CN118108216A - Cathode material for lithium ion battery prepared based on anthracite and preparation method thereof - Google Patents

Abstract

The invention provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the steps of sequentially carrying out reduction and graphitization on the anthracite; the graphitization degree of the negative electrode material for the lithium ion battery is more than or equal to 93 percent. According to the preparation method provided by the invention, the reduction process is arranged before the traditional graphitization treatment, the low-cost anthracite is used as a raw material, the reduction treatment is carried out on the anthracite, and oxygen-containing functional groups on the surface are removed, so that the heteroatom content in the anthracite is reduced, the carbon atom arrangement is more regular, the graphitization degree can be obviously improved at a lower temperature (less than or equal to 2800 ℃) later, the obtained negative electrode material has higher reversible capacity and energy density when being used for preparing lithium ion batteries, the preparation process flow is simplified, the advantages of low cost are realized under the dual-carbon and electricity limiting background, and the preparation method is beneficial to industrialized popularization and application.

Description

Cathode material for lithium ion battery prepared based on anthracite and preparation method thereof

Technical Field

The invention belongs to the technical field of lithium ion batteries, relates to a negative electrode material for a lithium ion battery and a preparation method thereof, and particularly relates to a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof.

Background

At present, the electrode cost of the lithium ion battery is increasingly raised, and the further popularization and application of the lithium battery are limited. Therefore, searching for low-cost and mass-producible electrode materials becomes an important research direction in the current lithium battery industry. Anthracite has the advantages of abundant resources, low price, high carbon content and the like, and becomes an ideal carbon source for large-scale production of lithium battery cathode materials.

However, anthracite has the characteristics of high graphitization temperature (more than 3000 ℃) and low graphitization degree, so that the electrode material formed by directly graphitizing the anthracite at high temperature has low capacity and poor cycle performance. The prior art has improved methods to realize higher capacity and cycle performance, for example, technicians mix anthracite with metal and prepare multi-layer graphite sheets at high temperature as lithium battery cathode materials, and the process is helpful for improving electrochemical performance, but the preparation process is very complex, the yield is low, and the industrial popularization and application are limited.

CN 102110805A discloses a negative electrode material for lithium ion battery prepared from anthracite and a preparation method thereof, firstly, the anthracite with specific quality is crushed and then mixed with sodium chloride and sodium fluoride, then carbonized in a high temperature kiln under the protection of nitrogen, and finally, the cryptocrystalline graphite is prepared through high temperature graphitization. However, the invention has higher quality requirement on anthracite, complex process flow of early screening, low yield and high cost.

Disclosure of Invention

The invention aims to provide a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method improves the graphitization degree of the graphite negative electrode material taking the anthracite as a raw material, simplifies the process flow, reduces the cost and is beneficial to industrialized popularization and application.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

In a first aspect, the present invention provides a method for preparing a negative electrode material for a lithium ion battery based on anthracite coal, the method comprising sequentially performing reduction and graphitization on the anthracite coal.

According to the invention, a reduction process is arranged before the traditional graphitization treatment, low-cost anthracite is used as a raw material, the raw material is subjected to reduction treatment, and oxygen-containing functional groups on the surface are removed, so that the heteroatom content in the anthracite is reduced, the carbon atom arrangement is more regular, the graphitization degree can be obviously improved at a lower temperature (less than or equal to 2800 ℃), the finally obtained negative electrode material is used for preparing a lithium ion battery, has higher reversible capacity and energy density, the graphitization time is shortened, the preparation process flow is simplified, and the preparation method has the advantage of low cost under the dual-carbon and electricity limiting background, and is beneficial to industrialized popularization and application.

Preferably, the reduction is performed in a mixed atmosphere of a reducing gas and a protective gas, and the volume fraction of the reducing gas is 1-15%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, but not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the invention, the volume fraction of the reducing gas is based on the total volume of the mixed gas, and is critical to the reduction effect. When the volume fraction is less than 1%, the reduction effect is poor, and the oxygen-containing functional groups cannot be removed well; when the volume fraction is more than 15%, the original polycyclic aromatic hydrocarbon in the anthracite is reduced and cracked, so that the subsequent graphitization degree is too low.

