CN111825088B - Preparation method of artificial graphite material special for lithium ion battery cathode - Google Patents
Preparation method of artificial graphite material special for lithium ion battery cathode Download PDFInfo
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- CN111825088B CN111825088B CN202010646862.7A CN202010646862A CN111825088B CN 111825088 B CN111825088 B CN 111825088B CN 202010646862 A CN202010646862 A CN 202010646862A CN 111825088 B CN111825088 B CN 111825088B
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- C01B32/00—Carbon; Compounds thereof
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- H—ELECTRICITY
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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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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- 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
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a preparation method of an artificial graphite material special for a lithium ion battery cathode, which is characterized in that raw material asphalt is subjected to thermal polymerization to prepare polymerized asphalt; mixing and separating the polymerized asphalt and the solvent I to obtain light-phase oil and heavy-phase oil; the heavy phase oil is matched with the solvent I and subjected to thermal separation treatment to obtain a soluble component and an insoluble component; mixing and filter-pressing insoluble components and a solvent II to obtain a filter cake and a filtrate, mixing the filtrate and soluble components, and distilling to recover the solvent I and the solvent II to obtain the rectified asphalt; the rectified asphalt is subjected to directional coking reaction to obtain wide-area intermediate-phase green coke, and the crushed green coke particles are subjected to calcination and high-temperature graphitization treatment to obtain the artificial graphite material special for the lithium ion battery cathode. The invention not only breaks through the technical difficulty that the high capacity and the high rate performance of the lithium ion battery cathode material cannot be obtained simultaneously, but also solves the problems of complex production process and high price of the traditional lithium ion battery cathode.
Description
Technical Field
The invention relates to the technical field of efficient utilization of coal tar pitch, in particular to a preparation method of an artificial graphite material special for a lithium ion battery cathode.
Background
The lithium ion battery has the advantages of high voltage, high specific energy, wide working temperature range, long charging and discharging service life, low self-discharging rate, no memory effect, small environmental pollution and the like, and simultaneously, the lithium ion battery quickly becomes a mainstream power supply of small energy storage devices such as mobile phones, notebook computers and the like by virtue of the advantages of high specific capacity, small volume, light weight, safety, stability, quick charging and discharging, no pollution and the like. In addition, since the new century, with the concept of low-carbon economy and life being deeply concentrated, electric vehicles have received a good chance for further development, and the investment in research and development work for electric vehicle-related products in the united states, japan, and China has been multiplied, and high-performance lithium ion batteries have gained importance in the development and research plans of three-country-related departments. In addition, the power lithium ion battery is the first choice of the matched energy storage battery in environment-friendly energy sources such as wind power generation, solar power generation and the like, and the lithium ion battery has huge development prospect and market value in the near term and a long period of time in the future.
The lithium ion battery mainly comprises a positive electrode, a negative electrode, electrolyte, a diaphragm and the like, wherein the selection of a negative electrode material is directly related to the energy density of the battery, and the negative electrode material mainly influences the first efficiency, the cycle performance and the like of the lithium battery and accounts for about 5-15% of the total cost of the lithium battery. The negative electrode material includes both graphitized carbon and non-graphitized carbon. Graphitized carbon has become a major commercial negative electrode material due to its low potential plateau, high capacity, high first coulombic efficiency, good cycle performance, and low cost. The graphite is divided into artificial graphite and natural graphite, and the natural graphite has the advantages of large reserves, low cost, safety, no toxicity and the like. However, the natural graphite has the defects of uneven reactivity of the outer surface of particles, larger grain size, easy damage to the surface crystal structure in the charge-discharge process, uneven SEI film covering on the surface, low initial coulombic efficiency, poor rate capability and the like.
Driven by power batteries, the demand of negative electrode materials in 2016 of China is the fastest growing artificial graphite, because natural graphite is mainly applied to digital products and notebook computers, and artificial graphite is mainly used in the field of power. In addition, the power battery has high requirements on stability under high-rate discharge. Therefore, with the increase of the future demand of the power battery, the lithium battery negative electrode material will also show a high-end trend in the future, i.e. the lithium ion battery negative electrode material will develop towards the directions of high energy density, high rate capability, high cycle performance and the like, and the traditional natural graphite or artificial graphite cannot meet the requirements, so that higher requirements are provided for the preparation and modification of various negative electrode materials.
Disclosure of Invention
The invention provides a preparation method of an artificial graphite material special for a lithium ion battery cathode, which is used for preparing a novel artificial graphite cathode material with high capacity and high multiplying power, not only breaks through the technical difficulty that the high capacity and the high multiplying power of the lithium ion battery cathode material cannot be obtained simultaneously, but also solves the problems of complex production process and high price of the traditional lithium ion battery cathode.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of an artificial graphite material special for a lithium ion battery cathode comprises the following steps:
firstly, according to the reactivity of a high-reactivity component contained in raw material asphalt, controlling thermal reaction conditions to enable the raw material asphalt to undergo thermal polymerization reaction in an inert atmosphere to form a microcrystal unit, so as to prepare polymerized asphalt; the temperature of the thermal polymerization reaction is 350-400 ℃, the constant temperature time is 0.5-8 h, and the heating rate is 0.5-5 ℃/min;
step two, mixing the polymerized asphalt obtained in the step one with a solvent I according to a set solvent-oil ratio, fully stirring, standing, settling and separating, and separating according to a set proportion to obtain light-phase oil and heavy-phase oil, wherein the light-phase oil is used as a byproduct of asphalt oil to be treated; the agent-oil ratio of the polymerized asphalt to the solvent I is (0.5-5): 1; the separation according to the set proportion refers to that the oil is light phase oil according to the mass ratio: heavy phase oil (5-9.5): (5-0.5) separating;
step three, returning the heavy phase oil obtained in the step two to the first solvent with a certain proportion, and performing thermal separation treatment to obtain a soluble component and an insoluble component; the first solvent is prepared from the following heavy phase oil in a blending ratio by mass: 1, the I solvent: (0.2-10); mixing the insoluble component with a solvent II according to a set solvent-oil ratio, and performing filter pressing treatment to obtain a filter cake and a filtrate, wherein the filter cake is insoluble solid particles containing inorganic impurities; mixing the filtrate with soluble components, and distilling to recover the first solvent and the second solvent to obtain the rectified asphalt; the solvent-oil ratio of the insoluble component to the solvent II is 1: (0.5 to 10); the distillation comprises atmospheric distillation and reduced pressure distillation, wherein the conditions of the atmospheric distillation are as follows: the gas phase temperature is 280-350 ℃, and the final temperature retention time is 0.5-2 h; the conditions of reduced pressure distillation were: the gas phase temperature is 200-300 ℃, the vacuum degree is 0.01-0.09 MPa, and the final temperature retention time is 0.5-2 h;
step four, under the set heat treatment condition, carrying out directional coking reaction on the rectified asphalt obtained in the step three to obtain wide area body intermediate phase green coke with uniform microstructure; the conditions of the directional coking reaction are as follows: the pressure is 0.1-0.5 MPa, the heating rate is 1-10 ℃/h, the final reaction temperature is 450-520 ℃, and the final temperature constant-temperature time is 1-10 h; crushing the intermediate-phase green coke to prepare green coke particles with the granularity meeting the requirement; calcining the raw coke particles to obtain calcined coke particles, and then carrying out high-temperature graphitization treatment on the calcined coke particles to obtain the special artificial graphite material for the lithium ion battery cathode.
