Graphitization heating device and process for lithium ion battery negative electrode material

Abstract

This invention relates to the technical field of graphitization heating devices for lithium-ion battery anode materials. It includes a base, a heating chamber, a furnace, and a heating furnace. The heating chamber is located on top of the base, and the furnace and heating furnace are located above it for graphitization operations. The heating furnace includes a first, second, and third heating furnace: the first heating furnace is in zone A of the furnace, simulating small-batch production in a box furnace to ensure high-precision testing; the second heating furnace is in zone B, simulating batch production in a crucible furnace to achieve high-consumption testing; and the third heating furnace is in zone C, simulating multi-variable comparative production to help find the optimal formula. The furnace and heating chamber contain heating elements and insulation layers to provide a high-temperature environment. A ventilation system is installed around the furnace for rapid cooling and timely product removal. This device can perform zoned heating, improving energy utilization, meeting various heating needs, and effectively solving the current problem of low graphitization yield.

Description

Technical Field

[0001] This invention relates to the field of technology, and in particular to a heating device and process for graphitizing lithium-ion battery anode materials. Background Technology

[0002] Graphite-based materials are the mainstream choice for anodes in commercial lithium-ion batteries. Graphitization is a key step in optimizing their performance. Heating devices, as core equipment, directly affect the production quality, capacity, and cost of anode materials. Developing efficient and low-cost heating devices is an urgent need in the industry.

[0003] Currently, the commonly used heating equipment in graphitization processes are box furnaces and crucible furnaces, both of which have significant drawbacks:

[0004] Box furnaces: These use a single furnace body structure, which can only create a single temperature field and cannot perform zoned heating. If materials with different temperature requirements need to be processed simultaneously, multiple machines are required, increasing costs and floor space. Currently, the average production cost in the industry is about 8,000 yuan / ton. Although the cost is relatively low, the low capacity utilization and poor flexibility restrict large-scale cost reduction.

[0005] Crucible furnaces: While multiple crucibles increase material throughput, they consume significant amounts of heat, and temperature dead zones can easily form inside the furnace, necessitating higher heating power and resulting in high energy consumption per unit. The industry average production cost reaches 12,000 yuan / ton, far exceeding that of box furnaces, limiting their large-scale application due to energy costs.

[0006] The industry has attempted nested heating devices, but they have encountered technical bottlenecks: poor heat insulation between large and small furnace bodies, mutual heat penetration leading to unstable and uneven temperature distribution; significant heat loss, low energy utilization, and energy costs even higher than traditional equipment, making it impossible to achieve energy conservation and cost reduction. In summary, existing heating equipment has poor functional adaptability, high cost, and high energy consumption, making it difficult to meet the needs of efficient zoned heating. Developing a multifunctional heating device that nests small furnace bodies within a large furnace body, allows for precise temperature control, provides uniform heat distribution, and is low in cost is an urgent need to drive technological upgrades in the industry. Summary of the Invention

[0007] The purpose of this invention is to provide a heating device and process for graphitizing lithium-ion battery anode materials, which can achieve zoned heating, improve energy utilization, and meet various heating requirements, especially solving the problem of low graphitization yield.

[0008] The technical implementation scheme of the present invention is as follows:

[0009] A graphitization heating device for lithium-ion battery anode materials includes a base, a heating chamber, a furnace, and a heating furnace. The heating chamber is located on the upper part of the base, and the furnace and heating furnace are located on the upper part of the heating chamber for graphitization operations. The heating furnace includes a first heating furnace, a second heating furnace, and a third heating furnace. The first heating furnace is located in area A inside the furnace and is used to simulate small-batch graphite production in a box furnace to ensure high-precision testing. The second heating furnace is located in area B inside the furnace and is used to simulate batch production in a crucible furnace to ensure high-consumption testing. The third heating furnace is located in area C inside the furnace and is used to simulate multi-variable comparative production to find the optimal formula. Heating elements and insulation layers are installed inside the furnace and heating chamber to provide a high-temperature heating environment. A ventilation system is provided around the furnace to regulate the surrounding airflow and ensure rapid cooling and timely product removal.

[0010] Preferably, the first heating furnace includes a first furnace body and a first sealing cover. The first furnace body is a cylindrical cavity structure with an open top, and the first sealing cover is provided on the first furnace body. The first sealing cover is provided with a first air outlet. The first furnace body is located in a first connection port inside the furnace, and the bottom of the first furnace body is connected to a second heater inside the heating chamber for directional heating.

[0011] Preferably, the second heater includes a heating box, a heating tank, a heating ring, and a first connecting hole. The heating ring is disposed in the connecting port of the heating tank, and the heating box is provided with a connecting hole for secondary heating of the bottom and sides of the first furnace body. The heating box is provided with a plurality of first connecting holes, and an electric heating rod is disposed in the first connecting hole for primary heating.

