CN112054165B

CN112054165B - Mesocarbon microbeads, graphite negative electrode material, preparation method of mesocarbon microbeads and graphite negative electrode material, and lithium ion battery

Info

Publication number: CN112054165B
Application number: CN201910485360.8A
Authority: CN
Inventors: 刘梦阳; 苗荣荣; 李念民; 吴志红; 丁晓阳
Original assignee: Shanghai Shanshan Technology Co Ltd
Current assignee: Shanghai Shanshan Technology Co Ltd
Priority date: 2019-06-05
Filing date: 2019-06-05
Publication date: 2022-02-08
Anticipated expiration: 2039-06-05
Also published as: CN112054165A

Abstract

The invention discloses a mesocarbon microbead, a graphite cathode material, a preparation method of the mesocarbon microbead and the graphite cathode material, and a lithium ion battery. The mesocarbon microbeads are prepared by the following method: mixing the silicon-containing slurry and the asphalt in a solvent capable of dissolving the asphalt, and performing polymerization reaction to obtain mesocarbon microbeads; the silicon-containing slurry comprises silicon-containing particles and an organic silane solvent; in the asphalt, quinoline insoluble substances are less than or equal to 0.5 percent, and the percentage refers to the mass percentage in the asphalt; the mass ratio of the silicon-containing particles to the asphalt is (0.001-0.1): 1. The mesocarbon microbeads are graphitized to obtain the graphite cathode material. The mesocarbon microbeads prepared by the method have good sphericity, and the graphite cathode material prepared by the mesocarbon microbeads has high discharge capacity and good quick charging performance. Compared with the traditional preparation process of the mesocarbon microbeads, the preparation process is simple, and the graphitization degree and the electrochemical quick charging performance of the negative electrode material are further improved.

Description

Mesocarbon microbeads, graphite negative electrode material, preparation method of mesocarbon microbeads and graphite negative electrode material, and lithium ion battery

Technical Field

The invention relates to the field of lithium ion battery materials, in particular to a mesocarbon microbead, a graphite negative electrode material, a preparation method of the mesocarbon microbead and the graphite negative electrode material, and a lithium ion battery.

Background

The lithium commercialized negative electrode material for lithium ion batteries is mainly graphite, and is mainly classified into mesophase graphite prepared from artificial graphite, natural graphite and mesophase carbon microbeads (MCMB for short). Compared with natural graphite, the three have the highest capacity, the second time artificial graphite and the lowest capacity of intermediate phase graphite. With the explosive growth of the automobile battery market, higher requirements are placed on the safety and the quick charging performance of the lithium battery. The cathode material with high capacity, high safety and fast charge has become the focus and hot spot of lithium ion battery research.

The pure products of the artificial graphite and the natural graphite can generally reach the capacity of 350-360mAh/g, but in order to have better quick charging and safety performance, the particle size of the raw materials needs to be controlled in a smaller range in the raw material treatment stage, and smaller single particles are bonded into the required size through secondary granulation. And the secondary particle graphite product needs to be reprocessed. The general processing method is to coat a layer of amorphous or amorphous pyrolytic carbon on the surface of a graphitized product, and then obtain the lithium ion battery cathode material with better quick charging performance after high-temperature carbonization treatment. The particles of the MCMB negative electrode material are spherical, so that the electrode plate has better orientation after preparation, and lithium ions are inserted and extracted in more directions, so that compared with the negative electrode material with the same capacity, the MCMB negative electrode material has better quick charge performance.

However, in the preparation process of the MCMB, raw quinoline insoluble substances are generated in the raw material pitch, and during polymerization, the quinoline insoluble substances form a shell layer on the surface of the mesophase, and the shell layer has a structure which is difficult to graphitize, so that the shell layer has a lower gram capacity after graphitization treatment, and the gram capacity of the whole MCMB graphitized material is reduced.

