Artificial graphite and preparation method thereof, negative pole piece, battery and electric equipment

Abstract

The invention discloses artificial graphite and a preparation method thereof, a negative pole piece, a battery and electric equipment. The preparation method comprises the steps that raw materials are put into a graphitization furnace, the raw materials comprise carbon particles, the particle size of the carbon particles ranges from 1 cm to 8 cm, and the graphitization furnace works in the inert gas atmosphere; the raw materials are controlled to enter a preheating zone of the graphitization furnace, so that the raw materials are preheated, and the temperature of the preheating zone is 800-1500 DEG C; feeding the preheated material into a graphitization area of a graphitization furnace so as to carry out graphitization treatment on the preheated material; and feeding the graphitized material into a cooling area of the graphitization furnace so as to cool the graphitized material. In the implementation mode, the graphitization process is continuous, the procedures do not need to be stopped and switched, all the procedures are carried out in the same graphitization furnace, the production period is shortened, and the productivity can be improved.

Description

Artificial graphite and preparation method thereof, negative electrode sheet, battery and electrical equipment Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to artificial graphite and its preparation method, negative electrode sheet, battery and electrical equipment. Background Art

[0002] Due to their low cost, good thermal stability, and low volume expansion, graphite-based negative electrode materials will remain the mainstream negative electrode material for batteries, and will continue to be so for a long time to come. Graphite-based negative electrode materials are derived partly from natural graphite and partly from synthetic graphite. The production of synthetic graphite requires high-temperature graphitization of the carbon raw material, converting the carbon in the raw material into a layered graphite structure at high temperatures. Existing graphitization processes have long production cycles and high energy consumption. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art.

[0003] Summary of the Invention

[0004] The main technical problem solved by the present application is to provide an artificial graphite and its preparation method, a negative electrode plate, a battery and an electrical equipment, which can shorten the production cycle of artificial graphite and help improve production capacity.

[0005] To solve the above technical problems, a technical solution adopted in this application is: to provide a method for preparing artificial graphite, the preparation method comprising feeding raw materials into a graphitization furnace, the raw materials comprising carbon particles, the particle size of the carbon particles being 1cm-8cm, and the graphitization furnace operating under an inert gas atmosphere; controlling the raw materials to enter the preheating zone of the graphitization furnace to preheat the raw materials, the temperature of the preheating zone being 800℃-1500℃; sending the preheated materials into the graphitization zone of the graphitization furnace to graphitize the preheated materials; sending the graphitized materials into the cooling zone of the graphitization furnace to cool the graphitized materials. In this embodiment, the graphitization process is continuous, and there is no need to stop and switch between the processes. All processes are carried out in the same graphitization furnace, which shortens the production cycle and is conducive to increasing production capacity. Furthermore, regulating the particle size of the carbon raw material can improve the product yield of the graphitization process; regulating the preheating temperature can improve the product yield of the graphitization process and reduce energy consumption.

[0006] In one embodiment, the graphitization furnace is a vertical graphitization furnace, which utilizes gravity to sequentially guide the raw materials through the preheating zone, graphitization zone, and cooling zone. By using a vertical graphitization furnace, gravity is utilized to transport the materials, reducing the material transportation costs between processes and lowering energy consumption. This enhances process continuity, eliminating the need for intermediate stops or processing between processes, and allowing the materials to flow directly into the next process, shortening the production cycle. Furthermore, the preheated materials can be directly transferred to the high-temperature zone, eliminating the need for intermediate transfer, cooling, or rehydration, thereby improving process efficiency and reducing energy consumption.

[0007] In one embodiment, the volatile matter content of the carbon particles is less than 15% and the sulfur content is less than 10%. By restricting the volatile matter and sulfur content of the carbon raw material, the product yield of the graphitization process can be improved.

[0008] In one embodiment, the feed rate of the raw material is 200 kg / h-600 kg / h. This configuration can enhance the smoothness of the process and improve the product yield of the graphitization process.

[0009] In one embodiment, the preheating zone and graphitization zone are heated by electric heating, with the operating power of the electric heating device being 600kW-1500kW. This arrangement can reduce energy consumption while maintaining stable temperatures in the preheating zone and graphitization zone.

[0010] In one embodiment, the temperature of the preheating zone is 800° C.-1500° C. This configuration can reduce energy consumption and improve process safety while removing volatile matter from the raw materials.

[0011] In one embodiment, the pressure in the preheating zone is -10 Pa to -70 Pa. This configuration can accelerate the removal of volatiles, while reducing the amount of outside air entering the graphitization furnace, thereby reducing the probability of material oxidation and improving product purity.

[0012] In one embodiment, the temperature of the graphitization zone is 2800° C.-3200° C. This setting can achieve greater graphitization of the material and improve the graphitization degree of the product.

[0013] In one embodiment, the graphitization furnace operates under an inert gas atmosphere at a rate of 40-80 cubic meters per hour. The oxygen content within the graphitization furnace is 0.02%-0.5%. This configuration reduces the oxygen content within the graphitization furnace, lowering the likelihood of material oxidation, thereby increasing the graphitization yield and reducing the graphite specific surface area (BET).

[0014] In one embodiment, the materials are directly processed in the furnace of the graphitization furnace, and the preheating process of the raw materials also includes loosening the materials in the preheating zone. This arrangement can increase production capacity, improve product yield, and help extend the service life of the graphitization furnace.

[0015] In one embodiment, the material in the preheating zone is subjected to a first degree of dispersion without stopping the feeding and unloading of the material. This arrangement can increase production capacity, improve product yield, and help extend the service life of the graphitization furnace.

