Coal-based needle coke proportioning granulation method for high-energy-density energy storage negative electrode material

Abstract

The invention relates to a coal-based needle coke proportioning granulation method for a high-energy-density energy storage negative electrode material, and belongs to the technical field of energy storage batteries. The modified Fe3O4-coated SiO2 magnetic microspheres are obtained by modifying Fe3O4-coated SiO2 magnetic microspheres, the surfaces of the modified Fe3O4-coated SiO2 magnetic microspheres are provided with pyridine structures, quinoline insoluble substances with fused ring structures can be specifically adsorbed by utilizing a pi-pi stacking effect and a coordination effect, the removal efficiency of the quinoline insoluble substances is effectively improved, and in addition, the modified Fe3O4-coated SiO2 magnetic microspheres have the advantages that the removal efficiency of the quinoline insoluble substances is improved, and in addition, the service life of the modified Fe3O4-coated SiO2 magnetic microspheres is prolonged, and the service life of the modified Fe3O4-coated SiO2 magnetic microspheres is prolonged. The surface of the modified Fe3O4 (at) SiO2 magnetic microsphere also has a quaternary ammonium salt structure, so that the modified Fe3O4 (at) SiO2 magnetic microsphere can generate electrostatic attraction with negative electricity groups in quinoline insoluble substances and destroy a hydrogen bond network among the quinoline insoluble substances, the adsorption efficiency of the quinoline insoluble substances is further improved, the magnetic separation effect of a magnetic separation step can be effectively improved, magnetic separation aggregation is promoted, and the quality of the quinoline insoluble substances is improved. The separation is accelerated; and the adsorption capacity of the Fe3O4 coated SiO2 magnetic microspheres is effectively enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy storage batteries, and particularly relates to a coal-based needle coke proportioning granulation method for high-energy-density energy storage negative electrode materials. BACKGROUND

[0002] As high-performance energy storage devices, the negative electrode materials of lithium ion batteries are the key to determine the energy density, cycle life and rate performance of the batteries. An ideal negative electrode material needs to have high reversible capacity, excellent electronic / ionic conductivity, good structural stability and low expansion rate. Although the traditional graphite negative electrode is widely used, its theoretical capacity has reached the limit and it is difficult to meet the increasing demand for high energy density. Therefore, developing carbon-based negative electrode materials with higher performance has become a research hotspot. Needle coke is a special kind of coke with highly directional "streamline" fibrous structure. After graphitization, it presents a highly ordered layered structure, low resistivity and low thermal expansion coefficient. According to the source of raw materials, needle coke is divided into oil-based needle coke and coal-based needle coke. Among them, coal-based needle coke uses coal tar pitch as raw material and has great potential in the field of high-end negative electrode materials due to its unique performance advantages. After high-temperature graphitization, coal-based needle coke forms a highly developed graphite-like microcrystalline structure with a layer spacing close to ideal graphite, which gives it high electronic conductivity and fast lithium ion diffusion channels, significantly improves the rate performance of the battery, and can also exhibit extremely low volume expansion rate, effectively avoiding electrode structure pulverization and ensuring long cycle stability.

[0003] Although coal-based needle coke has significant advantages, the residual quinoline insoluble problem in its preparation process seriously restricts the electrochemical performance of the negative electrode material. The quinoline insoluble is a high molecular weight polycyclic aromatic hydrocarbon, carbon black and inorganic ash impurities in coal tar pitch that are difficult to be dissolved in quinoline solvent. In the raw material pretreatment (such as solvent refining, centrifugal separation) stage of needle coke preparation, if the quinoline insoluble is not completely removed, it will remain in the intermediate product. The quinoline insoluble particles hinder the merging and growth of intermediate phase spherules during coking, resulting in local structural distortion and microcracks in the final coke body, reducing the graphitization degree. The heteroatoms (O, S, N) and edge defects in quinoline insoluble become active sites for electrolyte decomposition, aggravating the uneven growth of the solid electrolyte interface film and consuming active lithium ions. The traditional quinoline insoluble removal process has limited efficiency for removing submicron quinoline insoluble particles, and excessive refining will increase the loss and cost of raw materials. Therefore, how to achieve deep removal of quinoline insoluble under the premise of ensuring the rheological properties of needle coke raw materials is a core challenge faced by the current coal-based needle coke negative electrode material industry. In order to solve the above technical defects, the present application provides a coal-based needle coke proportioning granulation method for high-energy-density energy storage negative electrode materials. SUMMARY