Therefore, how to prepare a negative electrode material with high discharge capacity, good rate capability and simple preparation process is an urgent technical problem to be solved in the field.

Disclosure of Invention

The invention aims to solve the technical problem that the graphite cathode material in the prior art is either high in discharge capacity but poor in rate capability and needs a complex post-treatment process; or has good multiplying power performance but low discharge capacity, and provides the mesocarbon microbeads, the graphite cathode material, the preparation method thereof and the lithium ion battery. The mesocarbon microbeads prepared by the method have good sphericity, and the graphite cathode material prepared by the mesocarbon microbeads has high discharge capacity and good quick charging performance. Compared with the traditional preparation process of the mesocarbon microbeads, the preparation process is simple, and the graphitization degree and the electrochemical quick charging performance of the negative electrode material are further improved.

The invention provides a preparation method of mesocarbon microbeads, which comprises the following steps: mixing the silicon-containing slurry and the asphalt in a solvent capable of dissolving the asphalt, and performing polymerization reaction to obtain mesocarbon microbeads;

the silicon-containing slurry comprises silicon-containing particles and an organic silane solvent, the Dv50 particle size of the silicon-containing particles is 0.01-5 mu m, and the mass ratio of the silicon-containing particles to the organic silane solvent is more than or equal to 0.0001: 1;

in the asphalt, quinoline insoluble substances are less than or equal to 0.5 percent, and the percentage refers to the mass percentage in the asphalt;

the mass ratio of the silicon-containing particles to the asphalt is (0.001-0.1): 1.

In the present invention, the solvent capable of dissolving asphalt may be a solvent capable of dissolving asphalt, which is conventional in the art, and is generally a polar solvent containing an aromatic ring or a heterocyclic ring, such as one or more of an anthracene oil solvent, a naphthalene oil solvent, a wash oil solvent, and a toluene solvent, and further such as a wash oil solvent.

In the present invention, the silicon-containing particles are preferably present in the solvent in which the pitch is soluble in a percentage by mass of 0.1 to 30%, for example 1 to 30% or 0.1 to 10%, for example 10%.

In the present invention, the silicon-containing particles may be particles formed of silicon-containing materials that are conventional in the art. The silicon-containing substance is preferably one or more of elemental silicon, an oxide of silicon, and a carbide of silicon.

Among them, the oxide of silicon is preferably silicon dioxide.

Among them, the carbide of silicon is preferably silicon carbide.

In the present invention, the Dv50 particle size may be Dv50 particle size, which is a conventional particle size in the art, and generally refers to a number median particle size after counting the number distribution.

In the present invention, the Dv50 particle size of the silicon-containing particles is preferably 0.01-2 μm, for example 0.1 μm or 0.3 μm.

In the present invention, the organosilane solvent is preferably a silazane solvent.

Among them, the silazane-based solvent is preferably Hexamethyldisilazane (HMDS) and/or trimethylchlorosilane.

In the present invention, the mass ratio of the silicon-containing particles to the organosilane-based solvent is preferably (0.0001 to 0.2):1, more preferably (0.0001 to 0.1):1, for example, 0.005: 1.

In the present invention, the silicon-containing slurry may be prepared by a method conventional in the art, for example, by mixing the silicon-containing particles and the organosilane-based solvent.

The mixing method can be a mixing method conventional in the art, such as mixing at a stirring speed of more than 10m/s, and further mixing at a stirring speed of 15 m/s.

Wherein the temperature of the mixing is preferably 80-180 ℃, e.g. 100 ℃.

Wherein the mixing time is preferably 0.5-12h, e.g. 3 h.

Preferably, the silicon-containing particles are mixed with the solvent capable of dissolving the pitch, and then mixed with the organosilane solvent.

In the present invention, the asphalt may be asphalt conventional in the art, preferably coal refined asphalt and/or petroleum asphalt, such as coal refined asphalt.