In the first step, the raw material asphalt is coal asphalt obtained by high-temperature dry distillation of coal, the softening point is 20-150 ℃, and the mass content of quinoline insoluble substances is 1-20%.
In the first step, the inert atmosphere is a high-purity nitrogen atmosphere or a high-purity argon atmosphere.
In the first step, the high-reactivity components are heavy components, inorganic impurities and other solid particles which are insoluble in quinoline in the raw material asphalt.
In the first step, the density of the polymerized asphalt is 1.1-1.6 g/cm3The size of the microcrystal unit is controlled to be 2-15 μm.
In the second step, the first solvent is any one or a mixture of more than two of fractions at 200-350 ℃ in the separation process of coal tar, coal directly liquefied light oil, wash oil, first anthracene oil, second anthracene oil, coking heavy oil, coking light oil, naphthalene oil, kerosene, petroleum ether, gasoline, diesel oil, lubricating oil and paraffin oil.
In the second step, the mixing temperature of the polymerized asphalt and the solvent I is 100-200 ℃.
In the second step, the length-diameter ratio of the standing settling separation device for standing settling separation is (1-20): 1, the settling temperature is 80-200 ℃, and the settling time is 0.5-5 h.
In the second step, the density of the light phase oil is 0.85-1.1 g/cm3The density of the heavy phase oil is 1.0-1.35 g/cm3。
In the third step, the thermal separation treatment adopts a centrifugal separation device, and the treatment conditions are as follows: the separation temperature is 60-150 ℃, the separation time is 0.5-3 h, the centrifugal rotation speed is 800-2000 rad/min, and the solid phase density of the separated material is 0.9-1.3 g/cm3The mesh number of the screen in the centrifugal separation device is 300-1200 meshes.
In the third step, the solvent II is any one or a mixture of more than two of toluene, xylene, pyridine, heptane, pentane and tetrahydrofuran.
In the third step, the filter pressing treatment conditions are as follows: the filter pressing temperature is 80-150 ℃, the filter pressing time is 0.5-3 h, and the mesh number of a screen in the filter pressing device is 300-1200 meshes.
In the third step, the mass content of quinoline insoluble substances in the filtrate is less than 0.1%.
In the third step, the rectified asphalt is macromolecular polycyclic aromatic hydrocarbon with the molecular weight distributed in the range of 200-1200 and concentrated distributed in the range of 400-600, the softening point is 30-80 ℃, the mass content of quinoline insoluble substances is 0-0.2%, and the atomic ratio of H to C is (0.45-0.55): 1.
in the fourth step, the mesophase green coke of the wide area body is observed under a polarizing microscope, and the anisotropic component structure is as follows: the length is more than 30 mu m, the width is more than 30 mu m, the content of the mesophase is 80-100 percent, and the true density is more than 1.4g/cm3Ash content is less than 0.1%, sulfur content is less than 0.4%, nitrogen content is less than 0.5%, and volatile component is less than 5%.
In the fourth step, the particle size D of the green coke particles obtained after the crushing treatment5015 to 35 μm.
In the fourth step, the conditions of the calcination treatment are as follows: under the protection of nitrogen, the heating rate is 1-10 ℃/min, the calcination final temperature is 1000-1500 ℃, and the final temperature constant-temperature time is 1-10 h.
In the fourth step, the true density of the calcined coke particles is more than or equal to 2.13g/cm3The tap density is more than or equal to 0.9g/cm3Sulfur content less than 0.4%, nitrogen content less than 0.5%, ash content less than 0.1%, and particle size D 5010 to 30 μm.
In the fourth step, the conditions of the high-temperature graphitization treatment are as follows: under the protection of argon, the heating rate is 1-10 ℃/min, the graphitization final temperature is 2500-3000 ℃, and the final temperature constant temperature time is 1-10 h.
In the fourth step, the indexes of the artificial graphite material special for the lithium ion battery cathode are as follows: particle size distribution D10：6～12μm、D50：16～24μm、D90: 28-35 mu m and the true density is more than or equal to 2.24g/cm3The tap density is more than or equal to 0.9g/cm3The powder compacted density is more than or equal to 1.55g/cm3Ash content is less than or equal to 0.01 percent, and specific surface area is less than or equal to 1.5m2The graphitization degree is more than or equal to 90 percent, the primary coulombic efficiency is more than or equal to 94 percent, the primary discharge specific capacity is more than or equal to 358 mA.h/g, and the multiplying power performance (2C/0.2C) is more than or equal to 80 percent.
