Preparation method of petroleum coke-based high-tamped-density artificial graphite

Abstract

This invention discloses a method for preparing high-tap-density artificial graphite based on petroleum coke, belonging to the field of new energy materials technology. The preparation method provided by this invention includes the following steps: S1. Mixing petroleum coke and a solution to form a polymer in situ on the surface of the petroleum coke, wherein the solution contains monomers and organometallic salts, the organometallic salts including at least one selected from iron, cobalt, and nickel salts; S2. Graphitizing the product obtained in step S1; the graphitization atmosphere contains a hydrocarbon carbon source and an inert gas; S3. Acid washing the product obtained in step S2. The preparation method provided by this invention can effectively improve the tap density, energy, and cycle performance of artificial graphite, while maintaining or even improving rate performance.

Description

Technical Field

[0001] This invention relates to the field of new energy materials technology, and in particular to a method for preparing high tap density artificial graphite based on petroleum coke. Background Technology

[0002] With technological advancements, the selection of anode materials for lithium-ion batteries has become increasingly diversified, but graphite anodes remain the most mature and widely used. Commercially available graphite anodes consist of both artificial and natural graphite. Limited by the reserves of natural graphite, and benefiting from the advantages of artificial graphite in terms of cycle performance, safety, high-rate charge / discharge efficiency, and electrolyte compatibility, the proportion of artificial graphite in lithium-ion batteries is gradually increasing. Furthermore, artificial graphite exhibits better structural stability and higher isotropy, which to some extent enhances the compressibility of the electrode, improves its wettability with the electrolyte, and reduces electrode expansion, thus positively impacting the overall battery life.

[0003] The raw materials for artificial graphite are divided into two main categories: coal-based and petroleum-based. Based on coke quality, they can be further classified into needle coke, petroleum coke, isokinetic coke, and carbon microspheres, among which needle coke and petroleum coke are the most widely used: high-capacity anodes generally use needle coke as raw material, while ordinary-capacity anodes generally use petroleum coke. In terms of price, needle coke is significantly more expensive than petroleum coke, therefore, needle coke-based artificial graphite is also very expensive.

[0004] If inexpensive raw materials such as petroleum coke can be used to obtain artificial graphite with excellent properties in terms of tapping, it will greatly promote the development of the artificial graphite industry. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing high-tap-density artificial graphite based on petroleum coke, which can effectively improve the tap density, energy and cycle performance of artificial graphite, while maintaining or even improving its rate performance.

[0006] According to an embodiment of the first aspect of the present invention, a method for preparing petroleum coke-based high-tap-density artificial graphite is provided, the method comprising the following steps:

[0007] S1. A mixture of petroleum coke and a solution is reacted to form a polymer in situ on the surface of the petroleum coke, wherein the solution contains a monomer and an organometallic salt, the organometallic salt comprising at least one of an iron salt, a cobalt salt, and a nickel salt;

[0008] S2. The product obtained from graphitization step S1; the graphitization atmosphere contains a hydrocarbon carbon source and an inert gas;

[0009] S3. The product obtained from the acid washing step S2.

[0010] The preparation method according to embodiments of the present invention has at least the following beneficial effects:

[0011] The reason why petroleum coke is difficult to form high-taper, high-performance artificial graphite is that it has a high impurity content, high disorder, and rich pore structure. Furthermore, the pore structure changes during subsequent impurity removal and graphitization processes, making it difficult to precisely "repair" it.

[0012] This invention employs in-situ polymerization to initially repair the pore structure. To repair the changes in pore structure during the graphitization process, a hydrocarbon carbon source is introduced simultaneously with graphitization, generating highly crystalline carbon products such as graphene in situ, thus achieving precise pore structure "repair." The combined effect of multiple "repair" methods enhances the anisotropy of the resulting artificial graphite, improving its rate performance. Furthermore, the synergistic effect of the two "repair" methods significantly improves the density and structural stability of petroleum coke-based artificial graphite, thereby significantly enhancing its capacity and cycle performance.

[0013] Meanwhile, since a specific type of organometallic salt is introduced in step S2, the organometallic salt acts as a catalyst for the graphitization of hydrocarbon carbon sources, petroleum coke and polymers in step S3, which significantly improves the degree of graphitization and reduces the graphitization temperature.

