Fluorine-doped modified artificial graphite as well as preparation method and application thereof

Abstract

The invention discloses fluorine-doped modified artificial graphite and a preparation method and application thereof.The preparation method of the fluorine-doped modified artificial graphite comprises the steps that raw material coke and asphalt are subjected to batch mixing, granulation and shaping, and then an artificial graphite precursor is obtained; and carrying out doping reaction on the artificial graphite precursor and an inorganic fluorine source, graphitizing, screening and demagnetizing to obtain the fluorine-doped modified artificial graphite. The artificial graphite precursor and the inorganic fluorine source are subjected to doping reaction, fluorine doping of the artificial graphite can be realized, and when the artificial graphite is used as a lithium ion battery negative electrode material for formation, a layer of SEI film rich in LiF can be formed on the surface, so that the loss of Li in electrolyte is reduced, and the service life of the lithium ion battery is prolonged. And the stability and the first coulombic efficiency of the artificial graphite as the negative electrode material of the lithium ion battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of artificial graphite technology, and particularly relates to a fluorine-doped modified artificial graphite, its preparation method, and its application. Background Technology

[0002] With the development of the new energy industry, lithium-ion batteries are being used more and more widely, and the market demands for them are also increasing. As the most widely used synthetic graphite in lithium-ion anode materials, research is constantly being conducted to explore ways to improve battery performance. Currently, the mainstream method for preparing synthetic graphite involves coating the surface of the raw material coke with pitch to increase the electronic conductivity and tap density of the graphite material, thereby improving its cycle performance and charge / discharge efficiency.

[0003] However, during the initial charge and discharge process, irreversible reactions in the materials consume lithium ions to form an SEI film, leading to electrode material loss, capacity decay, and reduced battery cycle life and energy density. Patent CN117855441A discloses a fluorine-doped graphite anode material, which is formed by sintering fluorine-based organic compounds and amine-based organic compounds. While it can further improve the fast-charging performance of lithium-ion batteries while enhancing their energy density and cycle performance, the high cost of using organic fluorides and amine compounds, along with the need for sophisticated control equipment and reaction devices, makes the operation complex and costly. Summary of the Invention

[0004] Based on the above-mentioned technical problems, the present invention provides a fluorine-doped modified artificial graphite, its preparation method and application. By carrying out a doping reaction between the artificial graphite precursor and an inorganic fluorine source, fluorine doping of artificial graphite can be achieved. When used as a negative electrode material for lithium-ion batteries, a LiF-rich SEI film can be formed on the surface, reducing the loss of Li in the electrolyte and improving the stability and first coulombic efficiency of artificial graphite as a negative electrode material for lithium-ion batteries.

[0005] The present invention proposes a method for preparing fluorine-doped modified artificial graphite, comprising the following steps:

[0006] S1. The raw material coke and pitch are mixed, granulated, and shaped to obtain the artificial graphite precursor.

[0007] S2. After the artificial graphite precursor is doped with an inorganic fluorine source, it is then graphitized, sieved and demagnetized to obtain the fluorine-doped modified artificial graphite.

[0008] In this invention, the surface of the raw coke is coated by first granulating the raw coke with asphalt to obtain an artificial graphite precursor. Then, hydrogen fluoride is generated by pyrolysis of an inorganic fluorine source at the doping reaction temperature to dope the obtained artificial graphite precursor, thereby obtaining a fluorine-doped modified artificial graphite. The fluorine-doped modified artificial graphite obtained by this invention has the following advantages: First, the lithium storage mechanism is changed due to the doping of fluorine atoms, which can effectively improve the specific capacity and energy density of lithium-ion batteries. Second, the fluorine atoms at the edge of the fluorine-doped modified artificial graphite can form more stable fluorides with lithium salts in the electrolyte, ensuring the long cycle performance of lithium-ion batteries.

