CN113912054A - Preparation method of artificial graphite negative electrode material - Google Patents
Preparation method of artificial graphite negative electrode material Download PDFInfo
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- CN113912054A CN113912054A CN202111150406.4A CN202111150406A CN113912054A CN 113912054 A CN113912054 A CN 113912054A CN 202111150406 A CN202111150406 A CN 202111150406A CN 113912054 A CN113912054 A CN 113912054A
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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Abstract
The invention provides a preparation method of an artificial graphite cathode material, which comprises the steps of crushing and purifying coke powder, then shaping, and carrying out D treatment on the shaped coke powder50Controlling the particle size to be 10 +/-2 mu m, graphitizing the shaped coke powder in a multi-stage heating mode to obtain an artificial graphite cathode material intermediate product, mixing the artificial graphite cathode material intermediate product and a coating material uniformly in a ratio of 100:1-100:5, putting the mixture into a carbonization furnace, and keeping the temperature of the carbonization furnace to be not higher than 1100 DEG CCarbonizing, and sieving to obtain D10＝6±1μm、D50＝10±2μm、D90≤30μm、D100Artificial graphite negative electrode material less than or equal to 40 μm; according to the scheme, the coke powder is crushed and then reshaped, and the coating material and the artificial graphite negative electrode material are mixed according to a specific proportion for coating, so that the rate capability of the material is improved.
Description
Technical Field
The invention belongs to the technical field of electrode production, and particularly relates to a preparation method of an artificial graphite negative electrode material.
Background
Currently, newly developed lithium ion battery negative electrode materials such as titanium base, tin base, silicon base, nitride and the like have infinite development potential due to excellent performances. However, in terms of current market development, carbon materials are still mainstream in the development of negative electrode material markets for a long time, and particularly, artificial graphite is widely used due to its excellent characteristics of high capacity, relatively good cycle performance and the like, and is of research interest to various enterprises and scientific research institutions.
The graphite material has a layered structure which determines that lithium ions must be inserted from the end face of the material and then diffused into particles, so that a transmission path is long, irreversible capacity is large, and the slow lithium insertion process hinders the quick charge application of the lithium ion battery; the difference between the lithium intercalation potential of graphite and the lithium metal deposition potential is too small, the dynamic condition is poor, and under the condition of excessively high charging speed, the lithium intercalation potential of graphite is reduced to be below 0V due to larger polarization on the negative electrode side of graphite, so that metal lithium is separated out on the surface of the negative electrode, the loss of a limited lithium source, the increase of the internal resistance of the battery, the attenuation of the capacity and the like are easily caused, the instability of an interface is aggravated, the decline speed of the cycle performance is sharply increased, and the service life of the power battery is seriously influenced; meanwhile, the precipitated lithium metal may grow in the form of dendrites, and thus may pierce the separator, causing a short circuit inside the battery, causing a serious safety problem.
At present, in the production process of a negative electrode material, gaps are formed on the surface of graphite through etching, and the rate performance is improved by increasing diffusion channels of lithium ions, but the surface area of the material is increased through the scheme, so that the first effect and the cycle performance of the material are influenced.
The present invention has been made in view of this situation.
Disclosure of Invention
One of the objectives of the present invention is to provide a method for preparing an artificial graphite negative electrode material, which is to graphitize crushed and shaped coke powder, and then coat and carbonize the product to obtain a surface-modified artificial graphite negative electrode material with good rate capability.
In order to solve the problems in the prior art, the invention provides a preparation method of an artificial graphite negative electrode material, which comprises the following steps:
s1, shaping the crushed and purified coke powder;
s2, graphitizing the shaped coke powder to obtain an intermediate product of the artificial graphite cathode material;
and S3, mixing the intermediate product of the artificial graphite negative electrode material with a coating material, carbonizing, and screening to obtain the artificial graphite negative electrode material.
According to the scheme, the obtained artificial graphite cathode material intermediate product has higher consistency by performing graphitization treatment on the shaped coke powder, the subsequent coating uniformity is improved, a coating layer is generated on the surface of the artificial graphite cathode material intermediate product by performing carbonization treatment on the coating material, and the rate capability is improved by modifying the surface.