[0012] Preferably, the second heating furnace includes a second furnace body, a storage chamber, and a second sealing cover. The second furnace body is a cylindrical cavity structure with one end open, and the interior of the second furnace body is provided with a plurality of storage chambers. The upper part of the second furnace body is provided with a second sealing cover, and the upper part of the second sealing cover is provided with a second air outlet.

[0013] Preferably, the third heating furnace is horizontally arranged in the placement chamber inside the furnace, and the placement chamber is provided with an arc-shaped receiving block; the bottom of the third heating furnace is provided with a third heater, the interior of the third heater is provided with a heating plate, and the third heater is provided with a plurality of second connecting holes, and electric heating rods are provided in the second connecting holes.

[0014] Preferably, the first heating furnace, the second heating furnace, and the third heating furnace are connected by filling auxiliary materials to form a nested heating system, which improves the fixing and heat preservation effect; the electric heating rod is fixedly connected to the interior of the heating chamber through a connecting bracket.

[0015] Preferably, the outer wall of the heating chamber is provided with several air inlets, and the two ends of the heating chamber are provided with air outlets, each with a guide fan. A support plate is provided on the upper part of the furnace, and the support plate is connected to an external air purification unit through an air guide pipe to form independent exhaust. The other end of the air guide pipe is connected to a first air outlet on the first sealing cover to exhaust the flue gas.

[0016] A graphitization process based on the apparatus of claim 1 includes the following steps:

[0017] S1, Equipment and Material Pretreatment

[0018] 1.1 Check the condition of the large furnace body: Confirm that the heating elements such as the graphite rod at the bottom of the heating chamber, the second heater, and the third heater are undamaged, the bottom air inlet filter is clean, and the top exhaust equipment and the furnace body exhaust pipe are sealed; check the integrity of the large furnace body insulation layer to ensure there is no risk of heat leakage.

[0019] 1.2 Selection and preparation of small furnace: Select the corresponding type of heating furnace according to the type of material to be graphitized and the production simulation scenario, and clean the inner cavity of the small furnace to ensure that there are no residual impurities; if a third heating furnace is selected, the inner cavities corresponding to different raw materials to be tested should be clearly marked and distinguished.

[0020] 1.3 Material pretreatment: The material to be graphitized is ground and granulated according to the process requirements, the particle size is controlled, and its exhaust section is connected to the gas guide pipe;

[0021] S2. Charging the heating furnace and filling auxiliary materials

[0022] 2.1 Heating Furnace Positioning and Installation: According to the heating zone requirements of the furnace and kiln, install the heating furnace into the slot of the furnace and kiln receiving platform, ensuring that the bottom of the heating furnace fits snugly against the furnace and kiln connection port;

[0023] 2.2 Filling and fixing of auxiliary materials: Fill the gaps between the heating furnace and the inner wall of the furnace, and between the heating furnace and the connection port with auxiliary materials. During the filling process, gently compact the materials to ensure that the auxiliary materials fill the gaps, thereby fixing the heating furnace and transferring heat evenly. At the same time, prevent the auxiliary materials from entering the heating furnace exhaust hole or coming into direct contact with the materials.

[0024] S3, Setting heating parameters and raising temperature of the large furnace body

[0025] 3.1 Heating system startup: Connect the power supply equipment inside the heating chamber, set the basic heating temperature of the graphite rod at the bottom of the large furnace body through the main controller, and adjust the power of the corresponding first heater and second heater individually according to the process requirements of each small furnace body;

[0026] 3.2 Staged Heating: A staged heating mode is adopted. In the first stage, the temperature is increased to 1000℃ at a rate of 50-80℃ / h and held for 2-3 hours. In the second stage, the temperature is increased to the target graphitization temperature at a rate of 30-50℃ / h and held for 10-15 hours to ensure that the material is fully graphitized. During the heating process, the internal temperature of each heating furnace is monitored in real time by temperature sensors. If the temperature difference exceeds 20℃, the corresponding heater is finely adjusted in time.

[0027] S4, Exhaust and Insulation Control

[0028] 4.1 Exhaust system linkage: After the temperature is raised to 500℃, start the exhaust fan at the top of the furnace and set it to run for 5 minutes every 30 minutes. Small molecule impurities and waste gas volatilized from the material are collected in the main exhaust pipe through the exhaust pipe of the heating furnace and discharged after being treated by the terminal waste gas treatment unit. At the same time, natural air is made up by the air inlet at the bottom of the large furnace.

[0029] 4.2 Monitoring during the heat preservation stage: During the heat preservation period at the target temperature, the power of the heating elements is kept stable, and the overall temperature of the large furnace body and the internal temperature of each small furnace body are recorded every 1 hour;

[0030] S5. Cooling and Product Removal

[0031] 5.1 Staged cooling: After the graphitization insulation is completed, first turn off the heater, keep the bottom graphite rod running at low power, and cool down to 1000℃ at a rate of 100-150℃ / h. Then turn off the bottom graphite rod, start the top exhaust fan and bottom vent, and cool down to room temperature at a rate of 200-250℃ / h. The entire cooling process lasts 30-45 days.