[0016] In one embodiment, while feeding is paused and unloading is maintained, the preheating zone is subjected to a second degree of dispersion treatment. The cleanliness of the preheating zone after the second degree of dispersion treatment is greater than that after the second degree of dispersion treatment. This arrangement can increase production capacity, improve product yield, and extend the service life of the graphitization furnace.

[0017] In one embodiment, the first degree of dispersion treatment has a treatment period of 8-12 hours. This configuration can increase production capacity, improve product yield, and help extend the service life of the graphitization furnace.

[0018] In one embodiment, the second degree of dispersion treatment has a treatment cycle of 5-7 days. This setting can increase production capacity, improve product yield, and help extend the service life of the graphitization furnace.

[0019] To solve the above technical problems, another technical solution adopted in this application is: to provide an artificial graphite prepared using any of the above embodiments, wherein the obtained artificial graphite has a high degree of graphitization, a low impurity content, and a small specific surface area.

[0020] In one embodiment, the specific surface area of ​​the artificial graphite is 1.01-1.12 m 2 / g, ash content is less than 0.015%, and graphitization degree is greater than 90%. It can improve the gram capacity and cycle stability of artificial graphite.

[0021] To solve the above technical problems, another technical solution adopted in this application is to provide a negative electrode plate, the negative electrode plate comprising a negative electrode active material, wherein the negative electrode active material comprises any of the artificial graphites described above. The resulting negative electrode plate has stable performance, high capacity, and long cycle life.

[0022] In order to solve the above technical problems, another technical solution adopted by this application is to provide a battery comprising the above negative electrode sheet. The obtained battery has stable performance, high capacity and long cycle life.

[0023] To solve the above technical problems, another technical solution adopted by the present application is to provide an electrical device comprising the above battery, which has at least the same advantages as the battery.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] FIG1 is a schematic diagram of a simplified structure of a continuous graphitization furnace according to one or more embodiments;

[0027] FIG2 is a schematic flow diagram of a method for preparing artificial graphite according to one or more embodiments;

[0028] FIG3 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0029] FIG4 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0030] FIG5 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0031] In the accompanying drawings: 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, end cover; 21a, electrode terminal; 22, shell; 23, electrode assembly; 30, continuous graphitization furnace; feed port 31; preheating zone 32; graphitization zone 33; cooling zone 34; discharge port 35; exhaust port 36. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and effect of this application clearer and more specific, the following embodiments of the technical solution of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0037] Amounts, ratios, and other numerical values ​​are presented herein in a range format. It should be understood that such range formats are for convenience and simplicity, and should be flexibly understood to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges encompassed within the range, as if each numerical value and subrange were explicitly specified. For example, if a range of 60-120 and 80-110 is listed for a particular parameter, it is contemplated that the range would be 60-110 and 80-120. In this application, unless otherwise specified, the numerical range "ab" represents an abbreviation for any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is simply an abbreviation for these numerical value combinations.

[0038] Unless otherwise specified, all steps of the present application may be performed sequentially, randomly, or in parallel, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially, or may include steps (a) and (b) performed simultaneously in parallel. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0039] During the production of graphite anode materials, the carbon raw material undergoes a high-temperature graphitization process, converting the carbon elements in the raw material into a layered graphite structure at high temperatures. This high-temperature graphitization treatment offers significant advantages, including high capacity, long cycle life, and stable performance. The graphitization process typically involves multiple steps, including preheating, high-temperature graphitization, and cooling. Existing graphitization processes require intermediate stops for transfer between each step, resulting in lengthy production cycles.

[0040] Please refer to Figures 1 and 2 . Figure 1 is a simplified schematic diagram of a continuous graphitization furnace according to one or more embodiments, and Figure 2 is a flow chart of a method for preparing artificial graphite according to one or more embodiments. This application provides a method for preparing artificial graphite, which utilizes a continuous graphitization furnace to graphitize carbon raw material to produce artificial graphite.

[0041] As shown in Figure 1, the continuous graphitization furnace 30 includes a feed port 31, a preheating zone 32, a graphitization zone 33, a cooling zone 34, a discharge port 35 and an exhaust port 36. The preheating zone 32 and the graphitization zone 33 are provided with heating devices to heat and heat the corresponding areas; the cooling zone 34 is provided with a condensing device to cool the corresponding areas. Figure 1 is only a simple schematic diagram of the graphitization furnace, which is intended to reflect the main functions of the graphitization furnace. The graphitization furnace actually used in industrial production also has other components not shown in the figure, such as valves for controlling feeding and discharging; similarly, the dimensions of the structures shown in the figure are not to scale, and the specific dimensions shall be subject to the actual product. This application does not limit the specific implementation method of the graphitization furnace, as long as the equipment can realize the process of this application, it can be used.

[0042] In this embodiment, the method for preparing artificial graphite includes:

[0043] S410: Adding raw materials into the graphitization furnace.

[0044] The materials can be loaded manually by workers or automatically loaded by connecting to loading equipment. This application does not limit the loading method.

[0045] S420: Control the raw materials to enter the preheating zone of the graphitization furnace to preheat the raw materials.

[0046] Preheating can remove moisture, volatile matter, ash, etc. from the raw materials, and can also remove other volatile impurities.

[0047] S430: The preheated material is fed into a graphitization zone of a graphitization furnace to graphitize the preheated material.

[0048] The temperature of the graphitization zone is higher than that of the preheating zone. The material is treated at high temperature in this zone so that the carbon element in the raw material is converted into a layered graphite structure at high temperature.

