Artificial graphite material as well as preparation method and application thereof

Abstract

The invention relates to the field of graphite, in particular to an artificial graphite material and a preparation method and application thereof. The preparation method and the application of the artificial graphite material comprise the following steps: weighing the following raw materials in percentage by weight: 80-95% of a carbon source, 1-5% of a catalyst and 0-10% of an additive; uniformly mixing the raw materials to obtain a mixture; performing heat treatment on the mixture in an inert atmosphere to obtain a precursor material; and carrying out graphitization treatment on the precursor material at high temperature to obtain the artificial graphite material. According to the artificial graphite material and the preparation method and application thereof, the ratio of the carbon source, the catalyst and the additive is reasonably adjusted, so that the performance of the material is remarkably improved, the carbon source comprises petroleum coke, needle coke, pitch coke and the like, the catalyst comprises iron, cobalt, nickel and the like, and the additive comprises silicon, boron, phosphorus and the like; the reasonable proportioning of the raw materials can improve the conductivity, thermal stability, mechanical strength and other properties of the material.

Description

Technical Field

[0001] The present invention relates to the field of graphite, and in particular to an artificial graphite material and a preparation method and application thereof. Background Art

[0002] With the rapid development of the lithium-ion battery industry, graphite is widely used as the negative electrode material of the battery. Although natural graphite has the advantages of cost and specific capacity, artificial graphite is more excellent in cycle performance, safety performance, and charge and discharge rate, and its market share is currently stable at more than 80%. Graphitization is a key process in the production of artificial graphite. The carbonaceous material is heated to 2300-3000℃, and thermal activation is used to transform the thermodynamically unstable carbon atoms from the chaotic layer structure to the graphite crystal structure in an orderly manner. The energy for the transformation of the graphite crystal structure and the rearrangement of atoms comes from high-temperature heat treatment. As the temperature increases, the distance between graphite layers gradually decreases, generally between 0.343-0.346nm, and generally changes significantly at 2500℃, and gradually changes slowly at 3000℃ until the entire graphitization is completed. This process consumes a lot of energy and is a high-energy consumption link. In the current cost structure of artificial graphite, graphitization accounts for about 50%, which is an important link in reducing the cost of negative electrode materials.

[0003] As a unique carbon material, graphite is widely used in lithium-ion batteries, supercapacitors, conductive agents and other fields due to its excellent electrical conductivity, thermal conductivity, high temperature resistance and chemical stability, playing a vital role. In lithium-ion batteries, graphite is usually used as the negative electrode material. Its layered structure can efficiently embed and deintercalate lithium ions, providing excellent energy storage capacity and long cycle life. In supercapacitors, the high specific surface area and good electrical conductivity of graphite materials enable them to quickly conduct electrons and achieve efficient energy storage and release. In addition, as a conductive agent, graphite is also widely used in a variety of electronic devices to improve the overall conductivity and working efficiency of the material.

[0004] However, natural graphite resources are relatively limited and mainly concentrated in a few geographical areas, which leads to geographical restrictions on graphite supply and is vulnerable to fluctuations in the global supply chain. More importantly, the quality of natural graphite varies significantly between different mining areas, and its degree of graphitization, purity and crystal structure are uneven, resulting in unstable performance in practical applications, affecting the quality consistency and performance controllability of the final product. Therefore, relying on natural graphite resources faces many challenges in meeting industrial needs.

[0005] Therefore, it is necessary to provide a new artificial graphite material and its preparation method and application to solve the above technical problems. Summary of the invention

[0006] In order to overcome the defects of the prior art, an artificial graphite material and a preparation method and application thereof are provided to solve the above-mentioned problems.

[0007] The present invention provides an artificial graphite material and a preparation method and application thereof, comprising the following steps:

[0008] Step S1: weighing raw materials according to weight percentage, carbon source 80%-95%, catalyst 1%-5%, additive 0%-10%;

[0009] Step S2: Mix the raw materials evenly to obtain a mixture;

[0010] Step S3: heat-treating the mixture under an inert atmosphere to obtain a precursor material;

[0011] Step S4: graphitizing the precursor material at high temperature to obtain an artificial graphite material.

[0012] Preferably, the carbon source is one or more of petroleum coke, needle coke, and asphalt coke, the catalyst is one or more of iron, cobalt, and nickel, and the additive is one or more of silicon, boron, and phosphorus.

[0013] Preferably, the heat treatment temperature is 800-1200° C. and the time is 2-8 hours.