[0032] 5.2 Removal of Heating Furnace and Sample Processing: After cooling is completed, first shut off the exhaust system, disconnect the main exhaust pipe from the heating furnace, and clean the auxiliary materials filling the furnace; use a special hook to hook the lifting lug on the top of the heating furnace and remove the small furnace body from the connection port; open the furnace crucible cover, clean the attached negative electrode powder, remove the surface product with a stainless steel spoon, take the mixed product powder in the middle section as the test sample, and complete the graphitization process.

[0033] The present invention has the following advantages:

[0034] 1. In this invention, the interior of the furnace is divided into three zones: Zone A, Zone B, and Zone C. Different heating furnaces are installed in each zone for different graphitization applications. The heating furnaces include a first heating furnace, a second heating furnace, and a third heating furnace, which can be installed as needed. Each heating furnace is adapted to different requirements. The first heating furnace is used to simulate small-batch graphite production in a box furnace to ensure high-precision testing. The second heating furnace is horizontally positioned to simulate multi-variable comparative production to find the optimal formula. The third heating furnace is horizontally positioned inside the furnace to simulate batch production in a crucible furnace, ensuring high unit consumption testing.

[0035] 2. In this invention, the second heating furnace is provided with multiple storage chambers for storing different raw materials and simultaneously testing the graphitization of different raw materials, thus achieving simultaneous testing.

[0036] 3. The graphitization process of this invention relies on a device structure consisting of a large furnace and nested small furnaces, resulting in a simple and efficient operation process: On the one hand, through independent loading and zoned temperature control of the heating furnace, graphitization tests of multiple raw materials can be completed simultaneously in the same furnace without the need for multiple start-ups and shutdowns of the large furnace, significantly shortening the test cycle; on the other hand, the bottom graphite rod provides basic high temperature, and the annular heating ring provides precise heat supplementation. Combined with the auxiliary material filling and directional exhaust design, it can ensure that the materials in the heating furnace are heated evenly, reducing defective products caused by temperature differences, and also reducing heat loss and exhaust gas interference. At the same time, the small furnace is easy to disassemble and assemble, adapting to the simulation needs of different production scenarios, taking into account both efficiency and practicality. Attached Figure Description

[0037] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0038] Figure 2 This is a top view of the present invention.

[0039] Figure 3 This is a schematic diagram of the internal structure of the heating chamber of the present invention.

[0040] Figure 4 This is a schematic diagram of the electric heating rod part of the present invention.

[0041] Figure 5 This is a schematic diagram of the furnace / kiln section of the present invention.

[0042] Figure 6 This is a schematic diagram of the structure of the second heating furnace part of the present invention.

[0043] Figure 7 This is a schematic diagram of the structure of the first heating furnace part of the present invention.

[0044] Figure 8 This is a schematic diagram of the structure of the second heater part of the present invention.

[0045] The meanings of the reference numerals in the attached diagram are as follows: 1-base, 2-heating chamber, 3-air inlet, 4-guide fan, 5-first heating furnace, 501-first furnace body, 502-first sealing cover, 503-first air outlet, 6-second heating furnace, 601-second furnace body, 602-storage chamber, 603-second sealing cover, 604-second air outlet, 8-third heating furnace, 9-second heater, 901-heating box, 902-first connecting hole, 903-connection port, 904-connection hole, 905-heating ring, 10-third heater, 11-connecting bracket, 12-electric heating rod, 13-placement chamber, 14-arc-shaped receiving block, 15-first connection port, 16-support plate, 18-furnace. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0047] Example 1:

[0048] like Figures 1-8 As shown, a graphitization heating device for lithium-ion battery negative electrode materials includes a base 1, a heating chamber 2, a furnace 18, and a heating furnace. The heating chamber 2 is located on the upper part of the base 1, and the furnace 18 and heating furnace are located on the upper part of the heating chamber 2 for graphitization operations. The heating furnace includes a first heating furnace 5, a second heating furnace 6, and a third heating furnace 8. The first heating furnace 5 is located in area A inside the furnace 18 and is used to simulate small-batch graphite production in a box furnace to ensure high-precision testing. The second heating furnace 6 is located in area B inside the furnace 18 and is used to simulate multivariate comparative production to find the optimal formula. The third heating furnace 8 is located in area C inside the furnace 18 and is used to simulate batch production in a crucible furnace to ensure high-consumption testing. Heating elements and insulation layers are installed inside the furnace 18 and the heating chamber 2 to provide a high-temperature heating environment. A ventilation system is provided around the furnace 18 to regulate the surrounding airflow and ensure rapid cooling and timely product removal.

[0049] It should be noted that a heating chamber 2 is provided on the upper part of the base 1, and a furnace 18 and a heating furnace are provided on the upper part of the heating chamber 2. The furnace 18 is heated by the heating system inside the heating chamber 2, and the heating furnace is heated. The furnace 18 is a large furnace body and the heating furnace is a small furnace body. The structure of a large furnace body with a small furnace body can be used to independently load materials and control the temperature in different zones. The graphitization test of multiple raw materials can be completed simultaneously in the same large furnace without having to start and stop the large furnace many times, which greatly shortens the test cycle.