[0009] Preferably, in step S1, the raw material coke is at least one of needle coke, petroleum coke, pitch coke, or calcined coke; and the pitch is at least one of petroleum pitch, natural pitch, or coal pitch.

[0010] Preferably, the mass ratio of the raw material coke to pitch is 90-98:10-2.

[0011] Preferably, in step S1, before mixing the raw coke and asphalt, the raw coke and asphalt are ground separately to obtain raw coke powder with a D50 particle size of 9-11 μm and asphalt powder with a D50 particle size of 3-5 μm.

[0012] Preferably, in step S1, the granulation is carried out in a granulation kettle at a temperature of 650-750℃ for 6-9 hours.

[0013] Preferably, the shaping process includes depolymerizing and dispersing the granulated material, resulting in an artificial graphite precursor with a D50 particle size of 16-18 μm.

[0014] Preferably, in step S2, the doping reaction includes: pyrolyzing an inorganic fluorine source and then reacting it with the artificial graphite precursor;

[0015] Preferably, the inorganic fluorine source is NH4F, and the mass ratio of the artificial graphite precursor to the inorganic fluorine source is 1:1-5.

[0016] Preferably, the doping reaction temperature is 400-600℃ and the time is 2-4h.

[0017] Preferably, in step S2, the graphitization is carried out in a graphitization furnace at a temperature of 2800-3200℃ for a time of 12-72 hours.

[0018] Preferably, before the artificial graphite precursor is doped with a fluorine source, the surface of the artificial graphite precursor is further modified by tertiary amine formation, specifically including:

[0019] The artificial graphite precursor is surface-oxidized, then condensed with bromoacetyl bromide, and then subjected to tertiary amination with dialkyl alcoholamine to obtain a surface-tertiary amination modified artificial graphite precursor.

[0020] Preferably, the oxidant used for surface oxidation is at least one of hydrogen peroxide, potassium permanganate, sodium hypochlorite, or manganese dioxide; and the dialkyl alcoholamine is at least one of diethanolamine, diisopropanolamine, or N-methylethanolamine.

[0021] Preferably, the mass ratio of the artificial graphite precursor to chloroacetyl chloride and alkyl alcoholamine is 100:1-5:4-10.

[0022] In this invention, after surface oxidation, an oxygen-containing functional group hydroxyl group is formed on the surface of the artificial graphite precursor. This hydroxyl group can condense with bromoacetyl bromide to form a bromoalkyl compound. The bromoalkyl group contained therein can act as an electrophile to undergo a tertiary amination reaction with a dialkyl alcoholamine, thereby obtaining a surface-tertiary amination modified artificial graphite precursor. The positive charge and basicity of this surface-tertiary amination modified artificial graphite precursor are well-suited for adsorbing inorganic fluorine sources with strong negative charge and acidity. This facilitates the entry of fluorine atoms from the inorganic fluorine source into the carbon matrix of the artificial graphite precursor, which in turn promotes the formation of subsequent fluorine-doped graphite structures. At the same time, the surface-tertiary amination modified artificial graphite precursor also has alkyl hydroxyl groups, which have a stronger affinity for inorganic fluorine sources than general tertiary amine groups, thus further facilitating fluorine adsorption and doping. Considering that fluorine doping can improve lithium-ion transport capacity and construct a highly stable SEI film rich in LiF in situ, the stability and coulombic efficiency of the obtained artificial graphite can be further improved.

[0023] The present invention also proposes a fluorine-doped modified artificial graphite prepared by the above preparation method.

[0024] This invention also proposes an application of the above-mentioned fluorine-doped modified artificial graphite as a negative electrode material in lithium-ion batteries.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] The fluorine-doped modified artificial graphite prepared by the solid-phase fluorination method of this invention is significantly superior to undoped modified artificial graphite in terms of initial coulombic efficiency and cycle stability; this indicates that the solid-phase fluorination method is an effective and practical method for modifying artificial graphite and has broad application prospects. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the surface-tertiary amine-modified artificial graphite precursor described in Example 4. Detailed Implementation

[0028] The present invention will now be described in detail through specific embodiments. However, these embodiments are clearly provided for illustrative purposes and are not intended to limit the scope of the present invention.