[0014] The acid washing in step S3 serves two purposes: firstly, it removes the product of the organometallic salt, resulting in an ordered pore structure. This ordered pore structure acts as a lithium-ion transport channel, which can improve rate performance to some extent; secondly, it reduces the ash content of the obtained artificial graphite, significantly improving its electrochemical performance.

[0015] According to some embodiments of the present invention, in step S1, the sphericity of the petroleum coke is ≥70%. Specifically, it can be 75%, 80%, 85%, 90%, 95%, 99%, or a range of values ​​consisting of any two of the above points. Improving the sphericity is beneficial to increasing the tap density of the resulting artificial graphite. If the incoming petroleum coke does not meet the above sphericity requirements, granulation or grinding and powder selection operations are necessary.

[0016] Furthermore, the grinding process involves ball milling, and the grinding media used in the ball mill are selected from grinding beads with a small particle size, such as grinding beads with a particle size ≤3mm. This allows the ball mill to better perform a shaping function rather than a crushing function, thereby obtaining petroleum coke with higher sphericity.

[0017] The sphericity is the ratio of the particle's perimeter equivalent diameter to its area equivalent diameter in the SEM image.

[0018] According to some embodiments of the present invention, in step S1, the particle size of the petroleum coke is 5~30μm; for example, it can be 8μm, 10μm, 15μm, 20μm, 25μm, 30μm; or a range of values ​​composed of any two of the above points.

[0019] According to some embodiments of the present invention, in step S1, the petroleum coke is at least one of No. 1 petroleum coke and Grade 2A petroleum coke.

[0020] According to some embodiments of the present invention, in step S1, the monomer includes at least one selected from cyano, amino, aldehyde, amino, and amide groups. When cyano and amino groups are present, the monomer polymerization process can simultaneously complex the metal ions in the organometallic salt, improving the uniformity of the metal ions' dispersion in the petroleum coke. Therefore, during the graphitization process in step S2, the metal clusters formed by the organometallic salt will not agglomerate but will be nearly single-atom dispersed, thereby significantly improving its catalytic activity. Ultimately, the degree of graphitization of the product obtained in step S2 is significantly improved, and the pore structure of the product obtained in step S3 is also more ordered.

[0021] According to some embodiments of the present invention, in step S1, the polymer includes at least one selected from polyimide, polyacrylonitrile, phenolic resin, and aromatic polyamide. Compared with aromatic polyolefins, the above polymers are more easily graphitized under catalytic conditions, thereby increasing the tap density of the resulting artificial graphite while also improving its bulk density to some extent.

[0022] According to some embodiments of the present invention, in step S1, the mass ratio of the petroleum coke to the monomer is 5 to 15:1. For example, it can be 5:1, 8:1, 10:1, 12:1, 15:1; or a range of values ​​consisting of any two of the above points.

[0023] According to some embodiments of the present invention, in step S1, the mass concentration of the monomer is 10-30%. For example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%; or a range of values ​​composed of any two of the above points.

[0024] According to some embodiments of the present invention, in step S1, the solution further contains an initiator.

[0025] According to some embodiments of the present invention, the polymer is selected from polyacrylonitrile. In this case,

[0026] The solution contains a monomer, an organometallic salt, and an initiator.

[0027] The monomer includes acrylonitrile;

[0028] The initiator is selected from azo initiators. Compared with oxidizing initiators, azo initiators have less impact on organometallic salts, thus maintaining the catalytic activity of the resulting catalyst as much as possible.

[0029] The azo initiator includes azobisisobutyramidine hydrochloride, which is soluble in water and some polar solvents, thereby promoting the precipitation of the generated polyacrylonitrile onto the surface of petroleum coke, rather than dissolving in non-polar solvents.

[0030] The initiator accounts for 0.2% to 1% of the monomer by mass. For example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%; or a range of values ​​consisting of any two of the above points.

[0031] The solvent of the solution is a mixture of DMSO and water. Specifically, the volume percentage of water in the solvent is 30-80%; for example, it can be 30%, 40%, 50%, 60%, 70%, 80%; or a range of values ​​composed of any two of the above points.

[0032] The temperature of the mixing reaction is 55~65℃; for example, it can be 55℃, 60℃, 65℃; or a range of values ​​composed of any two of the above points.

[0033] The duration of the mixed reaction is 1 to 5 hours; for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours; or a range of values ​​composed of any two of the above points.