[0050] It should be further explained that the first heating furnace 5 is set in area A inside the furnace 18 and can be installed arbitrarily as needed. It is used to simulate small-batch graphite production in a box furnace to ensure high-precision testing. The second heating furnace 6 is set in area B and has multiple storage chambers 602 inside. It is used to add different materials to simulate multi-variable comparative production and find the optimal formula. The third heating furnace 8 is laid horizontally inside the furnace 18 and is used to simulate batch production in a crucible furnace. It can be selected and used as needed.

[0051] like Figures 1-8 As shown, the first heating furnace 5 includes a first furnace body 501 and a first sealing cover 502. The first furnace body 501 is a cylindrical cavity structure with an open top, and the first sealing cover 502 is provided on the first furnace body 501. The first sealing cover 502 is provided with a first air outlet 503. The first furnace body 501 is located in the first connection port 15 inside the furnace 18, and the bottom of the first furnace body 501 is connected to the second heater 9 inside the heating chamber 2 for directional heating. The second heater 9 includes a heating box 901, a heating groove 901, a heating ring 905, and a first connection hole 902. The heating ring 905 is located in the connection port 903 of the heating groove 901, and the heating box 901 is provided with a connection hole 904 for secondary heating of the bottom and sides of the first furnace body 501. The heating box 901 is provided with a plurality of first connection holes 902, and the first connection holes 902 are provided with electric heating rods 12 for primary heating.

[0052] It should be noted that the upper part of the first furnace body 501 is provided with a first sealing cover 502. After the material is introduced, it is heated by the heating system inside the heating chamber 2 to achieve the first heating. In order to improve the heating effect, a second heater 9 is provided at the bottom of the first furnace body 501. The outer wall of the first furnace body 501 can be heated by the heating ring 905 built into the heating box 901. Moreover, the heating box 901 is connected to the entire heating system and can achieve independent heating operation, which facilitates precise control of the heating temperature.

[0053] It should be further explained that a heating ring 905 is installed inside the heating box 901, and an electric heating rod 12 is installed at the bottom of the heating box 901. The two can be connected. The electric heating rod 12 can be a graphite rod. The graphite rod provides a basic high temperature, and the heating ring 905 provides precise heat supplementation, ensuring that the material in the first furnace body 501 is heated evenly, reducing the number of defective products caused by temperature differences, and also reducing heat loss and exhaust gas interference. Compared with the traditional single furnace single working condition process, energy consumption is reduced, and the graphitization qualification rate is increased to over 90%. At the same time, the first furnace body 501 is easy to disassemble and assemble, adapting to the simulation needs of different production scenarios, taking into account both efficiency and practicality.

[0054] Example 2:

[0055] like Figures 1-8 As shown, the second heating furnace 6 includes a second furnace body 601, a storage chamber 602, and a second sealing cover 603. The second furnace body 601 is a cylindrical cavity structure with one end open, and several storage chambers 602 are provided inside the second furnace body 601. The second sealing cover 603 is provided on the upper part of the second furnace body 601, and a second air outlet 604 is provided on the upper part of the second sealing cover 603. The third heating furnace 8 is horizontally arranged in the placement chamber 13 inside the furnace 18, and an arc-shaped receiving block 14 is provided inside the placement chamber 13. The bottom of the third heating furnace 8 is provided with a third heater 10, a heating plate is provided inside the third heater 10, and several second connecting holes are provided on the third heater 10, with electric heating rods 12 installed in the second connecting holes.

[0056] It should be noted that the second furnace body 601 has multiple storage chambers 602 inside, which can hold different materials respectively. The purpose of this design is to achieve simultaneous graphitization testing of multiple materials in a single furnace without increasing the space occupied by the furnace 18 or adding independent small furnace bodies. That is, different types of materials are put in at the same time, and relying on the unified heating conduction path of the furnace 18, it is ensured that the materials in all chambers are under the same core process conditions such as temperature and holding time, effectively avoiding data deviation caused by environmental differences in traditional multi-furnace testing. At the same time, the multi-storage chamber design does not require splitting the heating process of the furnace 18, and multiple sets of graphitization effect data of materials can be obtained in a single test, which significantly shortens the comparison and verification cycle of different materials, reduces energy consumption and material loss in the test stage, and is especially suitable for the "rapid screening of multiple formulas" scenario before artificial graphite production, providing accurate data support for subsequent large-scale production.

[0057] like Figures 1-8 As shown, the first heating furnace 5, the second heating furnace 6 and the third heating furnace 8 are connected by filling auxiliary materials to form a nested heating system, which improves the fixing and heat preservation effect; the electric heating rod 12 is fixedly connected to the inside of the heating chamber 2 through the connecting bracket 11.