[0029] Example 1

[0030] This embodiment proposes a method for preparing fluorine-doped modified artificial graphite, which specifically includes the following steps:

[0031] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0032] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 95:5 to obtain a mixture.

[0033] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 700℃ and the time is 8h to obtain granulated material.

[0034] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.3 μm is obtained;

[0035] (5) The above-mentioned artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:3. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 500℃ and the time was 3h to obtain fluorine-doped modified artificial graphite precursor.

[0036] (6) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 3000°C for 24 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0037] Example 2

[0038] This embodiment proposes a method for preparing fluorine-doped modified artificial graphite, which specifically includes the following steps:

[0039] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0040] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 90:10 to obtain a mixture.

[0041] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 650℃ and the time is 9h to obtain granulated material.

[0042] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.8 μm is obtained;

[0043] (5) The above-mentioned artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:2. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 400℃ and the time was 4h to obtain fluorine-doped modified artificial graphite precursor.

[0044] (6) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 3200°C for 18 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0045] Example 3

[0046] This embodiment proposes a method for preparing fluorine-doped modified artificial graphite, which specifically includes the following steps:

[0047] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0048] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 98:2 to obtain a mixture.

[0049] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 750℃ and the time is 6h to obtain granulated material.

[0050] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 16.9 μm is obtained;

[0051] (5) The above-mentioned artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:4. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 600℃ and the time was 2h to obtain fluorine-doped modified artificial graphite precursor.

[0052] (6) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 2800°C for 36 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0053] Example 4

[0054] This embodiment proposes a method for preparing fluorine-doped modified artificial graphite, which specifically includes the following steps:

[0055] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0056] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 95:5 to obtain a mixture.

[0057] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 700℃ and the time is 8h to obtain granulated material.

[0058] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.3 μm is obtained;

[0059] (5) The above-mentioned artificial graphite precursor was added to hydrogen peroxide (20 wt%), stirred and mixed for 1 h, and then added to a reaction vessel for surface oxidation reaction. The surface oxidation reaction temperature was 60 °C and the time was 2 h. After filtration, washing with water, and drying, a surface-oxidized artificial graphite precursor was obtained. The surface-oxidized artificial graphite precursor was added to petroleum ether, and 3 wt% of bromoacetyl bromide (by weight of the artificial graphite precursor) was added. After stirring and reacting for 6 h, 6 wt% of diethanolamine (by weight of the artificial graphite precursor) and 10 wt% of K2CO3 (by weight of the artificial graphite precursor) were added. The mixture was stirred and reacted at 50 °C for 24 h, filtered, washed, and dried to obtain a surface-tertiary amine-modified artificial graphite precursor. Its structural schematic is shown in the figure. Figure 1 As shown, It is a precursor to artificial graphite;

[0060] (6) The above-mentioned surface tertiary amine modified artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:3. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 500℃ and the time was 3h to obtain fluorine-doped modified artificial graphite precursor.

[0061] (7) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 3000°C for 24 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0062] Comparative Example 1

[0063] This comparative example presents a method for preparing artificial graphite, which specifically includes the following steps:

[0064] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0065] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 95:5 to obtain a mixture.

[0066] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 700℃ and the time is 8h to obtain granulated material.

[0067] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.3 μm is obtained;

[0068] (5) The above-mentioned artificial graphite precursor is added to a graphitization furnace for high-temperature graphitization at a temperature of 3000°C for 24 hours. After sieving and demagnetization, the artificial graphite is obtained.

[0069] Comparative Example 2

[0070] This comparative example presents a method for preparing fluorine-doped modified artificial graphite, specifically including the following steps:

[0071] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0072] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 95:5 to obtain a mixture.

[0073] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 700℃ and the time is 8h to obtain granulated material.

