxide microspheres, 6g of silane coupling agent KH-560, and 240mL of 60% ethanol solution in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 40℃ for 8h. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain epoxidized Fe3O4@SiO2 magnetic microspheres.

[0039] Step 2: Mix 12g of epoxidized Fe3O4@SiO2 magnetic microspheres, 6g of 4-aminopyridine, and 240mL of anhydrous ethanol in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 50℃ for 4h. After the reaction is completed, filter to separate the solid, wash it with anhydrous ethanol and deionized water in sequence, and then dry to obtain highly adsorbent Fe3O4@SiO2 magnetic microspheres.

[0040] Step 3: Mix 13g of highly adsorbent Fe3O4@SiO2 magnetic microspheres, 4g of 1-chlorobutane, and 240mL of acetonitrile in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 30℃ for 24h. After the reaction is complete, filter to separate the solid, wash it with anhydrous ethanol and deionized water in sequence, and then dry to obtain modified Fe3O4@SiO2 magnetic microspheres.

[0041] Example 2

[0042] A method for granulating coal-based needle coke into a high-energy-density energy storage anode material includes the following steps:

[0043] The first step involves heat-modifying kerosene pitch at 400℃ for 90 minutes, followed by extraction with a mixed hydrocarbon solvent. The mixed hydrocarbon solvent is obtained by mixing aliphatic hydrocarbon solvent and aromatic hydrocarbon solvent at a mass ratio of 0.9:1. The mass ratio of kerosene pitch to solvent is 1.1:1. After that, the mixture is allowed to stand at 50℃ for 3 hours and the solvent is removed by distillation to obtain refined pitch for later use.

[0044] The second step involves using modified Fe3O4@SiO2 magnetic microspheres to perform magnetic separation on refined asphalt under the following conditions: magnetic field strength of 0.75T, magnetic field direction parallel to the flow axis of the reactants, temperature of 500℃, pressure of 0.4MPa, and time of 4h. This yields ultra-clean asphalt, which is then coked by adding coking heavy oil. The mass ratio of ultra-clean asphalt to coking heavy oil is 1:4.5, the coking temperature is 550℃, and the coking time is 24h. The resulting raw coke powder is then calcined at 1175℃ for 7.5h.

[0045] The third step involves mixing the needle coke powder with the phenolic resin binder to obtain a shaped wet material. The wet material is then extruded through an extruder equipped with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke.

[0046] The modified Fe3O4@SiO2 magnetic microspheres are prepared by the following steps:

[0047] Step 1: Mix 10g of silica-coated magnetic iron oxide microspheres, 9g of silane coupling agent KH-560, and 270mL of 50% ethanol solution in a three-necked flask. Attach a condenser and thermometer, turn on magnetic stirring, and then react at 50℃ for 6 hours. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain epoxidized Fe3O4@SiO2 magnetic microspheres.

[0048] Step 2: Mix 13g of epoxidized Fe3O4@SiO2 magnetic microspheres, 8g of 4-aminopyridine, and 270mL of anhydrous ethanol in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 55℃ for 3.5h. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain highly adsorbent Fe3O4@SiO2 magnetic microspheres.

[0049] Step 3: Mix 14.5g of highly adsorbent Fe3O4@SiO2 magnetic microspheres, 6g of 1-chlorobutane, and 270mL of acetonitrile in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 35℃ for 24h. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain modified Fe3O4@SiO2 magnetic microspheres.

[0050] Example 3

[0051] A method for granulating coal-based needle coke into a high-energy-density energy storage anode material includes the following steps:

[0052] Step 1: The kerosene pitch is heat-modified at 420℃ for 60 minutes and then extracted with a mixed hydrocarbon solvent. The mixed hydrocarbon solvent is obtained by mixing aliphatic hydrocarbon solvent and aromatic hydrocarbon solvent at a mass ratio of 1:1. The mass ratio of kerosene pitch to solvent is 1.2:1. After that, the mixture is allowed to stand at 60℃ for 2 hours and the solvent is removed by distillation to obtain refined pitch for later use.

