Preparation process of high-power negative electrode coke

Abstract

The application relates to the technical field of negative electrode materials, in particular to a preparation process of high-power negative electrode coke. After catalytic oil slurry, pitch and petroleum residual oil are mixed to form a co-carbonization system, the co-carbonization system is heated and temperature and pressure are changed for coking, and the high-power negative electrode coke is obtained, the prepared high-power negative electrode coke has the high-power characteristics of high energy density, high initial efficiency, good rate performance and long cycle life, and can meet the use requirements of the negative electrode material in high-end power lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of negative electrode material technology, specifically to a preparation process for a high-dynamic-performance negative electrode coke. Background Technology

[0002] In the field of new energy batteries, lithium-ion batteries (lithium batteries) have advantages such as high energy density, stable discharge voltage, good low-temperature performance and cycle performance, and excellent safety performance, and are widely used in industries such as new energy vehicles. In lithium batteries, the selection and preparation of negative electrode materials have a significant impact on battery performance and lifespan, and are key to improving lithium battery capacity and charge / discharge performance.

[0003] Anode materials are mainly divided into carbon materials and non-carbon materials, with carbon materials being the most widely used, especially those whose main components are natural or artificial graphite. Anode coke is a carbon material prepared from high-purity natural or artificial graphite, possessing good conductivity, stable cycle performance, and high specific capacity, making it a high-quality material for preparing lithium-ion anode materials. In existing technologies, anode coke is often used to produce lithium-ion battery anode materials through processes such as crushing, grading, high-temperature graphitization, and initial sieving.

[0004] In existing technologies, petroleum residue oil is typically used as the sole coking feedstock. The coking process involves cracking and condensing the petroleum residue oil at high temperatures to produce negative electrode coke. However, negative electrode coke produced using petroleum residue oil as the sole coking feedstock suffers from drawbacks such as low energy density, low initial efficiency, poor low-temperature resistance, and unstable quality. These defects lead to unstable performance of the negative electrode material and affect the lifespan of lithium batteries. Summary of the Invention

[0005] To address the problems of low energy density, low initial efficiency, poor low-temperature performance, and unstable quality in the production of negative electrode coke using petroleum residue as a single raw material in existing technologies, this invention provides a preparation process for high-performance negative electrode coke that can meet the requirements for negative electrode materials used in high-end power lithium-ion batteries.

[0006] The technical solution of the present invention is as follows:

[0007] A process for preparing high-dynamic-performance negative electrode coke involves mixing catalytic slurry, asphalt, and petroleum residue to form a co-carbonization system, followed by heating and variable-temperature, variable-pressure coking of the co-carbonization system to obtain high-dynamic-performance negative electrode coke. The process includes the following steps:

[0008] (1) The catalytic oil slurry and asphalt are mixed and then refined to obtain a refined mixture;

[0009] (2) The refined mixture and petroleum residue are mixed in a mixer to form a uniform co-carbonization system;

[0010] (3) Heating the co-carbonization system;

[0011] (4) The heated co-carbonization system is fed into the coking tower for temperature and pressure variable coking to produce high dynamic negative electrode coke.

[0012] Among them, catalytic slurry is a heavy component obtained at the bottom of the catalytic unit during the process of preparing gasoline, diesel, liquefied gas and other products using heavy oil products as raw materials through catalytic cracking process.

[0013] Asphalt is a heavy component obtained from the bottom of the coke oven during the process of treating catalytic oil slurry using vacuum distillation.

[0014] Petroleum residue is the heavy oil remaining after crude oil has been extracted into light oil products through atmospheric and vacuum distillation.

[0015] Furthermore, in step (1), the catalytic slurry and asphalt are mixed in a mass ratio of 1-5:1-5.

[0016] Further, the specific operation of refining the catalytic slurry and asphalt mixture in step (1) is as follows: the catalytic slurry and asphalt mixture is heated to 300-350℃, then sent to a filter for filtration, and then cooled by a tube-type cooler. The filtration accuracy of the filter is ≤0.5μm.