In the fourth step, the graphite material sheet orientation degree OI value of the artificial graphite material special for the lithium ion battery cathode is I002And I110And OI value < 50.
Compared with the prior art, the invention has the beneficial effects that:
1) the method is used for preparing a novel artificial graphite cathode material with high capacity and high rate, and breaks through the technical difficulty that the high capacity and high rate performance of the lithium ion battery cathode material cannot be obtained simultaneously;
2) coal tar pitch is used as a raw material, the coal tar pitch has high processing degree, multiple varieties and high added value of products, the product structure is optimized, the industrial chain is extended, and the production cost is reduced;
3) the problems of complex process and high price caused by surface modification treatment such as shaping, coating, granulation and the like in the traditional preparation process of the lithium ion battery cathode material are solved, and a foundation is laid for breaking the dependence on imported products of the cathode material.
Drawings
FIG. 1 is a flow chart of a preparation method of the artificial graphite material special for the lithium ion battery cathode.
FIG. 2 is a structure diagram of a polarized light microscope of mesophase green coke obtained in example 1 of the present invention.
FIG. 3 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 1 of the present invention.
FIG. 4 is a structure diagram of a polarized light microscope of mesophase green coke obtained in example 2 of the present invention.
Fig. 5 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 2 of the present invention.
FIG. 6 is a structure diagram of a polarized light microscope of mesophase green coke obtained in example 3 of the present invention.
FIG. 7 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 3 of the present invention.
FIG. 8 is a structure diagram of a polarization microscope showing mesophase coke produced in example 4 of the present invention.
FIG. 9 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 4 of the present invention.
FIG. 10 is a structure diagram of a polarized light microscope of mesophase green coke obtained in example 5 of the present invention.
FIG. 11 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 5 of the present invention.
FIG. 12 is a structure diagram of a polarization microscope showing mesophase green coke obtained in example 6 of the present invention.
Fig. 13 is a scanning electron microscope image of the artificial graphite material specially used for the negative electrode of the lithium ion battery prepared in example 6 of the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings:
as shown in fig. 1, the preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery, provided by the invention, comprises the following steps:
firstly, according to the reactivity of a high-reactivity component contained in raw material asphalt, controlling thermal reaction conditions to enable the raw material asphalt to undergo thermal polymerization reaction in an inert atmosphere to form a microcrystal unit, so as to prepare polymerized asphalt; the temperature of the thermal polymerization reaction is 350-400 ℃, the constant temperature time is 0.5-8 h, and the heating rate is 0.5-5 ℃/min;
step two, mixing the polymerized asphalt obtained in the step one with a solvent I according to a set solvent-oil ratio, fully stirring, standing, settling and separating, and separating according to a set proportion to obtain light-phase oil and heavy-phase oil, wherein the light-phase oil is used as a byproduct of asphalt oil to be treated; the agent-oil ratio of the polymerized asphalt to the solvent I is (0.5-5): 1; the separation according to the set proportion refers to that the oil is light phase oil according to the mass ratio: heavy phase oil (5-9.5): (5-0.5) separating;
step three, returning the heavy phase oil obtained in the step two to the first solvent with a certain proportion, and performing thermal separation treatment to obtain a soluble component and an insoluble component; the first solvent is prepared from the following heavy phase oil in a blending ratio by mass: 1, the I solvent: (0.2-10); mixing the insoluble component with a solvent II according to a set solvent-oil ratio, and performing filter pressing treatment to obtain a filter cake and a filtrate, wherein the filter cake is insoluble solid particles containing inorganic impurities; mixing the filtrate with soluble components, and distilling to recover the first solvent and the second solvent to obtain the rectified asphalt; the solvent-oil ratio of the insoluble component to the solvent II is 1: (0.5 to 10); the distillation comprises atmospheric distillation and reduced pressure distillation, wherein the conditions of the atmospheric distillation are as follows: the gas phase temperature is 280-350 ℃, and the final temperature retention time is 0.5-2 h; the conditions of reduced pressure distillation were: the gas phase temperature is 200-300 ℃, the vacuum degree is 0.01-0.09 MPa, and the final temperature retention time is 0.5-2 h;
step four, under the set heat treatment condition, carrying out directional coking reaction on the rectified asphalt obtained in the step three to obtain wide area body intermediate phase green coke with uniform microstructure; the conditions of the directional coking reaction are as follows: the pressure is 0.1-0.5 MPa, the heating rate is 1-10 ℃/h, the final reaction temperature is 450-520 ℃, and the final temperature constant-temperature time is 1-10 h; crushing the intermediate-phase green coke to prepare green coke particles with the granularity meeting the requirement; calcining the raw coke particles to obtain calcined coke particles, and then carrying out high-temperature graphitization treatment on the calcined coke particles to obtain the special artificial graphite material for the lithium ion battery cathode.
In the first step, the raw material asphalt is coal asphalt obtained by high-temperature dry distillation of coal, the softening point is 20-150 ℃, and the mass content of quinoline insoluble substances is 1-20%.
In the first step, the inert atmosphere is a high-purity nitrogen atmosphere or a high-purity argon atmosphere.
In the first step, the high-reactivity components are heavy components, inorganic impurities and other solid particles which are insoluble in quinoline in the raw material asphalt.
In the first step, the density of the polymerized asphalt is 1.1-1.6 g/cm3The size of the microcrystal unit is controlled to be 2-15 μm.
In the second step, the first solvent is any one or a mixture of more than two of fractions at 200-350 ℃ in the separation process of coal tar, coal directly liquefied light oil, wash oil, first anthracene oil, second anthracene oil, coking heavy oil, coking light oil, naphthalene oil, kerosene, petroleum ether, gasoline, diesel oil, lubricating oil and paraffin oil.
In the second step, the mixing temperature of the polymerized asphalt and the solvent I is 100-200 ℃.
In the second step, the length-diameter ratio of the standing settling separation device for standing settling separation is (1-20): 1, the settling temperature is 80-200 ℃, and the settling time is 0.5-5 h.