Further, in step S1, the crushed coke powder D50＝18±4μm。
Further, in step S1, the crushed coke powder is purified with a hydrofluoric acid solution with a concentration of 5 wt%, the solid-liquid ratio of the purification is 1:4, the crushed coke powder is subjected to solid-liquid separation after full reaction, the filter cake is washed with water until the filter cake is neutral, and then the filter cake is dried until the moisture content is less than 1%.
Further, in step S1, the shaped coke powder D50＝6-12μm。
According to the scheme, the particle size of the crushed coke powder is controlled, so that the uniformity and consistency of the particle size of the coke powder are improved, the particle size difference of the coke powder in each direction is reduced, the particle size distribution of the coke powder subjected to shaping treatment is more controllable, and the rate performance of the material is favorably improved.
Secondly, the particle sizes of the coke powder before and after the shaping treatment are respectively controlled to improve the consistency of the coke powder, so that the phenomenon that the coating is uneven due to low material consistency in the subsequent coating process, for example, the coating layer is thick due to low particle size or the coating effect is poor due to high particle size, and the multiplying power performance of the material is affected by the thick coating layer and the incompletely coated coating layer, is avoided.
Further, in step S2, the graphitization treatment specifically includes: and heating the shaped coke powder to a graphitization temperature in a gradient heating manner.
Further, the gradient temperature rise comprises the following steps,
a first temperature gradient, raising the temperature from room temperature to 1000-1300 ℃;
a second temperature gradient, wherein the temperature is increased from 1300 ℃ of 1000-;
a third temperature gradient: the temperature is raised from 1800 ℃ to 2000 ℃ to 2800 ℃ to 3000 ℃.
The technical scheme divides the graphitization process into three stages, after the coke powder is preheated by the first temperature rise gradient, the structure of amorphous carbon in the coke powder is changed to a graphite crystal structure by the second temperature rise gradient, and the graphitization degree of the coke powder is perfected by the third temperature rise gradient, so that the artificial graphite cathode material intermediate product with higher graphitization degree is finally obtained.
Further, the gradient temperature rise specifically comprises:
a first temperature rise gradient, wherein the temperature is raised from room temperature to 1000-1300 ℃ at the temperature rise rate of 3-6 ℃/min;
a second temperature gradient, raising the temperature to 1800-2000 ℃ at a temperature raising rate of 0.5-2 ℃/min;
the third temperature gradient is raised to 2800-3000 ℃ at a temperature rate of 2-4 ℃/min.
The heating rate in the scheme is the preferable heating rate obtained by technicians on the basis of a large number of experiments, the heating rate of the first temperature gradient is set to be 3-6 ℃/min, so that the preheating can be completed at a higher speed while the generation of cracks caused by the excessively high temperature of the coke powder is avoided, and the production period is shortened; because the second temperature gradient is a key stage of graphitization, the heating rate of the second heating gradient is set to be 0.5-2 ℃/min, so that the coke powder can be fully graphitized, the amorphous carbon can be completely converted into a graphite crystal structure, the graphitization degree is improved, the crystal structure is prevented from being damaged under the action of thermal stress due to too fast heating, and the integrity of the graphitized structure is improved; the temperature rise rate of the third temperature gradient is 2-4 ℃/min, and as the graphitization at the stage is basically finished, even if material defects such as cracks and the like are not generated at a relatively high temperature rise rate, the graphitization degree is improved, the production efficiency is improved, and the production cost is reduced.
Further, in step S3, the ratio of the artificial graphite anode material intermediate product to the coating material is 100:1-100: 5.
Preferably, the ratio of the artificial graphite anode material intermediate product to the coating material is 100: 3.
The mixing proportion is a more preferable mixing proportion obtained by technicians on the basis of a large number of experiments, in the range, the coating material can coat the surface of the intermediate product of the artificial graphite cathode material to form a thin coating layer, the multiplying power performance of the material is improved while the surface of the artificial graphite cathode material is modified, when the coating material is used too much, the coating layer is thick, the thicker coating layer increases the diffusion resistance of electrons and ions, and the increase of the multiplying power performance is not facilitated; when the amount of the coating material is too small, the intermediate product of the artificial graphite cathode material cannot be completely coated by the coating material, and the rate capability of the material is not improved; meanwhile, the surface of the artificial graphite cathode material is modified by coating the binding material and coating the coke powder, so that the tap density of the material is improved, and the energy density of the battery is further improved; meanwhile, the coating binding material can protect the coke powder, so that the graphite layer is prevented from falling off, and the cycle performance of the cathode material is improved.