[0004] The present application aims to provide a coal-based needle coke proportioning granulation method of high-energy-density energy storage negative electrode material, which is used to solve the problems mentioned in the background.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] A coal-based needle coke proportioning granulation method of high-energy-density energy storage negative electrode material, comprising the following steps:

[0007] Firstly, kerosene pitch is heat-modified, then extracted by mixed hydrocarbon solvent, and then distilled to remove the solvent after water bath standing to obtain refined pitch for standby;

[0008] Secondly, the refined pitch is magnetically separated by using modified Fe3O4@SiO2 magnetic microspheres (silica-coated magnetic magnetite microspheres) to obtain super-clean pitch, then coking heavy oil is added to the super-clean pitch for coking, and then green coke powder is obtained by calcination;

[0009] Thirdly, the needle coke powder is mixed with a binder to obtain a shaped wet material, the wet material is extruded through an extruder equipped with a screen plate with a predetermined pore size, then the strip-shaped material is cut and rounded, dried and sieved to obtain coal-based needle coke.

[0010] Further, the binder is phenolic resin.

[0011] Further, the heat modification conditions are heat modification at a temperature of 380-420℃ for 60-120min.

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

[0013] Further, the water bath standing conditions are standing at a temperature of 40-60℃ for 2-4h.

[0014] Further, the magnetic field conditions of the magnetic separation are a magnetic field strength of 0.5-1.0T, the magnetic field direction is parallel to the reaction material flow axis, the temperature conditions are 480-520℃, the pressure conditions are 0.3-0.5MPa, and the time conditions are 3-5h.

[0015] Further, the mass fraction ratio of super-clean pitch to coking heavy oil during coking is 1:4-5, the coking temperature conditions are 520-580℃, and the coking time conditions are 24h.

[0016] Further, the calcination temperature conditions are 1100-1250℃, and the calcination time conditions are 3-12h.

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

[0018] Step 1: mix the silica-coated magnetic magnetite microspheres, silane coupling agent kh-560 and ethanol solution in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, then react at a temperature of 40-60 DEG C for 4-8 hours, after the reaction is completed, filter and separate the solid, then wash with anhydrous ethanol and deionized water in sequence, and dry to obtain the epoxidized Fe3O4@SiO2 magnetic microspheres;

[0019] Step 2: mix the epoxidized Fe3O4@SiO2 magnetic microspheres, 4-aminopyridine and anhydrous ethanol in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, then react at a temperature of 50-60 DEG C for 3-4 hours, after the reaction is completed, filter and separate the solid, then wash with anhydrous ethanol and deionized water in sequence, and dry to obtain the high-adsorption Fe3O4@SiO2 magnetic microspheres;

[0020] Step 3: mix the high-adsorption Fe3O4@SiO2 magnetic microspheres, 1-chlorobutane and acetonitrile in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, then react at a temperature of 30-40 DEG C for 24 hours, after the reaction is completed, filter and separate the solid, then wash with anhydrous ethanol and deionized water in sequence, and dry to obtain the modified Fe3O4@SiO2 magnetic microspheres.

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

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

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

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

[0025] The beneficial effects of the present application are as follows:

[0026] 1) The present application modifies Fe3O4@SiO2magnetic microspheres, and obtains epoxy Fe3O4@SiO2magnetic microspheres by grafting silane coupling agents with epoxy groups on the surface of the Fe3O4@SiO2magnetic microspheres, then obtains high adsorption Fe3O4@SiO2magnetic microspheres with a pyridine structure by ring-opening reaction of the epoxy groups on the surface of the epoxy Fe3O4@SiO2magnetic microspheres and the amino groups in 4-aminopyridine, and then obtains modified Fe3O4@SiO2magnetic microspheres with a quaternary ammonium salt structure by quaternary ammonium salt reaction of the chlorine atoms of 1-chlorobutane and the nitrogen atoms of the high adsorption Fe3O4@SiO2magnetic microspheres, the modified Fe3O4@SiO2magnetic microspheres of the present application have a pyridine structure on the surface, can specifically adsorb quinoline insoluble substances with a fused ring structure by using the pi-pi stacking effect and coordination effect, and effectively improve the removal efficiency of quinoline insoluble substances.

