Graphitization and high-carbon agent combined production method of lithium battery negative electrode material

Abstract

The application provides a graphitization and high-carbon agent combined production method of a lithium battery negative electrode material, and the method comprises the following steps: furnace loading: an Acheson graphitization furnace is used, pre-carbonized petroleum coke is filled in a graphite crucible, the graphite crucible is placed in the Acheson graphitization furnace in layers, and the graphite crucible is wrapped with a heat preservation material, and the D50 particle size of the heat preservation material is 1-5 mm calcined petroleum coke; power supply and temperature rising: the Acheson graphitization furnace is powered, and the pre-carbonized petroleum coke is heated to a graphitization temperature in a gradient heating mode; cooling: after heating is completed, power supply is stopped, and the pre-carbonized petroleum coke and the heat preservation material are naturally cooled in the furnace; and discharging: when the pre-carbonized petroleum coke is cooled to below 300 DEG C, the furnace is discharged, and the graphitized negative electrode material is obtained, and the high-carbon agent is obtained after the heat preservation material after graphitization is screened. The application not only realizes the graphitization and high-carbon agent combined production of the negative electrode material, but also obtains a high-value byproduct, the high-carbon agent.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a method for producing lithium battery anode materials by combining graphitization and high-carbonization. Background Technology

[0002] With the sustainable development of the national economy and society and the increasing demand for energy, lithium-ion batteries, as a new type of energy conversion device, have seen rapid development in the energy storage field and are being applied in many areas. From portable electronic products to power batteries, lithium-ion batteries are becoming increasingly widely used, and they offer advantages such as high energy density, long lifespan, and safety. The negative electrode material, as a key component of lithium-ion batteries, plays a decisive role in their performance. Currently, carbon materials, such as crystalline carbon and amorphous carbon, are still the main negative electrode materials for lithium-ion batteries. Among them, artificial graphite, a type of crystalline carbon, is gradually becoming the preferred negative electrode material for lithium-ion batteries. It possesses advantages such as high energy density, low voltage, good conductivity, abundant resources, and low price, and will remain the primary choice for LIB negative electrode materials for a long time to come.

[0003] The existing raw materials for graphite production include petroleum coke needle coke, coal-based needle coke, domestic coke, and imported coke. Among them, graphitization is the core process in the preparation of artificial graphite anode materials. Through graphitization, the hexagonal carbon atom planar grid is transformed from disordered overlap in two-dimensional space to ordered overlap in three-dimensional space. Graphitization can improve the thermal and electrical conductivity of carbon materials, reduce resistivity, and improve the purity and thermal conductivity of carbon materials, which to a certain extent determines the quality and stability of artificial graphite products.

[0004] Currently, the graphitization production of lithium-ion battery anode materials mostly uses Atchison graphitization furnaces. The anode material is filled into a graphite crucible, which is then placed inside the Atchison furnace. Calcined petroleum coke is used as insulation material around the crucible, forming a complete enclosure. The main functions of this insulation are: firstly, the calcined coke itself has a certain resistivity, serving as a carrier for electricity during heating in the graphitization furnace; and secondly, it isolates the material from air, enabling high-temperature heating in an oxygen-free environment to prevent oxidation of the material inside the crucible, while also providing insulation. However, after batch graphitization production, a small portion (approximately 20%) of the calcined coke used for insulation is reused as a cover on the furnace surface. The remaining portion, after being heated once at high temperatures during graphitization, has a resistivity approaching zero and cannot be reused as a resistive carrier for insulation. It is typically sold as low-value-added waste. Meanwhile, calcined petroleum coke, as an insulation material, consumes a certain proportion of heat energy during the graphitization production of anode materials, which means it consumes a certain amount of power energy. Secondly, its low fixed carbon content means it does not have high added value for external sale, and it is also impossible to realize the cost reduction and revenue increase benefits of calcined petroleum coke as a high added value by-product. As a result, the energy consumption cost of graphitization of anode materials is relatively high, and the cost of anode materials in graphitization production cannot be effectively reduced. Summary of the Invention

[0005] This application provides a method for combining graphitization and high-carbon agent production of lithium battery anode materials to solve the problems mentioned in the background art.

[0006] This application provides a method for producing lithium battery anode materials by combining graphitization and high-carbonization agents, comprising the following steps:

[0007] (1) Loading the furnace: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with insulation material, and the D50 particle size of the insulation material is calcined petroleum coke of 1-5mm.

[0008] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke and insulation material, wherein the pre-carbonized petroleum coke is heated to the graphitization temperature by gradient heating.

[0009] (3) Cooling: After heating is completed, power is stopped and the pre-carbonized petroleum coke and calcined petroleum coke are naturally cooled in the furnace.

[0010] (4) Discharge: When the pre-carbonized petroleum coke is cooled to below 300°C, it is discharged from the furnace layer by layer from top to bottom. After the graphitization process of the pre-carbonized petroleum coke through the electric heating step, the graphitized negative electrode material is obtained as a primary product. The graphitized insulation material is screened to obtain a high carbon agent.

[0011] Optionally, the gradient heating method includes the following stages:

[0012] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.2-2℃ / min.

[0013] The second stage: the temperature is increased from 1000-1200℃ to 2800-3200℃ at a heating rate of 1.05-1.85℃ / min.

[0014] Third stage: Maintain the temperature at 2800-3200℃ for 15-20 hours.

[0015] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0016] Optionally, the D50 particle size of the pre-carbonized petroleum coke is 10-25 μm.

[0017] Optionally, in the discharge step, the pre-carbonized petroleum coke is discharged from the furnace when it is cooled to 120-150℃.

[0018] Optionally, the insulation material is screened to obtain a high-carbon agent, including:

[0019] The graphitized insulation material after discharge is classified by particle size using a screening machine. The qualified material with a particle size of 1-5mm is used as raw material for high carbon agent or negative electrode material, while the unqualified material with the remaining particle size is recycled as insulation material.