Further, in the step S3, the carbonization temperature is not higher than 1100 ℃.
Further, in step S3, D of the sieved artificial graphite negative electrode material10＝6±1μm、D50＝10±2μm、D90≤30μm、D100≤40μm。
The particle size range of the artificial graphite negative electrode material is a more preferable particle size range obtained by technicians on the basis of a large number of experiments, and the compacted density of the material is improved and the energy density of the negative electrode material is improved by controlling the particle size distribution of the artificial graphite negative electrode material.
Further, in step S3, after the sieving, a demagnetizing step is further included, and the content of the magnetic substance in the demagnetized artificial graphite negative electrode material is less than 0.1 ppm.
Further, the coke powder comprises coal coke and petroleum coke; the coating material comprises asphalt, phenolic resin and sucrose.
The beneficial effects of the above technical scheme are:
the particle size difference of the crushed coke powder in all directions is reduced by controlling the particle size of the crushed coke powder, so that the particle size distribution of the shaped coke powder is more controllable, the coating uniformity of the coating material is improved, and the rate capability of the material is favorably improved; the shaped coke powder is subjected to a graphitization process through three temperature rise gradients, and the temperature rise speeds of the three temperature rise gradients are limited, so that the high graphitization degree is ensured, cracking of the material caused by too fast or too slow temperature rise is avoided, and the structural integrity of an intermediate product of the artificial graphite cathode material is improved; the intermediate product of the artificial graphite cathode material is coated by using the coating material, so that the surface of the material is modified, and the rate capability of the material is improved; the mixing ratio of the intermediate product of the artificial graphite cathode material to the coating material is 100:1-100:5, so that the problem that the multiplying power performance of the material is influenced by the fact that the coating layer is thick due to the fact that the coating material is less and cannot be completely coated or the coating material is more is avoided.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
Fig. 1 is a process flow chart of the preparation method of the artificial graphite anode material of the invention.
Fig. 2 is an SEM image of the artificial graphite negative electrode material prepared by the method of the first embodiment.
Fig. 3 is an SEM image of an artificial graphite anode material prepared by the method described in comparative example two.
Detailed Description
To make the objects, technical solutions and advantages of the present invention clearer and more fully described below with reference to some examples, it will be understood by those skilled in the art that the following embodiments are only used for explaining the technical principles of the present invention and are not intended to limit the scope of the present invention. For example, although the present application describes the steps of the method of the invention in a particular order, these orders are not limiting, and one skilled in the art can perform the steps in a different order without departing from the underlying principles of the invention.
Example one
As an embodiment of the present invention, this embodiment provides an artificial graphite anode material, the preparation method of which is shown in fig. 1, and the method includes the following steps:
(1) selecting coal coke powder with ash content less than or equal to 9%, water content less than or equal to 20%, volatile matter less than or equal to 2%, fixed carbon more than or equal to 88%, sulfur content less than or equal to 0.7% and granularity less than or equal to 0.5mm as raw material, drying the coal coke powder until water content is less than or equal to 1%, feeding the dried coal coke powder into a Raymond mill for crushing, and collecting D by using a cyclone collector50An acceptable material having a particle size of 18.51 μm was used as the material A.
(2) And (3) purifying the material A by using a 5.0 wt% hydrofluoric acid solution, wherein the solid-to-liquid ratio of the material A to the hydrofluoric acid solution is 1: 4; after 12 hours of full reaction, carrying out solid-liquid separation to obtain an acidic filter cake, centrifuging and rinsing the acidic filter cake to neutrality in a rinsing tank by using deionized water, and drying to obtain a material B.
(3) Feeding the material B into a rolling mill for shaping to obtain D5010.68 μm of Material C.
(4) Feeding the material C into a graphitization furnace, and heating to 1000 ℃ from room temperature at a speed of 3 ℃/min through a first temperature rise gradient; then heating to 1800 ℃ at a heating rate of 0.5 ℃/min through a second heating gradient; and then heating to 2800 ℃ at the heating rate of 2 ℃/min by a third heating gradient, and obtaining an intermediate product D of the artificial graphite cathode material through the three heating gradients.