[0027] 2) The modified Fe3O4@SiO2magnetic microspheres of the present application have a quaternary ammonium salt structure on the surface, the quaternary ammonium salt structure has positive electricity, can produce electrostatic attraction with negative groups in quinoline insoluble substances, and can destroy the hydrogen bond network between quinoline insoluble substances, further improving the adsorption efficiency of quinoline insoluble substances, 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, speed up separation, and effectively enhance the adsorption capacity of the Fe3O4@SiO2magnetic microspheres. DETAILED DESCRIPTION

[0028] It should be understood that the expression "one or more of something" includes each of the objects of the recited list individually as well as various combinations of two or more of the recited objects, unless otherwise specifically stated in the context or use of the expression. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise specifically stated in the context.

[0029] The use of the terms "including", "having" or "containing", including the grammatical variations thereof, should be understood as open-ended and non-limiting, for example, by not excluding other unrecited elements or steps, unless otherwise specifically stated or understood in the context of the use of such terms.

[0030] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present application remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

[0031] The use of any and all examples, or exemplary language herein, for example, "such as" or "including", is intended merely to better illustrate the present application and does not indicate a limitation on the scope of the present application unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the present application.

[0032] Embodiment 1

[0033] A coal-based needle coke proportioning granulation method of a high-energy-density energy storage negative electrode material, comprising the following steps:

[0034] Firstly, kerosene pitch is heat modified at a temperature of 380 DEG C for 120 min, 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 0.8:1, the mass ratio of kerosene pitch to solvent is 1:1, then the mixture is placed at a temperature of 40 DEG C for 4 h, and the solvent is removed by distillation to obtain refined pitch for standby;

[0035] Secondly, the refined pitch is magnetically separated under the conditions of a magnetic field strength of 0.5 T, a magnetic field direction parallel to the flow axis of the reactant, a temperature of 480 DEG C, a pressure of 0.3 MPa, and a time of 3 h to obtain super-clean pitch, then coking heavy oil is added to the super-clean pitch for coking, the mass ratio of super-clean pitch to coking heavy oil is 1:4, the coking temperature is 520 DEG C, the coking time is 24 h, and then the green coke powder is obtained by calcination, the calcination temperature is 1100 DEG C, and the calcination time is 12 h;

[0036] Thirdly, the needle coke powder is mixed with a phenolic resin binder to obtain a shaped wet material, the wet material is extruded through an extruder provided with a sieve plate with a predetermined pore size, then the strip-shaped material is cut, rounded, 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: 10 g of silica-coated magnetic magnetite microspheres, 6 g of silane coupling agent kh-560, and 240 mL of ethanol solution with a volume fraction of 60% are mixed in a three-necked flask, a condenser tube and a thermometer are installed, magnetic stirring is started, then the mixture is reacted at a temperature of 40 DEG C for 8 h, after the reaction is completed, the solid is separated by filtration and washed with anhydrous ethanol and deionized water in sequence, and then dried to obtain epoxy Fe3O4@SiO2 magnetic microspheres;

[0039] Step 2: 12 g of epoxy Fe3O4@SiO2 magnetic microspheres, 6 g of 4-aminopyridine, and 240 mL of anhydrous ethanol are mixed in a three-necked flask, a condenser tube and a thermometer are installed, magnetic stirring is started, then the mixture is reacted at a temperature of 50 DEG C for 4 h, after the reaction is completed, the solid is separated by filtration and washed with anhydrous ethanol and deionized water in sequence, and then dried to obtain high-adsorption Fe3O4@SiO2 magnetic microspheres;

[0040] Step 3: 13 g of high adsorption Fe3O4@SiO2 magnetic microspheres, 4 g of 1-chlorobutane, and 240 mL of acetonitrile were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was started, and then the reaction was carried out at a temperature of 30℃ for 24 h. 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 modified Fe3O4@SiO2 magnetic microspheres.