[0020] Optionally, the weight ratio of pre-carbonized petroleum coke to calcined petroleum coke is 1:1.5-1.8.

[0021] Optionally, the production method may also include a graphitization post-processing step:

[0022] The graphitized anode material precursor is mixed with modified asphalt powder, the modified asphalt powder is coated on the surface of the graphitized anode material precursor, and then passed into an electric carbonization furnace for high-temperature carbonization to obtain the graphitized anode material finished product.

[0023] Optionally, the high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1150-1300℃.

[0024] Optionally, the weight of the modified bitumen powder added is 3%-10% of the initial graphitized anode material.

[0025] Optionally, the graphitized anode material primary product and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method or mechanical mixing method, in which the modified asphalt powder is coated onto the surface of the graphitized anode material primary product.

[0026] The method for combining graphitization and high-carbon agent production of lithium battery anode materials provided in this application not only achieves the combined production of graphitization and high-carbon agent for anode materials, but also obtains high-value by-product high-carbon agent. Compared with the prior art, it has the following beneficial effects:

[0027] (1) This application uses an Atchison graphitization furnace to strictly control the temperature of pre-carbonized petroleum coke by gradient heating to carry out the graphitization process, so that the structure of the pre-carbonized petroleum coke changes from the disordered overlap of the hexagonal carbon atom planar grid in two-dimensional space to the ordered overlap in three-dimensional space. The spacing between graphite layers gradually decreases, the thermal and electrical conductivity is improved, and the resistivity is reduced. When used in lithium battery anode materials, it helps to improve the charge and discharge capacity of lithium batteries and improve the service life of lithium batteries. Meanwhile, this province recommends using calcined petroleum coke with a D50 particle size of 1-5mm as the insulation material. The suitable particle size not only ensures good air permeability, but also allows for faster and smoother output of volatiles and sulfur from the insulation material through the negative pressure gas collection device at the top of the Atchison graphitization furnace at high temperatures. This helps reduce the volatiles and sulfur content in the insulation material, thereby significantly increasing the fixed carbon content. This increased fixed carbon content, in turn, enhances the utilization value of the graphitized insulation material as a byproduct, enabling it to be reused not only as insulation material but also as a high-carbon agent in various electric furnace smelting of cast steel and cast iron. Furthermore, the insulation material heats up quickly and evenly, providing better insulation for pre-carbonized petroleum coke anode materials. This avoids temperature differences between different parts of the anode material, contributing to a higher degree of graphitization, increasing the charge and discharge capacity of lithium batteries, and extending their lifespan.

[0028] (2) Strict temperature control not only improves the graphitization degree of the negative electrode material, which is beneficial to improving the charge and discharge capacity of lithium-ion batteries, but also, by controlling the temperature gradient in combination with the particle size of the insulation material, it is beneficial to the uniform heating of the insulation material, thereby improving the insulation performance of the insulation material for the negative electrode material. Furthermore, under the premise of ensuring safety and the quality of the negative electrode material, it allows the volatiles and sulfur in the insulation material to escape, resulting in high-value by-products, reducing production costs and increasing enterprise profits.

[0029] (3) After the graphitization process, the thermal insulation material releases volatiles and sulfur, reducing its content, while increasing its fixed carbon content, meeting the standards for use as a carbon raiser. The thermal insulation material is screened, and different particle sizes are stored separately and transported to different processes. For example, qualified materials with a particle size of 1-5mm are used as high-carbon raisers in the production process of carbon products such as casting and steelmaking, or are crushed and used as raw materials for negative electrode materials. Powder with a particle size of less than 1-5mm is treated as a low-value by-product.

[0030] (4) While ensuring the smooth and efficient graphitization process of the negative electrode material, this application increases the added value of the insulation material as a by-product, so that the insulation material can not only be reused multiple times as insulation material, but also be used as a carbon raiser for high-value external sales in the iron casting and steelmaking processes. Therefore, this application realizes the reduction of energy consumption cost in the graphitization process of the negative electrode material, thereby reducing the production cost of the negative electrode material. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.

[0032] This application provides a method for producing lithium battery anode materials by combining graphitization and high-carbonization agents, comprising the following steps:

[0033] (1) Loading the furnace: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with insulation material, and the D50 particle size of the insulation material is calcined petroleum coke of 1-5mm.

[0034] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke and insulation material, wherein the pre-carbonized petroleum coke is heated to the graphitization temperature by gradient heating.

[0035] (3) Cooling: After heating is completed, power is stopped and the pre-carbonized petroleum coke and calcined petroleum coke are naturally cooled in the furnace.

[0036] (4) Discharge: When the pre-carbonized petroleum coke is cooled to below 300°C, it is discharged from the furnace layer by layer from top to bottom. After the graphitization process of the pre-carbonized petroleum coke through the electric heating step, the graphitized negative electrode material is obtained as a primary product. The graphitized insulation material is screened to obtain a high carbon agent.

[0037] Specifically, in the production of lithium-ion battery anode materials, based on the different precursors, they are divided into carbon materials and non-carbon materials. Carbon materials include graphitized carbon materials, such as artificial graphite, natural graphite, carbon nanomaterials, and amorphous carbon materials. Among these, artificial graphite anode materials are produced by processing raw materials such as needle coke, petroleum coke, and pitch coke through crushing and granulation processes to obtain materials with a specific particle size distribution, followed by high-temperature graphitization to form a graphite sheet structure. Due to its excellent properties, artificial graphite can improve and increase the fast-charging performance and cycle life of lithium-ion batteries during processing, and has gradually become the mainstream anode material in recent years. During graphitization, the hexagonal carbon atom planar grid is transformed from a disordered overlap in two-dimensional space to an ordered overlap in three-dimensional space. The intermolecular spacing of graphite decreases, and the crystal structure becomes more ordered. This structure gives graphite materials better conductivity and cycle stability.