(5) Adding the intermediate product D of the artificial graphite negative electrode material and the asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 100:3, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 1100 ℃ to complete carbonization treatment of the asphalt, and then screening to obtain an artificial graphite negative electrode material E, wherein an electron microscope photo of the prepared artificial graphite negative electrode material E is shown in fig. 2.
Example two
As another embodiment of the present invention, this embodiment provides an artificial graphite negative electrode material, which is prepared by the same method as that described in the first embodiment, except that in this embodiment, the coating binder material in step (5) is a phenolic resin.
The method specifically comprises the following steps:
(5) adding the intermediate product D of the artificial graphite negative electrode material and phenolic resin into a mixer, uniformly mixing the intermediate product D and the phenolic resin in a ratio of 100:3, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 900 ℃ to finish carbonization treatment of the phenolic resin, and then screening to obtain the artificial graphite negative electrode material E.
EXAMPLE III
As another example of the present invention, this example provides an artificial graphite negative electrode material, which is prepared in the same manner as described in example one except that the temperatures of the graphitization treatment and the carbonization treatment in step (4) and step (5) are different in this example.
The method specifically comprises the following steps:
(4) feeding the material C into a graphitization furnace, and heating to 1300 ℃ from room temperature at the speed of 6 ℃/min through a first temperature rise gradient; then, the temperature is increased to 2000 ℃ at the temperature increasing speed of 2 ℃/min through a second temperature increasing gradient; and then heating to 3000 ℃ at the heating rate of 4 ℃/min by a third heating gradient, and obtaining an intermediate product D of the artificial graphite cathode material through the three heating gradients.
(5) Adding the intermediate product D of the artificial graphite negative electrode material and asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 100:3, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 900 ℃ to finish carbonization treatment of the asphalt, and then screening to obtain the artificial graphite negative electrode material E.
Example four
As another example of the present invention, this example provides an artificial graphite negative electrode material, which is prepared in the same manner as described in the first example, except that the mixing ratio of the coke powder and the coating binder material in step (5) is different in this example.
The method specifically comprises the following steps:
(5) adding the intermediate product D of the artificial graphite negative electrode material and asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 100:5, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 1100 ℃ to complete carbonization treatment of the asphalt, and then screening to obtain the artificial graphite negative electrode material E.
EXAMPLE five
As another example of the present invention, this example provides an artificial graphite negative electrode material, which is prepared in the same manner as described in the first example, except that the mixing ratio of the coke powder and the coating binder material in step (5) is different in this example.
The method specifically comprises the following steps:
(5) adding the intermediate product D of the artificial graphite negative electrode material and asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 100:1, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 1100 ℃ to complete carbonization treatment of the asphalt, and then screening to obtain the artificial graphite negative electrode material E.
Comparative example 1
This comparative example is providedAn artificial graphite negative electrode material was prepared by a method different from that of example one in that there was no step (3) in this comparative example, and coke was directly pulverized to D50＝11.24μm。
The method specifically comprises the following steps:
(1) selecting coal coke powder with ash content less than or equal to 9%, water content less than or equal to 20%, volatile matter less than or equal to 2%, fixed carbon more than or equal to 88%, sulfur content less than or equal to 0.7% and granularity less than or equal to 0.5mm as raw material, drying the coal coke powder until water content is less than or equal to 1%, feeding the dried coal coke powder into a Raymond mill for crushing, and collecting D by using a cyclone collector50A qualified material having a particle size of 11.24 μm was used as Material A.
(2) And (3) purifying the material A by using a 5.0 wt% hydrofluoric acid solution, wherein the solid-to-liquid ratio of the material A to the hydrofluoric acid solution is 1: 4; after 12 hours of full reaction, carrying out solid-liquid separation to obtain an acidic filter cake, centrifuging and rinsing the acidic filter cake to neutrality in a rinsing tank by using deionized water, and drying to obtain a material B.
(3) Feeding the material B into a graphitization furnace, and heating to 1000 ℃ from room temperature at a speed of 3 ℃/min through a first temperature rise gradient; then heating to 1800 ℃ at a heating rate of 0.5 ℃/min through a second heating gradient; and then heating to 2800 ℃ at the heating rate of 2 ℃/min by a third heating gradient, and obtaining an intermediate product C of the artificial graphite cathode material through the three heating gradients.