[0034] According to some embodiments of the present invention, in step S1, the solution further contains a catalyst.

[0035] According to some embodiments of the present invention, the polymer is selected from phenolic resins. In this case,

[0036] The solution contains solutes including monomers, organometallic salts, and catalysts.

[0037] The monomers include aldehyde monomers and phenolic monomers; the aldehyde monomers include at least one of formaldehyde and paraformaldehyde, and the phenolic monomers include at least one of phenol and p-cresol; the molar ratio of phenol to aldehyde in the monomers is 1:2 to 5; for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5; or a range of values ​​composed of any two of the above points.

[0038] The catalyst includes acid catalysts. Basic catalysts may cause metal ion precipitation in organometallic salts; therefore, acid catalysts are selected, including p-toluenesulfonic acid.

[0039] The acid catalyst accounts for 0.2% to 1% of the monomer by mass. For example, it can be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%; or a range of any two of the above values.

[0040] The solvent of the solution is an alcohol solvent, specifically at least one of ethanol, methanol, propanol and isopropanol.

[0041] The temperature of the mixing reaction is 40~50℃; for example, it can be 40℃, 45℃, 50℃; or a range of values ​​composed of any two of the above points.

[0042] The duration of the mixed reaction is 1 to 5 hours; for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours; or a range of values ​​composed of any two of the above points.

[0043] According to some embodiments of the present invention, in step S1, the concentration of the organometallic salt is 1~10 mg / mL. For example, it can be 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL, 10 mg / mL; or a range of values ​​consisting of any two of the above points.

[0044] According to some embodiments of the present invention, in step S1, the organometallic salt includes at least one of ferrocene, cobalt dicene, and nickel dicene.

[0045] According to some embodiments of the present invention, step S1 further includes solid-liquid separation and drying operations after the mixing reaction. In actual production, suitable operating methods can be selected, but it should be carried out under oxygen-free conditions as much as possible to avoid catalyst deactivation.

[0046] According to some embodiments of the present invention, step S2 further includes a pre-firing platform before graphitization, wherein the temperature of the pre-firing platform is 250~350°C. For example, it can be 250°C, 280°C, 300°C, 320°C, 350°C; or a range of values ​​composed of any two of the above points.

[0047] According to some embodiments of the present invention, the isothermal duration of the pre-burning platform is 0.5 to 3 hours; for example, it can be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours; or a range of values ​​composed of any two of the above points.

[0048] This promotes the structural stability of the polymer and avoids adverse phenomena such as agglomeration or casting during graphitization; ultimately improving the pore-filling effect of the graphitized product obtained from the polymer.

[0049] According to some embodiments of the present invention, the atmosphere of the pre-burning platform is an inert atmosphere, such as argon or nitrogen.

[0050] According to some embodiments of the present invention, in step S2, the degree of graphitization is 900~1200℃. Specifically, it can be 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃; or a range of any two of the above values. Thanks to the introduction of the organometallic salt, the graphitization temperature is significantly reduced. Without the introduction of the organometallic salt, the graphitization temperature might need to reach above 2000℃.

[0051] According to some embodiments of the present invention, in step S2, the graphitization time is 10~25h. For example, it can be 10h, 12h, 14h, 16h, 18h, 20h, 22h, 25h; or a range of values ​​composed of any two of the above points.

[0052] According to some embodiments of the present invention, in step S2, the volume percentage of the hydrocarbon carbon source in the atmosphere is 30-50%. For example, it can be 30%, 35%, 40%, 45%, 50%; or a range of values ​​composed of any two of the above points.

[0053] According to some embodiments of the present invention, the isothermal platform and the heating rate of the graphitization are independently selected from any value of 1 to 5 °C / min. For example, it can specifically be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min; or a range of values ​​composed of any two of the above points.

[0054] According to some embodiments of the present invention, in step S3, the acid solution used for pickling includes at least one of HCl and H2SO4 as the solute. A non-oxidizing acid is used to avoid introducing oxygen-containing groups that could affect the electronic conductivity of the resulting artificial graphite.

[0055] According to some embodiments of the present invention, in step S3, the acid solution used for pickling has a concentration of 0.5~1.5 mol / L. For example, it can specifically be 0.5 mol / L, 1 mol / L, 1.5 mol / L; or a range of values ​​composed of any two of the above points.