[0038] In the production of lithium-ion battery anode materials, the Atchison graphitization furnace is used for the graphitization process. Inside the Atchison graphitization furnace, graphite crucibles are arranged in layers and rows. Pre-carbonized petroleum coke is filled into the graphite crucibles, and calcined petroleum coke is used as insulation material to completely surround the graphite crucibles. Electricity is supplied to the Atchison graphitization furnace, and electrical energy is converted into heat energy through a resistance material to heat the material, allowing the pre-carbonized petroleum coke to undergo graphitization at high temperatures. The volatile matter content of the pre-carbonized petroleum coke is ≤1%. Simultaneously, the insulation material covering the outer surface of the graphite crucibles prevents the intake of oxygen from the air during high-temperature heating, thus preventing oxidation of the raw materials and graphite crucibles, and providing air isolation, heat insulation, and thermal insulation. After graphitization, the power to the Atchison graphitization furnace is turned off, allowing the material to cool naturally. When the temperature cools to below 300℃, the material is removed from the furnace, yielding the initial graphitized anode material. Since the insulation material is calcined petroleum coke, after graphitization, the volatiles in the calcined petroleum coke volatilize at high temperature and are collected and processed by the negative pressure gas collection device at the top of the Atchison graphitization furnace. Simultaneously, the sulfur in the calcined petroleum coke is also removed at high temperature, increasing the fixed carbon content and purifying the calcined petroleum coke. The high-carbon agent obtained by sieving the high-temperature graphitized calcined petroleum coke insulation material is used as a carbon raiser in various electric furnace smelting of cast steel and cast iron. The high-carbon agent in this application refers to insulation material with a fixed carbon content of over 99.5% after graphitization using the technical solution of this application. This insulation material is used as a carbon raiser in the steel smelting process. Because its fixed carbon content is higher than that of traditional graphitized insulation materials, it is called a high-carbon agent.

[0039] During the graphitization process, the temperature is strictly controlled using a gradient heating method to raise the pre-carbonized petroleum coke to the graphitization temperature, causing the pre-carbonized petroleum coke and the insulation material to undergo graphitization. This process not only transforms the internal structure of the pre-carbonized petroleum coke into graphitic carbon with a three-dimensional, regularly ordered graphite structure, making it suitable as a negative electrode material for lithium-ion batteries, but also significantly reduces the volatile matter and sulfur content of the insulation material, increasing its added value. After heating, the power supply is stopped, allowing the pre-carbonized petroleum coke and calcined petroleum coke to cool naturally in the furnace. When the pre-carbonized petroleum coke cools to below 300°C, it is removed from the furnace layer by layer from top to bottom. After the graphitization process involving the heating step, the pre-carbonized petroleum coke yields the initial graphitized negative electrode material. The insulation material is sieved, and different particle sizes are stored separately and transported to different processes. For example, some are used as insulation material, some are used as a high-carbon agent in the production of carbon products such as casting and steelmaking, and the smaller particles are processed as low-value by-products.

[0040] The thermal insulation material of this application comprises calcined petroleum coke with a D50 particle size of 1-5 mm. Calcined petroleum coke is a product of high-temperature calcination of petroleum coke, which removes some moisture, volatile matter, and sulfur, while simultaneously shrinking in volume and increasing in strength. When used as a thermal insulation material, it not only provides thermal insulation and electrical insulation but also reduces the emission of volatile matter and harmful substances, preventing the accumulation of large amounts of volatile matter during graphitization and thus avoiding safety accidents in the furnace. Furthermore, the particle size of the thermal insulation material plays a crucial role in the graphitization process of the negative electrode material and the quality of the graphitized insulation material. Compared to traditional graphitized insulation materials with a D50 particle size of 0-2mm, the insulation material used in this application has a D50 particle size of 1-5mm. During the graphitization process, the appropriate particle size not only ensures good air permeability, but also, combined with the gradient heating method during graphitization, facilitates smoother and more efficient exhaust during high-temperature graphitization. This allows the volatiles and sulfur in the insulation material to be output more quickly and smoothly through the negative pressure gas collection device at the top of the Atchison graphitization furnace, avoiding furnace spraying caused by excessively small particle size and poor air permeability. This helps reduce the volatiles and sulfur in the insulation material, thereby significantly increasing the fixed carbon content. The increased fixed carbon content further enhances the usability of the graphitized insulation material as a by-product. Because the insulation material has increased fixed carbon content, reduced sulfur content, and increased strength after the graphitization process, it can not only be reused as insulation material, but also used as a carbon raiser in the production processes of carbon products such as casting and steelmaking. Meanwhile, the suitable particle size allows for faster heating during the graphitization process of the insulation material, resulting in more uniform heating and higher temperature consistency. This helps the insulation material reach the required temperature as quickly as possible, improving the efficiency of converting electrical energy into heat energy, saving energy consumption, and reducing production costs. Furthermore, the insulation material provides better insulation for pre-carbonized petroleum coke anode materials. The uniform temperature distribution of the insulation material promotes even heating of the anode material, avoiding temperature differences between different parts of the anode material. This contributes to increasing the degree of graphitization, transforming the anode material into graphitic carbon with a three-dimensional, ordered graphite structure. The amorphous, disordered carbon structure is transformed into an ordered graphitic crystalline structure. The interlayer spacing of the graphite in the anode material gradually decreases, improving thermal and electrical conductivity and reducing resistivity. When subsequently used as a lithium battery anode material, this helps improve the charge and discharge capacity of lithium batteries and extend their lifespan. However, excessively large particle size in insulation materials leads to high heat loss, increasing the electrical energy required for heating and reducing the electrical energy consumption of the anode material. To maintain the same output of anode material, increased power output is necessary, resulting in excessive energy consumption, higher production costs, and ultimately, reduced economic benefits for the company. Therefore, the appropriate particle size of insulation materials plays a crucial role in the quality of both the anode and insulation materials.

