Negative electrode material for fast-charging lithium ion battery and preparation method of negative electrode material

Abstract

The preparation method comprises the following steps: sulfonating iron composite porous graphite in a reaction kettle, then adding nano silicon and polyacrylic acid, carrying out annealing treatment after vacuum drying, then carrying out ball-milling centrifugation, and collecting sediment at the lowest layer, so as to obtain the negative electrode material for the fast-charging type lithium ion battery. And performing vacuum drying to obtain the negative electrode material for the fast-charging lithium ion battery. According to the prepared negative electrode material for the fast-charging type lithium ion battery, the nanometer silicon and the ferroferric oxide are embedded into the porous graphite, the conductivity and the ion transmission capacity of the negative electrode of the lithium ion battery are improved, the surface of the nanometer silicon is coated with the polyacrylic acid to form a carbon layer for wrapping, the volume expansion of the nanometer silicon during charging and discharging is reduced, and the conductivity and the ion transmission capacity of the negative electrode of the lithium ion battery are improved. According to the preparation method, the ferroferric oxide precursor is generated on the surface of the porous graphite in situ, so that the ferroferric oxide is generated on the basis of the structure of the precursor, the combination degree with the porous graphite is uniform, the specific surface area is large, the ion transmission efficiency is good, and the charging speed and the charging efficiency of the negative electrode material are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery materials, and particularly relates to a negative electrode material for a fast-charging lithium-ion battery and a preparation method thereof. Background Art

[0002] With the rapid growth of the global electric vehicle market and the increasing demand for fast-charging battery technology, the development of high-performance lithium-ion batteries with fast-charging capabilities has become an inevitable trend. However, there are key technical obstacles such as volume expansion, capacity degradation during fast charging, and safety hazards in the application of silicon-based negative electrodes in lithium-ion batteries.

[0003] Silicon has a band gap. Compared with traditional negative electrode materials such as graphite, the availability of charge carriers is limited, resulting in lower conductivity, which will hinder the efficient electron transport during fast charge and discharge cycles. During the fast charging process, the current is large and needs to pass through the negative electrode material quickly. The low conductivity of silicon leads to an increase in internal resistance, which limits the charging speed of the silicon-based negative electrode.

[0004] The Chinese patent application with the publication number CN118198292A discloses a fast-charging negative electrode material, a preparation method thereof, and an application, including porous graphite and a nano-solid electrolyte embedded in the pores of the porous graphite. The conductivity of graphite is improved by a nano-solid electrolyte slurry with strong conductivity. However, in this solution, the mixing method of the nano-solid electrolyte slurry and the porous graphite is only physical vibration mixing, which is greatly affected by the dispersibility of the nano-solid electrolyte slurry. Nano-scale substances are prone to agglomeration, and the improvement of the conductivity of the obtained negative electrode material is small.

[0005] The Chinese patent application with the publication number CN114538431A discloses a fast-charging graphite negative electrode material for a lithium battery and a preparation method thereof. Small-sized primary single particles are used to shorten the lithium-ion transmission path, and resin is used to make hard carbon coating the primary single particles to obtain larger-sized graphitized secondary particles, increasing the carbon layer spacing, which is beneficial to the transmission of lithium ions. However, in this solution, pure carbon materials are used as the battery negative electrode material, and the energy density of the battery negative electrode material is low. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem of how to improve the conductivity of the negative electrode material of a lithium-ion battery, improve the current transmission speed, and increase the energy density of the negative electrode material, and provide a negative electrode material for a fast-charging lithium-ion battery and a preparation method thereof.

[0007] The present invention embeds nano-silicon and iron tetroxide in porous graphite to improve the conductivity and ion transmission ability of the negative electrode material of a lithium-ion battery. A carbon layer formed by coating polyacrylic acid on the surface of the nano-silicon reduces the volume expansion of the nano-silicon during charge and discharge, and improves the energy density of the negative electrode material.