Preferably, the reducing gas comprises hydrogen and/or methane, preferably hydrogen.

In the invention, hydrogen is used as reducing gas to carry out hydrogenation treatment on anthracite, and in the treatment process, hydrogen can be heterolytic into hydride anions (H ^-) and diatomic hydrogen (H..H.), and the attack of H ^- can lead C-O bond to be broken and dehydroxylation reaction to take place, thereby removing oxygen-containing functional groups.

In addition, from the organic point of view, heteroatoms such as sulfur in anthracite are also removed by hydrogenation, but the hydrogenation reduction in the present invention is not solely for desulfurization, i.e., sulfur atoms are not the main concern of the present invention, but the oxygen-containing functional groups with oxidized edges are completely removed. Although oxygen atoms can be removed by conventional direct high-temperature treatment, the removal is not thorough, and the temperature is generally higher than 3000 ℃, and the energy consumption and the cost are high. The hydrogenation is carried out at a lower temperature, so that the crystal rearrangement under low energy consumption is realized, and the graphitization degree is obviously improved.

Preferably, the protective gas comprises any one or a combination of at least two of helium, argon or nitrogen, typically but not limited to combinations of helium and argon, combinations of argon and nitrogen, combinations of helium and nitrogen, or combinations of helium, argon and nitrogen.

The volume fraction of the reducing gas is preferably 5-10%, and may be, for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, but is not limited to the recited values, and other non-recited values within the range are equally applicable.

The temperature of the reduction is preferably 150 to 400 ℃, and may be 150 ℃,160 ℃,180 ℃, 200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃, 300 ℃, 320 ℃, 340 ℃, 360 ℃, 380 ℃ or 400 ℃, and more preferably 250 to 300 ℃, for example, but the reduction is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.

In the invention, when the temperature of the reduction is lower than 150 ℃, the reduction efficiency is lower, and the oxygen-containing functional groups cannot be completely removed; when the reduction temperature is higher than 400 ℃, the reduction degree is deeper, and the original polycyclic aromatic hydrocarbon can be partially cracked, so that the structure of the subsequent graphitized product is affected.

Preferably, the time of the reduction is 2-6h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, and more preferably 3h, but not limited to the recited values, and other non-recited values within the range are equally applicable.

In the invention, when the reduction time is less than 2 hours, the reduction degree is insufficient, and other functional groups still exist; when the reduction time is higher than 6 hours, the reduction degree is deeper, and partial structures are destroyed, so that the structure of the subsequent graphitized product is influenced.

Preferably, the temperature rise rate of the graphitization is 2-4 ℃/min, and may be, for example, 2 ℃/min, 2.2 ℃/min, 2.4 ℃/min, 2.6 ℃/min, 2.8 ℃/min, 3 ℃/min, 3.2 ℃/min, 3.4 ℃/min, 3.6 ℃/min, 3.8 ℃/min or 4 ℃/min, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the target temperature of graphitization is not less than 2600 ℃, preferably 2600-2800 ℃, for example, 2600 ℃, 2620 ℃, 2640 ℃, 2660 ℃, 2680 ℃, 2700 ℃, 2720 ℃, 2740 ℃, 2760 ℃, 2780 ℃ or 2800 ℃, but the target temperature is not limited to the recited values, and other non-recited values within the recited values are equally applicable. Under the same conditions, the higher the graphitization temperature is, the higher the graphitization degree is, and compared with anthracite which is not subjected to reduction treatment, the reduced anthracite can be graphitized at a lower temperature, and the higher the graphitization degree can be achieved.

Preferably, the graphitization is performed for a period of time equal to or longer than 40min, preferably 40-60min, for example 40min, 42min, 44min, 46min, 48min, 50min, 52min, 54min, 56min, 58min or 60min, but not limited to the recited values, and other non-recited values within the range of values are equally applicable. Under the same conditions, the longer the graphitization time is, the higher the graphitization degree is, and compared with anthracite which is not subjected to reduction treatment, the reduced anthracite can be graphitized in a shorter time, and the higher the graphitization degree can be achieved.