In the present invention, the quinoline insoluble content is preferably 0.27% or less, and the percentage is the mass percentage in the asphalt.

In the present invention, the mass ratio of the siliceous particles to the pitch is preferably (0.005-0.1):1, for example 0.005:1 or 0.01: 1.

In the present invention, the polymerization reaction conditions may be reaction conditions for preparing mesocarbon microbeads, which are conventional in the art. The temperature of the polymerization reaction is preferably 390-450 deg.C, for example 440 deg.C. The polymerization time is preferably from 0.5 to 20h, for example 8 h.

In the present invention, after the mesophase carbon microbeads are prepared, post-treatment such as washing treatment and/or drying treatment may be performed according to the conventional operation in the art.

Wherein, the washing treatment can be conventional in the art, for example, the mesophase carbon microspheres are cooled (for example, 300 ℃), mixed with a solvent, washed and filtered, and the product is obtained.

The solvent may be a washing solvent conventional in the art, such as toluene.

The solvent may be used in an amount conventional in the art, for example, in a mass ratio of (4-6) to 1, for example, 5:1, of the solvent to the asphalt.

After the washing and filtering, the solvent with the same mass can be adopted for leaching.

Wherein, the drying treatment can be conventional drying treatment in the field, for example, vacuum drying at 100-150 ℃ for 12-48 h.

The temperature of the drying is preferably 110 ℃. The drying time is preferably 24 h.

The invention also provides the mesocarbon microbeads prepared by the method.

The invention also provides the mesocarbon microbeads, wherein the silicon-containing particles are embedded on the surface and in the mesocarbon microbeads, the content of silicon element in the mesocarbon microbeads is more than 1 percent, and the percentage is the mass percentage in the mesocarbon microbeads.

In the present invention, the content of silicon element in the mesocarbon microbeads is preferably 3 to 6%, for example, 3.80%, 3.62%, 4.01%, 5.20%, 3.15% or 4.90%, and the percentage is the mass percentage in the mesocarbon microbeads.

The invention also provides an application of the mesocarbon microbeads as a raw material for preparing a graphite cathode material.

The invention also provides a preparation method of the graphite cathode material, which comprises the following steps of carrying out graphitization treatment on the mesocarbon microbeads to obtain the mesographite.

In the present invention, the graphitization treatment may be a graphitization treatment conventional in the art, for example, a treatment at 2800-3000 ℃ (for example, 3000 ℃).

In the invention, after the intermediate phase carbon microsphere is subjected to graphitization treatment, silicon-containing particles volatilize to prepare the intermediate phase graphite of pure graphite spherical particles, the gram capacity of the intermediate phase graphite is improved, the graphitized intermediate phase carbon microsphere has more pore channel structures inside, lithium ion embedding and removing channels are increased, and the quick charging and quick discharging performance is further improved.

In the present invention, after the graphitization treatment, a coating treatment may be performed according to a conventional operation in the art, for example, by mixing the mesophase graphite and a coating agent and coating.

The surface of the graphitized mesocarbon microbeads is coated with a layer of pyrolytic carbon through coating treatment, so that the quick charging performance of the material is further improved, and the stability and the compaction density of the material are improved, so that the graphitized mesocarbon microbeads have higher quick charging performance, gram volume and safety.

Wherein the coating agent can be a coating agent conventional in the art, such as one or more of resin, coated asphalt and tar, and is preferably coated asphalt.

The amount of the coating agent may be an amount conventionally used in the art, for example, the mass ratio of the mesophase graphite to the coating agent is (0.005-0.1):1, for example, 0.1: 1.

Wherein the coating is generally carried out in a coating kettle, a roller oven or a VC mixer.

Wherein the temperature of the coating can be 300-800 ℃, for example 600 ℃.

Wherein the coating time may be 0.5-6h, for example 2 h.