[0053] The second step involves using modified Fe3O4@SiO2 magnetic microspheres to perform magnetic separation on refined asphalt under the following conditions: magnetic field strength of 1.0T, magnetic field direction parallel to the flow axis of the reactants, temperature of 520℃, pressure of 0.5MPa, and time of 5h. This yields ultra-clean asphalt, which is then coked by adding coking heavy oil at a mass ratio of 1:5. The coking temperature is 580℃ and the coking time is 24h. The resulting raw coke powder is then calcined at 1250℃ for 3h.

[0054] The third step involves mixing the needle coke powder with the phenolic resin binder to obtain a shaped wet material. The wet material is then extruded through an extruder equipped with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke.

[0055] The modified Fe3O4@SiO2 magnetic microspheres are prepared by the following steps:

[0056] Step 1: Mix 10g of silica-coated magnetic iron oxide microspheres, 12g of silane coupling agent KH-560, and 300mL of 40% ethanol solution in a three-necked flask. Attach a condenser and thermometer, turn on magnetic stirring, and then react at 60℃ for 4 hours. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain epoxidized Fe3O4@SiO2 magnetic microspheres.

[0057] Step 2: Mix 14g of epoxidized Fe3O4@SiO2 magnetic microspheres, 10g of 4-aminopyridine, and 300mL of anhydrous ethanol in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 60℃ for 3h. After the reaction is completed, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain highly adsorbent Fe3O4@SiO2 magnetic microspheres.

[0058] Step 3: Mix 16g of highly adsorbent Fe3O4@SiO2 magnetic microspheres, 8g of 1-chlorobutane, and 300mL of acetonitrile in a three-necked flask, attach a condenser and a thermometer, turn on magnetic stirring, and then react at 40℃ for 24h. After the reaction is complete, filter to separate the solid, wash with anhydrous ethanol and deionized water in sequence, and then dry to obtain modified Fe3O4@SiO2 magnetic microspheres.

[0059] Comparative Example 1

[0060] A method for granulating coal-based needle coke into a high-energy-density energy storage anode material includes the following steps:

[0061] Step 1: The kerosene pitch is heat-modified at 420℃ for 60 minutes and then extracted with a mixed hydrocarbon solvent. The mixed hydrocarbon solvent is obtained by mixing aliphatic hydrocarbon solvent and aromatic hydrocarbon solvent at a mass ratio of 1:1. The mass ratio of kerosene pitch to solvent is 1.2:1. After that, the mixture is allowed to stand at 60℃ for 2 hours and the solvent is removed by distillation to obtain refined pitch for later use.

[0062] The second step involves using Fe3O4@SiO2 magnetic microspheres to perform magnetic separation on refined asphalt under the following conditions: magnetic field strength of 1.0T, magnetic field direction parallel to the flow axis of the reactants, temperature of 520℃, pressure of 0.5MPa, and time of 5h. This yields ultra-clean asphalt, which is then coked by adding coking oil at a mass ratio of 1:5. The coking temperature is 580℃ and the coking time is 24h. The resulting raw coke powder is then calcined at 1250℃ for 3h.

[0063] The third step involves mixing the needle coke powder with the phenolic resin binder to obtain a shaped wet material. The wet material is then extruded through an extruder equipped with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke.

[0064] Experimental Example 1

[0065] Anode materials were prepared from the coal-based needle coke in Examples 1-3 and Comparative Example 1. The performance of the anode materials was then tested using an electrochemical workstation. The test results are shown in Table 1.

[0066] Table 1

[0067] Example 1 342 7634 Example 2 341 7612 Example 3 344 7649 Comparative Example 1 Comparative Example 2 325 6425

[0068] As can be seen from Table 1, the coal-based needle coke obtained by the granulation method of the present invention in Examples 1 to 3 has better energy density and cycle life.