Preferably, the reduction is preceded by pulverizing anthracite coal.

The pulverized anthracite powder preferably has an average particle diameter of 1 to 100. Mu.m, for example, 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100. Mu.m, more preferably 5 to 30 μm, still more preferably 10 to 15. Mu.m, but not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are applicable.

Preferably, the process further comprises drying the anthracite coal between the crushing and the reduction so as to remove moisture and small molecular impurities in the anthracite coal.

The temperature of the drying is preferably 80 to 300 ℃, and may be, for example, 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃,200 ℃, 220 ℃, 240 ℃, 260 ℃, 280 ℃ or 300 ℃, and more preferably 120 to 200 ℃, but is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.

Preferably, the reduction further comprises: the reduced anthracite powder and the non-reduced anthracite powder are mixed.

According to the invention, the reduced anthracite powder is used as the raw material for preparing the negative electrode material through subsequent carbonization and graphitization, so that the graphitization degree and the comprehensive performance of the negative electrode material can be improved to the greatest extent; and the reduced anthracite powder and the non-reduced anthracite powder can be mixed and carbonized and graphitized, the whole graphitization degree and the comprehensive performance are improved by utilizing the partially reduced anthracite, and the cost brought by the earlier reduction of the partially non-reduced anthracite powder after mixing and dilution is met, so that the dual requirements of performance improvement and economic benefit improvement are met.

Preferably, the reduced anthracite powder may be 50% by mass or more, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, and more preferably 80%, but not limited to the recited values, and other non-recited values within the range are equally applicable.

In the invention, the mass fraction of the reduced anthracite powder is based on the total mass of the anthracite.

Preferably, carbonization of anthracite coal is also included between the reduction and graphitization.

The carbonization temperature is preferably 900 to 1100 ℃, and may be, for example, 900 ℃, 920 ℃, 940 ℃, 960 ℃, 980 ℃, 1000 ℃, 1020 ℃, 1040 ℃, 1060 ℃, 1080 ℃, or 1100 ℃, but is not limited to the values listed, and other values not listed in the range are equally applicable.

Preferably, the carbonization time is 6-12h, for example, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h, but not limited to the recited values, and other non-recited values within the range are equally applicable.

As a preferred technical solution of the first aspect of the present invention, the method includes the following steps:

(1) Crushing: pulverizing anthracite to average particle size of 10-15 μm to obtain anthracite powder;

(2) And (3) drying: fully drying the anthracite powder obtained in the step (1) at 120-200 ℃;

(3) And (3) reduction: placing the anthracite powder obtained in the step (2) in a mixed atmosphere of hydrogen and protective gas to perform reduction for 3h at 250-300 ℃; the protective gas comprises any one or a combination of at least two of helium, argon and nitrogen, and the hydrogen accounts for 5-10% of the total volume;

(4) Carbonizing: carbonizing the reduced anthracite powder obtained in the step (3) at 900-1100 ℃ for 6-12 hours;

(5) Graphitizing: heating the anthracite powder obtained in the step (4) to a target temperature of 2600-2800 ℃ at a speed of 2-4 ℃/min, and graphitizing for 40-60min to obtain the negative electrode material for the lithium ion battery.

In a second aspect, the present invention provides a negative electrode material for a lithium ion battery, which is prepared by the method according to the first aspect, and has a graphitization degree of 93% or more, for example, 93%, 94%, 95%, 96%, 97%, 98% or 99%, but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Compared with the prior art, the invention has the following beneficial effects:

According to the invention, a reduction process is arranged before the traditional graphitization treatment, the low-price anthracite is used as a raw material, the raw material is subjected to reduction treatment, and oxygen-containing functional groups on the surface are removed, so that the heteroatom content in the anthracite is reduced, the carbon atom arrangement is more regular, the graphitization degree can be obviously improved at a lower temperature (less than or equal to 2800 ℃), the graphitization degree can be obviously improved later, the graphitization method is used for preparing the lithium ion battery, the reversible capacity and the energy density are higher, the graphitization time is shortened, the preparation process flow is simplified, the advantage of low cost is realized under the double carbon and electricity limiting background, and the graphitization method is beneficial to industrial popularization and application.