Wherein, after the coating, the carbonization treatment can be carried out according to the conventional operation in the field, for example, the carbonization treatment by a roller kiln. The temperature of the carbonization treatment can be 900-1500 ℃, for example 1100 ℃. The time of the carbonization treatment can be 2-6 h.

The invention also provides a graphite cathode material prepared by the method.

The invention also provides a graphite anode material which is a spherical structure with porous inside, and the spherical structure is internally provided with the porous spherical structure: the porosity is more than or equal to 0.5 percent and the specific surface area is more than or equal to 1m²The graphitization degree of the graphite negative electrode material is more than 95%.

In the present invention, the particle size of the graphite negative electrode material is preferably 5 to 50 μm, for example, 12.1 μm, 11.8 μm, 10.8 μm, 9 μm, 13.1 μm, or 12.7 μm.

In the invention, the tap density of the graphite negative electrode material is preferably 0.89-1g/cm³，0.97g/cm³、0.96g/cm³、1g/cm³、0.89g/cm³、0.95g/cm³Or 0.98g/cm³。

In the present invention, the specific surface area of the graphite negative electrode material is preferably 1 to 3.2m²In g, e.g. 1.7m²/g、3.2m²/g、1m²/g、2.9m²/g、2.7m²G or 2.6m²/g。

In the invention, the discharge capacity of the graphite negative electrode material is preferably 345.9-354.2mAh/g, 354.2mAh/g, 351mAh/g, 349mAh/g, 345.9mAh/g, 352.9mAh/g or 351.5 mAh/g.

In the present invention, the discharge efficiency of the graphite negative electrode material is preferably 90.2 to 91.9%, for example, 92.2%, 91.1%, 91.8%, 91.6%, 91.7%, or 91.9%.

The invention also provides an application of the graphite cathode material as a lithium ion battery cathode material.

The invention also provides a lithium ion battery which comprises the graphite cathode material.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows:

(1) the mesocarbon microbeads prepared by the method have better sphericity, and silicon-containing particles are embedded on the surface and inside of the mesocarbon microbeads; the content of silicon element in the mesocarbon microbeads is more than 1 percent, and the percentage is the mass percentage in the mesocarbon microbeads.

(2) The graphite cathode material prepared by the invention has high discharge capacity, the gram capacity is more than 355mAh/g, the surface of the graphite cathode material is not provided with a shell layer formed by quinoline insoluble substances with lower capacity, the interior of the graphite cathode material has more pore channel structures, lithium ion embedding and extracting channels are increased, the fast charge and fast discharge performance is further improved, and the discharge multiplying power (3C/0.2C) is more than 90%. Further, through coating treatment, a layer of pyrolytic carbon is coated on the surface of the graphitized mesocarbon microbeads, so that the quick-filling performance of the material is further improved, and the stability and the compaction density of the material are improved, so that the material has higher quick-filling performance, gram volume and safety.

(3) Compared with the traditional MCMB preparation process, the preparation process is simpler, the gram volume of the mesocarbon microbeads is improved by adding the secondary quinoline insoluble substances, meanwhile, rich internal pore channel structures are generated, and the prepared cathode material is high in graphitization degree and excellent in electrochemical quick charging performance.

Drawings

FIG. 1 is an SEM photograph of the dry powder of silicon carbide in example 1.

FIG. 2 is an SEM image of a silicon-mesophase carbon microsphere composite prepared in example 1.

Fig. 3 is an SEM image of the silicon-mesophase carbon microsphere composite material prepared in example 1 after graphitization.

Fig. 4 is an SEM image of the graphitized carbon-coated silicon-mesophase carbon microsphere composite prepared in example 1.

Fig. 5 is a first cycle charge and discharge curve of a battery prepared from the negative electrode material obtained in example 1.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

In the following examples and comparative examples:

the coal refined pitch is purchased from Jining Keneng energy materials, and the quinoline content is 0.27 percent, and the percentage is mass percentage;

coated bitumen is available from Jining Kennent materials, Inc.