[0058] It should be noted that when filling the auxiliary material at the connection between the first heating furnace 5, the second heating furnace 6, the third heating furnace 8 and the heating chamber 2, it is only necessary to ensure that one end of the auxiliary material is tightly attached to the outer wall of the small furnace body. Fill the auxiliary material to the gap between its bottom and the receiving platform, so that one end of the auxiliary material is tightly attached to the outer wall of the third heating furnace 8 and the other end is naturally attached to the surface of the platform. This can not only fix the small furnace body with the support of the auxiliary material, avoiding displacement due to thermal expansion and contraction during heating, but also efficiently transfer the heat generated by the electric heating rod to the small furnace body through the heat insulation and heat conduction characteristics of the auxiliary material, while blocking the heat loss at the gap, ensuring that different materials in the multiple storage chambers 602 of the small furnace body are heated evenly, solving the problem of "insufficient temperature at one end of the small furnace body" when there is no auxiliary material filling in the traditional way, and helping to improve the graphitization qualification rate.

[0059] like Figures 1-8 As shown, the outer wall of the heating chamber 2 is provided with several air inlets 3, and the two ends of the heating chamber 2 are provided with air outlets, and the air outlets are provided with guide fans 4; the upper part of the furnace 18 is provided with a support plate 16, and the support plate 16 is connected to the external air purification unit through the air guide pipe on it to form an independent exhaust; the other end of the air guide pipe is connected to the first air outlet 503 provided on the first sealing cover 502 to exhaust the flue gas.

[0060] It should be noted that the outer wall of the heating chamber 2 is provided with several air inlets 3, which, together with the guide fans 4 at both ends of the heating chamber 2, can introduce outside air to achieve airflow circulation, thereby regulating the surrounding airflow and ensuring rapid cooling and timely removal of the product.

[0061] It should be further explained that a support plate 16 is provided on the upper part of the furnace 18, which can be connected to the upper connection port of the furnace 18 by snap-fit. Moreover, one end of the air guide pipe on the support plate 16 is connected to the air outlet on the sealing cover, and the other end is connected to the purification unit, which can guide and purify the exhaust gas generated by heating.

[0062] Example 3:

[0063] A graphitization process based on the apparatus of claim 1 includes the following steps:

[0064] S1, Equipment and Material Pretreatment

[0065] 1.1 Check the condition of the large furnace body: Confirm that the heating elements such as the graphite rod at the bottom of the heating chamber 2, the second heater 9, and the third heater 10 are undamaged, the bottom air inlet filter is clean, and the top exhaust equipment and furnace body exhaust pipe are sealed; check the integrity of the large furnace body insulation layer to ensure there is no risk of heat leakage.

[0066] 1.2 Selection and preparation of small furnace: Select the corresponding type of heating furnace according to the type of material to be graphitized and the production simulation scenario, and clean the inner cavity of the small furnace to ensure that there are no residual impurities; if the third heating furnace 8 is selected, the inner cavities corresponding to different raw materials to be tested need to be clearly marked and distinguished.

[0067] 1.3 Material pretreatment: The material to be graphitized is ground and granulated according to the process requirements, the particle size is controlled, and its exhaust section is connected to the gas guide pipe;

[0068] S2. Charging the heating furnace and filling auxiliary materials

[0069] 2.1 Heating Furnace Positioning and Installation: According to the heating zone requirements of Furnace 18, install the heating furnace into the slot of the receiving platform of Furnace 18, ensuring that the bottom of the heating furnace fits snugly with the connection port of Furnace 18;

[0070] 2.2 Filling and fixing of auxiliary materials: Fill the gaps between the heating furnace and the inner wall of the furnace 18, and between the heating furnace and the connection port with auxiliary materials. During the filling process, gently compact the materials to ensure that the auxiliary materials fill the gaps, thereby fixing the heating furnace and uniformly transferring heat, while preventing the auxiliary materials from entering the heating furnace exhaust hole or coming into direct contact with the materials.

[0071] S3, Setting heating parameters and raising temperature of the large furnace body

[0072] 3.1 Heating system startup: Connect the power supply equipment inside the heating chamber 2, set the basic heating temperature of the graphite rod at the bottom of the large furnace body through the main controller, and adjust the power of the corresponding first heater 9 and second heater 10 individually according to the process requirements of each small furnace body;

[0073] 3.2 Staged heating: A staged heating mode is adopted. In the first stage, the temperature is increased to 1000℃ at a rate of 60℃ / h and held for 2.5h. In the second stage, the temperature is increased to the target graphitization temperature at a rate of 40℃ / h and held for 13h to ensure that the material is fully graphitized. During the heating process, the internal temperature of each heating furnace is monitored in real time by temperature sensors. If the temperature difference exceeds 20℃, the corresponding heater is finely adjusted in time.

[0074] S4, Exhaust and Insulation Control

[0075] 4.1 Exhaust system linkage: After the temperature is raised to 500℃, the exhaust fan at the top of the furnace 18 is started and set to run for 5 minutes every 30 minutes. Small molecule impurities and waste gas volatilized from the material are collected in the main exhaust pipe through the exhaust pipe of the heating furnace and discharged after being treated by the terminal waste gas treatment unit. At the same time, natural air is made up by the air inlet at the bottom of the large furnace body.