[0056] According to some embodiments of the present invention, in step S3, the solid-liquid ratio of the pickling is 1:1 to 10; for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10; or a range of values ​​composed of any two of the above points.

[0057] According to some embodiments of the present invention, in step S3, the pickling time is 10-60 minutes. For example, it can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes; or a range of values ​​composed of any two of the above points.

[0058] According to some embodiments of the present invention, in step S3, the pickling is carried out under pressure, and the pressure used is 1~1.5MPa. For example, it can be 1MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa; or a range of values ​​composed of any two of the above points.

[0059] Compared with atmospheric pressure pickling, pressure pickling can significantly remove impurities from the artificial graphite, resulting in a more thorough removal; and avoids the impact of impurities on subsequent electrochemical performance.

[0060] According to some embodiments of the present invention, step S3 further includes a water washing and drying step after the pickling. The parameters of the above steps can be selected according to actual production conditions, and the present invention does not impose strict limitations.

[0061] According to some embodiments of the present invention, the tap density of the artificial graphite prepared by the method is ≥1.25 g / cm³. 3 For example, it could be 1.25 g / cm³. 3 1.26 g / cm 3 1.28g / cm 3 1.3g / cm 3 1.32g / cm 3 ; or the range of values ​​formed by any two of the above point values.

[0062] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0063] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0064] Example 1

[0065] This example demonstrates the preparation of an artificial graphite, with the following specific steps:

[0066] S1. Large pieces of petroleum coke (meeting grade 2A as specified in "Petroleum Coke (Green Coke)" (NB / SH / T 0527—2019)) were ball-milled to select powder with a particle size in the range of 8~15μm; the results showed that the sphericity of the obtained petroleum coke was 81%; the ball milling used zirconia beads as the grinding medium, the particle size of the zirconia beads was 3mm, and the ball-to-material ratio was 3:1;

[0067] The petroleum coke obtained from grinding is mixed with a solution and reacted to form a polymer in situ on the surface of the petroleum coke. Among these reactions,

[0068] The solutes in the solution are monomer, organometallic salt, and initiator; the monomer is acrylonitrile, the organometallic salt is ferrocene, and the initiator is azobisisobutyramidine hydrochloride (CAS: 2997-92-4); the initiator accounts for 0.5% of the monomer by mass; the mass concentration of acrylonitrile is 15%; the mass ratio of petroleum coke to acrylonitrile is 8:1; and the concentration of the organometallic salt in the solution is 3 mg / mL.

[0069] The solvent in the solution is a mixture of DMSO (dimethyl sulfoxide) and water in a mass ratio of 3:7.

[0070] The temperature of the mixing reaction was controlled at 60℃±2℃; the mixing reaction time was 2h; the mixing reaction was carried out under stirring, and stirring was only to improve mass transfer and prevent petroleum coke from settling to the bottom, so the stirring speed did not need to be strictly limited.

[0071] After solid-liquid separation, the resulting solid product is dried. The drying is carried out under inert gas protection or vacuum conditions at a temperature of 60°C.

[0072] The polymer coated with petroleum coke obtained in this step is polyacrylonitrile.

[0073] S2. The product obtained in step S1 is sequentially passed through a pre-calcination platform and then through a graphitization process; wherein,

[0074] The specific temperature curve for this step is as follows: first, heat to 300℃ at a heating rate of 2℃ / min and hold for 1 hour; then continue heating to 1000℃ at a heating rate of 2℃ / min and hold for 12 hours.

[0075] During the heating and isothermal stages of the pre-calcination platform, argon is used as the gas atmosphere. In the subsequent heating and isothermal stages of graphitization, a mixture of argon and ethylene in a 6:4 volume ratio is used as the gas atmosphere.

[0076] After graphitization, the furnace is cooled to below 200°C under argon protection before being removed from the furnace. Ideally, it should be cooled to room temperature before being removed from the furnace.

[0077] S3. The product obtained from acid washing step S2, wherein,

[0078] The acid used was 1 mol / L hydrochloric acid, the solid-liquid ratio during the pickling process was 1:4, the pickling pressure was 1.2 MPa (i.e., the absolute pressure was: standard atmospheric pressure + 1.2 MPa), and the pickling time was 30 min.

[0079] After acid washing, the product is washed with water until the pH of the washing solution is ≥5.5.

[0080] The washed product was dried under vacuum at 120°C for 12 hours.