[0049] S440: sending the graphitized material into the cooling zone of the graphitization furnace to cool the graphitized material.

[0050] After graphitization is completed, it enters the cooling zone of the graphitization furnace for cooling, and the temperature gradually drops from a high temperature of about 3000℃ to below 300℃, and then the material is discharged. The material is discharged after cooling to prevent the high-temperature artificial graphite from being oxidized in the air.

[0051] In this embodiment, the graphitization process is continuous, and there is no need to stop for conversion between processes. All processes are carried out in the same graphitization furnace, which shortens the production cycle and is conducive to improving production capacity.

[0052] In one embodiment, the continuous graphitization furnace is a vertical graphitization furnace. In the vertical direction, the feed port 31, the preheating zone 32, the graphitization zone 33, the cooling zone 34, and the discharge port 35 are distributed in order from top to bottom, so that the material can pass through the preheating zone 32, the graphitization zone 33 and the cooling zone 34 in sequence under the action of gravity.

[0053] Specifically, the graphitization process provided herein involves feeding raw materials into a feed port. Once unloading begins, the materials automatically flow into a preheating zone 32 by gravity for preheating. The preheated materials then continue to move downward by gravity to a graphitization zone 33 for high-temperature graphitization. The graphitized materials then continue to move downward to a cooling zone 34 for discharge after cooling. In this process, the only requirement is to control the unloading rate and discharge cycle; all other steps are automatically performed within the graphitization furnace.

[0054] In this embodiment, by selecting a vertical graphitization furnace, gravity is used to realize material transportation; the consumption of material transportation between processes can be reduced, and energy consumption is reduced; the continuity between processes is enhanced, and there is no need for intermediate stops and intermediate processing between processes, and the next process can be directly entered, shortening the production cycle; further, the material after preheating treatment can directly enter the high-temperature zone without the need for intermediate transfer, reducing the cooling and moisture regain during the transfer process, improving the process efficiency, and reducing energy consumption.

[0055] In one embodiment, the raw material includes carbon particles, and the carbon particle raw material is petroleum coke particles or a bonded body of petroleum coke particles.

[0056] The particle size of the carbon particles is 1-8 cm, for example, the particle size can be 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, etc. If the particle size is too small, the contact surface of the particles is larger, making it easy for the material in the preheating zone 32 to coke, making it difficult to discharge volatile matter, and thus causing the furnace to burn; if the particle size is too large, the feeding process is not smooth, and the volatile matter inside the carbon particles is difficult to discharge.

[0057] Furthermore, the volatile content of the carbon particles is less than 18%. Volatile matter refers to the organic matter in the sample that is heated under specified conditions in an airtight state, and decomposes into a portion of liquid with a smaller molecular weight (in a vapor state at this time). The volatile content is less than 18%, optionally, the volatile content is less than 15%, and the volatile content is less than 13%; specifically, the volatile content can be less than 18%, 15%, 13%, 11%, 10%, 8%, 5%, etc. If the volatile content is too much, the preheating treatment time will be extended, and the excessive volatiles are not easy to discharge, resulting in excessive volatile content in the final product, affecting the purity of the artificial graphite, and further affecting the capacity and life of the graphite. Furthermore, if the volatiles in the carbon particle raw material are too much, it is easy to cause the material in the preheating zone 32 to coke, and the volatiles are difficult to discharge, which in turn leads to spraying of the furnace.

[0058] Furthermore, the sulfur content of the carbon particles is less than 10%; alternatively, the sulfur content is less than 8%; specifically, the sulfur content may be less than 10%, 9%, 8%, 7%, 6%, 5%, etc. Excessive sulfur content will prolong the preheating process and make it difficult to remove the excess sulfur, resulting in excessive sulfur content in the final product, affecting the purity of the artificial graphite and, in turn, the capacity and cycle life of the graphite.

[0059] In this embodiment, by restricting the particle size, volatile matter, and sulfur of the carbon raw material, the product yield of the graphitization process can be improved, and the operational safety of the production process can be improved. The carbon raw material can be purchased commercially or prepared by itself; before loading, the raw material needs to be tested to determine whether it meets the above-mentioned loading standards. If it does, it can be loaded directly. If it does not, the raw material needs to be pretreated until it meets the above-mentioned standards. For example, the particle size distribution can be controlled to be within 1cm to 8cm by screening with a sieve. In addition, before entering the furnace, a 1cm*1cm sieve can be used to sieve to remove fine powder to prevent fine powder from entering the furnace and causing coking.

[0060] In one embodiment, the temperature of the preheating zone is 800-1500° C. Optionally, the temperature of the preheating zone may be 1000-1200° C. Specifically, the temperature may be 800° C., 900° C., 1000° C., 1100° C., 1200° C., 1300° C., 1400° C., 1500° C., etc., or a range consisting of any two of the above values, for example, 800-1000° C., 1000-1200° C., 1200-1500° C., etc.

[0061] Preheating the raw materials removes moisture, volatile matter, ash, sulfur, and other volatile components. These volatile components are discharged through exhaust port 36. The discharged volatile matter, sulfur, and ash are drawn into the afterburning chamber for combustion and further drawn into the exhaust flue pipe, entering the exhaust gas treatment system.

[0062] Graphitization flue gas is generated in the graphitization furnace body. Once the temperature in the graphitization furnace body fluctuates greatly, the flue gas will be rapidly generated and gathered into larger flue gas clusters and flue gas layers, which will impact the graphitization material channel and become an unstable factor in the graphitization production process. It is very easy to cause the occurrence of furnace spraying accidents, which will bring serious safety hazards to production operators and seriously affect the normal progress of production.