[0014] Preferably, the graphitization temperature is 2500-3000° C., and the time is 10-30 hours.

[0015] Preferably, during the heat treatment process, a programmed temperature increase method is adopted, and the heating rate is 2-10°C / min.

[0016] Preferably, during the graphitization process, inert gas protection is adopted with a pressure of 0.1-1.0 MPa.

[0017] An artificial graphite material is prepared by the above method.

[0018] Preferably, the true density of the artificial graphite material is 1.9-2.2 g / cm 3 , the porosity of artificial graphite material is 5-15%, and the electrical conductivity of artificial graphite material is 1000-2000S / m.

[0019] Preferably, the tensile strength of the artificial graphite material is 50-100 MPa, and the bending strength of the artificial graphite material is 80-150 MPa.

[0020] Preferably, the artificial graphite material is suitable for negative electrode material of lithium-ion batteries.

[0021] Compared with the related art, the artificial graphite material and its preparation method and application provided by the present invention have the following beneficial effects:

[0022] The present invention significantly improves the performance of the material by reasonably adjusting the ratio of carbon source, catalyst and additive. The carbon source includes petroleum coke, needle coke, asphalt coke, etc., the catalyst includes iron, cobalt, nickel, etc., and the additive includes silicon, boron, phosphorus, etc. The reasonable ratio of these raw materials can improve the electrical conductivity, thermal stability, mechanical strength and other properties of the material.

[0023] The present invention achieves a significant improvement in material performance by optimizing the heat treatment and graphitization processes. During the heat treatment stage, the temperature is precisely controlled within the range of 800-1200°C. This temperature range ensures that the precursor material can fully react without violent decomposition, and provides the necessary thermal energy support for subsequent structural rearrangement. The heat treatment time is 2-8 hours, which not only ensures the adequacy of the reaction, but also avoids the increase in energy consumption and excessive material changes caused by too long a time. A programmed temperature rise method is adopted, and the heating rate is controlled at 2-10°C / min. Through the slow heating process, excessive thermal stress inside the material can be avoided, and the destruction of the crystal structure can be prevented. At the same time, it ensures that the reaction between the carbon source and the catalyst is more uniform, and promotes the structural order of the material.

[0024] During the graphitization stage, the temperature is strictly controlled between 2500-3000℃. The higher temperature causes the carbon atoms to rearrange and form a more regular graphite crystal structure, thereby improving the degree of graphitization of the material. The graphitization process lasts for 10-30 hours. The extension of time helps the migration and rearrangement of carbon atoms, further improving the orderliness of graphite crystals. During this process, inert gas protection is used to prevent the material from reacting with oxygen or other impurities in the environment, thereby ensuring the purity and stability of the material. In addition, operating at a pressure of 0.1-1.0MPa can accelerate the graphitization process and further enhance the electrical conductivity and thermal stability of the material. This optimization scheme makes the final material have excellent electrical conductivity and high temperature resistance, greatly expanding its application potential in electronic devices, energy storage equipment and other fields, while improving the long-term stability and service life of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A table parameter diagram of a preferred embodiment of the artificial graphite material and its preparation method and application provided by the present invention; DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0028] Example 1

[0029] An embodiment of the present invention provides an artificial graphite material and a preparation method and application thereof. The artificial graphite material and a preparation method and application thereof include the following steps:

[0030] Raw material ratio: carbon source: petroleum coke 90%, catalyst: nickel 3%, additive: silicon 7%.

[0031] Preparation steps:

[0032] Step S1: weighing raw materials according to the above weight percentage;

[0033] Step S2: Mix the raw materials evenly, and a high-speed mixer or a ball mill may be used for mixing;

[0034] Step S3: heat treating the mixture in an inert atmosphere (such as argon) at a temperature of 900°C for 4 hours at a heating rate of 5°C / min;

[0035] Step S4: graphitizing the precursor material obtained by heat treatment at high temperature, the temperature is 2800°C, the time is 15 hours, argon protection is used, and the pressure is 0.5MPa;

[0036] Step S5: Cooling, crushing and screening the graphitized material to obtain the final artificial graphite material.

[0037] Example 2

[0038] Raw material ratio: carbon source: needle coke 90%, catalyst: iron 5%, additive: boron 5%.