[0041] This application utilizes an Atchison graphitization furnace to strictly control the temperature of pre-carbonized petroleum coke through a gradient heating process, thereby transforming the structure of the pre-carbonized petroleum coke from a disordered two-dimensional overlap of hexagonal carbon atom planar grid to an ordered three-dimensional overlap. The interlayer spacing of the graphite gradually decreases, resulting in improved thermal and electrical conductivity and reduced resistivity. When subsequently used as a negative electrode material for lithium batteries, this helps to improve the charge and discharge capacity of lithium batteries and extend their service life. Meanwhile, this province recommends using calcined petroleum coke with a D50 particle size of 1-5mm as the insulation material. The suitable particle size not only ensures good air permeability, but also allows for faster and smoother output of volatiles and sulfur from the insulation material through the negative pressure gas collection device at the top of the Atchison graphitization furnace at high temperatures. This helps reduce the volatiles and sulfur content in the insulation material, thereby significantly increasing the fixed carbon content. This increased fixed carbon content, in turn, enhances the utilization value of the graphitized insulation material as a byproduct, enabling it to be reused not only as insulation material but also as a high-carbon agent in various electric furnace smelting of cast steel and cast iron. Furthermore, the insulation material heats up quickly and evenly, providing better insulation for pre-carbonized petroleum coke anode materials. This avoids temperature differences between different parts of the anode material, contributing to a higher degree of graphitization, increasing the charge and discharge capacity of lithium batteries, and extending their lifespan. Compared to the traditional graphitization process of anode materials, this application ensures the smooth and efficient graphitization process of anode materials while increasing the added value of insulation materials as by-products. This allows the insulation materials to not only be reused multiple times as insulation materials, but also to be sold as carbon raisers in casting, steelmaking, ironmaking, or carbon product processes with high added value. Therefore, this application reduces the spread of energy consumption costs during the graphitization process of anode materials, thereby reducing the production cost of anode materials.

[0042] Optionally, the gradient heating method includes the following stages:

[0043] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.2-2℃ / min.

[0044] The second stage: the temperature is increased from 1000-1200℃ to 2800-3200℃ at a heating rate of 1.05-1.85℃ / min.

[0045] Third stage: Maintain the temperature at 2800-3200℃ for 15-20 hours.

[0046] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0047] Specifically, this application employs a gradient heating method to strictly control the graphitization temperature during the graphitization process. The process, from the start of power supply to the cessation of heating, is divided into four stages. The first and second stages are the heating stages, the third stage is the heat preservation stage, and the fourth stage is the cooling stage after the heating process ends and power is cut off. In the first stage, the temperature is increased from room temperature to 1000-1200℃ at a rate of 1.2-2℃ / min. In the second stage, the temperature is increased from 1000-1200℃ to 2800-3200℃ at a rate of 1.05-1.85℃ / min. The heating rate in the first stage is lower than that in the second stage. At the start of power supply, the heating rate is lower because the high-temperature escape of inorganic sulfur causes crystal expansion. An excessively rapid heating rate would cause the furnace core temperature to rise too quickly, leading to cracks in the negative electrode material. This not only negatively impacts the quality of the negative electrode material but may also cause the heat preservation material to heat up too quickly, resulting in rapid release of volatiles and sulfur, potentially causing furnace blowouts and endangering the environmental safety of the production site. The room temperature refers to the temperature of the production site, which is -50 to 50°C. The specific temperature is determined by the actual working environment and is not specifically limited in this application.

[0048] The second stage involves heating from 1000-1200℃ to 2800-3200℃ at a rapid rate. During this process, the physical structure and chemical composition of the pre-carbonized petroleum coke undergo significant changes. The disordered layer structure of amorphous carbon gradually transforms into a graphite crystal structure. Simultaneously, unstable low-molecular-weight hydrocarbons and impurity element groups bound at the edges of the amorphous carbon microcrystalline structure continuously decompose and escape, generating structural defects and leading to relatively concentrated thermal stress, making it highly susceptible to cracking and scrap. Strict control of the heating rate in this stage is crucial to mitigate the effects of thermal stress, prevent excessive stress concentration, and avoid cracking of the negative electrode material. The third stage maintains the temperature at 2800-3200℃ to further enhance the graphitization degree of the negative electrode material, improve its lithium intercalation capability, and increase its capacity. After high-temperature graphitization, power is cut off, allowing the materials inside the furnace to cool naturally. This strict temperature control not only improves the graphitization degree of the negative electrode material but also contributes to increasing the charge and discharge capacity of the lithium-ion battery. At the same time, gradient temperature control combined with the particle size of the insulation material is conducive to uniform heating of the insulation material, thereby improving the insulation performance of the insulation material for the negative electrode material. It also allows the volatiles and sulfur in the insulation material to escape while ensuring safety and the quality of the negative electrode material, resulting in high-value by-products, reducing production costs and increasing corporate profits.

[0049] Furthermore, in the second stage of heating, the temperature is increased from 1000-1200℃ to 2000-2200℃ at a rate of 1.05-1.6℃ / min, and then from 2000-2200℃ to 2800-3200℃ at a rate of 1.3-1.85℃ / min. In this second stage, the heating rate gradually increases from 1000-1200℃ to 2000-2200℃. During this process, the disordered layer structure of amorphous carbon tends to gradually transform into the crystalline structure of graphite electrodes. Simultaneously, unstable low-molecular-weight hydrocarbons and impurity element groups bound at the edges of the amorphous carbon microcrystalline structure continuously decompose and escape, generating structural defects and easily leading to cracked and defective products. Furthermore, volatiles and sulfur in the insulation material escape. Strictly controlling the heating rate in this stage is beneficial for the smooth transformation of the anode material's crystal structure and for increasing the fixed carbon content of the insulation material. By raising the temperature from 2000-2200℃ to 2800-3200℃, the crystal structure of the anode material is basically formed. The increased heating rate allows the anode material to reach the graphitization temperature more quickly, reducing the graphitization cycle, improving the efficiency of converting electrical energy into heat energy, reducing production costs, and improving the quality and value of the anode material and insulation material as by-products.