[0063] In this embodiment, by controlling the temperature of the preheating zone, energy consumption can be reduced while removing volatiles from the raw materials. This improves process safety. If the preheating zone temperature is too low, the volatiles will be discharged at a reduced rate, which can easily lead to volatiles accumulating and coking in the preheating zone, which in turn cannot be discharged, causing the furnace to burn out. If the preheating zone temperature is too high, the life of the continuous graphitization furnace cover will be shortened, and more heat dissipated from the furnace cover will increase the energy consumption of the graphitization furnace.

[0064] In one embodiment, the pressure in the preheating zone is -10Pa to -70Pa, optionally, -30Pa to -50Pa. Specifically, it can be -10Pa, -20Pa, -30Pa, -40Pa, -50Pa, -60Pa, -70Pa, etc. Or it can be a range consisting of any two of the above values, for example, -10Pa to -30Pa, -30Pa to -50Pa, -50Pa to -70Pa, etc. By regulating the pressure in the preset zone, the removal of volatiles can be accelerated, and at the same time, the entry of external air into the graphitization furnace can be reduced, the probability of material oxidation can be reduced, and the purity of the product can be improved. If the negative pressure in the preheating zone is too low, the discharge rate of volatiles from the preheating zone is low, and it is easy to gather and coke in the preheating zone, and then it cannot be discharged, resulting in furnace spraying. If the negative pressure in the preheating zone is too high, it is easy to draw more air in from the gaps in the furnace wall, causing oxidation of the material in the furnace. The pressure in the preheating zone can be controlled by adjusting the frequency of the induced draft fan.

[0065] In one embodiment, the temperature of the graphitization zone is 2800-3200°C. Optionally, the temperature of the graphitization zone may be 2900-3100°C. Specifically, it may be 2800°C, 2900°C, 3000°C, 3100°C, 3200°C, etc., or a range consisting of any two of the above values, for example, 2800-2900°C, 2900-3000°C, 3000-3100°C, 3100-3200°C, etc. By regulating the temperature of the graphitization zone, the material can be graphitized to a greater extent.

[0066] In one embodiment, the preheating zone and the graphitization zone can be heated by electric heating, electromagnetic heating, etc. The transformer can be connected to the electrodes of the graphitization furnace, and the graphitization furnace can be powered on for electric heating. Controlling the output power of the transformer can control the heating effect. The power transmission (output of the transformer) of the graphitization furnace is 600kW-1500kW. Optionally, the power transmission power can be 800kW-1200kW. Specifically, the power transmission power can be 800kW, 900kW, 1000kW, 1100kW, 1200kW, 1300kW, 1400kW, 1500kW, etc. Or it can be a range consisting of any two of the above values, for example, 800kW-1000kW, 1000kW-1200kW, 1200kW-1500kW, etc. By controlling the power transmission power, energy consumption can be reduced while maintaining the temperature stability of the preheating zone and the graphitization zone. If the power supply is too low, the temperature inside the graphitization furnace will be too low, the graphitization effect will be limited, and the product graphitization degree and gram capacity will be low. If the power supply is too high, the temperature inside the graphitization furnace will be too high, the product graphitization degree and gram capacity will exceed the specifications, the furnace wall refractory temperature will be high, and the graphitization furnace life will be shortened. The power supply can be adjusted by adjusting the gear of the continuous graphitization furnace transformer.

[0067] In one embodiment, the graphitization furnace operates under an inert gas atmosphere. Specifically, nitrogen or argon is introduced as a protective gas into the preheating zone, high-temperature zone, buffer zone, and cooling zone of the graphitization furnace to prevent oxygen from entering. The inert gas atmosphere reduces the oxygen content in the graphitization furnace, lowering the likelihood of material oxidation, thereby increasing the graphitization yield and reducing the graphite specific surface area (BET).

[0068] In one embodiment, the inert gas is introduced at a rate of 40-80 cubic meters per hour; optionally 50-60 cubic meters per hour, specifically 40 cubic meters per hour, 50 cubic meters per hour, 60 cubic meters per hour, 70 cubic meters per hour, 80 cubic meters per hour, etc. Or it can be a range consisting of any two of the above values, for example, 40-50 cubic meters per hour, 50-60 cubic meters per hour, 60-70 cubic meters per hour, 70-80 cubic meters per hour, etc. If the protective gas introduction rate is too low, the protective effect is limited, the material is easily oxidized, resulting in a reduced yield and the product BET exceeding the specification. If the protective gas introduction rate is too high, the cost increases excessively and the gas pressure in the furnace is excessively high, which poses certain safety risks.

[0069] In one embodiment, the oxygen content in the graphitization furnace is 0.02%-0.5%. For example, it can be 0.02%, 0.05%, 0.10%, 0.15%, 0.25%, 0.30%, 0.40%, 0.50%, etc. The oxygen content in the graphitization furnace should be minimized to reduce the possibility of material oxidation, thereby increasing the graphitization yield and reducing the graphite specific surface area (BET).

[0070] The continuous graphitization process involves the continuous flow of materials, and smooth material flow is crucial. However, during the continuous graphitization process, the powder material has poor fluidity in the graphitization heat treatment channel, and powder accumulation leads to poor material permeability, resulting in high fluctuations in the removal of volatiles and flue gas emission rates, which in turn affects the stability of the flow field and temperature field of the graphitization furnace.