(4) Adding the intermediate product C of the artificial graphite negative electrode material and the asphalt into a mixer, uniformly mixing the intermediate product C and the asphalt in a ratio of 100:3, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 1100 ℃ to complete carbonization treatment of the asphalt, and then screening to obtain an artificial graphite negative electrode material D, wherein an electron microscope photo of the artificial graphite negative electrode material D is shown in FIG. 3.
Comparative example No. two
This comparative example provides an artificial graphite negative electrode material, the preparation method of which is different from that of example one in that the mixing ratio in step (5) is different in this comparative example.
The method specifically comprises the following steps:
(5) adding the intermediate product D of the artificial graphite negative electrode material and asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 100:8, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 900 ℃ to finish carbonization treatment of the asphalt, and then screening to obtain the artificial graphite negative electrode material E.
Comparative example No. three
This comparative example provides an artificial graphite negative electrode material, the preparation method of which is different from that of example one in that the mixing ratio in step (5) is different in this comparative example.
The method specifically comprises the following steps:
(5) adding the intermediate product D of the artificial graphite negative electrode material and asphalt into a mixer, uniformly mixing the intermediate product D and the asphalt in a ratio of 200:1, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 900 ℃ to finish carbonization treatment of the asphalt, and then screening to obtain the artificial graphite negative electrode material E.
Comparative example No. four
This comparative example provides an artificial graphite negative electrode material, which is prepared by a method different from that of example one in that the respective steps of the preparation method in this comparative example are operated in the same order but in a different order.
The method specifically comprises the following steps:
(1) selecting coal coke powder with ash content less than or equal to 9%, water content less than or equal to 20%, volatile matter less than or equal to 2%, fixed carbon more than or equal to 88%, sulfur content less than or equal to 0.7% and granularity less than or equal to 0.5mm as raw material, drying the coal coke powder until water content is less than or equal to 1%, feeding the dried coal coke powder into a Raymond mill for crushing, and collecting D by using a cyclone collector50A17.23 μm-sized acceptable material was used as material A.
(2) And (3) purifying the material A by using a 5.0 wt% hydrofluoric acid solution, wherein the solid-to-liquid ratio of the material A to the hydrofluoric acid solution is 1: 4; after 12 hours of full reaction, carrying out solid-liquid separation to obtain an acidic filter cake, centrifuging and rinsing the acidic filter cake to neutrality in a rinsing tank by using deionized water, and drying to obtain a material B.
(3) Feeding the material B into a rolling mill for shaping to obtain D508.95 μm of feed C.
(4) Adding the material C and the asphalt into a mixer, uniformly mixing the materials according to the proportion of 100:3, taking out, filling the mixture into a sagger, putting the sagger into a carbonization furnace, gradually heating to 1100 ℃ to complete carbonization treatment of the asphalt, and then screening to obtain a material D.
(5) Feeding the material D into a graphitization furnace, and heating to 1000 ℃ from room temperature at a speed of 3 ℃/min through a first temperature rise gradient; then heating to 1800 ℃ at a heating rate of 0.5 ℃/min through a second heating gradient; and then heating to 2800 ℃ at the heating rate of 2 ℃/min by a third heating gradient, and obtaining the artificial graphite cathode material E through the three heating gradients.
Examples of the experiments
The experimental example aims to compare the performances of the artificial graphite anode materials obtained by different preparation methods, and the comparison results are shown in the following table:
in the test results, it can be seen from the first, second, fourth and fifth examples that the first efficiency of the artificial graphite negative electrode material prepared by the present application is higher than 91%, wherein the first, fourth and fifth examples are coated at different mixing ratios, and since the mixing ratio of the fifth example is only 100:1, the coating layer is thin and the particle size is low as a whole, and the tap density and the specific surface area of the material are improved, which results in a higher energy density when the material is made into a negative electrode plate, and therefore the first discharge capacity is still relatively high under the condition of relatively low first efficiency; the mixing ratio of the fourth embodiment is 100:5, the surface of the material is fully coated, so the particle size is improved, the tap density and the specific surface area are correspondingly reduced, the energy density of the manufactured negative electrode piece is relatively low, but the high mixing ratio enables the surface of the artificial graphite negative electrode material to be fully coated, the thickness of an SEI film formed in the first charge-discharge process is reduced, so the first effect of the material is improved, and the first discharge capacity of the material is slightly reduced but not obvious compared with that of the fourth comparative document.