[0074] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.3 μm is obtained;

[0075] (5) The above-mentioned artificial graphite precursor was added to hydrogen peroxide (20wt%), stirred and mixed for 1h, and then added to a reaction vessel for surface oxidation reaction. The surface oxidation reaction temperature was 60℃ and the time was 2h. After filtration, washing with water and drying, the surface-oxidized artificial graphite precursor was obtained.

[0076] (6) The above-mentioned surface-oxidized artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:3. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 500℃ and the time was 3h to obtain fluorine-doped modified artificial graphite precursor.

[0077] (7) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 3000°C for 24 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0078] Comparative Example 3

[0079] This comparative example presents a method for preparing fluorine-doped modified artificial graphite, specifically including the following steps:

[0080] (1) After drying the needle coke and coal tar pitch, they were respectively added to a mechanical grinding mill for grinding, thereby obtaining needle coke powder with a D50 particle size of 10.2 μm and coal tar pitch powder with a D50 particle size of 3.8 μm.

[0081] (2) The needle-shaped coke powder and coal tar pitch powder are added to a mixer at a mass ratio of 95:5 to obtain a mixture.

[0082] (3) Add the above mixture into a vertical granulation kettle and granulate it in a high-temperature kettle under nitrogen protection. The granulation temperature is 700℃ and the time is 8h to obtain granulated material.

[0083] (4) After depolymerizing and dispersing the above granulated material, an artificial graphite precursor with a D50 particle size of 17.3 μm is obtained;

[0084] (5) The above-mentioned artificial graphite precursor was added to hydrogen peroxide (20wt%), stirred and mixed for 1h, and then added to a reaction vessel for surface oxidation reaction. The surface oxidation reaction temperature was 60℃ and the time was 2h. After filtration, washing with water and drying, the surface-oxidized artificial graphite precursor was obtained. The surface-oxidized artificial graphite precursor was added to petroleum ether, and 3wt% of bromoacetyl bromide of the artificial graphite precursor was added. After stirring and reacting for 6h, 6wt% of diethylamine of the artificial graphite precursor and 10wt% of acid-binding agent K2CO3 of the artificial graphite precursor were added. The mixture was stirred and reacted at 50℃ for 24h, filtered, washed and dried to obtain the surface-tertiary amine-modified artificial graphite precursor.

[0085] (6) The above-mentioned surface-oxidized artificial graphite precursor and NH4F were added to a quartz boat at a mass ratio of 1:3. The artificial graphite precursor was placed downstream of the gas flow in the tube furnace, and NH4F was placed upstream of the gas flow in the tube furnace. The doping reaction was carried out under the protection of argon atmosphere. The doping reaction temperature was 500℃ and the time was 3h to obtain fluorine-doped modified artificial graphite precursor.

[0086] (7) The above-mentioned fluorine-doped modified artificial graphite precursor was added to a graphitization furnace for high-temperature graphitization at a temperature of 3000°C for 24 hours. After sieving and demagnetization, the fluorine-doped modified artificial graphite was obtained.

[0087] The artificial graphite, conductive carbon black, and binder polyvinylidene fluoride (PVDF) prepared in the above examples or comparative examples were stirred and mixed in a mass ratio of 80:10:10, wherein the PVDF was dissolved in an appropriate amount of N-methylpyrrolidone (NMP). The mixed slurry was uniformly coated on a pre-prepared copper foil, dried in a vacuum drying oven at 110°C for 12 hours, and weighed. It was used as the negative electrode of the simulated battery, the lithium metal sheet as the counter electrode, the separator as Celgard 2400, and the electrolyte as a 1 mol / L LiPF6 solution (EC:DMC volume ratio of 1:1 as solvent). The coin cell CR 2016 was assembled in an argon-filled, deoxygenated, and dehydrated glove box.