[0050] Optionally, the D50 particle size of the pre-carbonized petroleum coke is 10-25 μm.

[0051] Specifically, the smaller the particle size of the anode material, the smaller the van der Waals forces that need to be overcome during lithium-ion intercalation, making intercalation easier. Furthermore, smaller particles result in shorter channels for lithium-ion intercalation and deintercalation, which is more conducive to quickly achieving a fully intercalated lithium state, thus giving the lithium-ion battery better charge-discharge performance. Smaller graphite anode particles have a larger initial capacity, but also a larger irreversible capacity; as the particle size increases, the initial charge-discharge capacity decreases, and the irreversible capacity also decreases. Simultaneously, smaller anode material particles have a larger specific surface area in contact with the electrolyte, resulting in more charge consumed by the SEI film formed during the initial charge-discharge process, and thus greater irreversible capacity loss. Therefore, a reasonable particle size distribution can not only improve the initial capacity and initial efficiency of lithium-ion batteries but also enhance their cycle performance.

[0052] Optionally, in the discharge step, the pre-carbonized petroleum coke is discharged from the furnace when it is cooled to 120-150℃.

[0053] Specifically, when the pre-carbonized petroleum coke exits the furnace at a high temperature, it is easily oxidized, resulting in a large specific surface area. At the same time, the graphite crucible is also prone to oxidation. If the pre-carbonized petroleum coke exits the furnace at a low temperature, it will also result in a large specific surface area, but it will also lead to a longer cooling time and a longer production cycle, thereby increasing production costs.

[0054] Optionally, the insulation material is screened to obtain a high-carbon agent, including:

[0055] The graphitized insulation material after discharge is classified by particle size using a screening machine. The qualified material with a particle size of 1-5mm is used as raw material for high carbon agent or negative electrode material, while the unqualified material with the remaining particle size is recycled as insulation material.

[0056] Specifically, after the graphitization process, the thermal insulation material releases volatiles and sulfur, reducing their content, while increasing its fixed carbon content, meeting the standards for use as a carbon raiser. The thermal insulation material is sieved, and different particle sizes are stored separately and transported to different processes. For example, qualified material with a particle size of 1-5mm is used as a high-carbon agent in the production of carbon products such as casting and steelmaking, or it can be crushed and used as raw material for negative electrode materials, or it can be recycled as thermal insulation material. Powder with a particle size smaller than 1-5mm is treated as a low-value by-product. The high-carbon agent in this application refers to thermal insulation material with a fixed carbon content of 99.5% or higher after the graphitization process according to the technical solution of this application. This thermal insulation material is used as a carbon raiser in the steelmaking process. Because its fixed carbon content is higher than that of traditional graphitized thermal insulation materials, it is called a high-carbon agent.

[0057] Optionally, the weight ratio of pre-carbonized petroleum coke to calcined petroleum coke is 1:1.5-1.8.

[0058] Specifically, calcined petroleum coke is used as an insulation material during the graphitization process to keep the pre-carbonized petroleum coke anode material warm and air-isolated. Excessive use of calcined petroleum coke will require more electrical energy to heat both the pre-carbonized and calcined petroleum coke, while insufficient use will result in poor insulation of the anode material.

[0059] Meanwhile, using the appropriate amount of calcined petroleum coke, along with its particle size and gradient heating rate, as a heat-insulating material not only achieves the heat-insulating effect on the negative electrode material, but also makes the graphitization temperature of the negative electrode material rise more rapidly and the temperature distribution more uniform, thus improving the graphitization effect of the negative electrode material. This is beneficial for the internal structure of the negative electrode material to change from disordered overlap in two-dimensional space to ordered overlap in three-dimensional space, and for the graphite interlayer spacing to gradually decrease and become uniform, thereby improving the charge and discharge capacity of the negative electrode material when used in lithium-ion batteries.

[0060] Optionally, the method may also include a graphitization post-processing step:

[0061] The graphitized anode material precursor is mixed with modified asphalt powder, the modified asphalt powder is coated on the surface of the graphitized anode material precursor, and then passed into an electric carbonization furnace for high-temperature carbonization to obtain the graphitized anode material finished product.

[0062] Specifically, after graphitization, the specific surface area of ​​pre-carbonized petroleum coke anode material increases, and the surface pores enlarge, resulting in cracks. This is detrimental to the rapid and stable charge and discharge of lithium-ion batteries. Therefore, by coating the surface of the graphitized anode material with modified asphalt powder, the modified asphalt powder fills the pores and cracks, repairing them and forming a uniform anode material with good plasticity and a certain degree of density. Simultaneously, it reduces the specific surface area of ​​the graphitized anode material, decreases the active ends on the surface, and improves its conductivity as an anode material. Then, high-temperature carbonization yields the finished graphitized anode material, which improves the charge and discharge capacity of the finished graphitized anode material when used in lithium-ion batteries and enhances the stability of the lithium-ion battery during the charge and discharge process.

[0063] The modified asphalt powder has a particle size of 10-25μm, which is similar to that of the graphitized anode material. This facilitates the uniform mixing of the graphitized anode material and the modified asphalt powder. It also helps the modified asphalt powder soften and coat the surface of the graphitized anode material during high-temperature carbonization, repairing the pores and cracks in the graphitized anode material and improving its conductivity as an anode material.

[0064] Optionally, the high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1150-1300℃.

[0065] Specifically, high-temperature carbonization facilitates the decomposition of unstable substances and allows modified asphalt powder to form an amorphous carbon coating layer on the surface of the graphitized negative electrode material. When used in lithium-ion batteries, this prevents direct contact and reaction between the negative electrode metal and the electrolyte, ensuring stable operation and extending the battery's lifespan. Simultaneously, the modified asphalt powder also enhances the battery's mechanical strength.

[0066] Optionally, the weight of the modified bitumen powder added is 3%-10% of the initial graphitized anode material.