[0017] Further, in step (2), the refined mixture with a mass ratio of 3-9:1-7 is mixed with petroleum residue oil.

[0018] Furthermore, the mixing temperature in step (2) is 200-300℃, the mixing time is 2-6h, and the mixing method is anchor mechanical stirring in the mixer.

[0019] Furthermore, the heating temperature in step (3) is 600-750℃, and the holding time is 10-30min. After heating, some materials undergo a slight cracking reaction, and the co-carbonization system is in a state of extremely high fluidity.

[0020] Furthermore, in step (4), the temperature inside the coking tower is 430-550℃, the pressure inside the coking tower is 0.3-0.8MPa, the duration of temperature and pressure variable coking is 36-60h, and the circulation ratio is 0.3-2:1. The circulation ratio is the ratio of the flow rate of the bottom circulating oil separated from the reaction product in the fractionation tower to the flow rate of the fresh raw material, that is, the circulation oil (kg / h): fresh raw material (kg / h) is 0.3-2:1.

[0021] During the coking process, the co-carbonization system undergoes cracking and polycondensation reactions sequentially to obtain high-dynamic-performance negative electrode coke, with gasoline and diesel as byproducts. Controlling the coking tower temperature to 330-550℃ and the coking tower pressure to 0.2-0.8MPa ensures sufficient high activation energy for the cracking reaction, making it more thorough. Controlling the temperature and pressure variable coking time to 36-60 hours moderates the polycondensation reaction, resulting in uniform shape and stable properties of the generated negative electrode coke. Controlling the recycle ratio to 0.3-6:1 alters the overall feed properties and increases the yield of high-dynamic-performance negative electrode coke.

[0022] Furthermore, the temperature and pressure variable coking process includes:

[0023] (a) Start feeding by controlling the temperature inside the coking tower at 430-470℃, then raise the temperature and lower the pressure. After 4-8 hours, raise the temperature inside the coking tower to 450-490℃ and gradually lower the pressure inside the coking tower to 0.6-0.8MPa.

[0024] (b) Maintain constant temperature and pressure, keep the temperature inside the coking tower at 450-490℃ for 8-14 hours, and gradually reduce the pressure of the coking tower to 0.5-0.7MPa;

[0025] (c) Heating and depressurizing: After 10-18 hours, the temperature inside the coking tower is raised to 500-550℃, and the pressure inside the coking tower is gradually reduced to 0.4-0.6MPa;

[0026] (d) Maintain constant temperature and pressure, keep the temperature inside the coking tower at 500-550℃ for 14-20 hours, and gradually reduce the pressure of the coking tower to 0.3-0.5MPa.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention uses catalytic slurry, asphalt, and petroleum residue as raw materials to form a co-carbonization system. The co-carbonization system is then heated and subjected to temperature and pressure variable coking to obtain high-power negative electrode coke. The obtained high-power negative electrode coke has high energy density, high initial efficiency, good rate performance, and long cycle life, which can meet the requirements for negative electrode materials in high-end power lithium-ion batteries. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0030] Example 1

[0031] A process for preparing a high-dynamic-performance negative electrode coke includes the following steps:

[0032] (1) The catalytic oil slurry and asphalt were mixed in a mass ratio of 1:1 and heated to 320°C. Then the mixture was filtered through a filter with a filtration accuracy of 0.5 μm and cooled through a shell-and-tube cooler to obtain a refined mixture.

[0033] (2) The refined mixture and petroleum residue oil with a mass ratio of 2:1 are mixed in a mixer at a mixing temperature of 230°C for 3 hours. The mixing method is to use anchor mechanical stirring in the mixer to form a uniform co-carbonization system.