[0088] The charge-discharge tests of the button cells were conducted on the battery testing system of Wuhan Landian Electronics Co., Ltd. Constant current charge-discharge was performed at room temperature, with the charge-discharge voltage limited to 0.005-2V. Activation was performed at 0.05C rate, and charge-discharge cycle tests were performed at 0.2C rate. The results are shown in Table 1 below.

[0089] Table 1. Electrical performance results of the artificial graphite described in the embodiments and comparative examples.

[0090]

[0091] In Table 1 above, compared with Comparative Example 1, Example 1 omitted the fluorination modification treatment, and its cycle performance and first-efficiency performance were significantly reduced; compared with Comparative Examples 2 and 3, Example 1 underwent surface oxidation treatment or tertiary amine treatment, but the performance improvement was limited.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing fluorine-doped modified artificial graphite, characterized in that, Includes the following steps: S1. The raw material coke and pitch are mixed, granulated, and shaped to obtain the artificial graphite precursor. S2. After the artificial graphite precursor is doped with an inorganic fluorine source, it is then graphitized, sieved and demagnetized to obtain the fluorine-doped modified artificial graphite.

2. The method for preparing fluorine-doped modified artificial graphite according to claim 1, characterized in that, In step S1, the raw material coke is at least one of needle coke, petroleum coke, pitch coke, or calcined coke; the pitch is at least one of petroleum pitch, natural pitch, or coal pitch. Preferably, the mass ratio of the raw material coke to pitch is 90-98:10-2.

3. The method for preparing fluorine-doped modified artificial graphite according to claim 1 or 2, characterized in that, In step S1, before the raw coke and asphalt are mixed, the raw coke and asphalt are ground separately to obtain raw coke powder with a D50 particle size of 9-11 μm and asphalt powder with a D50 particle size of 3-5 μm.

4. The method for preparing fluorine-doped modified artificial graphite according to any one of claims 1-3, characterized in that, In step S1, the granulation is carried out in a granulation kettle at a temperature of 650-750℃ for 6-9 hours. Preferably, the shaping process includes depolymerizing and dispersing the granulated material, resulting in an artificial graphite precursor with a D50 particle size of 16-18 μm.

5. The method for preparing fluorine-doped modified artificial graphite according to any one of claims 1-4, characterized in that, In step S2, the doping reaction includes: pyrolyzing the inorganic fluorine source and then reacting it with the artificial graphite precursor; Preferably, the inorganic fluorine source is NH4F, and the mass ratio of the artificial graphite precursor to the inorganic fluorine source is 1:1-5. Preferably, the doping reaction temperature is 400-600℃ and the time is 2-4h.

6. The method for preparing fluorine-doped modified artificial graphite according to any one of claims 1-5, characterized in that, In step S2, the graphitization is carried out in a graphitization furnace at a temperature of 2800-3200℃ for a time of 12-72 hours.

7. The method for preparing fluorine-doped modified artificial graphite according to any one of claims 1-6, characterized in that, In step S2, before the artificial graphite precursor is doped with a fluorine source, the surface of the artificial graphite precursor is further modified by tertiary amine formation, specifically including: The artificial graphite precursor is surface-oxidized, then condensed with bromoacetyl bromide, and then subjected to tertiary amination with dialkyl alcoholamine to obtain a surface-tertiary amination modified artificial graphite precursor.

8. The method for preparing fluorine-doped modified artificial graphite according to claim 7, characterized in that, The oxidant used for surface oxidation is at least one of hydrogen peroxide, potassium permanganate, sodium hypochlorite, or manganese dioxide; the dialkyl alcoholamine is at least one of diethanolamine, diisopropanolamine, or N-methylethanolamine. Preferably, the mass ratio of the artificial graphite precursor to chloroacetyl chloride and alkyl alcoholamine is 100:1-5:4-10.

9. A fluorine-doped modified artificial graphite prepared by the preparation method according to any one of claims 1-8.

10. The application of the fluorine-doped modified artificial graphite of claim 9 as a negative electrode material in a lithium-ion battery.

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