[0008] The object of the present invention can be achieved by the following technical solutions:

[0009] A preparation method of a negative electrode material for a fast-charging lithium-ion battery, comprising the following steps:

[0010] Step 1: Mix iron composite porous graphite with an ethanol aqueous solution of 65 - 75 wt% in a reaction kettle. Dissolve p-toluenesulfonic acid in deionized water, add it to the reaction kettle, stir for 20 - 24 h, then add nano-silicon, heat to 80 - 90 °C, perform ultrasonic treatment for 1 - 2 h, then add polyacrylic acid, stir for 3 - 4 h, filter to collect the precipitate, wash the precipitate, and vacuum dry to obtain silicon / iron composite porous graphite.

[0011] Step 2: Place the silicon / iron composite porous graphite in a tubular furnace, heat it to 450 - 480 °C at a rate of 5 °C / min in an argon atmosphere for annealing treatment for 120 - 150 min to obtain iron trioxide / silicon composite porous graphite. Ball-mill the iron trioxide / silicon composite porous graphite to a particle size of 10 - 20 μm, perform centrifugation treatment in an ethanol solution, collect the precipitate in the bottom layer, and vacuum dry at 60 - 70 °C to obtain the negative electrode material for a fast-charging lithium-ion battery.

[0012] Furthermore, in Step 1, the dosage ratio of the iron composite porous graphite, ethanol aqueous solution, p-toluenesulfonic acid, deionized water, nano-silicon, and polyacrylic acid is 10 - 20 g : 500 - 800 mL : 4 - 6 g : 200 - 400 mL : 10 - 15 g : 2 - 3 g.

[0013] Furthermore, the iron composite porous graphite is prepared by the following steps:

[0014] Mix a porous graphite dispersion liquid and a trimesic acid ethanol solution in a reaction kettle. Dissolve ferric nitrate nonahydrate in an ethanol aqueous solution, add it to the reaction kettle for ultrasonic mixing, heat to 110 - 130 °C for a closed reaction for 20 - 24 h, cool and then filter to collect the precipitate, wash the precipitate, and vacuum dry to obtain the iron composite porous graphite; the ethanol aqueous solution has a mass fraction of 65 - 75%.

[0015] Furthermore, the dosage ratio of the porous graphite dispersion liquid, trimesic acid ethanol solution, ferric nitrate nonahydrate, and ethanol aqueous solution is 500 - 800 mL : 100 - 150 mL : 10 - 20 g : 100 - 150 mL.

[0016] Furthermore, the porous graphite dispersion liquid is prepared by mixing porous graphite and an ethanol aqueous solution according to a dosage ratio of 10 - 20 g : 500 - 800 mL; the trimesic acid ethanol solution is prepared by mixing trimesic acid and absolute ethanol according to a dosage ratio of 8 - 10 g : 100 - 150 mL.

[0017] Further, the porous graphite is prepared by the following steps:

[0018] In a reaction kettle, sodium chloride, cellulose fiber, and mesophase pitch at 300 - 350 °C are stirred and mixed in an argon atmosphere for 3 - 4 h. Then, the temperature of the reaction kettle is raised to 400 - 450 °C, and the reaction is carried out at a pressure of 2 - 2.5 MPa for 2 - 3 h. After cooling, it is washed with deionized water and dried at 100 - 120 °C to obtain an asphalt intermediate foam. Under nitrogen protection, it is heated to 850 - 900 °C at a rate of 5 °C / min for carbonization for 60 - 70 min to obtain a carbonized foam. Finally, it is graphitized by heating to 2500 - 2600 °C to obtain the porous graphite.

[0019] Further, the mass ratio of sodium chloride, cellulose fiber, and mesophase pitch is 8 - 10:20 - 30:350 - 400.

[0020] Further, both the mesophase pitch and sodium chloride are ground through a 200 - mesh sieve.

[0021] Further, the cellulose fiber is wood fiber with a length of 10 - 15 μm and a diameter of 1 - 2 μm.