[0071] In one embodiment, after the raw materials are put into the feed port, the rate at which the raw materials are fed into the preheating zone can be controlled to regulate the reaction process. The feed rate of the raw materials is 200-600 kg / h, for example, 200 kg / h, 300 kg / h, 400 kg / h, 500 kg / h, 600 kg / h, etc. Or it can be a range consisting of any two of the above values, for example, 200-300 kg / h, 300-400 kg / h, 400-500 kg / h, 500-600 kg / h, etc. If the feed rate is too low, it is easy to cause coking of the material in the preheating zone, and the volatile matter is difficult to discharge, which leads to spraying of the furnace. If the feed rate is too high, the time for passing through the preheating section and the graphitization section is insufficient, the graphitization effect is insufficient, and the high discharge temperature causes oxidation of the finished graphite. If the feeding speed is too high, the volatile matter accumulated in the preheating zone will be too large, which will put a greater risk on the temperature resistance of the afterburning chamber and the flue gas treatment in the later stage. The feeding speed can be adjusted by adjusting the transformer gear of the continuous graphitization furnace.

[0072] In the above embodiments, the continuous graphitization furnace can perform high-temperature treatment and cooling of materials in different areas; compared to intermittent graphitization processes, it reduces energy consumption and shortens the production cycle to a certain extent. However, when some continuous graphitization furnaces perform high-temperature treatment on materials, crucibles and other containers are generally required to hold the materials. On the one hand, the containers occupy a certain amount of space, affecting production capacity; on the other hand, the containers will heat up and cool down together, increasing energy consumption. Furthermore, the containers have a certain sealing effect, which affects the discharge of volatile matter, ash, and sulfur during the graphitization process, resulting in a high impurity content in the graphitized product. Furthermore, crucibles and other containers are consumable parts and are frequently consumed, increasing production costs.

[0073] In the graphitization method provided by the present application, the material is reacted directly in the furnace of the graphitization furnace, and no containers such as crucibles are required, which reduces energy consumption and improves the purity of the obtained artificial graphite. As mentioned above, materials may coke and adhere to the furnace wall during the reaction. Among them, the preheating zone of the graphitization furnace is large, the material flow rate in this section is low, and the material near the periphery of the graphitization furnace basically does not flow, so coking is very likely to occur in this area. If the process conditions are not well controlled, the degree of coking will be greater. The presence of coking will occupy the furnace space, reduce production capacity, and may also introduce impurities, reduce product purity, etc. Based on this, the graphitization process provided by the present application will clean the furnace wall at regular intervals to remove coked substances.

[0074] In one embodiment, the graphitization process provided herein also loosens the material in the preheating zone. Specifically, this can be done by using a tool such as a crowbar to pry or pry to break up the coke. This can be accomplished by inserting a crowbar through an observation window or a dedicated loosening window in the preheating zone.

[0075] Among them, different degrees of loosening treatment can be carried out. Specifically, it includes the first degree of loosening treatment and the second degree of loosening treatment; the cleanliness of the preheating zone after the second degree of loosening treatment is greater than the cleanliness of the preheating zone after the first degree of loosening treatment. Cleanliness is used to measure the materials adhering to the furnace wall. It is better to have no adhering materials; if there is adhesion, smaller amounts, and looser materials are cleaner, and those that are not cleaned for a long time and coked and agglomerated are unclean. In other words, it can be done once or more times at a shorter time interval to remove a part of the coked materials that are not highly coked and are easier to remove; then, at a longer time interval, a more thorough cleaning can be done at a longer time interval to remove more stubborn coked materials.

[0076] In one embodiment, the material in the preheating zone is subjected to a first degree of loosening without stopping the feeding and unloading of materials. This operation has a relatively short cleaning time, does not substantially affect the normal operation of the graphitization furnace, and can be performed without stopping the graphitization furnace. The loosened material can then continue the preheating process and enter subsequent steps. This first degree of loosening operation is also referred to herein as "loosening furnace."

[0077] In one embodiment, the first degree of decomposition treatment is performed over a period of 8-12 hours. For example, the first degree of decomposition treatment may be performed every 8 hours. The treatment period may also be 8 hours, 9 hours, 10 hours, 12 hours, etc.

[0078] In one embodiment, while pausing the feeding and maintaining the unloading, the preheating zone is subjected to a second degree of dispersion treatment. The specific operation is as follows:

[0079] Maintain the graphitization furnace discharge, but stop feeding the graphitization furnace. At this time, the accumulated material in the graphitization furnace will gradually be discharged downward, including the slow-flowing or non-flowing material in the preheating zone and the coked coke. After the material in the preheating zone is basically emptied into the high-temperature zone, the graphitization furnace is fed again. New material will refill the preheating zone. The new material is not oxidized, has a low degree of powdering, and has a low tendency to coke, which can maintain normal and safe production of the graphitization furnace. The second level of loosening processing operation is also referred to as furnace unloading in this application.

[0080] In one embodiment, the second degree of decomposition treatment is performed for a period of 5-7 days. For example, the second degree of decomposition treatment may be performed every 5 days. The treatment period may also be 5 days, 6 days, 7 days, etc.

[0081] In this embodiment, by loosening the furnace and unloading the furnace, the process capacity can be increased and the product purity can be increased. If the furnace is not loosened or the frequency is too low, the long-term high-temperature oxidation in the preheating zone will aggravate the pulverization and coking of the preheating zone material, and the volatile matter is difficult to discharge, which will lead to the furnace spraying. If the frequency of loosening the furnace is too high, it will cause serious pulverization of the material surface, hindering gas circulation, which may cause the volatile matter to gather and coke, resulting in the risk of furnace spraying. If the furnace is not unloaded or the frequency of unloading the furnace is too low, the long-term high-temperature oxidation in the preheating zone will aggravate the pulverization and coking of the preheating zone material, and the volatile matter is difficult to discharge, which will lead to the furnace spraying. If the frequency of unloading the furnace is too high, the performance of the graphitization furnace discharge product is unstable and the life of the graphitization furnace is reduced.