[0067] Specifically, the higher the content of modified asphalt powder, the greater the density of the surface coating layer of the graphitized anode material, which can better protect the anode metal and also enhance mechanical strength. However, if the content of modified asphalt powder is too high, it will affect the conductivity of the lithium-ion battery, leading to a decrease in battery performance.

[0068] Optionally, the graphitized anode material primary product and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method or mechanical mixing method, in which the modified asphalt powder is coated onto the surface of the graphitized anode material primary product.

[0069] Specifically, the Tanggula T-MIX powder surface coating method employs an atomization coating process, in which solid modified asphalt powder is atomized and then mixed for coating. The modified substrate contains multiple hot air turbulence systems, which allow for better dispersion of the graphitized anode material, resulting in a more uniform bond with the atomized modified asphalt powder. Mechanical mixing refers to mixing graphite powder and asphalt powder together at high speed to complete the coating. This application, by using modified asphalt powder for coating, has minimal impact on the particle size of the initial graphitized anode material and achieves more uniform coating. In specific operations, the coating method is selected based on actual working conditions. Modified asphalt powder coating improves the compatibility between the graphitized anode material and the electrolyte. It reduces the specific surface area of ​​the graphitized anode material, thereby improving the initial charge reversible capacity and cycle stability.

[0070] The technical solution of this application will be illustrated in detail below with specific embodiments.

[0071] Example 1

[0072] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0073] (1) Loading the furnace: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with heat-insulating material. The D50 particle size of the heat-insulating material is 1mm of calcined petroleum coke, and the D50 particle size of the pre-carbonized petroleum coke is 10-25μm. The weight ratio of pre-carbonized petroleum coke to calcined petroleum coke is 1:1.5.

[0074] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0075] The gradient heating method includes the following stages:

[0076] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.2℃ / min.

[0077] The second stage involves heating from 1000-1200℃ to 2800-3200℃ at a heating rate of 1.05℃ / min.

[0078] Third stage: Maintain the temperature at 2800-3200℃ for 15 hours.

[0079] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0080] (3) Cooling: After heating is completed, power is stopped and the pre-carbonized petroleum coke and calcined petroleum coke are naturally cooled in the furnace.

[0081] (4) Discharge: When the pre-carbonized petroleum coke is cooled to below 300°C, it is discharged from the furnace layer by layer from top to bottom. After the graphitization process of the pre-carbonized petroleum coke through the electric heating step, the graphitized negative electrode material is obtained as a primary product. The graphitized insulation material is classified by particle size through a screening machine. The qualified material with a particle size of 1-5mm obtained by screening is used as a raw material for high carbon agent or negative electrode material, and the unqualified material with the remaining particle size is recycled as insulation material.

[0082] Example 2

[0083] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0084] The difference from Example 1 is that:

[0085] (1) Furnace loading: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with heat-insulating material. The heat-insulating material has a D50 particle size of 3mm for calcined petroleum coke and a D50 particle size of 10-25μm for pre-carbonized petroleum coke. The weight ratio of pre-carbonized petroleum coke to calcined petroleum coke is 1:1.7.

[0086] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0087] The gradient heating method includes the following stages:

[0088] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0089] The second stage: the temperature is increased from 1000-1200℃ to 2800-3200℃ at a heating rate of 1.5℃ / min.

[0090] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0091] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0092] Example 3

[0093] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0094] The difference from Example 1 is that:

[0095] (1) Furnace loading: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with heat-insulating material. The heat-insulating material has a D50 particle size of 5mm for calcined petroleum coke and a D50 particle size of 10-25μm for pre-carbonized petroleum coke. The weight ratio of pre-carbonized petroleum coke to calcined petroleum coke is 1:1.8.

[0096] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0097] The gradient heating method includes the following stages:

[0098] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 2℃ / min.

[0099] The second stage: the temperature is increased from 1000-1200℃ to 2800-3200℃ at a heating rate of 1.85℃ / min.

[0100] Third stage: Maintain the temperature at 2800-3200℃ for 20 hours.

[0101] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0102] Example 4

[0103] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0104] The difference from Example 2 is that:

[0105] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0106] The gradient heating method includes the following stages:

[0107] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0108] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.05℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.3℃ / min.

[0109] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0110] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0111] Example 5

[0112] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0113] The difference from Example 2 is that:

[0114] (1) The D50 of the thermal insulation material is calcined petroleum coke with a particle size of 4 mm.

[0115] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0116] The gradient heating method includes the following stages:

[0117] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0118] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.3℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.5℃ / min.

[0119] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0120] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0121] Example 6

[0122] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0123] The difference from Example 2 is that:

[0124] (1) The D50 of the thermal insulation material is calcined petroleum coke with a particle size of 4.5 mm.

[0125] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0126] The gradient heating method includes the following stages:

[0127] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0128] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.6℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.85℃ / min.

[0129] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0130] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0131] Example 7

[0132] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0133] The difference from Example 2 is that:

[0134] (1) The D50 of the thermal insulation material is calcined petroleum coke with a particle size of 5mm.

[0135] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0136] The gradient heating method includes the following stages:

[0137] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0138] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.05℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.85℃ / min.

[0139] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0140] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0141] Example 8

[0142] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0143] The difference from Example 7 is that:

[0144] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0145] The gradient heating method includes the following stages:

[0146] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0147] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.05℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.85℃ / min.

[0148] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0149] Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours.

[0150] After exiting the furnace, the graphitized anode material precursor and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method. The modified asphalt powder is coated onto the surface of the graphitized anode material precursor, which is then passed into an electric carbonization furnace for high-temperature carbonization to obtain the finished graphitized anode material. The high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1150℃. The weight of the modified asphalt powder added is 3% of the graphitized anode material precursor, and the particle size of the modified asphalt powder is 10-25μm.