Example 1

(1) Silicon carbide dry powder (SEM image is shown in figure 1) with the Dv50 particle size of 0.3 mu m is added into the solvent of the wash oil, and the mass fraction of the silicon carbide in the solvent is 10%. Adding Hexamethyldisilazane (HMDS) according to 0.5 percent of the mass of the silicon carbide dry powder, stirring at a high speed (the linear velocity is 15m/s), heating to 100 ℃, and carrying out constant-temperature treatment for 3 hours to obtain silicon carbide slurry.

(2) Adding the silicon carbide and the coal refined asphalt in the step (1) into the molten coal refined asphalt according to the mass ratio of 0.005:1, and stirring. The temperature of the system was raised to 440 ℃ and maintained at the same temperature for 8 hours. Stopping heating, cooling to 300 ℃, adding toluene which is five times the weight of the coal refined pitch into the reaction, filtering while the mixture is hot, leaching the mixture with toluene with the same mass, and drying in vacuum at 110 ℃ for 24 hours to obtain the mesophase carbon microspheres containing silicon carbide particles, wherein the SEM picture is shown in figure 2.

(3) Graphitizing the mesocarbon microbeads in the step (2) at 3000 ℃ to obtain a graphitized material, wherein an SEM image of the graphitized material is shown in FIG. 3.

(4) Mixing the graphitized material and the coating asphalt in the step (3) according to the mass ratio of 0.1:1, heating the mixture in a stirring coating kettle to 600 ℃ for constant temperature treatment for 2 hours, discharging the mixture, and carbonizing the mixture in a roller kiln at 1100 ℃ to obtain a pure graphite cathode material finished product, wherein an SEM picture of the pure graphite cathode material finished product is shown in figure 4, the porosity of the pure graphite cathode material finished product is not less than 0.5%, and the specific surface area of the pure graphite cathode material finished product is not less than 1m²The graphitization degree is more than 95 percent.

Example 2

The dispersant hexamethyldisilazane in the step (1) in the example 1 was changed to trimethylchlorosilane, and the sample of the example 2 was obtained without changing other conditions and compounding parameters.

Example 3

The median Dv50 of the silicon carbide obtained in step (1) of example 1 was changed to 0.1 μm, and the samples of example 3 were obtained without changing the other conditions and compounding ratio parameters.

Example 4

The mass ratio of the silicon carbide and the coal refined pitch in the step (2) in the example 1 was adjusted to 0.01:1, and the sample of the example 4 was obtained without changing other conditions and compounding ratio parameters.

Example 5

The silicon carbide in step (1) in example 1 was changed to silicon dioxide, and the sample of example 5 was obtained without changing other conditions and compounding ratio parameters.

Example 6

The silicon carbide in the step (1) in the example 1 was changed to elemental silicon, and the sample of the example 6 was obtained without changing other conditions and compounding parameters.

Comparative example 1

The method is carried out in the same manner as in step (3) and step (4) of example 1, except that commercially available mesocarbon microbeads (purchased from shunhao shunhui chemical industry) are used to prepare the negative electrode material.

Comparative example 2

Adding silicon carbide dry powder with the Dv50 particle size of 0.005 mu m into a solvent of the wash oil, wherein the mass fraction of the silicon carbide in the solvent is 10%. Adding Hexamethyldisilazane (HMDS) according to 0.5 percent of the mass of the silicon carbide dry powder, stirring at a high speed (the linear velocity is 15m/s), heating to 100 ℃, and carrying out constant-temperature treatment for 3 hours to obtain silicon carbide slurry. The rest is the same as example 1.

No spherical microspheres are generated in the process of the step (2), and granular mesocarbon microspheres cannot be prepared.