[0082] In the above embodiments, the method for preparing artificial graphite provided by this application can rapidly complete the graphitization process of carbon raw materials with extremely low energy consumption, significantly improving production efficiency. The tail gas collection and treatment significantly reduces environmental pollution. Therefore, this process can be used to graphitize high-sulfur coke raw materials, which are difficult to use in traditional graphitization due to the difficulty of tail gas collection. This method has lower energy consumption, greater production capacity, and is more environmentally friendly.

[0083] The present application also provides an artificial graphite, which can be prepared, for example, according to any of the above embodiments. The obtained graphite has a high degree of graphitization, a small specific surface area, and a low ash content.

[0084] In one embodiment, the specific surface area of ​​the artificial graphite is 1.01-1.12 m 2 / g, for example, it can be 1.01m 2 / g, 1.02m 2 / g, 1.05m 2 / g, 1.08m 2 / g, 1.10m 2 / g, 1.12m 2 / g, etc. The obtained artificial graphite has a small specific surface area, which is beneficial to improving the energy density of the artificial graphite.

[0085] In one embodiment, the ash content of the artificial graphite is less than 0.015%, for example, 0.015%, 0.013%, 0.010%, 0.008%, 0.006%, 0.004%, 0.002%, etc. The low ash content of the obtained artificial graphite is beneficial to improving the capacity and stability of the artificial graphite.

[0086] In one embodiment, the degree of graphitization of the artificial graphite is greater than 90%, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, etc. The high degree of graphitization of the obtained artificial graphite is beneficial to improving the capacity and stability of the artificial graphite.

[0087] The present application also provides a negative electrode plate, comprising a negative electrode active material, wherein the negative electrode active material comprises artificial graphite prepared in any of the above embodiments. The obtained negative electrode plate has stable performance, high capacity, and long cycle life.

[0088] The negative electrode sheet includes a base layer and an active material layer.

[0089] Among them, the base layer is a conductive base layer, which can be used as a current collector and can be made of metal foil or composite materials. For example, it can be a composite conductive material formed by mixing a metal material with a polymer substrate. For example, aluminum foil can be used as the metal foil. The composite conductive material may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite conductive material can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.). The base layer can be in the shape of a cube, having a first surface and a second surface arranged opposite to each other along its thickness direction, so as to support the arrangement of other layer structures.

[0090] The active layer comprises at least an active material. The active layer can be a layered structure primarily composed of the active material, specifically a thin film. The active layer can be provided only on the first or second surface of the substrate, or on both surfaces. The active layer can be provided directly on the substrate, or a layer of other functional materials can be provided between the active layer and the substrate. The active layer is the primary structural layer of the electrode, fulfilling the basic functions of the battery.

[0091] The active layer may further include a binder, a conductive agent, and other optional additives. As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As an example, the binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As an example, other optional additives may be thickening and dispersing agents (e.g., sodium carboxymethyl cellulose CMC-Na), and PTC thermistor materials.

[0092] The present application also provides an electrochemical device, which includes any device that undergoes an electrochemical reaction. Specific examples include all types of primary batteries or secondary batteries. For example, these may be different types of secondary batteries, such as lithium batteries, sodium batteries, and potassium batteries. Lithium secondary batteries may include lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.

[0093] Please refer to Figure 3, which is a schematic diagram of the exploded structure of a battery according to one or more embodiments. Battery 100 includes a housing 10 and battery cells 20, with battery cells 20 housed within housing 10. Housing 10 provides storage space for battery cells 20 and can have various structures. In some embodiments, housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for battery cells 20. Second portion 12 can be a hollow structure with one end open. First portion 11 can be a plate-like structure, overlapping the open side of second portion 12, so that the first and second portions 11 and 12 together define a storage space. Alternatively, first portion 11 and second portion 12 can each be a hollow structure with one end open, with the open side of first portion 11 overlapping the open side of second portion 12. Housing 10 formed by first portion 11 and second portion 12 can have various shapes, such as a cylinder or a rectangular parallelepiped.

[0094] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0095] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0096] Please refer to Figure 4, which shows an exploded view of a battery cell according to one or more embodiments. A battery cell 20 is the smallest unit of a battery. As shown in Figure 4, a battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23, and other functional components.

[0097] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 for inputting or outputting electrical energy from the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0098] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0099] The electrode assembly 23 is a component in the battery cell 100 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0100] In one embodiment, the positive electrode sheet includes a current collector and a positive active layer disposed on the current collector.

[0101] The positive electrode active layer includes a positive electrode active material, and the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0102] In one embodiment, the positive electrode active layer also includes a conductive agent, thereby giving the electrode conductivity. The positive electrode conductive material can include any conductive material as long as it does not cause chemical changes. Non-limiting examples of positive electrode conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives) and mixtures thereof. Alternatively, the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black and acetylene black.

[0103] In one embodiment, the positive electrode active layer further includes a binder to improve the adhesion stability of the active layer and reduce the probability of powder shedding. The binder can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). Alternatively, the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0104] In one embodiment, the positive electrode active layer further includes other optional additives, which may be thickening and dispersing agents (such as sodium carboxymethyl cellulose CMC-Na) and PTC thermistor materials.