[0151] Example 9

[0152] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0153] The difference from Example 8 is that:

[0154] After exiting the furnace, the graphitized anode material precursor and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method. The modified asphalt powder is coated onto the surface of the graphitized anode material precursor, which is then passed into an electric carbonization furnace for high-temperature carbonization to obtain the finished graphitized anode material. The high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1200℃. The weight of the modified asphalt powder added is 7% of the weight of the graphitized anode material precursor.

[0155] Example 10

[0156] The combined production method of graphitization and high-carbon agent for lithium battery anode materials in this embodiment operates as follows:

[0157] The difference from Example 8 is that:

[0158] After exiting the furnace, the graphitized anode material precursor and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method. The modified asphalt powder is coated onto the surface of the graphitized anode material precursor, which is then passed into an electric carbonization furnace for high-temperature carbonization to obtain the finished graphitized anode material. The high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1300℃. The weight of the modified asphalt powder added is 10% of the weight of the graphitized anode material precursor.

[0159] Comparative Example 1

[0160] The difference from Example 9 is that:

[0161] (1) Furnace loading: calcined petroleum coke with a D50 particle size of 0.5mm for insulation material.

[0162] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0163] The gradient heating method includes the following stages:

[0164] First stage: Increase the temperature from room temperature to 1100-1300℃ at a heating rate of 2℃ / min.

[0165] The second stage: the temperature is increased from 1100-1300℃ to 1800-2000℃ at a heating rate of 3℃ / min.

[0166] The third stage: the temperature is increased from 1800-2000℃ to 2800-3000℃ at a heating rate of 1℃ / min.

[0167] Comparative Example 2

[0168] The difference from Example 9 is that:

[0169] (1) Furnace loading: calcined petroleum coke with a D50 particle size of 0.5mm for insulation material.

[0170] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0171] The gradient heating method includes the following stages:

[0172] First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.6℃ / min.

[0173] The second stage involves raising the temperature from 1000-1200℃ to 2000-2200℃ at a rate of 1.05℃ / min, and then raising it from 2000-2200℃ to 2800-3200℃ at a rate of 1.85℃ / min.

[0174] Third stage: Maintain the temperature at 2800-3200℃ for 17 hours.

[0175] Comparative Example 3

[0176] The difference from Example 9 is that:

[0177] (1) Furnace loading: Calcinated petroleum coke with a D50 particle size of 5mm for insulation material.

[0178] (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke to the graphitization temperature in a gradient heating manner.

[0179] The gradient heating method includes the following stages:

[0180] First stage: Increase the temperature from room temperature to 1100-1300℃ at a heating rate of 2℃ / min.

[0181] The second stage: the temperature is increased from 1100-1300℃ to 1800-2000℃ at a heating rate of 3℃ / min.

[0182] The third stage: the temperature is increased from 1800-2000℃ to 2800-3000℃ at a heating rate of 1℃ / min.

[0183] Experimental Example 1

[0184] The degree of graphitization, specific surface area, and initial discharge capacity of the lithium-ion battery anode materials prepared using the technical solutions provided in Examples 1 to 10 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1. Each experiment was performed at least three times, and the average value was taken. The testing was based on the national standard GB / T 24533-2019, entitled "Graphite Anode Materials for Lithium-ion Batteries".

[0185] Table 1

[0186]

[0187]

[0188] As observed in Table 1, compared to Comparative Examples 1 to 3 and Examples 1 to 3, Examples 4-7 showed a significant improvement in graphitization degree, initial discharge capacity, and initial efficiency. This indicates that the lithium-ion anode materials produced in Examples 4-7 have a lower amorphous carbon content, higher crystallinity, and a more ordered crystal structure. This improves the thermal conductivity and electrical conductivity of the lithium-ion anode materials. Increased electrical conductivity increases the contact area between the electrode and the electrolyte, thereby improving the charge / discharge rate and cycle life of the lithium-ion battery. It also enhances the mechanical properties of the lithium-ion anode materials. Furthermore, in Examples 8-10, it is evident that the specific surface area of ​​the lithium-ion anode materials decreased. This is because after high-temperature graphitization, modified asphalt powder was coated onto the surface of the graphitized anode material precursor. The modified asphalt powder filled the pores and cracks in the precursor, repairing them and reducing the specific surface area. This reduces the active ends on the surface of the graphitized anode material precursor, improving its electrical conductivity as an anode material. A small specific surface area in lithium-ion anode materials helps improve battery energy density because more lithium ions can be stored per unit volume. Furthermore, a small specific surface area also improves the safety performance of lithium-ion batteries. If the specific surface area is too large, a large amount of Li-ion... + Embedded on the surface of the negative electrode material, its initial efficiency is low.

[0189] Furthermore, comparing Examples 4 to 10 with Examples 1 and 3, it can be seen that although the degree of graphitization of the thermal insulation material is improved when the D50 particle size is 1-5 mm compared with the comparative example, more preferably, when the D50 particle size of the thermal insulation material is 3-5 mm, the degree of graphitization, first discharge capacity and first efficiency of the lithium-ion anode material are better.

[0190] Experiment Example 2

[0191] The sulfur content and fixed carbon content of the calcined petroleum coke insulation materials prepared using the technical solutions provided in Examples 1 to 10 and Comparative Examples 1 to 3 were tested according to the industry standard YB / T 192-2015, entitled "Carbonizer for Steelmaking". Power consumption for each production run was also recorded. The results are shown in Table 2.