[0039] Preparation steps:

[0040] Step S1: weighing raw materials according to the above weight percentage;

[0041] Step S2: Mix the raw materials evenly, and a high-speed mixer or a ball mill may be used for mixing;

[0042] Step S3: heat treating the mixture in an inert atmosphere (such as nitrogen) at a temperature of 1000°C for 6 hours at a heating rate of 8°C / min;

[0043] Step S4: graphitizing the precursor material obtained by heat treatment at high temperature, the temperature is 2600°C, the time is 20 hours, nitrogen protection is used, and the pressure is 0.8MPa;

[0044] Step S5: Cooling, crushing and screening the graphitized material to obtain the final artificial graphite material.

[0045] Example 3

[0046] Raw material ratio: carbon source: asphalt coke 88%, catalyst: cobalt 4%, additive: phosphorus 8%.

[0047] Step S1: weighing raw materials according to the above weight percentage;

[0048] Step S2: Mix the raw materials evenly, and a high-speed mixer or a ball mill may be used for mixing;

[0049] Step S3: heat treating the mixture in an inert atmosphere (such as helium) at a temperature of 1100°C for 8 hours at a heating rate of 3°C / min;

[0050] Step S4: graphitizing the precursor material obtained by heat treatment at high temperature, the temperature is 2900°C, the time is 10 hours, helium protection is used, and the pressure is 0.3MPa;

[0051] Step S5: Cooling, crushing and screening the graphitized material to obtain the final artificial graphite material.

[0052] Through these examples 1-3, it can be seen that by finely adjusting the ratio of carbon source, catalyst and additive, and controlling the process conditions of heat treatment and graphitization, the structure and performance of artificial graphite materials can be effectively adjusted. Specifically, the selection of carbon source and the synergistic effect of catalyst determine the degree of graphitization, and the introduction of different additives can further optimize the key parameters such as conductivity, specific surface area and pore structure of the material. The process conditions such as temperature, time and atmosphere of heat treatment also significantly affect the crystal structure and interlayer spacing of graphite materials, which is directly related to its application performance in the field of energy storage. Therefore, through the precise control of the above variables, artificial graphite materials that meet different application requirements can be designed. For example, in lithium-ion batteries, such materials can effectively improve the cycle life and energy density of the battery; while in supercapacitors, artificial graphite can provide excellent fast charge and discharge performance and long life stability. These improvements not only expand the scope of application of artificial graphite materials in existing fields, but also provide new possibilities for the development of future energy storage technologies. 。

[0053] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An artificial graphite material and a preparation method thereof, characterized in that: The following steps are involved: Step S1; Weigh the raw materials according to weight percentage, carbon source 80%-95%, catalyst 1%-5%, additive 0%-10%; Step S2: Mix the raw materials evenly to obtain a mixture; Step S3: heat-treating the mixture under an inert atmosphere to obtain a precursor material; Step S4: graphitizing the precursor material at high temperature to obtain an artificial graphite material.

2. The artificial graphite material and its preparation method and application according to claim 1, characterized in that: The carbon source is one or more of petroleum coke, needle coke, and asphalt coke; the catalyst is one or more of iron, cobalt, and nickel; and the additive is one or more of silicon, boron, and phosphorus.

3. The artificial graphite material and its preparation method and application according to claim 2, characterized in that: The heat treatment temperature is 800-1200° C. and the time is 2-8 hours.

4. The artificial graphite material and its preparation method and application according to claim 3, characterized in that: The graphitization temperature is 2500-3000° C. and the time is 10-30 hours.

5. The artificial graphite material and its preparation method and application according to claim 4, characterized in that: During the heat treatment, a programmed temperature increase method is adopted, and the heating rate is 2-10°C / min.

6. The artificial graphite material and its preparation method and application according to claim 5, characterized in that: During the graphitization process, inert gas protection is used with a pressure of 0.1-1.0 MPa, and the inert gas includes but is not limited to one of argon and nitrogen.

7. An artificial graphite material, characterized in that: It is prepared by the method according to any one of claims 1 to 6.

8. The artificial graphite material according to claim 7, characterized in that: The true density of the artificial graphite material is 1.9-2.2 g / cm 3 , the porosity of artificial graphite material is 5-15%, and the electrical conductivity of artificial graphite material is 1000-2000S / m.

9. The artificial graphite material according to claim 8, characterized in that: The tensile strength of the artificial graphite material is 50-100 MPa, and the bending strength of the artificial graphite material is 80-150 MPa.

10. The artificial graphite material according to claim 9, characterized in that: The artificial graphite material is suitable for negative electrode materials of lithium ion batteries.

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