[0081] Example 2

[0082] This example prepares an artificial graphite, which differs from Example 1 in that:

[0083] In step S1, the composition of the solution is as follows:

[0084] The solute in the solution is a monomer, p-toluenesulfonic acid (acid catalyst), and an organometallic salt; the monomer is a mixture of p-benzophenol and paraformaldehyde, wherein the molar ratio of p-benzophenol to paraformaldehyde is 1:3.5; the acid catalyst is 0.2% of the monomer mass.

[0085] The solvent for the solution is ethanol.

[0086] The temperature of the mixed reaction was 45℃ and the duration was 4 hours.

[0087] All other conditions not specified are the same as in Example 1, such as the concentration of monomers, the type and concentration of organometallic salts, etc.

[0088] Therefore, the polymer coated with petroleum coke obtained in this example is an acidic phenolic resin.

[0089] Example 3

[0090] This example prepares an artificial graphite, which differs from Example 1 in that:

[0091] In step S2, no pre-firing platform is used; instead, the temperature is directly raised from room temperature to 1000°C for graphitization sintering.

[0092] Comparative Example 1

[0093] This example prepares an artificial graphite, which differs from Example 1 in that:

[0094] The solution in step S1 does not contain organometallic salts.

[0095] Between step S1 and step S2, an impregnation step with an organometallic salt solution is added, specifically:

[0096] The organometallic salt solution has a concentration of 3 mg / mL, is ferrocene, and is in ethanol.

[0097] The soaking time is 5 minutes. After the solid material is removed, it is dried using the same steps as in step S1 of Example 1.

[0098] Comparative Example 2

[0099] This example prepares an artificial graphite, which differs from Example 1 in that:

[0100] In step S2, the atmosphere is maintained as argon.

[0101] The CVD reaction takes place between step S2 and step S3, specifically:

[0102] Perform the same graphitization process as step S2 in Example 1.

[0103] Test case

[0104] The first aspect of this example tested the tap density of the artificial graphite obtained in the embodiment and the comparative example, specifically using a 100cm³ tap density. 3 The graduated cylinder was used for testing in accordance with the standard "Graphite Anode Materials for Lithium-ion Batteries" (GB / T 24533-2019).

[0105] The second aspect of this example tested the particle size of the artificial graphite obtained in the embodiments and comparative examples, specifically using a laser particle size analyzer.

[0106] The second aspect of this example tested the sphericity of the artificial graphite obtained in the examples and comparative examples. Specifically, under a scanning electron microscope, ≥50 samples were selected, and the perimeter and area of ​​each particle were measured, and the sphericity 4π was calculated. Area / (perimeter) 2 ), calculate the average value of all sample results for a single group of specimens.

[0107] The third aspect of this example tested the first-week discharge capacity and first-efficiency of the artificial graphite obtained in the examples and comparative examples. The tests were conducted in accordance with the "Graphite Anode Materials for Lithium-ion Batteries" (GB / T 24533-2019), in which the counter electrode directly used a lithium metal sheet.

[0108] The fourth aspect of this example tested the rate performance of the artificial graphite obtained in the embodiments and comparative examples. The button cells used were the same as those in the third aspect of this example, and the tested charge and discharge rates were 0.5C, 1C, and 5C, respectively.

[0109] The fifth aspect of this example tested the cycle performance of the artificial graphite obtained in the examples and comparative examples, specifically using pouch cells. In the pouch cells, the composition of the negative electrode, electrolyte, and separator is the same as in the third aspect of this example; only the dimensions need to be adjusted according to actual conditions. The composition of the positive electrode is as follows: lithium nickel cobalt manganese oxide (NCM111) with a D50 of 2μm to 4μm, conductive carbon black, and PVDF are added to an appropriate amount of N-methylpyrrolidone (NMP) solvent at a mass percentage of 94%, 3%, and 3%, respectively. A positive electrode slurry with a solid content of 76% is obtained by stirring. The positive electrode sheet is then prepared through coating, rolling, and die-cutting processes. During the testing process, the voltage range is 2.5~4.2V. An activation process of 3 weeks of 0.1C charge-discharge is performed first, followed by a 500-week 1C charge-discharge test. The ratio of the discharge capacity at the 500th week to the discharge capacity at the 1st week is calculated during the 1C test.

[0110] In the above electrochemical tests, the specific capacity at 1C was set to 355 mAh / g.