In the second step, the density of the light phase oil is 0.85-1.1 g/cm3The density of the heavy phase oil is 1.0-1.35 g/cm3。
In the third step, the thermal separation treatment adopts a centrifugal separation device, and the treatment conditions are as follows: the separation temperature is 60-150 ℃, the separation time is 0.5-3 h, the centrifugal rotation speed is 800-2000 rad/min, and the solid phase density of the separated material is 0.9-1.3 g/cm3The mesh number of the screen in the centrifugal separation device is 300-1200 meshes.
In the third step, the solvent II is any one or a mixture of more than two of toluene, xylene, pyridine, heptane, pentane and tetrahydrofuran.
In the third step, the filter pressing treatment conditions are as follows: the filter pressing temperature is 80-150 ℃, the filter pressing time is 0.5-3 h, and the mesh number of a screen in the filter pressing device is 300-1200 meshes.
In the third step, the mass content of quinoline insoluble substances in the filtrate is less than 0.1%.
In the third step, the rectified asphalt is macromolecular polycyclic aromatic hydrocarbon with the molecular weight distributed in the range of 200-1200 and concentrated distributed in the range of 400-600, the softening point is 30-80 ℃, the mass content of quinoline insoluble substances is 0-0.2%, and the atomic ratio of H to C is (0.45-0.55): 1.
in the fourth step, the mesophase green coke of the wide area body is observed under a polarizing microscope, and the anisotropic component structure is as follows: the length is more than 30 mu m, the width is more than 30 mu m, the content of the mesophase is 80-100 percent, and the true density is more than 1.4g/cm3Ash content is less than 0.1%, sulfur content is less than 0.4%, nitrogen content is less than 0.5%, and volatile component is less than 5%.
In the fourth step, the particle size D of the green coke particles obtained after the crushing treatment5015 to 35 μm.
In the fourth step, the conditions of the calcination treatment are as follows: under the protection of nitrogen, the heating rate is 1-10 ℃/min, the calcination final temperature is 1000-1500 ℃, and the final temperature constant-temperature time is 1-10 h.
In the fourth step, the true density of the calcined coke particles is more than or equal to 2.13g/cm3The tap density is more than or equal to 0.9g/cm3Sulfur content less than 0.4%, nitrogen content less than 0.5%, ash content less than 0.1%, and particle size D 5010 to 30 μm.
In the fourth step, the conditions of the high-temperature graphitization treatment are as follows: under the protection of argon, the heating rate is 1-10 ℃/min, the graphitization final temperature is 2500-3000 ℃, and the final temperature constant temperature time is 1-10 h.
In the fourth step, the indexes of the artificial graphite material special for the lithium ion battery cathode are as follows: particle size distribution D10：6～12μm、D50：16～24μm、D90: 28-35 mu m and the true density is more than or equal to 2.24g/cm3The tap density is more than or equal to 0.9g/cm3The powder compacted density is more than or equal to 1.55g/cm3Ash content is less than or equal to 0.01 percent, and specific surface area is less than or equal to 1.5m2The graphitization degree is more than or equal to 90 percent, the primary coulombic efficiency is more than or equal to 94 percent, the primary discharge specific capacity is more than or equal to 358 mA.h/g, and the multiplying power performance (2C/0.2C) is more than or equal to 80 percent.
In the fourth step, the graphite material sheet orientation degree OI value of the artificial graphite material special for the lithium ion battery cathode is I002And I110And OI value < 50.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.
[ example 1 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 30 ℃, the mass content of quinoline insoluble substances is 1.83%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is increased from normal temperature to 400 ℃ at the heating rate of 3 ℃/min, and the mixture stays for 4 hours at the constant temperature to form a microcrystal unit, so that the polymeric asphalt is prepared.
Mixing polymerized asphalt with wash oil according to the mass ratio of 3: 1, fully stirring at the temperature of 120 ℃, and pouring the mixture with the length-diameter ratio of 8: 1, settling and separating in a standing and settling device, wherein the settling temperature is 130 ℃, the settling time is 3h, and then the mass ratio of the components is 8: 2 separating light phase oil and heavy phase oil, and determining the density of the light phase oil to be 1.0g/cm3The density of heavy phase oil is 1.3g/cm3. According to the weight phase oil: the mass ratio of the washing oil is 1: 3 mixing, heating to 70 ℃, fully stirring for 2h, centrifuging at the rotating speed of 800rad/min, and separating the solid phase with the density of 0.9g/cm3And centrifuging under the condition that the mesh number of the screen is 400 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components and toluene according to a mass ratio of 1: 3, mixing, heating to 80 ℃, fully stirring for 1.5h, and performing pressure filtration under the conditions that the vacuum degree is 0.08MPa and the mesh number of a screen is 400 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.02%. Mixing the filtrate with the above soluble components, pouring into a distillation kettle, keeping the gas phase at final temperature of 320 deg.C for 1.5 h; the performance indexes of the rectified asphalt obtained after the toluene and the wash oil are recovered by atmospheric distillation are shown in table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 480 ℃ at the heating rate of 3 ℃/h under the pressure of 0.2MPa, keeping the temperature for 4h to obtain intermediate-phase green coke, wherein the performance indexes are shown in table 2, and the polarizing microstructure is shown in figure 2.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 22 mu m. And calcining the green coke particles, heating the green coke particles from room temperature to 1000 ℃ at the heating rate of 5 ℃/min under the protection of nitrogen, keeping the temperature for 6 hours, wherein the granularity D50 of the calcined coke particles is 19 mu m, and the performance index of the calcined coke particles is shown in Table 3. Graphitizing the calcined coke particles, heating from room temperature to 2800 ℃ at a heating rate of 3 ℃/min under the protection of argon, keeping the temperature for 4 hours, and thus obtaining the special artificial graphite material for the cathode of the lithium ion battery, wherein the performance indexes are shown in table 4, and the scanning electron microscope image is shown in fig. 3.