[0022] Advantages of the present invention:

[0023] (1) The negative electrode material for fast - charging lithium - ion batteries prepared by the present invention improves the electrical conductivity and ion transport ability of the negative electrode of the lithium - ion battery by embedding nano - silicon and iron trioxide in the porous graphite. By forming a carbon layer coating on the surface of the nano - silicon with polyacrylic acid, the volume expansion of the nano - silicon during charge and discharge is reduced. By in - situ generating the precursor Fe - MOF of iron trioxide on the surface of the porous graphite, iron trioxide is generated on the basis of the structure of Fe - MOF, with a uniform binding degree to the porous graphite, a large specific surface area, good ion transport efficiency, and the charging speed and charging efficiency of the negative electrode material are improved.

[0024] (2) The preparation method of the present invention prepares porous graphite by mixing refined coal tar pitch with sodium chloride and cellulose fiber. The obtained porous graphite has abundant pores and cracks, a high specific surface area, and strong electrical conductivity. By in - situ generating Fe - MOF on the surface of the porous graphite, Fe - MOF is uniformly combined in the pores and cracks of the porous graphite. Utilizing the modification effect of sulfonic acid groups on the porous graphite and Fe - MOF, the nano - silicon is uniformly attached under the cross - linking action of sulfonic acid groups, increasing the dispersion degree of the nano - silicon in the porous graphite. Finally, the nano - silicon is coated with polyacrylic acid and annealed at high temperature, and Fe - MOF is oxidized to iron trioxide to improve the ion transport ability. By using the carbonization effect at high temperature, the polyacrylic acid and the ligands in Fe - MOF are carbonized, so that the nano - silicon is coated with a carbon layer, reducing the volume expansion effect of the nano - silicon and enhancing the binding strength among the nano - silicon, iron trioxide, and porous graphite. Specific embodiments

[0025] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0026] Embodiment 1: A method for preparing a negative electrode material for a fast-charging lithium-ion battery, comprising the following steps:

[0027] S1. In a reaction kettle, refined coal tar pitch is heated to 400 °C under a nitrogen atmosphere, stirred and reacted for 5 h, purged with nitrogen for 3 h, then cooled, ground and sieved through a 200-mesh sieve to obtain mesophase pitch. In the reaction kettle, 8 g of sodium chloride sieved through a 200-mesh sieve, 20 g of cellulose fiber and 350 g of 300 °C mesophase pitch are stirred and mixed in an argon atmosphere for 3 h, then the reaction kettle is heated to 400 °C and reacted under a pressure of 2 MPa for 2 h. After cooling, it is washed with deionized water, dried at 100 °C to obtain an asphalt intermediate foam, carbonized at a rate of 5 °C / min to 850 °C for 60 min under nitrogen protection to obtain a carbonized foam, and finally heated to 2500 °C for graphitization to obtain porous graphite.

[0028] S2. In a reaction kettle, 10 g of porous graphite is mixed with 500 mL of 65 wt% ethanol aqueous solution to obtain a porous graphite dispersion. 8 g of trimesic acid is dissolved in 100 mL of absolute ethanol to obtain a trimesic acid ethanol solution. 500 mL of the porous graphite dispersion and 100 mL of the trimesic acid ethanol solution are added to the reaction kettle and ultrasonically mixed for 20 min. Then, 10 g of ferric nitrate nonahydrate is dissolved in 100 mL of 65 wt% ethanol aqueous solution, added to the reaction kettle and ultrasonically mixed for 20 min. The temperature is raised to 110 °C and the reaction is carried out in a closed state for 20 h. After cooling, the precipitate is collected by filtration, washed with ethanol and deionized water, and vacuum dried at 60 °C for 10 h to obtain iron-composite porous graphite.