Drawings

FIG. 1 is an X-ray diffraction chart of a negative electrode material for a lithium ion battery obtained in example 1;

fig. 2 is an X-ray diffraction pattern of the negative electrode material for lithium ion batteries obtained in comparative example 1.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

The embodiment provides a cathode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) And (3) reduction: placing anthracite powder with the average particle size of 12 mu m in a mixed atmosphere of hydrogen and helium for reduction at 275 ℃ for 3 hours, wherein the volume fraction of the hydrogen is 8%;

(2) Carbonizing: carbonizing the reduced anthracite powder obtained in the step (1) at 1000 ℃ for 9 hours;

(3) Graphitizing: and (3) heating the anthracite powder obtained in the step (2) to a target temperature of 2700 ℃ at a speed of 3 ℃/min, and graphitizing for 50min to obtain the anode material for the lithium ion battery.

Fig. 1 is an X-ray diffraction chart of the negative electrode material for lithium ion batteries obtained in this example.

As can be seen from fig. 1: XRD of the obtained substance has strong diffraction peak belonging to graphitized C (002) crystal face and weaker wide diffraction peak belonging to amorphous substance, and graphitization degree can be calculated by utilizing Mering-Maire formula after peak separation.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 97.5%.

Example 2

The embodiment provides a cathode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) And (3) reduction: taking anthracite powder with the average particle size of 10 mu m, drying at 200 ℃, and placing in a mixed atmosphere of hydrogen and argon for reduction at 250 ℃ for 3 hours, wherein the volume fraction of the hydrogen is 5%;

(2) Carbonizing: mixing the reduced anthracite powder obtained in the step (1) with unreduced anthracite powder, and carbonizing at 1000 ℃ for 9 hours; the mass fraction of the reduced anthracite powder is 80%;

(3) Graphitizing: and (3) heating the anthracite powder obtained in the step (2) to a target temperature of 2700 ℃ at a speed of 3 ℃/min, and graphitizing for 50min to obtain the anode material for the lithium ion battery.

The X-ray diffraction pattern of the anode material for lithium ion batteries obtained in this example is similar to that of example 1, and thus will not be described here.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 96.5%.

Example 3

The embodiment provides a cathode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) Crushing: pulverizing anthracite to an average particle size of 15 μm to obtain anthracite powder;

(2) And (3) drying: fully drying the anthracite powder obtained in the step (1) at 120 ℃;

(3) And (3) reduction: placing the anthracite powder obtained in the step (2) in a mixed atmosphere of methane and nitrogen for reduction at 300 ℃ for 3 hours, wherein the volume fraction of hydrogen is 10%;

(4) Carbonizing: mixing the reduced anthracite powder obtained in the step (3) with the unreduced anthracite powder obtained in the step (2), and carbonizing at 1000 ℃ for 9 hours; the mass fraction of the reduced anthracite powder is 80%;

(5) Graphitizing: and (3) heating the anthracite powder obtained in the step (4) to a target temperature of 2700 ℃ at a speed of 3 ℃/min, and graphitizing for 50min to obtain the anode material for the lithium ion battery.

The X-ray diffraction pattern of the anode material for lithium ion batteries obtained in this example is similar to that of example 1, and thus will not be described here.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 96.0%.