[ example 2 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 70 ℃, the mass content of quinoline insoluble substances is 3.85%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is raised from normal temperature to 390 ℃ at the heating rate of 2 ℃/min, and the mixture stays for 5 hours at the constant temperature, so that a microcrystal unit is formed, and the polymerized asphalt is prepared.
Mixing polymerized asphalt and dianthracene oil according to a mass ratio of 2: 1, fully stirring at the temperature of 150 ℃, and pouring the mixture with the length-diameter ratio of 9: 1, settling and separating in a standing and settling device, wherein the settling temperature is 140 ℃, the settling time is 3h, and then the mass ratio of the components is 7: 3 separating out light phase oil and heavy phase oil, and determining the density of the light phase oil to be 0.9g/cm3The density of heavy phase oil is 1.2g/cm3. According to the weight phase oil: the mass ratio of dianthracene oil is 1: 4 mixing, heating to 80 ℃, fully stirring for 2h, centrifuging at 1000rad/min, separating the solid phase density to 1.1g/cm3And centrifuging under the condition that the mesh number of the screen is 500 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components and xylene according to a mass ratio of 1: 4, heating to 90 ℃, fully stirring for 2h, and performing pressure filtration under the conditions that the vacuum degree is 0.09MPa and the mesh number of a screen is 500 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.01%. Mixing the filtrate with the above soluble components, pouring into a distillation still, distilling under reduced pressure at gas phase final temperature of 260 deg.C for 1h and vacuum degree of 0.08MPa to recover dianthracene oil and xylene, and obtaining the rectified asphalt, wherein the performance indexes are shown in Table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 490 ℃ at the heating rate of 5 ℃/h under the condition of the pressure of 0.3MPa, keeping the temperature for 6h, and obtaining intermediate-phase green coke, wherein the performance indexes are shown in table 2, and the polarized light microstructure is shown in figure 4.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 28 μm. And calcining the green coke particles, heating the green coke particles from room temperature to 1200 ℃ at the heating rate of 4 ℃/min under the protection of nitrogen, keeping the temperature for 4 hours, wherein the granularity D50 of the calcined coke particles is 24 mu m, and the performance index of the calcined coke particles is shown in Table 3. Graphitizing the calcined coke particles, heating the calcined coke particles from room temperature to 2500 ℃ at the heating rate of 2 ℃/min under the protection of argon, keeping the temperature for 8 hours, and thus obtaining the special artificial graphite material for the cathode of the lithium ion battery, wherein the performance indexes are shown in table 4, and the scanning electron microscope picture is shown in fig. 5.
[ example 3 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 95 ℃, the mass content of quinoline insoluble substances is 6.82%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is increased from normal temperature to 380 ℃ at the heating rate of 2 ℃/min, and the mixture stays at the constant temperature for 6 hours to form a microcrystal unit, so that the polymeric asphalt is prepared.
Mixing polymerized asphalt and anthracene oil according to a mass ratio of 1: 1, fully stirring at the temperature of 160 ℃, and pouring the mixture with the length-diameter ratio of 10: 1, settling and separating in a standing and settling device, wherein the settling temperature is 140 ℃, the settling time is 3h, and then the mass ratio of the components is 8: 2 separating out light phase oil and heavy phase oil, and determining the density of the light phase oil to be 1.06g/cm3The heavy phase oil density is 1.34g/cm3. According to the weight phase oil: the mass ratio of anthracene oil is 1: 5 mixing, heating to 100 deg.C, stirring for 1.5h, centrifuging at 1200rad/min, and separating to obtain solid phase with density of 1.2g/cm3And centrifuging under the condition that the mesh number of the screen is 600 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components with pyridine according to a mass ratio of 1: 5, mixing, heating to 100 ℃, fully stirring for 2h, and carrying out pressure filtration under the conditions that the vacuum degree is 0.08MPa and the mesh number of a screen is 600 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.04%. Mixing the filtrate with the above soluble components, pouring into a distillation still, keeping the gas phase at final temperature of 330 deg.C for 1h, distilling under normal pressure to recover anthracene oil and pyridine to obtain the rectified asphalt, wherein the performance indexes are shown in Table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 510 ℃ at the heating rate of 4 ℃/h under the pressure of 0.4MPa, keeping the temperature for 5h, and obtaining intermediate-phase green coke, wherein the performance indexes of the intermediate-phase green coke are shown in a table 2, and the polarized light microstructure of the intermediate-phase green coke is shown in a figure 6.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 25 mu m. And calcining the green coke particles, heating the green coke particles from room temperature to 1100 ℃ at the heating rate of 6 ℃/min under the protection of nitrogen, keeping the temperature for 5 hours, wherein the granularity D50 of the calcined coke particles is 23 mu m, and the performance index of the calcined coke particles is shown in Table 3. Graphitizing the calcined coke particles, heating the calcined coke particles from room temperature to 2700 ℃ at the heating rate of 4 ℃/min under the protection of argon, keeping the temperature for 6 hours, and thus obtaining the special artificial graphite material for the lithium ion battery cathode, wherein the performance indexes are shown in Table 4, and the scanning electron microscope image is shown in FIG. 7.
[ example 4 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 120 ℃, the mass content of quinoline insoluble substances is 8.52%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is increased from normal temperature to 380 ℃ at the heating rate of 1.5 ℃/min, the mixture is kept at the constant temperature for 7 hours, a microcrystal unit is formed, and the polymerized asphalt is prepared.