[0029] S3. In a reaction kettle, 10 g of iron-composite porous graphite is mixed with 500 mL of 65 wt% ethanol aqueous solution. 4 g of p-toluenesulfonic acid is dissolved in 200 mL of deionized water, added to the reaction kettle, stirred for 20 h, then 10 g of nano-silicon powder is added, the temperature is raised to 80 °C, ultrasonically treated for 1 h, then 2 g of polyacrylic acid is added, stirred for 3 h, the precipitate is collected by filtration, washed with ethanol and deionized water, and vacuum dried at 60 °C for 10 h to obtain silicon / iron-composite porous graphite.

[0030] S4. After crushing the silicon / iron composite porous graphite through a 200-mesh sieve, place it in a tubular furnace and heat it to 450 °C at a rate of 5 °C / min in an argon atmosphere for annealing treatment for 120 min to obtain iron trioxide / silicon composite porous graphite. Ball-mill the iron trioxide / silicon composite porous graphite to a particle size of 10 μm, perform centrifugation treatment in an ethanol solution, collect the precipitate in the bottom layer, and vacuum-dry it at 60 °C to obtain the negative electrode material for a fast-charging lithium-ion battery.

[0031] Example 2: A preparation method of a negative electrode material for a fast-charging lithium-ion battery, comprising the following steps:

[0032] S1. In a reaction kettle, heat the refined coal tar pitch to 425 °C under a nitrogen atmosphere, stir and react for 5.5 h, purge with nitrogen for 3.5 h and then cool. Grind it through a 200-mesh sieve to obtain mesophase pitch. In the reaction kettle, stir and mix 9 g of sodium chloride ground through a 200-mesh sieve, 25 g of cellulose fiber, and 375 g of 325 °C mesophase pitch under an argon atmosphere for 3.5 h. Then raise the temperature of the reaction kettle to 425 °C and react under a pressure of 2.25 MPa for 2.5 h. After cooling, wash with deionized water, dry at 110 °C to obtain an asphalt intermediate foam, carbonize it at a rate of 5 °C / min to 875 °C for 65 min under nitrogen protection to obtain a carbonized foam, and finally raise the temperature to 2550 °C for graphitization to obtain porous graphite.

[0033] S2. In a reaction kettle, mix 15 g of porous graphite with 650 mL of 70 wt% ethanol aqueous solution to obtain a porous graphite dispersion. Dissolve 9 g of trimellitic acid in 125 mL of absolute ethanol to obtain a trimellitic acid ethanol solution. Add 650 mL of the porous graphite dispersion and 125 mL of the trimellitic acid ethanol solution to the reaction kettle and ultrasonically mix for 25 min. Then dissolve 15 g of ferric nitrate nonahydrate in 125 mL of 70 wt% ethanol aqueous solution, add it to the reaction kettle and ultrasonically mix for 25 min. Raise the temperature to 120 °C and react in a closed system for 22 h. After cooling, filter to collect the precipitate, wash the precipitate with ethanol and deionized water, and vacuum-dry it at 65 °C for 11 h to obtain iron composite porous graphite.

[0034] S3. In a reaction kettle, mix 15 g of iron composite porous graphite with 650 mL of 70 wt% ethanol aqueous solution. Dissolve 5 g of p-toluenesulfonic acid in 300 mL of deionized water, add it to the reaction kettle, stir for 22 h, then add 12.5 g of nano-silicon powder, raise the temperature to 85 °C, ultrasonically treat for 1.5 h, add 2.5 g of polyacrylic acid, and stir for 3.5 h. Filter to collect the precipitate, wash the precipitate with ethanol and deionized water, and vacuum-dry it at 65 °C for 11 h to obtain silicon / iron composite porous graphite.

[0035] S4. After pulverizing the silicon / iron composite porous graphite through a 200-mesh sieve, place it in a tube furnace and heat it to 465 °C at a rate of 5 °C / min in an argon atmosphere for annealing treatment for 135 min to obtain iron oxide / silicon composite porous graphite. Ball-mill the iron oxide / silicon composite porous graphite to a particle size of 15 μm, perform centrifugation treatment in an ethanol solution, collect the precipitate in the bottom layer, and vacuum-dry it at 65 °C to obtain the anode material for fast-charging lithium-ion batteries.