Example 4

The embodiment provides a cathode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) Crushing: pulverizing anthracite to an average particle size of 5 μm to obtain anthracite powder;

(2) And (3) drying: fully drying the anthracite powder obtained in the step (1) at 300 ℃;

(3) And (3) reduction: placing the anthracite powder obtained in the step (2) in a mixed atmosphere of hydrogen and helium for reduction at 150 ℃ for 6 hours, wherein the volume fraction of the hydrogen is 1%;

(4) Carbonizing: mixing the reduced anthracite powder obtained in the step (3) with the unreduced anthracite powder obtained in the step (2), and carbonizing at 900 ℃ for 12 hours; the mass fraction of the reduced anthracite powder is 60%;

(5) Graphitizing: and (3) heating the anthracite powder obtained in the step (4) to a target temperature of 2800 ℃ at a speed of 4 ℃/min, and graphitizing for 40min to obtain the anode material for the lithium ion battery.

The X-ray diffraction pattern of the anode material for lithium ion batteries obtained in this example is similar to that of example 1, and thus will not be described here.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 95.7%.

Example 5

The embodiment provides a cathode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) Crushing: pulverizing anthracite to an average particle size of 30 μm to obtain anthracite powder;

(2) And (3) drying: fully drying the anthracite powder obtained in the step (1) at 80 ℃;

(3) And (3) reduction: placing the anthracite powder obtained in the step (2) in a mixed atmosphere of hydrogen and argon to carry out reduction at 400 ℃ for 2 hours, wherein the volume fraction of the hydrogen is 15%;

(4) Carbonizing: mixing the reduced anthracite powder obtained in the step (3) with the unreduced anthracite powder obtained in the step (2), and carbonizing at 1100 ℃ for 6 hours; the mass fraction of the reduced anthracite powder is 50%;

(5) Graphitizing: and (3) heating the anthracite powder obtained in the step (4) to a target temperature of 2600 ℃ at a speed of 2 ℃/min, and graphitizing for 60min to obtain the anode material for the lithium ion battery.

The X-ray diffraction pattern of the anode material for lithium ion batteries obtained in this example is similar to that of example 1, and thus will not be described here.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 95.3%.

Example 6

The present embodiment provides a negative electrode material for lithium ion battery prepared based on anthracite and a preparation method thereof, and the preparation method is the same as that of embodiment 2 except that the reduction temperature in step (1) is changed to 100 ℃, so that the details are not repeated here.

The X-ray diffraction front of the anode material for lithium ion battery obtained in this example shows that: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 94.8%.

Example 7

The present embodiment provides a negative electrode material for lithium ion battery prepared based on anthracite and a preparation method thereof, and the preparation method is the same as that of embodiment 2 except that the reduction temperature in step (1) is changed to 450 ℃, so that the details are not repeated here.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 93.7%.

Example 8

The embodiment provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is the same as the embodiment 2 except that the reduction time in the step (1) is changed to 1h, and the rest steps and conditions are the same as those in the embodiment 2, so that the description thereof is omitted.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 94.5%.

Example 9

The embodiment provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is the same as the embodiment 2 except that the reduction time in the step (1) is changed to 7h, and the rest steps and conditions are the same as those in the embodiment 2, so that the description thereof is omitted.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 93.8%.

Example 10

The embodiment provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is the same as the embodiment 2 except that the volume fraction of hydrogen in the step (1) is changed to 0.8%, and the rest steps and conditions are the same, so that no description is repeated here.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the peak fraction of the ascribed amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 93.6%.

Example 11

The embodiment provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is the same as embodiment 2 except that the volume fraction of hydrogen in the step (1) is changed to 18%, and the rest steps and conditions are the same, so that no description is repeated here.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 93.1%.

Example 12

The embodiment provides a negative electrode material for a lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is not carbonized, namely, the step (2) is changed into: mixing the reduced anthracite powder obtained in the step (1) with unreduced anthracite powder, wherein the mass fraction of the reduced anthracite powder is 80%; the other steps and conditions are the same as those of embodiment 2, and thus are not described in detail herein.

The negative electrode material for lithium ion batteries obtained in this example showed an X-ray diffraction spectrum peak: there is a significant increase in the proportion of peaks ascribed to the amorphous state.

Through calculation, the graphitization degree of the negative electrode material for the lithium ion battery obtained in the embodiment is 96.1%.