Mixing polymerized asphalt and coking light oil according to the mass ratio of 2: 1, fully stirring at the temperature of 180 ℃, and pouring the mixture with the length-diameter ratio of 12: 1, settling and separating in a standing and settling device, wherein the settling temperature is 150 ℃, the settling time is 2h, and the mass ratio of the materials is 6: 4 separating out light phase oil and heavy phase oil, and determining the density of the light phase oil to be 0.85g/cm3The heavy phase oil density is 1.18g/cm3. According to the weight phase oil: the mass ratio of the coking light oil is 1: 6 mixing, heating to 120 ℃, fully stirring for 1.5h, centrifuging at the rotation speed of 1200rad/min, and separating the solid phase with the density of 1.2g/cm3And centrifuging under the condition that the mesh number of the screen is 600 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components with heptane in a mass ratio of 1: 6, mixing, heating to 110 ℃, fully stirring for 2h, and carrying out filter pressing under the conditions that the vacuum degree is 0.09MPa and the mesh number of a screen is 600 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.06%. Mixing the filtrate with the above soluble components, pouring into a distillation still, distilling under reduced pressure at gas phase final temperature of 280 deg.C for 1h and vacuum degree of 0.09MPa to recover coked light oil and heptane to obtain rectified asphalt, with performance index shown in Table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 500 ℃ at the heating rate of 2 ℃/h under the pressure of 0.5MPa, keeping the temperature for 4h, and obtaining intermediate-phase green coke, wherein the performance indexes are shown in table 2, and the polarizing microstructure is shown in figure 8.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 30 mu m. And calcining the green coke particles, heating the green coke particles from room temperature to 1300 ℃ at the heating rate of 3 ℃/min under the protection of nitrogen, keeping the temperature for 4 hours, wherein the granularity D50 of the calcined coke particles is 25 mu m, and the performance index of the calcined coke particles is shown in Table 3. And finally, graphitizing the calcined coke particles, heating the calcined coke particles from room temperature to 2600 ℃ at the heating rate of 5 ℃/min under the protection of argon, keeping the temperature for 5 hours, and thus obtaining the special artificial graphite material for the lithium ion battery cathode, wherein the performance indexes are shown in Table 4, and the scanning electron microscope image is shown in FIG. 9.
[ example 5 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 45 ℃, the mass content of quinoline insoluble substances is 2.54%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is increased from normal temperature to 400 ℃ at the heating rate of 4 ℃/min, and the mixture stays for 4 hours at the constant temperature to form a microcrystal unit, so that the polymeric asphalt is prepared.
Mixing polymerized asphalt with coking heavy oil according to the mass ratio of 3: 1, fully stirring at the temperature of 150 ℃, and pouring the mixture with the length-diameter ratio of 8: 1, settling and separating in a standing and settling device, wherein the settling temperature is 130 ℃, the settling time is 4h, and then the mass ratio of the components is 7: 3 separating out light phase oil and heavy phase oil, and determining the density of the light phase oil to be 0.94g/cm3The heavy phase oil density is 1.19g/cm3. According to the weight phase oil: the mass ratio of the coking heavy oil is 1: 3 mixing, heating to 150 ℃, fully stirring for 2h, centrifuging at 1500rad/min, separating the solid phase density to 1.0g/cm3And centrifuging under the condition that the mesh number of the screen is 400 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components with pentane according to a mass ratio of 1: 3, heating to 85 ℃, fully stirring for 1.5h, and carrying out filter pressing under the conditions that the vacuum degree is 0.08MPa and the mesh number of a screen is 400 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.05%. Mixing the filtrate with the above soluble components, pouring into a distillation still, keeping the gas phase at the final temperature of 330 ℃ for 1h, and distilling under normal pressure to recover coked heavy oil and pentane to obtain the rectified asphalt, wherein the performance indexes are shown in Table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 460 ℃ at the heating rate of 3 ℃/h under the pressure of 0.1MPa, keeping the temperature for 7h, and obtaining intermediate-phase green coke, wherein the performance indexes are shown in Table 2, and the polarizing microstructure is shown in figure 10.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 34 μm. And calcining the coke particles, heating the coke particles from room temperature to 1450 ℃ at the heating rate of 5 ℃/min under the protection of nitrogen, keeping the temperature for 3 hours, wherein the granularity D50 of the calcined coke particles is 29 mu m, and the performance index of the calcined coke particles is shown in Table 3. And finally, graphitizing the calcined coke particles, heating the calcined coke particles from room temperature to 3000 ℃ at the heating rate of 3 ℃/min under the protection of argon, keeping the temperature for 3 hours, and thus obtaining the special artificial graphite material for the lithium ion battery cathode, wherein the performance indexes are shown in table 4, and the scanning electron microscope image is shown in fig. 11.
[ example 6 ]
In the embodiment, the raw material asphalt is coal-series soft asphalt with a softening point of 142 ℃, the mass content of quinoline insoluble substances is 10.08%, the raw material asphalt is added into a stainless steel reaction kettle under the protection of high-purity nitrogen, the temperature is increased from normal temperature to 370 ℃ at the heating rate of 2 ℃/min, and the mixture stays for 6 hours at the constant temperature to form a microcrystal unit, so that the polymeric asphalt is prepared.
Mixing polymerized asphalt and naphthalene oil according to a mass ratio of 1: 1, fully stirring at the temperature of 170 ℃, and pouring the mixture with the length-diameter ratio of 14: 1, settling and separating in a standing and settling device, wherein the settling temperature is 150 ℃, the settling time is 3h, and the mass ratio of the materials is 8: 2 separating out light phase oil and heavy phase oil, and determining the density of the light phase oil to be 1.09g/cm3The heavy phase oil density is 1.33g/cm3. According to the weight phase oil: the mass ratio of the naphthalene oil is 1: 6 mixing, heating to 130 ℃, fully stirring for 2h, centrifuging at a rotation speed of 1400rad/min, and separating the solid phase with a density of 1.1g/cm3And centrifuging under the condition that the mesh number of the screen is 600 meshes to obtain a soluble component and an insoluble component.
Mixing insoluble components with tetrahydrofuran according to a mass ratio of 1: 5, mixing, heating to 110 ℃, fully stirring for 2h, and carrying out pressure filtration under the conditions that the vacuum degree is 0.09MPa and the mesh number of a screen is 600 meshes to obtain a filter cake and a filtrate, wherein the QI mass content in the filtrate is 0.08%. Mixing the filtrate with the above soluble components, pouring into a distillation still, standing at gas phase final temperature of 290 deg.C for 0.5h, and recovering naphthalene oil and tetrahydrofuran by vacuum distillation under vacuum degree of 0.09MPa to obtain the rectified asphalt, with performance index shown in Table 1.