[0036] Example 3: A preparation method of an anode material for fast-charging lithium-ion batteries, comprising the following steps:

[0037] S1. In a reaction kettle, heat the refined coal tar pitch to 450 °C under a nitrogen atmosphere, stir and react for 6 h, purge with nitrogen for 4 h, then cool, grind through a 200-mesh sieve to obtain mesophase pitch. In the reaction kettle, stir and mix 10 g of sodium chloride ground through a 200-mesh sieve, 30 g of cellulose fiber, and 400 g of 350 °C mesophase pitch under an argon atmosphere for 4 h. Then raise the temperature of the reaction kettle to 450 °C, react under a pressure of 2.5 MPa for 3 h, cool, wash with deionized water, dry at 120 °C to obtain an asphalt intermediate foam, carbonize at a rate of 5 °C / min to 900 °C for 70 min under nitrogen protection to obtain a carbonized foam, and finally raise the temperature to 2600 °C for graphitization to obtain porous graphite.

[0038] S2. In a reaction kettle, mix 20 g of porous graphite with 800 mL of 75 wt% ethanol aqueous solution to obtain a porous graphite dispersion. Dissolve 10 g of trimellitic acid in 150 mL of absolute ethanol to obtain a trimellitic acid ethanol solution. Add 800 mL of porous graphite dispersion and 150 mL of trimellitic acid ethanol solution to the reaction kettle and ultrasonically mix for 30 min. Then dissolve 20 g of ferric nitrate nonahydrate in 150 mL of 75 wt% ethanol aqueous solution, add it to the reaction kettle and ultrasonically mix for 30 min. Raise the temperature to 130 °C and react in a closed system for 24 h. After cooling, filter and collect the precipitate, wash the precipitate with ethanol and deionized water, and vacuum-dry it at 70 °C for 12 h to obtain iron composite porous graphite.

[0039] S3. In a reaction kettle, mix 20 g of iron composite porous graphite with 800 mL of 75 wt% ethanol aqueous solution. Dissolve 6 g of p-toluenesulfonic acid in 400 mL of deionized water, add it to the reaction kettle, stir for 24 h, then add 15 g of nano-silicon powder, raise the temperature to 90 °C, ultrasonically treat for 2 h, then add 3 g of polyacrylic acid, stir for 4 h, filter and collect the precipitate, wash the precipitate with ethanol and deionized water, and vacuum-dry it at 70 °C for 12 h to obtain silicon / iron composite porous graphite.

[0040] S4. After crushing the silicon / iron composite porous graphite through a 200-mesh sieve, it is placed in a tubular furnace and annealed at 480 °C for 150 min at a rate of 5 °C / min in an argon atmosphere to obtain iron oxide / silicon composite porous graphite. The iron oxide / silicon composite porous graphite is ball-milled to a particle size of 20 μm, centrifuged in an ethanol solution, and the precipitate in the bottom layer is collected and vacuum-dried at 70 °C to obtain the anode material for a fast-charging lithium-ion battery.

[0041] Principle of the invention: Using pitch mesophase as the raw material, sodium chloride as the template, and cellulose fiber as the porous channel, porous graphite with a porous structure is prepared. By utilizing the differences in the graphitization rate and volume between cellulose and pitch intermediate graphite, the proportion of pores and fissures in the porous graphite is increased, thereby increasing the deposition area of Fe-MOF and nanosilicon. Fe-MOF is in-situ hydrothermally generated on the surface of the porous graphite, and Fe-MOF is uniformly compounded on the surface and pores of the conductive graphite. The ligand of Fe-MOF in the iron / graphite composite powder is sulfonated by p-toluenesulfonic acid, and the surface of the porous graphite is sulfonic acid-modified. By means of the electrostatic attraction and hydrogen bond interaction between the sulfonic acid group and the basic center of nanosilicon, nanosilicon is uniformly compounded on the surface of the iron / graphite composite powder. Then, by means of the grafting action between polyacrylic acid and the sulfonic acid group, polyacrylic acid is coated on the surface of the porous graphite to coat the nanosilicon on the surface of the porous graphite. Then, through high-temperature annealing treatment, Fe-MOF is oxidized into iron oxide, and the anode material doped with iron oxide has high specific capacity, cycle stability, and rate performance. The high-temperature annealing treatment simultaneously carbonizes the ligand in Fe-MOF and polyacrylic acid to form a firm carbon structure to wrap the nanosilicon in the porous graphite, reducing the volume expansion of nanosilicon during charge and discharge, improving the electrical conductivity and ion transport efficiency, and increasing the charging speed.