[0041] Example 2

[0042] A coal-based needle coke proportioning granulation method of a high-energy-density energy storage negative electrode material includes the following steps:

[0043] First step, after kerosene pitch is heat modified at a temperature of 400℃ for 90 min, it is extracted with a mixed hydrocarbon solvent, the mixed hydrocarbon solvent is obtained by mixing an aliphatic hydrocarbon solvent and an aromatic hydrocarbon solvent at a mass fraction ratio of 0.9:1, the mass fraction ratio of the kerosene pitch to the solvent is 1.1:1, then it is placed at a temperature of 50℃ for 3 h and distilled to remove the solvent to obtain refined pitch for standby;

[0044] Second step, the refined pitch is magnetically separated under the conditions of a magnetic field strength of 0.75T, a magnetic field direction parallel to the flow axis of the reactant, a temperature of 500℃, a pressure of 0.4MPa, and a time of 4h to obtain super-clean pitch, then coking heavy oil is added to the super-clean pitch for coking, the mass fraction ratio of the super-clean pitch to the coking heavy oil is 1:4.5, the coking temperature is 550℃, the coking time is 24h, and then green coke powder is obtained by calcination, the calcination temperature is 1175℃, and the calcination time is 7.5h;

[0045] Third step, the needle coke powder is mixed with a phenolic resin binder to obtain a shaped wet material, the wet material is extruded through an extruder equipped with a screen plate with a predetermined pore size, then the strip-shaped material is cut, rounded, 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: 10 g of silica-coated magnetic magnetite microspheres, 9 g of silane coupling agent kh-560, and 270 mL of ethanol solution with a volume fraction of 50% are mixed in a three-necked flask, a condenser and a thermometer are installed, magnetic stirring is started, and then the reaction is carried out at a temperature of 50℃ for 6 h. After the reaction is completed, the solid is separated by filtration and washed with anhydrous ethanol and deionized water in sequence, and then dried to obtain epoxy-modified Fe3O4@SiO2 magnetic microspheres;

[0048] Step 2: 13 g of Fe3O4@SiO2 magnetic microspheres, 8 g of 4-aminopyridine, and 270 mL of anhydrous ethanol were mixed in a three-necked flask, which was equipped with a condenser and a thermometer, and magnetic stirring was started. Then the mixture was reacted at 55℃ for 3.5 h. After the reaction, the solid was separated by filtration and washed with anhydrous ethanol and deionized water successively, and then dried to obtain high-adsorption Fe3O4@SiO2 magnetic microspheres.

[0049] Step 3: 14.5 g of high-adsorption Fe3O4@SiO2 magnetic microspheres, 6 g of 1-chlorobutane, and 270 mL of acetonitrile were mixed in a three-necked flask, which was equipped with a condenser and a thermometer, and magnetic stirring was started. Then the mixture was reacted at 35℃ for 24 h. After the reaction, the solid was separated by filtration and washed with anhydrous ethanol and deionized water successively, and then dried to obtain modified Fe3O4@SiO2 magnetic microspheres.

[0050] Example 3

[0051] A coal-based needle coke proportioning granulation method of a high-energy-density energy storage negative electrode material includes the following steps:

[0052] First step, after kerosene pitch is heat modified at 420℃ for 60 min, it is extracted with a mixed hydrocarbon solvent, which is obtained by mixing a fatty hydrocarbon solvent and an aromatic hydrocarbon solvent at a mass ratio of 1:1. The mass ratio of kerosene pitch to solvent is 1.2:1. Then the mixture is left to stand at 60℃ for 2 h and distilled to remove the solvent to obtain refined pitch for later use.

[0053] Second step, the refined pitch is subjected to magnetic separation under the conditions of a modified Fe3O4@SiO2 magnetic microsphere, a magnetic field strength of 1.0 T, a magnetic field direction parallel to the flow axis of the reactant, a temperature of 520℃, a pressure of 0.5 MPa, and a time of 5 h to obtain super-clean pitch. Then coking is performed on the super-clean pitch by adding coking heavy oil, the mass ratio of super-clean pitch to coking heavy oil is 1:5, the coking temperature is 580℃, the coking time is 24 h, and then green coke powder is obtained by calcination, the calcination temperature is 1250℃, and the calcination time is 3 h.