And (3) carrying out directional coking reaction on the prepared rectified asphalt, heating the rectified asphalt from room temperature to 520 ℃ at the heating rate of 8 ℃/h under the pressure of 0.3MPa, keeping the temperature for 2h, and obtaining intermediate-phase green coke, wherein the performance indexes are shown in table 2, and the polarizing microstructure is shown in figure 12.
The intermediate-phase raw coke is crushed to obtain raw coke particles with the particle size D50 of 20 mu m. And calcining the green coke particles, heating the green coke particles from room temperature to 1100 ℃ at the heating rate of 2 ℃/min under the protection of nitrogen, keeping the temperature for 5 hours, wherein the granularity D50 of the calcined coke particles is 18 mu m, and the performance index of the calcined coke particles is shown in Table 3. Graphitizing the calcined coke particles, heating from room temperature to 2900 ℃ at the heating rate of 6 ℃/min under the protection of argon, keeping the temperature for 4 hours, and obtaining the special artificial graphite material for the cathode of the lithium ion battery, wherein the performance indexes are shown in table 4, and the scanning electron microscope picture is shown in fig. 13.
TABLE 1 Properties of the rectified asphalts
| Examples | SP/℃ | QI/％ | H/C |
| Example 1 | 30 | 0.05 | 0.55:1 |
| Example 2 | 50 | 0.1 | 0.5:1 |
| Example 3 | 60 | 0.09 | 0.48:1 |
| Example 4 | 70 | 0.12 | 0.46:1 |
| Example 5 | 40 | 0.06 | 0.52:1 |
| Example 6 | 80 | 0.08 | 0.45:1 |
TABLE 2 mesophase coke formation Performance index
| Examples | Mesophase content/%) | True density/g/cm3 | Ash content% | S/％ | N/％ | Volatile fraction/%) |
| Example 1 | 90 | 1.42 | 0.04 | 0.37 | 0.45 | 4.0 |
| Example 2 | 94 | 1.43 | 0.03 | 0.35 | 0.44 | 3.3 |
| Example 3 | 97 | 1.45 | 0.02 | 0.32 | 0.43 | 3.5 |
| Example 4 | 95 | 1.44 | 0.02 | 0.32 | 0.44 | 3.6 |
| Example 5 | 88 | 1.41 | 0.04 | 0.36 | 0.46 | 4.2 |
| Example 6 | 100 | 1.45 | 0.01 | 0.31 | 0.42 | 3.0 |
TABLE 3 calcined coke particle Performance index
| Examples | True density/g/cm3 | Tap density/g/cm3 | S/％ | N/％ | Ash content% |
| Example 1 | 2.13 | 0.91 | 0.32 | 0.41 | 0.02 |
| Example 2 | 2.14 | 0.93 | 0.31 | 0.38 | 0.02 |
| Example 3 | 2.13 | 0.92 | 0.31 | 0.38 | 0.01 |
| Example 4 | 2.14 | 0.93 | 0.30 | 0.37 | 0.01 |
| Example 5 | 2.15 | 0.94 | 0.32 | 0.40 | 0.03 |
| Example 6 | 2.13 | 0.92 | 0.29 | 0.36 | 0.01 |
TABLE 4 Performance index of artificial graphite material
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (21)
1. A preparation method of an artificial graphite material special for a lithium ion battery cathode is characterized by comprising the following steps:
firstly, according to the reactivity of a high-reactivity component contained in raw material asphalt, controlling thermal reaction conditions to enable the raw material asphalt to undergo thermal polymerization reaction in an inert atmosphere to form a microcrystal unit, so as to prepare polymerized asphalt; the temperature of the thermal polymerization reaction is 350-400 ℃, the constant temperature time is 0.5-8 h, and the heating rate is 0.5-5 ℃/min;
step two, mixing the polymerized asphalt obtained in the step one with a solvent I according to a set solvent-oil ratio, fully stirring, standing, settling and separating, and separating according to a set proportion to obtain light-phase oil and heavy-phase oil, wherein the light-phase oil is used as a byproduct of asphalt oil to be treated; the agent-oil ratio of the polymerized asphalt to the solvent I is (0.5-5): 1; the separation according to the set proportion refers to that the oil is light phase oil according to the mass ratio: heavy phase oil (5-9.5): (5-0.5) separating;
step three, returning the heavy phase oil obtained in the step two to the first solvent with a certain proportion, and performing thermal separation treatment to obtain a soluble component and an insoluble component; the first solvent is prepared from the following heavy phase oil in a blending ratio by mass: 1, the I solvent: (0.2-10); mixing the insoluble component with a solvent II according to a set solvent-oil ratio, and performing filter pressing treatment to obtain a filter cake and a filtrate, wherein the filter cake is insoluble solid particles containing inorganic impurities; mixing the filtrate with soluble components, and distilling to recover the first solvent and the second solvent to obtain the rectified asphalt; the solvent-oil ratio of the insoluble component to the solvent II is 1: (0.5 to 10); the distillation comprises atmospheric distillation and reduced pressure distillation, wherein the conditions of the atmospheric distillation are as follows: the gas phase temperature is 280-350 ℃, and the final temperature retention time is 0.5-2 h; the conditions of reduced pressure distillation were: the gas phase temperature is 200-300 ℃, the vacuum degree is 0.01-0.09 MPa, and the final temperature retention time is 0.5-2 h;
step four, under the set heat treatment condition, carrying out directional coking reaction on the rectified asphalt obtained in the step three to obtain wide area body intermediate phase green coke with uniform microstructure; the conditions of the directional coking reaction are as follows: the pressure is 0.1-0.5 MPa, the heating rate is 1-10 ℃/h, the final reaction temperature is 450-520 ℃, and the final temperature constant-temperature time is 1-10 h; crushing the intermediate-phase green coke to prepare green coke particles with the granularity meeting the requirement; calcining the raw coke particles to obtain calcined coke particles, and then carrying out high-temperature graphitization treatment on the calcined coke particles to obtain the special artificial graphite material for the lithium ion battery cathode.