[0042] The cellulose fiber is wood fiber with a length of 10 - 15 μm and a diameter of 1 - 2 μm.

[0043] Comparative Example 1: The difference from Example 1 is that in S1, no cellulose fiber is added, and the anode material for a fast-charging lithium-ion battery is prepared.

[0044] Comparative Example 2: The difference from Example 1 is that in S2, 10 g of porous graphite is mixed with 500 mL of 65 wt% ethanol aqueous solution in a reaction kettle, and 8 g of nanoiron is added to the reaction kettle and ultrasonically mixed for 20 min to obtain iron composite porous graphite, and the anode material for a fast-charging lithium-ion battery is prepared.

[0045] Comparative Example 3: The difference from Example 1 is that in S3, no p-toluenesulfonic acid is added, and the anode material for a fast-charging lithium-ion battery is prepared.

[0046] The performance of the anode materials for fast - charging lithium - ion batteries prepared in Examples 1 - 3 and Comparative Examples 1 - 3 was tested. 80 mg of the anode material for fast - charging lithium - ion batteries was used as the active material, 10 mg of conductive carbon black and 10 mg of polyvinylidene fluoride were mixed in an agate mortar to form a uniform ink. After coating it on an 18 - μm copper foil with a scraper, it was dried at 80 °C for 1 h and then dried under vacuum for 3 h. The prepared electrode was made into a disk with a diameter of 10 mm. The electrolyte used was a silicon - based anode material electrolyte (1 mol / L LiPF6, EC:DEC = 1:1, 10% FEC), the separator was made of PP material, and the lithium foil was used as the counter electrode to assemble a CR2032 - type lithium half - cell. The batteries corresponding to Examples 1 - 3 and Comparative Examples 1 - 3 were respectively tested for their rate performance at a current density of 0.2 A g -1 and 1 A g -1 , and after 50 cycles, the discharge capacity was tested, and the capacity degradation rate was calculated. The results are shown in Table 1 as follows:

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, the batteries assembled with the anode materials for fast - charging lithium - ion batteries prepared by the present invention have a high specific capacity. Even when charged and discharged at a high current density, they can still maintain a relatively high battery capacity. After 50 cycles, the capacity degradation rate is low. Even at a high current density, the capacity degradation rate is still lower than 50%, indicating that the anode materials for fast - charging lithium - ion batteries prepared by the present invention have high stability, fast current transmission speed, and high discharge capacity.

[0050] In Comparative Example 1, due to the absence of cellulose fibers, the content of cracks in the prepared porous graphite is small, and the degree of composite of Fe - MOF and porous graphite is low. Therefore, its performance is slightly lower than that of Examples 1 - 3.

[0051] In Comparative Example 2, since nano - iron and porous graphite are physically mixed, nano - iron is prone to agglomeration, and its dispersion degree on the surface of porous graphite is low. The performance of the prepared anode material is poor.

[0052] In Comparative Example 3, due to the absence of p - toluenesulfonic acid, nano - silicon is prone to agglomeration, and its dispersion degree in porous graphite is low. The volume expansion rate of the agglomerated nano - silicon particles during charge and discharge is large, resulting in damage to the anode material and a large capacity degradation rate.