[0076] 4.2 Monitoring during the heat preservation stage: During the heat preservation period at the target temperature, the power of the heating elements is kept stable, and the overall temperature of the large furnace body and the internal temperature of each small furnace body are recorded every 1 hour;

[0077] S5. Cooling and Product Removal

[0078] 5.1 Staged cooling: After the graphitization insulation is completed, the heater is turned off first, and the bottom graphite rod is kept running at low power to cool down to 1000℃ at a rate of 1350℃ / h. Then the bottom graphite rod is turned off, and the top exhaust fan and bottom vent are started to cool down to room temperature at a rate of 230℃ / h. The entire cooling process lasts for 38 days.

[0079] 5.2 Removal of Heating Furnace and Sample Processing: After cooling is completed, first shut off the exhaust system, disconnect the main exhaust pipe from the heating furnace, and clean the auxiliary materials filling the furnace 18; use a special hook to hook the lifting lug on the top of the heating furnace and remove the small furnace body from the connection port; open the crucible cover of furnace 18, clean the attached negative electrode powder, remove the surface product with a stainless steel spoon, take the mixed product powder in the middle section as the test sample, and complete the graphitization process.

[0080] It should be noted that by adopting the above-mentioned graphitization process, through precise pretreatment of the equipment and materials, positioning and installation of the heating furnace and fixing of auxiliary materials, combined with staged heating and precise temperature control, coordinated exhaust and heat preservation monitoring, and a scientific staged cooling process, simultaneous graphitization treatment of multiple types of heating furnaces can be achieved in the same furnace. Among them, the multi-cavity design of the third heating furnace can simultaneously complete comparative tests of different materials. Auxiliary material filling ensures the stable fixing of the heating furnace and uniform heat transfer. Staged temperature control and exhaust coordination effectively reduce temperature fluctuations and impurity interference during the graphitization process. Ultimately, this not only significantly shortens the graphitization test cycle of multiple groups of materials and reduces energy consumption loss, but also significantly improves the pass rate and quality stability of graphitized products, providing an efficient and reliable process reference for large-scale production.

[0081] Example 4:

[0082] Approximately 5 kg of newly purchased petroleum coke A was selected and granulated at the front end to achieve a particle size D50 of 14 micrometers and a compaction rate of 0.60, among other relevant indicators. It was then placed into the first heating furnace. At the same time, another type of petroleum coke B, which needed to be verified together, was loaded into the same furnace and placed in the box furnace prepared for the production of product X1. After the furnace was loaded, it was powered on normally, reaching the required power supply of 800,000 kilowatts. After cooling, the upper layer of insulation material was removed. After 30 days, the small crucible was taken out, and the attached negative electrode powder was cleaned. Using a sampling stainless steel spoon, the surface product was first cleaned off, and the middle section of the mixed product powder was taken as a sample, obtaining sample ① and sample ②.

[0083] Example 5:

[0084] Approximately 7 kg of unqualified product powder C was selected and graphitized to achieve a particle size D50 of 14 micrometers and a tapping density of 0.96, among other relevant indicators. This powder was then placed in the first heating furnace, specifically in a box furnace prepared for the production of product X2. After loading, the furnace was powered on normally, reaching the required power output of 1 million kilowatts. After cooling, the upper insulating material was removed. After 38 days, the small crucible was removed, and the attached negative electrode powder was cleaned. Using a sampling stainless steel spoon, the surface product was first removed, and the middle section of the mixed product powder was taken as a sample, obtaining sample ③. Similarly, approximately 7 kg of unqualified product powder C was loaded into the same furnace and placed in a box furnace prepared for the production of product X3. After loading, the furnace was powered on normally, reaching the required power output of 1.3 million kilowatts. After cooling, the upper insulating material was removed. After 38 days, the small crucible was removed, and the attached negative electrode powder was cleaned. Using a sampling stainless steel spoon, the surface product was first removed, and the middle section of the mixed product powder was taken as a sample, obtaining sample ④.

[0085] Example 6:

[0086] Approximately 10 kg of the large-box verification failure improvement product powder D was selected and graphitized to achieve a particle size D50 of 13 micrometers and a tapping density of 0.70, among other relevant indicators. This powder was then placed in the first heating furnace, specifically in a box furnace prepared for the production of product X4. After loading, the furnace was powered on normally, reaching the required power output of 900,000 kilowatts. After cooling, the upper insulating material was removed. After 45 days, the small crucible was removed, and the attached negative electrode powder was cleaned. Using a sampling stainless steel spoon, the surface product was first cleaned, and the middle section mixed product powder was taken as a sample, obtaining sample ⑤. Similarly, approximately 10 kg of the large-box verification failure improvement product powder D was loaded and placed in a box furnace prepared for the production of product X5. After loading, the furnace was powered on normally, reaching the required power output of 1,100,000 kilowatts. After cooling, the upper insulating material was removed. After 45 days, the small crucible was removed, and the attached negative electrode powder was cleaned. Using a sampling stainless steel spoon, the surface product was first cleaned, and the middle section mixed product powder was taken as a sample, obtaining sample ⑥.