[0054] Third step, the needle coke powder is mixed with a phenolic resin binder to obtain a shaped wet material. The wet material is extruded through an extruder equipped with a screen plate of a predetermined pore size, and then the strip-shaped material is cut, rounded, 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: 10 g of silica-coated magnetic Fe3O4 microspheres, 12 g of silane coupling agent kh-560, and 300 mL of ethanol solution with a volume fraction of 40% were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was started, and then the reaction was carried out at a temperature of 60°C for 4 h. 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 epoxy Fe3O4@SiO2 magnetic microspheres;

[0057] Step 2: 14 g of epoxy Fe3O4@SiO2 magnetic microspheres, 10 g of 4-aminopyridine, and 300 mL of anhydrous ethanol were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was started, and then the reaction was carried out at a temperature of 60°C for 3 h. 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 high-adsorption Fe3O4@SiO2 magnetic microspheres;

[0058] Step 3: 16 g of high-adsorption Fe3O4@SiO2 magnetic microspheres, 8 g of 1-chlorobutane, and 300 mL of acetonitrile were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was started, and then the reaction was carried out at a temperature of 40°C for 24 h. 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 modified Fe3O4@SiO2 magnetic microspheres.

[0059] Comparative Example 1

[0060] A coal-based needle coke proportioning granulation method of a high-energy-density energy storage negative electrode material, comprising the following steps:

[0061] First step, after kerosene pitch is heat modified at a temperature of 420°C for 60 min, it is extracted with a mixed hydrocarbon solvent, the mixed hydrocarbon solvent is obtained by mixing a fatty hydrocarbon solvent and an aromatic hydrocarbon solvent at a mass fraction ratio of 1:1, the mass fraction ratio of the kerosene pitch to the solvent is 1.2:1, then it is placed at a temperature of 60°C for 2 h and distilled to remove the solvent to obtain refined pitch for standby;

[0062] Second step, the refined pitch is magnetically separated under the conditions of a magnetic field strength of 1.0 T, a magnetic field direction parallel to the reaction material flow axis, a temperature of 520°C, a pressure of 0.5 MPa, and a time of 5 h to obtain super-clean pitch, then coking heavy oil is added to the super-clean pitch for coking, the mass fraction ratio of the super-clean pitch to the coking heavy oil is 1:5, the coking temperature is 580°C, the coking time is 24 h, and then the raw coke powder is obtained by calcination, the calcination temperature is 1250°C, and the calcination time is 3 h;

[0063] Third step, after mixing the needle coke powder with phenolic resin binder uniformly, the shaped wet material is obtained, the wet material is extruded through the extruder equipped with a screen plate with a predetermined aperture, then the strip-shaped material is cut, rounded, dried and sieved to obtain the coal-based needle coke.

[0064] Experimental example 1

[0065] The coal-based needle coke in examples 1-3 and comparative example 1 is prepared to obtain the negative electrode material, then the performance of the negative electrode material is tested by using an electrochemical workstation, and the test results are shown in Table 1:

[0066] Table 1

[0067] Item Energy density mAh / g Cycle life cyls Example 1 342 7634 Example 2 341 7612 Example 3 344 7649 Comparative Example 1 325 6425

[0068] As shown in Table 1, the coal-based needle coke obtained by the granulation method in examples 1-3 has better energy density and cycle life.

[0069] The above examples are only used to help understand the method of the present application and its core idea. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these examples shown herein, but will conform to 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 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. The second step involves using modified Fe3O4@SiO2 magnetic 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. The third step is to mix the needle coke powder with 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.

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 adhesive is phenolic resin, and the volume fraction of the ethanol solution used in step 1 is 40-60%.

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 conditions for thermal modification are as follows: thermal modification is carried out at a temperature of 380–420°C for 60–120 minutes.

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 mixed hydrocarbon solvent is obtained by mixing aliphatic hydrocarbon solvent and 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.

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, The water bath settling conditions are 2 to 4 hours at a temperature of 40 to 60°C.

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

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, The mass ratio of ultra-clean pitch to coking heavy oil during coking is 1:4-5. The coking temperature is 520-580℃, the coking time is 24h, the calcination temperature is 1100-1250℃, and the calcination time is 3-12h.

8. 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.

9. 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.

10. 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.