[0192] Table 2

[0193] Fixed carbon content / % Sulfur content / % Power consumption per ton of product (kWh / t) Example 1 99.52 0.04 4430 Example 2 99.51 0.042 4439 Example 3 99.56 0.04 4456 Example 4 99.62 0.032 4025 Example 5 99.65 0.036 4102 Example 6 99.67 0.028 4169 Example 7 99.62 0.033 4012 Example 8 99.61 0.035 4165 Example 9 99.66 0.034 4205 Example 10 99.63 0.038 4214 Comparative Example 1 93.2 0.64 8136 Comparative Example 2 94.1 0.59 8022 Comparative Example 3 93.8 0.56 8041

[0194] Table 2 clearly shows that the fixed carbon content of the insulation materials obtained through the graphitization process in Examples 1 to 10 is significantly higher than that in Comparative Examples 1 to 3, and the sulfur content is also lower. Furthermore, the gradient heating during the graphitization process in Examples 4 to 10 was further precisely controlled, resulting in a further increase in the fixed carbon content and a significant reduction in sulfur content in the insulation materials. This indicates that the appropriate particle size of the insulation material not only provides good air permeability, but also, combined with the gradient heating method during graphitization, facilitates smoother and more efficient exhaust during high-temperature graphitization. This allows for faster and more efficient release of volatiles and sulfur from the insulation material at high temperatures, thereby significantly increasing the fixed carbon content. This increased fixed carbon content, in turn, enhances the usability of the graphitized insulation material as a byproduct. Because the graphitization process increases the fixed carbon content, reduces sulfur content, and increases strength, the insulation material can not only be reused as insulation material but also used as a carbon additive in the production processes of carbon products such as casting and steelmaking. Compared to industry standards for steelmaking recarburizers, which require a fixed carbon content ≥95% and a sulfur content ≤0.2%, the present application achieves a fixed carbon content of over 99.5% and a sulfur content ≤0.045%, far exceeding the industry standards for steelmaking recarburizers. This indicates that the insulation material produced during the graphitization process of this application can not only be used as a recarburizer in the steelmaking and ironmaking industries, but also as a recarburizer in the production process of carbon products such as casting, or as a raw material for the deep processing of energy storage materials such as battery anode materials. Compared to the traditional graphitization process of lithium-ion anode materials, the insulation material, a byproduct of the graphitization process in this application, has higher added value. This reduces the average energy consumption and production cost in the production of lithium-ion anode materials. Furthermore, comparing Examples 4 to 10 with Examples 1 and 3, it can be seen that although the fixed carbon content is increased when the D50 particle size of the thermal insulation material is 1-5 mm compared with the comparative example, more preferably, when the D50 particle size of the thermal insulation material is 3-5 mm, the fixed carbon content of the lithium-ion anode material is higher and the sulfur content is lower. This indicates that the effect of the gradient heating rate of this application is better when the D50 particle size of the thermal insulation material is 3-5 mm.

[0195] Meanwhile, the electricity consumption during production in Examples 1 to 10 was also greatly reduced, indicating that the gradient heating process of this application not only achieves graphitization of the negative electrode material, but also helps to reduce power consumption and save energy. Moreover, under long-term operation, it saves a lot of costs for enterprise production.

[0196] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for producing a lithium battery anode material by combining graphitization and high-carbonization agent, characterized in that, Includes the following steps: (1) Loading the furnace: Using an Atchison graphitization furnace, pre-carbonized petroleum coke is loaded into a graphite crucible, and then the graphite crucible is placed in the Atchison graphitization furnace in layers and rows. The graphite crucible is completely wrapped with heat-insulating material, and the D50 particle size of the heat-insulating material is calcined petroleum coke of 1-5mm. (2) Powering on and heating: Powering on the Atchison graphitization furnace to heat the pre-carbonized petroleum coke and the insulation material, wherein the pre-carbonized petroleum coke is heated to the graphitization temperature in a gradient heating manner. The gradient heating method includes the following stages: First stage: Increase the temperature from room temperature to 1000-1200℃ at a heating rate of 1.2-2℃ / min; The second stage: the temperature is increased from 1000-1200℃ to 2000-2200℃ at a heating rate of 1.05-1.6℃ / min, and then from 2000-2200℃ to 2800-3200℃ at a heating rate of 1.3-1.85℃ / min. Third stage: Maintain the temperature at 2800-3200℃ for 15-20 hours; Fourth stage: Power supply is stopped, and the pre-carbonized petroleum coke and the calcined petroleum coke enter the natural cooling stage, which takes 10-15 hours. (3) Discharge: When the pre-carbonized petroleum coke is cooled to below 300°C, it is discharged from the furnace layer by layer from top to bottom. After the graphitization process of the pre-carbonized petroleum coke in the heating step, the graphitized negative electrode material is obtained as a primary product. The graphitized insulation material is then classified by particle size using a screening machine. The qualified material with a particle size of 1-5mm obtained by screening is used as a raw material for high carbon agent or negative electrode material, while the unqualified material with the remaining particle size is recycled as insulation material. The weight ratio of the pre-carbonized petroleum coke to the calcined petroleum coke is 1:1.5-1.8; The method further includes a graphitization post-processing step: The graphitized anode material precursor is mixed with modified asphalt powder, the modified asphalt powder is coated on the surface of the graphitized anode material precursor, and then passed into an electric carbonization furnace for high-temperature carbonization to obtain the graphitized anode material finished product.

2. The method for producing lithium battery anode materials by combining graphitization and high-carbonization agent production according to claim 1, characterized in that, The D50 particle size of the pre-carbonized petroleum coke is 10-25 μm.

3. The method for producing lithium battery anode materials by combining graphitization and high-carbonization agents according to claim 1, characterized in that, In the discharge step, the pre-carbonized petroleum coke is discharged from the furnace when it is cooled to 120-150°C.

4. The method for producing lithium battery anode materials by combining graphitization and high-carbonization agent production according to claim 1, characterized in that, The high-temperature carbonization time is 3-5 hours, and the high-temperature carbonization temperature is 1150-1300℃.

5. The method for producing lithium battery anode materials by combining graphitization and high-carbonization agent production according to claim 4, characterized in that, The weight of the modified asphalt powder added is 3%-10% of the initial graphitized anode material.

6. The method for producing lithium battery anode materials by combining graphitization and high-carbonization agent according to claim 5, characterized in that, The graphitized anode material primary product and modified asphalt powder are mixed using the Tanggula T-MIX powder surface coating method or mechanical mixing method, in which the modified asphalt powder is coated onto the surface of the graphitized anode material primary product.

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