Comparative example 3

Adding silicon carbide dry powder with the Dv50 particle size of 8 mu m into a solvent of the wash oil, wherein the mass fraction of the silicon carbide in the solvent is 10%. Adding Hexamethyldisilazane (HMDS) according to 0.5 percent of the mass of the silicon carbide dry powder, stirring at a high speed, heating to 100 ℃, and carrying out constant-temperature treatment for 3 hours to obtain silicon carbide slurry. The rest is the same as example 1.

Comparative example 4

The mass ratio of the silicon carbide and the coal-refined pitch in step (2) in example 1 was adjusted to 0.2: 1. The rest is the same as example 1.

The formed spherical microsphere particles are broken in the process of the step (2), are difficult to form spheres and have poor economy.

Comparative example 5

The mass ratio of the silicon carbide and the coal-refined pitch in step (2) in example 1 was adjusted to 0.0008:1, and the sample of comparative example 5 was obtained without changing other conditions.

Comparative example 6

The hexamethyldisilazane in step (1) in example 1 was replaced with sodium hexadecyl sulfonate and the other conditions were not changed to obtain the sample of comparative example 5.

Effect example 1

Taking the mesocarbon microbeads of the examples and the comparative examples, EDS (scanning electron Spectroscopy) results show that the content of silicon element in the mesocarbon microbeads prepared by the method is more than 1 percent, and the percentage is the mass percentage of the mesocarbon microbeads. Specifically, the following table 1 shows.

TABLE 1 comparison of mesophase carbon microbeads performance indexes between examples and comparative examples

Effect example 2

And (3) taking the negative electrode materials prepared in the examples and the comparative examples to prepare a button cell for performance detection. The method comprises the following specific steps:

the button cell testing method comprises the following steps: adding conductive carbon black into a carboxymethyl cellulose (CMC) aqueous solution, then adding the negative electrode material prepared in the embodiment or the comparative example, finally adding Styrene Butadiene Rubber (SBR), uniformly stirring, and uniformly coating the slurry on a copper foil on a coating machine to prepare a pole piece. And (3) putting the coated pole piece into a vacuum drying oven at the temperature of 110 ℃ for vacuum drying for 4 hours, taking out the pole piece, and rolling the pole piece on a roller press for later use. The simulated cell assembly was carried out in an argon-filled german braun glove box with an electrolyte of 1M LiPF6+ EC: DEC: DMC 1: 1:1 (volume ratio), and the metal lithium sheet is a counter electrode. The capacity test was carried out on an ArbinBT2000 model U.S. Battery tester, with a charge-discharge voltage range of 0.005 to 2.0V and a charge-discharge rate of 0.1C.

The discharge multiplying power test method comprises the following steps: the graphite of the examples of the present invention or the comparative examples was used as the negative electrode, lithium cobaltate was used as the positive electrode, and the ratio of 1M-LiPF6 EC: DMC: EMC 1: 1:1 (volume ratio) solution is used as electrolyte to assemble a full cell.

(1) The physical and chemical properties and discharge capacities of the graphite negative electrode materials prepared in the examples and comparative examples were compared, and the results are shown in table 2. As can be seen from table 2, the charge gram capacity of the mesophase graphite material in the present application can be improved by 4% (15mAh/g) compared to the conventional mesophase graphite material.

TABLE 2 comparison of half-cell Performance indices for the example and comparative example materials

(2) Fig. 5 is a charge and discharge curve of a button cell made using the sample prepared in example 1 for the negative electrode.

As can be seen from fig. 5, the charge/discharge curve is a standard graphite charge/discharge curve, and the charge/discharge plateau is excellent.

(3) The graphite negative electrode materials prepared in the examples and the comparative examples were compared in rate lithium intercalation performance, and the results are shown in table 3.

As can be seen from Table 3: compared with the common intermediate phase graphite material in the comparative example 1, the rate charging capability of the intermediate phase graphite material is remarkably improved, and the lithium intercalation rate (3C/0.2C) is more than 12%.