Secondly, as can be seen from the test result of the first comparative example, because the first comparative example has no shaping step, the distribution of the particle size of the material is obviously widened compared with the first example, the particles with larger particle size are not favorable for the intercalation and deintercalation of lithium ions, especially under the condition of rate charge and discharge, the larger particle size may cause more obvious voltage hysteresis, and the rate performance is obviously reduced; the improvement of the particle size of the large particles also leads to the reduction of the tap density of the material, and although the fine powder can be filled in the gaps among the large particles to improve the energy density of the material, the surface modification effect is reduced because the coating material cannot be uniformly coated on the surface of the artificial graphite anode material which is not subjected to shaping treatment, so that the first effect of the material is reduced.
Finally, the artificial graphite cathode material prepared according to the coating proportion of 100:8 and 200:1 is respectively compared with the comparative example II and the comparative example III, in the comparative example II, the particle size of the artificial graphite cathode material is integrally increased due to more coating materials, the energy density of the material is reduced, even if the coating material fully modifies the surface, the first effect is obviously improved, but the energy density is lower, even if the first effect is very high, the first discharge capacity is still lower compared with the first embodiment; in contrast to the comparative example, the third comparative example has a relatively poor rate capability because the coating material is less and cannot sufficiently coat the surface of the artificial graphite anode material, and although the overall particle size is reduced to increase the energy density of the anode, the first effect is relatively low.
The above embodiments are only preferred embodiments of the present invention, and not intended to limit the present invention in any way, and although the present invention has been disclosed by the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make various changes and modifications to the equivalent embodiments by using the technical contents disclosed above without departing from the technical scope of the present invention, and the embodiments in the above embodiments can be further combined or replaced, but any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention still fall within the technical scope of the present invention.
Claims (10)
1. A preparation method of an artificial graphite cathode material is characterized by comprising the following steps,
s1, shaping the crushed and purified coke powder;
s2, graphitizing the shaped coke powder to obtain an intermediate product of the artificial graphite cathode material;
and S3, mixing the intermediate product of the artificial graphite negative electrode material with a coating material, carbonizing, and screening to obtain the artificial graphite negative electrode material.
2. The method for preparing artificial graphite anode material according to claim 1, wherein in step S1, the crushed coke powder D50＝18±4μm。
3. The method for preparing artificial graphite anode material according to claim 2, wherein in step S1, the shaped coke powder D50＝6-12μm。
4. The method for preparing the artificial graphite anode material according to any one of claims 1 to 3, wherein in step S2, the graphitization treatment is specifically: and heating the shaped coke powder to a graphitization temperature in a gradient heating manner.
5. The method for preparing the artificial graphite anode material according to claim 4, wherein the gradient temperature rise comprises,
a first temperature gradient, raising the temperature from room temperature to 1000-1300 ℃;
a second temperature gradient, wherein the temperature is increased from 1300 ℃ of 1000-;
a third temperature gradient: the temperature is raised from 1800 ℃ to 2000 ℃ to 2800 ℃ to 3000 ℃.
6. The preparation method of the artificial graphite anode material according to claim 5, wherein the gradient temperature rise is specifically as follows:
a first temperature rise gradient, wherein the temperature is raised from room temperature to 1000-1300 ℃ at the temperature rise rate of 3-6 ℃/min;
a second temperature gradient, raising the temperature to 1800-2000 ℃ at a temperature raising rate of 0.5-2 ℃/min;
the third temperature gradient is raised to 2800-3000 ℃ at a temperature rate of 2-4 ℃/min.
7. The method for preparing the artificial graphite anode material according to any one of claims 1 to 3, wherein in step S3, the ratio of the artificial graphite anode material intermediate product to the coating material is 100:1 to 100: 5;
preferably, the ratio of the artificial graphite anode material intermediate product to the coating material is 100: 3.
8. The method for preparing the artificial graphite anode material according to claim 7, wherein the carbonization temperature is not higher than 1100 ℃ in step S3.
9. The method for preparing the artificial graphite anode material according to claim 1, wherein the D of the sieved artificial graphite anode material is obtained in step S350＝10±2μm；D100≤40μm。
10. The method for preparing the artificial graphite anode material according to claim 1, wherein the coke powder comprises coal coke, petroleum coke; the coating material comprises asphalt, phenolic resin and sucrose.
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