Comparative example 1

The comparative example provides a negative electrode material for lithium ion battery prepared based on anthracite and a preparation method thereof, wherein the preparation method is not described in detail herein except for removing the reduction in the step (1), namely directly carbonizing the anthracite powder obtained by drying, and raising the graphitization temperature to 3100 ℃, and the other steps and conditions are the same as those in the example 2.

Fig. 2 is an X-ray diffraction chart of the negative electrode material for lithium ion batteries obtained in this comparative example.

As can be seen from fig. 2: the peak ratio ascribed to the amorphous state is obviously increased, and the graphitization degree of the anode material for the lithium ion battery obtained by the comparative example is 87.5 percent through calculation.

Therefore, the reduction process is arranged before the traditional graphitization treatment, the low-cost anthracite is used as a raw material, the reduction treatment is carried out, and oxygen-containing functional groups on the surface are removed, so that the heteroatom content in the anthracite is reduced, the carbon atom arrangement is more regular, and the graphitization degree can be obviously improved at a lower temperature (less than or equal to 2800 ℃).

The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims (10)

1. The method for preparing the anode material for the lithium ion battery based on the anthracite is characterized by comprising the steps of sequentially carrying out reduction and graphitization on the anthracite.

2. The method according to claim 1, wherein the reduction is performed in a mixed atmosphere of a reducing gas and a protective gas, and the reducing gas accounts for 1-15% by volume.

3. The method according to claim 2, characterized in that the reducing gas comprises hydrogen and/or methane, preferably hydrogen;

Preferably, the protective gas comprises any one or a combination of at least two of helium, argon or nitrogen;

preferably, the volume fraction of the reducing gas is 5-10%.

4. A method according to any one of claims 1-3, wherein the temperature of the reduction is 150-400 ℃, preferably 250-300 ℃;

preferably, the time of the reduction is 2 to 6 hours, more preferably 3 hours.

5. The method of any one of claims 1-4, wherein the graphitization has a rate of elevation of 2-4 ℃/min;

Preferably, the target temperature of graphitization is 2600-2800 ℃;

Preferably, the graphitization has a holding time of 40-60min.

6. The method of any one of claims 1-5, further comprising pulverizing anthracite coal prior to the reducing;

preferably, the pulverized anthracite powder has an average particle diameter of 1 to 100. Mu.m, preferably 5 to 30. Mu.m, more preferably 10 to 15. Mu.m;

preferably, the process further comprises drying the anthracite coal between the crushing and the reduction;

Preferably, the temperature of the drying is 80-300 ℃, and more preferably 120-200 ℃.

7. The method of any one of claims 1-6, wherein the reducing further comprises, after the reducing: the reduced anthracite powder and the non-reduced anthracite powder are mixed.

8. The method of any one of claims 1-7, further comprising carbonizing anthracite coal between the reducing and graphitizing;

Preferably, the carbonization temperature is 900-1100 ℃;

preferably, the carbonization time is 6-12 hours.

9. The method according to any one of claims 1-8, characterized in that the method comprises the steps of:

(1) Crushing: pulverizing anthracite to average particle size of 10-15 μm to obtain anthracite powder;

(2) And (3) drying: fully drying the anthracite powder obtained in the step (1) at 120-200 ℃;

(3) And (3) reduction: placing the anthracite powder obtained in the step (2) in a mixed atmosphere of hydrogen and protective gas to perform reduction for 3h at 250-300 ℃; the protective gas comprises any one or a combination of at least two of helium, argon and nitrogen, and the hydrogen accounts for 5-10% of the total volume;

(4) Carbonizing: carbonizing the reduced anthracite powder obtained in the step (3) at 900-1100 ℃ for 6-12 hours;

(5) Graphitizing: heating the anthracite powder obtained in the step (4) to a target temperature of 2600-2800 ℃ at a speed of 2-4 ℃/min, and graphitizing for 40-60min to obtain the negative electrode material for the lithium ion battery.

10. The negative electrode material for a lithium ion battery prepared by the method according to any one of claims 1 to 9, wherein the graphitization degree of the negative electrode material for the lithium ion battery is more than or equal to 93%.