Table 3 rate charge test data for example and comparative samples

Claims

1. The preparation method of the mesocarbon microbeads is characterized by comprising the following steps: mixing the silicon-containing slurry and the asphalt in a solvent capable of dissolving the asphalt, and performing polymerization reaction to obtain mesocarbon microbeads;

the mass ratio of the silicon-containing particles to the asphalt is (0.001-0.1): 1;

the content of silicon element in the mesocarbon microbeads is more than 1 percent, and the percentage is the mass percentage in the mesocarbon microbeads.

2. The method for preparing mesocarbon microbeads according to claim 1, wherein said solvent capable of dissolving pitch is a polar solvent containing aromatic or heterocyclic rings;

and/or, the silicon-containing particles are 0.1-30% by mass in the solvent capable of dissolving the asphalt;

and/or the silicon-containing particles are one or more of simple substance silicon particles, silicon oxide particles and silicon carbide particles;

and/or the particle size Dv50 of the silicon-containing particles is 0.01-2 μm;

and/or the organosilane solvent is a silazane solvent;

and/or the mass ratio of the silicon-containing particles to the organosilane-based solvent is (0.0001-0.2): 1;

and/or, the silicon-containing slurry is prepared by mixing the silicon-containing particles and the organosilane solvent;

and/or the asphalt is coal refined asphalt and/or petroleum asphalt;

and/or the content of quinoline insoluble substances is less than or equal to 0.27 percent, and the percentage refers to the mass percentage in the asphalt;

and/or the mass ratio of the silicon-containing particles to the asphalt is (0.005-0.1): 1;

and/or the temperature of the polymerization reaction is 390-450 ℃;

and/or the time of the polymerization reaction is 0.5-20 h;

and/or after the mesocarbon microbeads are prepared, washing treatment and/or drying treatment are carried out; wherein the washing treatment is carried out according to the following steps: cooling the mesocarbon microbeads, mixing the mesocarbon microbeads with a solvent, washing and filtering the mixture to obtain the mesocarbon microbeads; the drying treatment is carried out according to the following steps: vacuum drying at 100-150 deg.c for 12-48 hr.

3. The method for preparing mesocarbon microbeads according to claim 2, wherein said solvent capable of dissolving pitch is one or more of anthracene oil solvent, naphthalene oil solvent, wash oil solvent and toluene solvent.

4. The method for preparing mesocarbon microbeads according to claim 3, wherein said solvent capable of dissolving pitch is a solvent for washing oil.

5. The method for preparing mesocarbon microbeads of claim 2, wherein said siliceous particles are present in said solvent capable of dissolving pitch in a mass percentage of 1-30% or 0.1-10%.

6. The method of claim 2, wherein the siliceous particles are present in the solvent in which the pitch is soluble in an amount of 10% by mass.

7. The method of preparing mesocarbon microbeads of claim 2 wherein said silicon oxide is silicon dioxide.

8. The method of claim 2, wherein the silicon carbide is silicon carbide.

9. The method of preparing mesocarbon microbeads of claim 2 wherein said silicon-containing particles have a Dv50 size of 0.1 μm or 0.3 μm.

10. The method for preparing mesocarbon microbeads according to claim 2, wherein said silazane-based solvent is hexamethyldisilazane and/or trimethylchlorosilane.

11. The method for producing mesocarbon microbeads according to claim 2, wherein the mass ratio of said silicon-containing particles to said organosilane-based solvent is (0.0001-0.1): 1.

12. The method for preparing mesocarbon microbeads according to claim 11, wherein the mass ratio of said silicon-containing particles to said organosilane-based solvent is 0.005: 1.

13. The method of preparing mesocarbon microbeads according to claim 2, wherein said silicon-containing particles and said organosilane based solvent are mixed at a stirring speed higher than 10 m/s.

14. The method for preparing mesocarbon microbeads according to claim 2, wherein the temperature at which said silicon-containing particles and said organosilane-based solvent are mixed is 80-180 ℃.