2. The preparation method of the artificial graphite material special for the lithium ion battery cathode according to claim 1, wherein in the first step, the raw material asphalt is coal asphalt obtained by high-temperature dry distillation of coal, the softening point is 20-150 ℃, and the mass content of quinoline insoluble substances is 1-20%.
3. The method for preparing the artificial graphite material specially used for the negative electrode of the lithium ion battery according to claim 1, wherein in the first step, the inert atmosphere is a high-purity nitrogen atmosphere or a high-purity argon atmosphere.
4. The preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the step one, the high-reactivity component is a heavy component insoluble in quinoline in the raw material asphalt, inorganic impurities and other solid particles.
5. The preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery as claimed in claim 1, wherein in the first step, the density of the polymerized asphalt is 1.1-1.6 g/cm3The size of the microcrystal unit is controlled to be 2-15 μm.
6. The preparation method of the artificial graphite material special for the lithium ion battery cathode according to claim 1, wherein in the second step, the first solvent is any one or a mixture of more than two of 200-350 ℃ fractions, coal directly liquefied light oil, wash oil, first anthracene oil, second anthracene oil, coking heavy oil, coking light oil, naphthalene oil, kerosene, petroleum ether, gasoline, diesel oil, lubricating oil and paraffin oil in a coal tar separation process.
7. The preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery as claimed in claim 1, wherein in the second step, the mixing temperature of the polymerized asphalt and the first solvent is 100-200 ℃.
8. The preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the second step, the length-diameter ratio of the standing settling separation device for the standing settling separation is (1-20): 1, the settling temperature is 80-200 ℃, and the settling time is 0.5-5 h.
9. The preparation method of the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, characterized by comprising the following stepsIn the second step, the density of the light phase oil is 0.85-1.1 g/cm3The density of the heavy phase oil is 1.0-1.35 g/cm3。
10. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the third step, a centrifugal separation device is adopted for the thermal separation treatment, and the treatment conditions are as follows: the separation temperature is 60-150 ℃, the separation time is 0.5-3 h, the centrifugal rotation speed is 800-2000 rad/min, and the solid phase density of the separated material is 0.9-1.3 g/cm3The mesh number of the screen in the centrifugal separation device is 300-1200 meshes.
11. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the third step, the solvent II is any one or a mixture of more than two of toluene, xylene, pyridine, heptane, pentane and tetrahydrofuran.
12. The preparation method of the artificial graphite material special for the lithium ion battery cathode according to claim 1, wherein in the third step, the filter pressing treatment conditions are as follows: the filter pressing temperature is 80-150 ℃, the filter pressing time is 0.5-3 h, and the mesh number of a screen in the filter pressing device is 300-1200 meshes.
13. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the third step, the mass content of quinoline insoluble substances in the filtrate is less than 0.1%.
14. The preparation method of the artificial graphite material special for the lithium ion battery cathode according to claim 1, wherein in the third step, the rectified asphalt is macromolecular condensed ring aromatic hydrocarbon with molecular weight distribution of 200-1200 and concentrated distribution of 400-600, softening point is 30-80 ℃, mass content of quinoline insoluble substance is 0-0.2%, H/C atomic ratio is (0.45-0.55): 1.
15. the method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the fourth step, the wide-area mesophase green coke is observed under a polarization microscope, and the anisotropic component structure is as follows: the length is more than 30 mu m, the width is more than 30 mu m, the content of the mesophase is 80-100 percent, and the true density is more than 1.4g/cm3Ash content is less than 0.1%, sulfur content is less than 0.4%, nitrogen content is less than 0.5%, and volatile component is less than 5%.
16. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the fourth step, the particle size D of the green coke particles obtained after the crushing treatment is5015 to 35 μm.
17. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the fourth step, the calcining conditions are as follows: under the protection of nitrogen, the heating rate is 1-10 ℃/min, the calcination final temperature is 1000-1500 ℃, and the final temperature constant-temperature time is 1-10 h.
18. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the fourth step, the true density of the calcined coke particles is more than or equal to 2.13g/cm3The tap density is more than or equal to 0.9g/cm3Sulfur content less than 0.4%, nitrogen content less than 0.5%, ash content less than 0.1%, and particle size D5010 to 30 μm.
19. The method for preparing the artificial graphite material special for the negative electrode of the lithium ion battery according to claim 1, wherein in the fourth step, the conditions of the high-temperature graphitization treatment are as follows: under the protection of argon, the heating rate is 1-10 ℃/min, the graphitization final temperature is 2500-3000 ℃, and the final temperature constant temperature time is 1-10 h.
20. The special person for the negative electrode of the lithium ion battery according to claim 1The preparation method of the artificial graphite material is characterized in that in the fourth step, the indexes of the artificial graphite material special for the lithium ion battery cathode are as follows: particle size distribution D10：6～12μm、D50：16～24μm、D90: 28-35 mu m and the true density is more than or equal to 2.24g/cm3The tap density is more than or equal to 0.9g/cm3The powder compacted density is more than or equal to 1.55g/cm3Ash content is less than or equal to 0.01 percent, and specific surface area is less than or equal to 1.5m2The graphitization degree is more than or equal to 90 percent, the primary coulombic efficiency is more than or equal to 94 percent, the primary discharge specific capacity is more than or equal to 358 mA.h/g, and the multiplying power performance (2C/0.2C) is more than or equal to 80 percent.
21. The method of claim 1, wherein in the fourth step, the degree of orientation OI of the graphite material sheet of the artificial graphite material for the negative electrode of the lithium ion battery is I002And I110And OI value < 50.
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