[0105] In some embodiments, the negative electrode sheet includes a current collector and a negative electrode active layer disposed on the current collector. The negative electrode active layer includes a negative electrode active material, and the negative electrode active material includes the graphite material prepared in any of the above embodiments.

[0106] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0107] In one embodiment, the electrolyte includes one or more of carbonate solvents and ether solvents.

[0108] Carbonates are generally small molecule cyclic or chain carbonates; including but not limited to one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methylpropyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and fluorocarbonates; and may also be at least one ester solvent selected from γ-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, and fluorocarboxylic acid esters.

[0109] Ether solvents include, but are not limited to, one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyltetrahydrofuran, ethylene oxide, 1,3-dioxolane, fluoroether, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether and dibutyl ether.

[0110] In other embodiments, the electrolyte may also include any one or a mixture of several of an amine solvent, a sulfone solvent, and a nitrile solvent. The amine solvent includes at least one of N-methylacetamide, N-methylformamide, dimethylformamide, and diethylformamide. The sulfone solvent includes at least one of dimethyl sulfoxide, cyclopentane sulfone, diphenyl sulfoxide, thionyl chloride, and dipropyl sulfone. The nitrile solvent includes at least one of acetonitrile, succinonitrile, adiponitrile, and glutaronitrile. The electrolyte is preferably a high-voltage resistant electrolyte, which has reduced acidity under high voltage, can facilitate the transmission of active ions, significantly reduce side reactions on the electrode surface, and improve battery stability.

[0111] In some embodiments, the electrolyte further includes an electrolyte salt, which can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0112] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0113] In some embodiments, the purpose of the electrochemical device of the present application is not particularly limited, and it can be used for any electronic device known in the prior art. The battery disclosed in the embodiment of the present application can be used for various energy storage systems using a battery as an electrical device for power supply or using a battery as an energy storage element. That is, a kind of electrical device is provided. In some embodiments, the electrical device of the present application can be used for, but not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a ship, a spacecraft, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large-scale household battery and a lithium-ion capacitor, etc.

[0114] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0115] Please refer to Figure 5, which is a schematic structural diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0116] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0117] The beneficial effects of the present application are further illustrated below with reference to the examples.

[0118] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0119] Example 1

[0120] Provide carbon particles, wherein the carbon particles have a volatile matter content of 10%, a sulfur content of 0.50%, and a particle size of 3 cm.

[0121] The carbon particles are put into the graphitization furnace for graphitization treatment. The temperature of the preheating zone of the graphitization furnace is 1000℃, the pressure of the preheating zone is -20Pa, and the amount of protective gas introduced into the graphitization furnace is 60m 3 / h; loosen the furnace every 8 hours and unload the furnace every 5 days.

[0122] Examples 2-5

[0123] Compared with Example 1, the graphitization process parameters were adjusted. Please refer to Table 1 for details.

[0124] Comparative Examples 1-4

[0125] Compared with Example 1, the graphitization process parameters were adjusted. Please refer to Table 1 for details.

[0126] Performance parameter test

[0127] (1) Volatile content test

[0128] Heat the sample to 850±10°C in the absence of air and hold for 7 minutes. Determine the volatile matter based on the difference between the total mass loss and the evaporated water content. For specific test methods, refer to SH / T 0026-90, "Determination of Volatile Matter in Petroleum Coke."

[0129] (2) Sulfur content test

[0130] The sulfur content in a sample is usually measured by infrared absorption, such as an infrared carbon-sulfur instrument, or by inductively coupled plasma emission spectrometry (GB / T24533-2019 ("Graphite-based Anode Materials for Lithium-ion Batteries" Appendix J). For example, a high-frequency induction furnace is used to burn the sample in oxygen to convert carbon and sulfur into CO2 and SO2. After entering the absorption cell, the detector converts the resulting signal into a corresponding signal. This signal is sampled by a computer and converted into a numerical value proportional to the CO2 and SO2 concentrations after linear correction. The values ​​obtained during the entire analysis process are then accumulated. After the analysis is completed, this accumulated value is divided by the weight value in the computer, multiplied by the correction factor, and the blank is subtracted to obtain the sulfur content in the sample.

[0131] (3) Coking degree

[0132] No coking: Insert the crowbar into the furnace through the observation hole, insert the crowbar into the material and pry it. The material is loose and there is almost no resistance when prying.

[0133] Slight coking: Insert the crowbar into the furnace through the observation hole, insert the crowbar into the material and pry it. If the material is slightly clumped, simply prying it can break up the lumps.

[0134] Moderate coking: Insert the crowbar into the furnace through the observation hole, insert the crowbar into the material and pry it. If there are many lumps in the material, the prying resistance will be greater. Prying multiple times can break up the lumps.

[0135] Severe coking: Insert the crowbar into the furnace through the observation hole, insert the crowbar into the material and pry it, but the material will be clumped together and difficult to pry.

[0136] (4) Graphitization degree test

[0137] The degree of graphitization can be measured using instruments and methods known in the art. For example, reference can be made to Appendix E of the national standard GB / T24533-2019, "Graphite Anode Materials for Lithium-ion Batteries." For example, the degree of graphitization G of the negative electrode active material is determined by automatically recording the carbon 002, 004, 110, and 112 diffraction line patterns using an XRD diffractometer, while simultaneously reading the diffraction angle (2θobs)c. The corrected diffraction angle (2θcor)c is then obtained using the internal standard method and substituted into the interplanar spacing formula to calculate the graphite interlayer spacing d002. The d002 data value is then substituted into the Mering-Maire formula: g = [(3.440-d002) / (3.440-3.354)]*100% to obtain the degree of graphitization G.