[0111] The results of the above tests are shown in Table 1:

[0112] Table 1. Overall properties of the artificial graphite prepared in the examples and comparative examples.

[0113]

[0114] Comparing the results of Examples 1, 2, and 1, it is evident that the preparation method provided by this invention significantly improves the dispersion uniformity of the catalyst precursor (organometallic salt), thereby enhancing the particle size uniformity of the resulting catalyst (metal nanoclusters or particles), preventing agglomeration, and thus significantly improving the catalytic performance of the catalyst. The degree of graphitization is higher during the subsequent graphitization process. Simultaneously, the CVD-derived carbon, such as acetylene, exhibits superior gap-filling effect, and after acid washing, the resulting pores have more uniform size. The combined effect of these factors significantly improves the overall performance of the obtained artificial graphite. If a post-impregnation method is used, the catalyst is prone to agglomeration, and the subsequent stacking of acetylene cracking carbon also tends to agglomerate, resulting in decreased sphericity and tapping. Due to catalyst agglomeration, the catalytic effect on graphitization also decreases, thus reducing the overall electrochemical performance. Compared to using phenolic resin, using polyacrylonitrile as the coating polymer allows the acrylonitrile functional groups to complex iron ions, further improving the dispersion uniformity of the catalyst precursor.

[0115] Comparing Examples 1 and 3, it can be seen that by adding a pre-sintering platform, the polymer coating layer can be pre-sintered, which is equivalent to curing, thus avoiding the influence of polymer flow and other phenomena on sphericity during graphitization, thereby significantly improving the overall performance of the obtained artificial graphite.

[0116] Comparing Example 1 and Comparative Example 2, it can be seen that if the CVD process is carried out after graphitization, the subsequent CVD process is difficult to carry out because the polymer decomposes and embeds the catalyst during the graphitization process; therefore, the repair effect on the porous structure of petroleum coke is reduced, which in turn affects the sphericity, tapping, capacity and other properties.

[0117] In summary, the preparation method provided by this invention can utilize inexpensive petroleum coke raw materials to produce artificial graphite with excellent physicochemical and electrochemical properties. Furthermore, due to the excellent overall performance of the aforementioned artificial graphite, lithium-ion batteries incorporating the aforementioned artificial graphite are expected to achieve widespread application.

[0118] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing high-tap-density artificial graphite based on petroleum coke, characterized in that, The preparation method includes the following steps: S1. A mixture of petroleum coke and a solution is reacted to form a polymer in situ on the surface of the petroleum coke, wherein the solution contains a monomer and an organometallic salt, the organometallic salt including at least one of an iron salt, a cobalt salt, and a nickel salt; S2. The product obtained from graphitization step S1; the graphitization atmosphere contains a hydrocarbon carbon source and an inert gas; S3. The product obtained from the acid washing step S2.

2. The preparation method according to claim 1, characterized in that, In step S1, the sphericity of the petroleum coke is ≥70%.

3. The preparation method according to claim 1, characterized in that, In step S1, the monomer includes at least one selected from cyano, amino, aldehyde, and amide groups; and / or, In step S1, the polymer includes at least one of polyimide, polyacrylonitrile, phenolic resin and aromatic polyamide.

4. The preparation method according to claim 1, characterized in that, In step S1, the concentration of the organometallic salt is 1~10 mg / mL; and / or, In step S1, the mass ratio of the petroleum coke to the monomer is 5~15:

1.

5. The preparation method according to claim 1, characterized in that, In step S1, the solution also contains an initiator and / or a catalyst.

6. The preparation method according to claim 1, characterized in that, Step S2 also includes a pre-firing platform before graphitization, wherein the temperature of the pre-firing platform is 250~350℃.

7. The preparation method according to claim 1, characterized in that, In step S2, the graphitization temperature is 900~1200℃.

8. The preparation method according to claim 1, characterized in that, In step S2, the volume percentage of the hydrocarbon carbon source in the atmosphere is 30-50%.

9. The preparation method according to claim 1, characterized in that, In step S3, the acid solution used for pickling includes at least one of HCl and H2SO4 as the solute; and / or, in step S3, the acid solution used for pickling has a concentration of 0.5~1.5 mol / L.

10. The preparation method according to claim 1, characterized in that, In step S3, the pickling is carried out under pressure, with a pressure of 1~1.5MPa.

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