[0069] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for granulating coal-based needle coke in a high-energy-density energy storage anode material, characterized in that, Includes the following steps: The first step is to thermally reform the coal tar pitch and then extract it with a mixed hydrocarbon solvent. After that, the mixture is allowed to stand in a water bath and the solvent is removed by distillation to obtain refined pitch for later use. The second step involves using modified Fe3O4@SiO2 magnetic microspheres to magnetically separate refined asphalt to obtain ultra-clean asphalt. Then, coking heavy oil is added to the ultra-clean asphalt for coking, followed by calcination to obtain raw coke powder. The third step is to mix the raw coke powder and the binder evenly to obtain the shaped wet material. The wet material is then extruded through an extruder with a sieve plate of a predetermined aperture. The strips are then cut, rolled, dried, and sieved to obtain coal-based needle coke. The modified Fe3O4@SiO2 magnetic microspheres are prepared by the following steps: Step 1: Magnetic Fe3O4@SiO2 microspheres coated with silica, silane coupling agent KH-560, and ethanol solution are mixed in a container, stirred evenly, and reacted at 40-60℃ for 4-8 hours to obtain epoxidized Fe3O4@SiO2 magnetic microspheres. Step 2: Mix epoxidized Fe3O4@SiO2 magnetic microspheres, 4-aminopyridine, and anhydrous ethanol in a container, stir evenly, and react at 50-60℃ for 3-4 hours to obtain highly adsorbed Fe3O4@SiO2 magnetic microspheres. Step 3: Mix highly adsorbent Fe3O4@SiO2 magnetic microspheres, 1-chlorobutane, and acetonitrile in a container, stir evenly, and react at 30-40℃ for 24 hours to obtain modified Fe3O4@SiO2 magnetic microspheres. The adhesive is phenolic resin, and the volume fraction of the ethanol solution used in step 1 is 40-60%. The conditions for thermal modification are: thermal modification at a temperature of 380–420°C for 60–120 min; The mixed hydrocarbon solvent is obtained by mixing an aliphatic hydrocarbon solvent and an aromatic hydrocarbon solvent at a mass ratio of 0.8 to 1:1, and the mass ratio of coal tar pitch to solvent is 1 to 1.2:

1.

2. The method for granulating coal-based needle coke in a high-energy-density energy storage anode material according to claim 1, characterized in that, The water bath settling conditions are 2 to 4 hours at a temperature of 40 to 60°C.

3. The method for granulating coal-based needle coke in a high-energy-density energy storage anode material according to claim 1, characterized in that, The magnetic field conditions for the magnetic separation are: magnetic field strength 0.5~1.0 T, magnetic field direction parallel to the flow axis of the reactants, temperature 480~520℃, pressure 0.3~0.5MPa, and time 3~5h.

4. The method for granulating coal-based needle coke in a high-energy-density energy storage negative electrode material according to claim 1, characterized in that, The mass ratio of ultra-clean pitch to coking heavy oil during coking is 1:4 to 5. The coking temperature is 520 to 580℃, the coking time is 24 hours, the calcination temperature is 1100 to 1250℃, and the calcination time is 3 to 12 hours.

5. The method for granulating coal-based needle coke in a high-energy-density energy storage negative electrode material according to claim 1, characterized in that, In step 1, the ratio of silica-coated magnetic iron oxide microspheres, silane coupling agent KH-560, and ethanol solution used is 10g:6-12g:240-300mL.

6. The method for granulating coal-based needle coke in a high-energy-density energy storage anode material according to claim 1, characterized in that, In step 2, the ratio of epoxidized Fe3O4@SiO2 magnetic microspheres, 4-aminopyridine, and anhydrous ethanol is 12-14 g: 6-10 g: 240-300 mL.

7. The method for granulating coal-based needle coke in a high-energy-density energy storage anode material according to claim 1, characterized in that, In step 3, the ratio of highly adsorbent Fe3O4@SiO2 magnetic microspheres, 1-chlorobutane, and acetonitrile used is 13-16 g: 4-8 g: 240-300 mL.