[0053] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a negative electrode material for a fast-charging lithium-ion battery, characterized in that, It includes the following steps: Step 1: Mix iron composite porous graphite with an ethanol aqueous solution of 65 - 75 wt% in a reaction kettle. Dissolve p-toluenesulfonic acid in deionized water, add it to the reaction kettle, stir for 20 - 24 h, then add nano-silicon, heat up to 80 - 90 °C, perform ultrasonic treatment for 1 - 2 h, then add polyacrylic acid, stir for 3 - 4 h, filter to collect the precipitate, wash the precipitate, and dry it under vacuum to obtain silicon / iron composite porous graphite. Step 2: Place the silicon / iron composite porous graphite in a tubular furnace, heat it to 450 - 480 °C at a rate of 5 °C / min in an argon atmosphere for annealing treatment for 120 - 150 min to obtain iron oxide / silicon composite porous graphite. Grind the iron oxide / silicon composite porous graphite to a particle size of 10 - 20 μm, perform centrifugation treatment in an ethanol solution, collect the precipitate at the bottom layer, and dry it under vacuum at 60 - 70 °C to obtain the anode material for fast-charging lithium-ion batteries.

2. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 1, wherein, In Step 1, the dosage ratio of the iron composite porous graphite, ethanol aqueous solution, p-toluenesulfonic acid, deionized water, nano-silicon, and polyacrylic acid is 10 - 20 g : 500 - 800 mL : 4 - 6 g : 200 - 400 mL : 10 - 15 g : 2 - 3 g.

3. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 2, characterized in that, The iron composite porous graphite is prepared by the following steps: In a reaction kettle, mix the porous graphite dispersion and the trimesic acid ethanol solution. Dissolve ferric nitrate nonahydrate in an ethanol aqueous solution of 65 - 75 wt%, add it to the reaction kettle for ultrasonic mixing, heat up to 110 - 130 °C for a closed reaction for 20 - 24 h, cool and then filter to collect the precipitate, wash the precipitate, and dry it under vacuum to obtain the iron composite porous graphite.

4. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 3, characterized in that, The dosage ratio of the porous graphite dispersion, trimesic acid ethanol solution, ferric nitrate nonahydrate, and ethanol aqueous solution is 500 - 800 mL : 100 - 150 mL : 10 - 20 g : 100 - 150 mL.

5. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 4, characterized in that, The porous graphite dispersion is prepared by mixing porous graphite and an ethanol aqueous solution according to a dosage ratio of 10 - 20 g : 500 - 800 mL; the trimesic acid ethanol solution is prepared by mixing trimesic acid and absolute ethanol according to a dosage ratio of 8 - 10 g : 100 - 150 mL.

6. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 5, wherein, The porous graphite is prepared by the following steps: In a reaction kettle, stir and mix sodium chloride, cellulose fiber, and 300 - 350 °C mesophase pitch in an argon atmosphere for 3 - 4 h, then heat the reaction kettle to 400 - 450 °C, react under a pressure of 2 - 2.5 MPa for 2 - 3 h, cool and wash with deionized water, dry at 100 - 120 °C to obtain an asphalt intermediate foam, carbonize it at a rate of 5 °C / min to 850 - 900 °C for 60 - 70 min under nitrogen protection to obtain a carbonized foam, and finally heat it to 2500 - 2600 °C for graphitization to obtain the porous graphite.

7. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 6, characterized in that, The mass ratio of the sodium chloride, cellulose fiber, and mesophase pitch is 8 - 10 : 20 - 30 : 350 - 400.

8. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 7, characterized in that, Both the mesophase pitch and sodium chloride are ground through a 200-mesh sieve.

9. The preparation method of the anode material for a fast-charging lithium-ion battery according to claim 6, characterized in that, The cellulose fiber is wood fiber, with a length of 10 - 15 μm and a diameter of 1 - 2 μm.

10. A negative electrode material for a fast-charging lithium-ion battery, characterized in that, Prepared by the method for preparing the anode material for fast-charging lithium-ion battery according to any one of claims 1-9.

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