[0034] (3) The co-carbonization system is heated to 750℃ and held for 30 minutes;

[0035] (4) The heated co-carbonization system is fed into a coking tower for temperature and pressure variable coking. The duration of temperature variable coking is 48 hours, and the circulation ratio is 0.5:1 to obtain high dynamic negative electrode coke. The temperature and pressure variable coking process is as follows:

[0036] (a) The temperature inside the coking tower is controlled at 450°C to start feeding, and then the temperature is increased and the pressure is decreased. After 4 hours, the temperature inside the coking tower is increased to 490°C, and the pressure of the coking tower is gradually reduced to 0.8MPa.

[0037] (b) Constant temperature and pressure reduction: control the temperature inside the coking tower at 490℃ for 8 hours, and gradually reduce the pressure of the coking tower to 0.7MPa;

[0038] (c) Heating and depressurizing: After 18 hours, the temperature inside the coking tower is raised to 550°C, and the pressure inside the coking tower is gradually reduced to 0.6 MPa;

[0039] (d) Constant temperature and pressure reduction: control the temperature inside the coking tower at 550℃ for 18 hours, and gradually reduce the pressure of the coking tower to 0.5MPa.

[0040] Example 2

[0041] A process for preparing a high-dynamic-performance negative electrode coke includes the following steps:

[0042] (1) The catalytic oil slurry and asphalt were mixed in a mass ratio of 2:1 and heated to 310°C. Then the mixture was filtered through a filter with a filtration accuracy of 0.5 μm and cooled through a tube-type cooler to obtain a refined mixture.

[0043] (2) The refined mixture and petroleum residue oil with a mass ratio of 3:2 are mixed in a mixer at a mixing temperature of 260°C for 2 hours. The mixing method is to use anchor mechanical stirring in the mixer to form a uniform co-carbonization system.

[0044] (3) The co-carbonization system is heated to 700℃ and held for 30 minutes;

[0045] (4) The heated co-carbonization system is fed into a coking tower for temperature and pressure variable coking. The duration of temperature variable coking is 40 hours, and the circulation ratio is 1:1 to obtain high dynamic negative electrode coke. The temperature and pressure variable coking process is as follows:

[0046] (a) The temperature inside the coking tower is controlled at 440°C to start feeding, and then the temperature is increased and the pressure is decreased. After 4 hours, the temperature inside the coking tower is increased to 480°C, and the pressure of the coking tower is gradually reduced to 0.7MPa.

[0047] (b) Constant temperature and pressure reduction: control the temperature inside the coking tower at 480℃ for 8 hours, and gradually reduce the pressure of the coking tower to 0.6MPa;

[0048] (c) Heating and depressurizing: After 14 hours, the temperature inside the coking tower is raised to 540℃, and the pressure inside the coking tower is gradually reduced to 0.5MPa;

[0049] (d) Constant temperature and pressure reduction: control the temperature inside the coking tower at 540℃ for 14 hours, and gradually reduce the pressure of the coking tower to 0.4MPa.

[0050] Example 3

[0051] A process for preparing a high-dynamic-performance negative electrode coke includes the following steps:

[0052] (1) The catalytic oil slurry and asphalt were mixed in a mass ratio of 3:1 and heated to 350°C. Then the mixture was filtered through a filter with a filtration accuracy of 0.5 μm and cooled through a shell-and-tube cooler to obtain a refined mixture.

[0053] (2) The refined mixture and petroleum residue oil with a mass ratio of 1:1 are mixed in a mixer at a mixing temperature of 280℃ for 6 hours. The mixing method is to use anchor mechanical stirring in the mixer to form a uniform co-carbonization system.

[0054] (3) The co-carbonization system is heated to 650℃ and held for 20 minutes.

[0055] (4) The heated co-carbonization system is fed into a coking tower for temperature and pressure variable coking. The duration of temperature and pressure variable coking is 54 hours, and the circulation ratio is 2:1 to obtain high dynamic negative electrode coke. The process of temperature and pressure variable coking is as follows:

[0056] (a) The temperature inside the coking tower is controlled at 430°C to start feeding, and then the temperature is increased and the pressure is decreased. After 6 hours, the temperature inside the coking tower is increased to 470°C, and the pressure of the coking tower is gradually reduced to 0.8MPa.

