Preparation method of high-processability and high-capacity negative electrode material precursor

Abstract

The application discloses a preparation process of high-processing-performance and high-capacity negative electrode material precursor, belongs to the field of production of needle coke and preparation and processing of negative electrode material precursor, and comprises a preparation stage of heavy mixed oil, a green coke reaction stage and a steam blowing and coking stage, and is characterized in that: refined product oil obtained in an oil slurry pretreatment stage is mixed with a promoter and a mixing agent according to a certain proportion to obtain the heavy mixed oil, and the needle coke is obtained through the green coke reaction stage and the steam blowing and coking stage by using the heavy mixed oil; the application has the beneficial effects that: the mixing agent and the promoter are creatively added, the fibrous and domain structure of the needle coke is improved, the true density of the needle coke is improved, the capacity and the graphitization degree of the needle coke after crushing and graphitization are improved, the operation of variable temperature and variable pressure is adopted in the green coke stage, the better fusion and coalescence of the intermediate phase are ensured, the true density is improved, and a certain amount of volatile components are reserved, the good processing performance is ensured, the yield in the crushing stage is improved, and the processing cost of the negative electrode enterprise is reduced.

Description

Technical fields:

[0001] This invention relates to the fields of needle coke production and the preparation and processing of anode material precursors, specifically to the preparation process of anode material precursors with high processing performance and high capacity. Background technology:

[0002] With the rapid development of the new energy industry, lithium-ion batteries have broad application prospects in electric vehicles and large-scale energy storage. The anode material is mainly artificial graphite. Due to its advantages such as low sulfur content, low ash content, low metal content and easy graphitization, needle coke is currently the main application material for lithium-ion battery anode materials and has a key impact on battery performance.

[0003] The raw materials for producing needle coke need to meet the following requirements: high aromatic content, preferably 3-5 rings, moderate resin content, and low asphaltene content. Resins are a type of macromolecular fused ring, which is conducive to the formation of a stable needle coke structure, and helps to improve the true density and quality of needle coke.

[0004] Different raw material compositions and process combinations have a decisive impact on the quality of needle coke. Currently, needle coke production mainly uses raw materials such as catalytic cracking clarified oil, ethylene tar, vacuum residue, and coal tar. The quality of the produced needle coke is suitable for mid-range power batteries or ordinary consumer batteries. However, within this field, the true density of needle coke measured by the kerosene displacement method varies very little, and these minute changes result in significant differences in performance. Currently, the true density of needle coke can reach 1.36-1.37, and further improvement faces technical bottlenecks.

[0005] In the fields of high-end power batteries and high-end digital 3C batteries, calcined needle coke or carbonization of raw coke after secondary coating is generally used to improve their electrochemical performance. The true density of needle coke can reach 1.36-1.37, but it cannot meet the needs of the high-end digital 3C battery field. Summary of the Invention:

[0006] To address the aforementioned problems and overcome the shortcomings of existing technologies, this invention provides a preparation process for a high-processability and high-capacity anode material precursor, which can effectively solve the problem that needle coke prepared by existing technologies cannot meet the high requirements for true density of high-capacity anode material precursors.

[0007] The specific technical solution of this invention to solve the above-mentioned technical problems is as follows: a method for preparing a precursor of a negative electrode material with high processing performance and high capacity, comprising a heavy mixed oil preparation stage, a coking reaction stage, and a steam blowing and coking stage, characterized in that:

[0008] The preparation stage of the heavy mixed oil: the refined product oil obtained from the oil slurry pretreatment stage is mixed with accelerator and compounding agent in a certain proportion to obtain heavy mixed oil, and needle coke is obtained by passing the heavy mixed oil through the coking reaction stage and the steam blowing and coking stage.

[0009] The coking reaction stage is a variable temperature and variable pressure process;

[0010] The steam blowing and coking stage uses high-temperature oil and gas for coking.

[0011] Furthermore, the accelerator is raffinate oil, and the raffinate oil has a cycloalkane content of ≥45%.

[0012] Furthermore, the raffinate oil is the residual oil component after the oil slurry has been extracted with furfural.

[0013] Furthermore, the mixing agent is rubbery asphalt.

[0014] Furthermore, the gum content of the gum asphalt is ≥15%.

[0015] Furthermore, the mass ratio of the refined product oil, the compounding agent, and the accelerator is 30%-90%: 5%-50%: 5%-30%.