[0087] Experimental Procedure and Data

[0088] The samples were mixed and stirred according to the CATL low-current-water system (4 cells) test method to prepare each electrode. The samples were then placed in a capacity measurement cabinet to calculate their discharge capacity. Simultaneously, the specific surface area of ​​the samples was measured according to the Bester test method. The results are shown in the table below:

[0089]

[0090] New raw material A is suitable for producing samples with discharge capacity requirements, and its specific surface area is also suitable for a wide range of products, making it relatively versatile. New raw material B has a lower discharge capacity at low charge levels, and its specific surface area is not easy to achieve at a low value, making it only suitable for producing some digital products. The limit of the unqualified product C is only at the test value; increasing the charge by 400,000 kilowatts will not improve this indicator data, but it can meet the product indicators after re-firing, and it is possible to try producing 200 tons of products in a whole furnace. Improved raw material D can meet the product requirements at low charge levels, so there is no need to increase the charge by 200,000 kilowatts.

[0091] By comparing the discharge capacity and specific surface area test data of different samples, it can be seen that new raw material A has a wide range of discharge capacity adaptability and strong specific surface area compatibility, making it suitable for a variety of applications; new raw material B is limited by low charge and specific surface area, making it only suitable for some digital products; although the unqualified product C has limited indicators at present, it can meet the standards after re-firing and has the value of whole-furnace production; improved raw material D can meet the requirements with low charge and does not require additional charge, thus reducing energy consumption. These conclusions provide a basis for raw material selection, production process adjustment and cost control, and can guide the optimization of production processes to improve product adaptability and production economy.

[0092] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A heating device for graphitizing lithium-ion battery negative electrode materials, comprising a base (1), a heating chamber (2), a furnace (18), and a heating furnace, characterized in that, The heating chamber (2) is located on the upper part of the base (1), and a furnace (18) and a heating furnace are provided on the upper part of the heating chamber (2) for graphitization operations; The heating furnace includes a first heating furnace (5), a second heating furnace (6), and a third heating furnace (8); The first heating furnace (5) is located in area A inside the furnace (18) to simulate small-batch graphite production in a box furnace and ensure high-precision testing. The second heating furnace (6) is located in area B inside the furnace (18) and is used to simulate multivariate comparative production to find the optimal formula. The third heating furnace (8) is located in area C inside the furnace (18) and is used to simulate batch production in a crucible furnace to ensure high unit consumption testing. The furnace (18) and heating box (2) are equipped with heating elements and insulation layers to provide a high-temperature heating environment; The furnace (18) is equipped with a ventilation system to regulate the surrounding airflow and ensure rapid cooling and timely product removal.

2. The graphitization heating device for lithium-ion battery negative electrode material according to claim 1, characterized in that, The first heating furnace (5) includes a first furnace body (501) and a first sealing cover (502). The first furnace body (501) is a cylindrical cavity structure with an opening at the top, and the first furnace body (501) is provided with a first sealing cover (502), and the first sealing cover (502) is provided with a first air outlet (503). The first furnace body (501) is located inside the first connection port (15) inside the furnace (18), and the bottom of the first furnace body (501) is connected to the second heater (9) inside the heating chamber (2) for directional heating.

3. The graphitization heating device for lithium-ion battery negative electrode material according to claim 2, characterized in that, The second heater (9) includes a heating box (901), a heating groove (901), a heating ring (905) and a first connecting hole (902). The heating ring (905) is disposed in the connecting port (903) of the heating groove (901), and the heating box (901) is provided with a connecting hole (904) for secondary heating of the bottom and sides of the first furnace body (501). The heating box (901) is provided with a number of first connection holes (902) inside, and each first connection hole (902) is provided with an electric heating rod (12) for the first heating.

4. A graphitization heating device for lithium-ion battery negative electrode materials according to claim 3, characterized in that, The second heating furnace (6) includes a second furnace body (601), a storage chamber (602) and a second sealing cover (603). The second furnace body (601) is a cylindrical cavity structure with one end open, and the interior of the second furnace body (601) is provided with several storage chambers (602). The upper part of the second furnace body (601) is provided with a second sealing cover (603), and the upper part of the second sealing cover (603) is provided with a second air outlet (604).

5. A graphitization heating device for lithium-ion battery negative electrode materials according to claim 1, characterized in that, The third heating furnace (8) is horizontally arranged in the placement chamber (13) inside the furnace (18), and an arc-shaped receiving block (14) is provided inside the placement chamber (13); The bottom of the third heating furnace (8) is provided with a third heater (10), the interior of the third heater (10) is provided with a heating plate, and the third heater (10) is provided with a plurality of second connection holes, and an electric heating rod (12) is provided in the second connection hole.