15. The method for preparing mesocarbon microbeads according to claim 2, wherein the mixing time of said silicon-containing particles and said organosilane solvent is 0.5-12 hours.

16. The method for producing mesocarbon microbeads according to claim 2, wherein said siliceous particles are mixed with said solvent for pitch dissolution and then mixed with said organosilane solvent.

17. The method of preparing mesocarbon microbeads of claim 2, wherein said pitch is coal-refined pitch.

18. The method for preparing mesocarbon microbeads according to claim 2, wherein the mass ratio of the siliceous particles to the pitch is 0.005:1 or 0.01: 1.

19. The method of preparing mesocarbon microbeads of claim 2, wherein said polymerization reaction temperature is 440 ℃.

20. The method for preparing mesocarbon microbeads of claim 2, wherein said polymerization reaction time is 8 hours.

21. The method of preparing mesocarbon microbeads of claim 2, wherein said solvent is toluene.

22. The method for preparing mesocarbon microbeads according to claim 2, wherein the mass ratio of the solvent to the pitch is (4-6): 1.

23. The method of preparing mesocarbon microbeads of claim 2, wherein said drying temperature is 110 ℃.

24. The method for preparing mesocarbon microbeads of claim 2, wherein said drying time is 24 hours.

25. Mesophase carbon microbeads prepared by the method as claimed in any one of claims 1 to 24.

26. Mesophase carbon microbeads, which are embedded with silicon-containing particles having a particle size according to any one of claims 1, 2 and 9 on the surface and in the interior thereof.

27. Use of mesocarbon microbeads according to claim 25 or 26 as raw material for preparing graphite anode material.

28. A method for preparing a graphite negative electrode material, comprising the step of graphitizing the mesocarbon microbeads of claim 26 or 27 to obtain mesographite.

29. The method for preparing the graphite anode material of claim 28, wherein the temperature of the graphitization treatment is 2800-3000 ℃.

30. The method for preparing a graphite negative electrode material according to claim 28 or 29, wherein after the graphitization treatment, a coating treatment is performed by mixing the mesophase graphite with a coating agent and coating.

31. The method of preparing a graphite anode material of claim 30, wherein the coating agent is one or more of a resin, a coating pitch, and tar.

32. The method of preparing a graphitic negative electrode material according to claim 31, wherein said coating agent is a coating pitch.

33. The method for producing a graphite negative electrode material according to claim 30, wherein the mass ratio of the mesophase graphite to the coating agent is (0.005-0.1): 1.

34. The method for preparing a graphite negative electrode material of claim 33, wherein the mass ratio of the mesophase graphite to the coating agent is 0.1: 1.

35. The method for preparing the graphite anode material as claimed in claim 30, wherein the coating temperature is 300-800 ℃.

36. The method of preparing a graphitic negative electrode material according to claim 35, wherein the temperature of said coating is 600 ℃.

37. The method of preparing a graphitic negative electrode material according to claim 30, wherein the coating time is 0.5 to 6 hours.

38. The method of preparing a graphitic negative electrode material according to claim 37, wherein the coating time is 2 hours.

39. The method for preparing a graphite negative electrode material according to claim 30, wherein a carbonization treatment is further performed after the coating.

40. The method for preparing the graphite anode material as claimed in claim 39, wherein the temperature of the carbonization treatment is 900-1500 ℃.

41. The method for preparing the graphite negative electrode material of claim 39, wherein the carbonization treatment time is 2-6 h.

42. A graphite negative electrode material prepared by the preparation method of the graphite negative electrode material as claimed in any one of claims 28 to 41.

43. A graphitic negative electrode material according to claim 42, characterized in that it is an internally porous spherical structure in which: the porosity is more than or equal to 0.5 percent and the specific surface area is more than or equal to 1m²The graphitization degree of the graphite negative electrode material is more than 95%.

44. A lithium ion battery comprising the graphitic negative electrode material according to claim 42 or 43.