[0057] (b) Maintain constant temperature and pressure, keep the temperature inside the coking tower at 470℃ for 10 hours, and gradually reduce the pressure of the coking tower to 0.5MPa;

[0058] (c) Heating and depressurizing: After 18 hours, the temperature inside the coking tower was raised to 530°C, and the pressure inside the coking tower was gradually reduced to 0.4 MPa;

[0059] (d) Constant temperature and pressure reduction: control the temperature inside the coking tower at 530℃ for 20 hours, and gradually reduce the pressure of the coking tower to 0.3MPa.

[0060] The negative electrode coke obtained in Implementation Cases 1-3 was crushed, calcined, and graphitized to produce negative electrode materials for lithium-ion batteries. The particle size, true density, tap density, and specific surface area of ​​the obtained negative electrode materials were tested. The initial discharge capacity and initial discharge efficiency of coin cells made from the negative electrode materials and lithium sheets were also tested. The testing methods followed GB / T-24533-2019 "Graphite-based Negative Electrode Materials for Lithium-ion Batteries". The test results are shown in Table 1.

[0061] Table 1. Performance test results of anode materials prepared using the anode coke from Examples 1-3.

[0062]

[0063] It is evident that the negative electrode materials prepared using the negative electrode coke of Examples 1-3 have high tap density and specific surface area, resulting in high initial discharge capacity and efficiency after being fabricated into coin cells, thus meeting the requirements for the use of negative electrode materials in lithium-ion batteries.

[0064] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A process for preparing high-dynamic-performance negative electrode coke, characterized in that, The process involves mixing catalytic slurry, asphalt, and petroleum residue to form a co-carbonization system. This co-carbonization system is then heated and subjected to temperature and pressure variable-pressure coking to obtain high-dynamic-performance negative electrode coke. The steps include: (1) After mixing the catalytic oil slurry and asphalt in a mass ratio of 1-5:1-5, the mixture is refined to obtain a refined mixture. The specific operation of the refining process is as follows: after mixing the catalytic oil slurry and asphalt, the mixture is heated to 300-350℃, then sent to a filter for filtration, and then cooled by a shell-and-tube cooler. The filtration accuracy of the filter is ≤0.5μm. (2) The refined mixture and petroleum residue oil with a mass ratio of 3-9:1-7 are mixed in a mixer to form a uniform co-carbonization system; (3) Heating the co-carbonization system; (4) The heated co-carbonization system is fed into the coking tower for temperature and pressure variable coking to produce high dynamic negative electrode coke; The temperature inside the coking tower is 430-550℃, the pressure inside the coking tower is 0.3-0.8MPa, the duration of variable temperature and pressure coking is 36-60h, and the circulation ratio is 0.3-2:

1. The process of temperature and pressure variable coking includes: (a) Start feeding by controlling the temperature inside the coking tower at 430-470℃, then raise the temperature and lower the pressure. After 4-8 hours, raise the temperature inside the coking tower to 450-490℃ and gradually lower the pressure inside the coking tower to 0.6-0.8MPa. (b) Maintain constant temperature and pressure, keep the temperature inside the coking tower at 450-490℃ for 8-14 hours, and gradually reduce the pressure of the coking tower to 0.5-0.7MPa; (c) Heating and depressurizing: After 10-18 hours, the temperature inside the coking tower is raised to 500-550℃, and the pressure inside the coking tower is gradually reduced to 0.4-0.6MPa; (d) Maintain constant temperature and pressure, keep the temperature inside the coking tower at 500-550℃ for 14-20 hours, and gradually reduce the pressure of the coking tower to 0.3-0.5MPa.

2. The preparation process according to claim 1, characterized in that, The mixing temperature in step (2) is 200-300℃, the mixing time is 2-6h, and the mixing method is anchor mechanical stirring in the mixer.

3. The preparation process according to claim 1, characterized in that, The heating temperature in step (3) is 600-750℃, and the holding time is 10-30min.

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