6. A graphitization heating device for lithium-ion battery negative electrode materials according to claim 1, characterized in that, The first heating furnace (5), the second heating furnace (6) and the third heating furnace (8) are connected by filling auxiliary materials to form a nested heating system, which improves the fixing and heat preservation effect; The electric heating rod (12) is fixedly connected to the interior of the heating chamber (2) via a connecting bracket (11).

7. A graphitization heating device for lithium-ion battery negative electrode materials according to claim 1, characterized in that, Several air inlets (3) are provided on the outer wall of the heating chamber (2), and air outlets are provided at both ends of the heating chamber (2). A guide fan (4) is provided inside the air outlet. A support plate (16) is provided on the upper part of the furnace (18). The support plate (16) is connected to the external air purification unit through the air guide pipe on it to form an independent exhaust. The other end of the duct is connected to the first vent (503) provided on the first sealing cover (502) to exhaust the flue gas.

8. A graphitization process based on the apparatus of claim 1, characterized in that, Includes the following steps: S1, Equipment and Material Pretreatment 1.1 Check the condition of the large furnace body: Confirm that the heating elements such as the graphite rod at the bottom of the heating chamber (2), the second heater (9) and the third heater (10) are undamaged, the bottom air inlet filter is clean, and the top exhaust equipment and the furnace body exhaust pipe are sealed; check the integrity of the furnace body insulation layer to ensure that there is no risk of heat leakage. 1.2 Selection and preparation of small furnace: Select the appropriate type of heating furnace according to the type of material to be graphitized and the production simulation scenario, and clean the inner cavity of the small furnace to ensure that there are no residual impurities; If the third heating furnace (8) is selected, the inner cavities corresponding to different raw materials to be tested need to be clearly marked and distinguished. 1.3 Material pretreatment: The material to be graphitized is ground and granulated according to the process requirements, the particle size is controlled, and its exhaust section is connected to the gas guide pipe; S2. Charging the heating furnace and filling auxiliary materials 2.1 Heating furnace positioning and installation: According to the heating zone requirements of the furnace (18), the heating furnace is installed in the slot of the receiving platform of the furnace (18) to ensure that the bottom of the heating furnace fits in close with the connection port of the furnace (18); 2.2 Filling and fixing of auxiliary materials: Fill the gap between the heating furnace and the inner wall of the furnace (18), and between the heating furnace and the connection port with auxiliary materials. During the filling process, gently compact the materials to ensure that the auxiliary materials fill the gaps, thereby fixing the heating furnace and uniformly transferring heat, while preventing the auxiliary materials from entering the heating furnace exhaust hole or directly contacting the materials. S3, Setting heating parameters and raising temperature of the large furnace body 3.1 Heating system startup: Connect the power supply equipment inside the heating chamber (2), set the basic heating temperature of the graphite rod at the bottom of the large furnace body through the main controller, and adjust the power of the corresponding first heater (9) and second heater (10) separately according to the process requirements of each small furnace body; 3.2 Staged heating: A staged heating mode is adopted. In the first stage, the temperature is increased to 1000℃ at a rate of 50-80℃ / h and held for 2-3 hours. In the second stage, the temperature is increased to the target graphitization temperature at a rate of 30-50℃ / h and held for 10-15 hours to ensure that the material is fully graphitized. During the heating process, the internal temperature of each heating furnace is monitored in real time by temperature sensors. If the temperature difference exceeds 20℃, the corresponding heater is finely adjusted in time. S4, Exhaust and Insulation Control 4.1 Exhaust system linkage: After the temperature is raised to 500℃, start the exhaust fan at the top of the furnace (18) and set it to run for 5 minutes every 30 minutes. The small molecule impurities and waste gas volatilized from the material are collected into the main exhaust pipe through the exhaust pipe of the heating furnace. After being treated by the terminal waste gas treatment unit, the exhaust gas is discharged in compliance with the standard. At the same time, the air is naturally replenished by the air inlet at the bottom of the large furnace body. 4.2 Monitoring during the heat preservation stage: During the heat preservation period at the target temperature, the power of the heating elements is kept stable, and the overall temperature of the large furnace body and the internal temperature of each small furnace body are recorded every 1 hour; S5. Cooling and Product Removal 5.1 Staged cooling: After the graphitization insulation is completed, first turn off the heater, keep the bottom graphite rod running at low power, and cool down to 1000℃ at a rate of 100-150℃ / h. Then turn off the bottom graphite rod, start the top exhaust fan and bottom vent, and cool down to room temperature at a rate of 200-250℃ / h. The entire cooling process lasts 30-45 days. 5.2 Removal of heating furnace and sample processing: After cooling is completed, first shut off the exhaust system, disconnect the main exhaust pipe from the heating furnace, and clean the auxiliary materials filled in the furnace (18); use a special hook to hook the top lug of the heating furnace and remove the small furnace body from the connection port; open the crucible cover of the furnace (18), clean the attached negative electrode powder, remove the surface product with a stainless steel spoon, take the middle section mixed product powder as the test sample, and complete the graphitization process.

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