[0138] (5) Specific surface area test

[0139] According to GB / T 19587-2004 gas adsorption BET method, after the sample is heated and degassed, the adsorption amount of gas on the solid surface at different adsorption pressures is measured at a constant low temperature. The monolayer adsorption amount of the sample is obtained based on the BET multilayer adsorption theory and its formula, and the specific surface area per unit mass of the solid sample is calculated.

[0140] (6) Ash content test

[0141] Calcine the sample in a muffle furnace at 850°C ± 20°C. Ash and calcine to constant weight at the same temperature. Calculate the ash content based on the difference in mass before and after calcination. For specific testing methods, refer to SH / T 0029-90, "Determination of Ash Content in Petroleum Coke."

[0142] Table 1: Graphitization process parameters and artificial graphite performance parameters of various embodiments and comparative examples

[0143] From the data in Table 1, it can be seen that the process parameters in Examples 1-5 are set within the preferred range, there is basically no coking in the preheating zone during the process, the volatile matter is discharged relatively completely, and the obtained graphite material has a small specific surface area and a low ash content.

[0144] Comparing Example 1 with Comparative Examples 1-2, it can be seen that when the particle size of the raw materials is too small, the contact surface of the particles is larger, which makes the material in the preheating zone easily coke. When the particle size is too large, the feeding process is not smooth, and the volatile matter inside the carbon particles is difficult to discharge, resulting in a high ash content in the resulting graphite.

[0145] By comparing Example 1 with Comparative Example 3, it can be seen that if the temperature in the preheating zone is too low, the volatile matter discharge rate is reduced, which easily causes the volatile matter to aggregate and coke in the preheating zone, resulting in a higher ash content in the obtained graphite.

[0146] Comparison of Example 1 and Comparative Example 4 shows that, when there is no inert gas protection, the materials in the furnace are oxidized, resulting in an increase in the specific surface area of ​​the obtained graphite.

[0147] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing artificial graphite, characterized in that: include: Putting raw materials into a graphitization furnace, wherein the raw materials include carbon particles, and the particle size of the carbon particles is 1 cm-8 cm, and the graphitization furnace operates under an inert gas atmosphere; Controlling the raw material to enter the preheating zone of the graphitization furnace to preheat the raw material, the temperature of the preheating zone is 800° C.-1500° C.; The preheated material is fed into the graphitization zone of the graphitization furnace to graphitize the preheated material; The graphitized material is fed into the cooling zone of the graphitization furnace to cool the graphitized material.

2. The method for preparing artificial graphite according to claim 1, characterized in that: The graphitization furnace is a vertical graphitization furnace, and gravity is used to control the raw materials to pass through the preheating zone, the graphitization zone and the cooling zone in sequence.

3. The method for preparing artificial graphite according to claim 1 or 2, characterized in that: The volatile matter content of the carbon particles is less than 18%, optionally, less than 15%; The sulfur content of the carbon particles is less than 10%.

4. The method for preparing artificial graphite according to any one of claims 1 to 3, characterized in that: The step of controlling the raw material to enter the preheating zone of the graphitization furnace comprises: The feeding speed of the raw materials is 200Kg / h-600Kg / h.

5. The method for preparing artificial graphite according to any one of claims 1 to 4, characterized in that: The preheating zone and the graphitization zone are heated by electric heating, and the working power of the electric heating device is 600kW-1500kW.

6. The method for preparing artificial graphite according to any one of claims 1 to 5, characterized in that: The pressure of the preheating zone is -10Pa to -70Pa; and / or The temperature of the graphitization zone is 2800°C-3200°C.

7. The method for preparing artificial graphite according to any one of claims 1 to 6, characterized in that: The inert gas introduction rate is 40-80 cubic meters per hour; the oxygen content in the graphitization furnace is 0.02%-0.5%.

8. The method for preparing artificial graphite according to any one of claims 1 to 7, characterized in that: The material is directly processed in the furnace of the graphitization furnace, and the preheating process of the raw material also includes: loosening the material in the preheating zone.

9. The method for preparing artificial graphite according to claim 8, characterized in that: The loosening of the material in the preheating zone includes: Without stopping feeding and unloading, performing a first degree of dispersion treatment on the material in the preheating zone; and / or Under the condition of suspending feeding and maintaining unloading, the preheating zone is subjected to a second degree of dispersing treatment, and the cleanliness of the preheating zone after the second degree of dispersing treatment is greater than the cleanliness of the preheating zone after the second degree of dispersing treatment.

10. The method for preparing artificial graphite according to claim 9, characterized in that: The treatment period of the first degree of dispersion treatment is 8-12 hours; and / or The processing period of the second degree of disintegration treatment is 5-7 days.

11. An artificial graphite, characterized in that: The artificial graphite is prepared by the method for preparing the artificial graphite according to any one of claims 1 to 10.

12. The artificial graphite according to claim 11, characterized in that: The specific surface area of ​​the artificial graphite is 1.01-1.12m 2 / g; and / or The ash content of the artificial graphite is less than 0.015%; and / or The graphitization degree of the artificial graphite is greater than 90%.

13. A negative electrode plate, characterized in that: The invention comprises a negative electrode active material, wherein the negative electrode active material comprises the artificial graphite as claimed in claim 11 or 12.

14. A battery, characterized in that: Comprising the negative electrode sheet as described in claim 13.

15. An electrical equipment, characterized in that: Comprising the battery of claim 14.

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