[0016] Furthermore, the coking reaction stage is a variable temperature and pressure process, and the total coking reaction cycle is 24-48 hours; in the early stage of the reaction, a low temperature and high pressure coking method is adopted, with a coking temperature of 460-480℃, a reaction pressure of 0.5-1MPa, and a reaction time of 5-12 hours.

[0017] In the later stages of the reaction, the reaction temperature is gradually increased to 480-520℃, and the reaction pressure is reduced to 0-0.6MPa.

[0018] Furthermore, the coking cycle of the steam blowing stage is 6-24h, the steam blowing temperature is 470-550℃, the steam blowing oil and gas volume is 10-35t / h, the oil and gas ratio is 10-30t / h, the steam volume ratio is 0-10t / h, and the pressure of the steam blowing stage is 0.1-1MPa.

[0019] Furthermore, the obtained needle coke is processed through crushing, shaping, and grading to obtain a negative electrode material precursor with a D50 of 14-16 μm.

[0020] Furthermore, the oil slurry pretreatment stage includes: using catalytic cracking oil slurry as raw material, removing light components and impurity components through vacuum cutting to obtain intermediate high-quality component aromatic oil, and after hydrorefining, reducing its sulfur content to ≤0.5% to obtain refined product oil.

[0021] The beneficial effects of this invention are:

[0022] (1) The present invention creatively incorporates a compounding agent and an accelerator, thereby improving the fibrous and domain structure of needle coke, increasing its true density, and improving its capacity and degree of graphitization after crushing and graphitization.

[0023] (2) Based on the coking principle of needle coke, the present invention adopts variable temperature and pressure operation in the coking stage to ensure better fusion of the intermediate phase, improve its true density, retain a certain amount of volatile matter, ensure its good processing performance, improve the yield in the crushing stage, and reduce the processing cost of negative electrode enterprises.

[0024] (3) In this invention, high-temperature oil and gas coking is used in the coking stage, which improves the fiber structure of needle coke, reduces pores, increases fiber content, ensures the uniformity of the upper, middle and lower samples in the coke tower, and ensures the stability and consistency of raw materials for negative electrode material enterprises. Attached image description:

[0025] Appendix Figure 1 This is a polarizing microscope image of Embodiment 1 of the present invention;

[0026] Appendix Figure 2 This is a polarizing microscope image of Comparative Example 1 of this invention;

[0027] Appendix Figure 3 This is a polarizing microscope image of Comparative Example 2 of this invention;

[0028] Appendix Figure 4 This is a polarizing microscope image of Comparative Example 3 of the present invention;

[0029] Appendix Figure 5 This is a polarizing microscope image of Comparative Example 4 of the present invention;

[0030] Appendix Figure 6 This is a polarizing microscope image of Comparative Example 5 of the present invention; Detailed implementation method:

[0031] Specific details in the description of this invention are merely to provide a thorough understanding of the embodiments thereof; however, those skilled in the art should understand that the implementation of this invention is not limited to these details. Furthermore, well-known structures and functions have not been described or shown in detail to avoid obscuring the key points of the embodiments of this invention. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Specific embodiments of the present invention:

[0033] To better understand the present invention, specific embodiments are described. It is worth emphasizing that the effects of these embodiments are not substantially different from those of various embodiments within the scope of protection of the present invention, including their respective reagents and reagent content ratios. All of them can achieve the effects described in the present invention and solve the above-mentioned problems. Other combinations are not described here.

[0034] Example 1:

[0035] 1. Pre-treatment stage of pulp:

[0036] The specific process steps include: using catalytic cracking slurry as raw material, removing light components and impurity components through vacuum cutting to obtain intermediate high-quality aromatic oil, and then hydrorefining the aromatic oil to reduce its sulfur content to ≤0.5% to obtain refined product oil;

[0037] 2. Preparation stage of heavy blended oil:

[0038] The specific process steps include: mixing the refined product oil obtained from the oil slurry pretreatment stage with accelerators and compounding agents in a certain proportion to obtain a heavy mixed oil.

[0039] The mass fractions of the refined product oil, compounding agent, and accelerator are: 30%-90%: 5%-50%: 5%-30%.

[0040] The accelerator is raffinate oil, the raffinate oil has a cycloalkanes content of ≥45%, and the raffinate oil is the residual oil component after the oil slurry is extracted with furfural.

[0041] The mixing agent is rubber asphalt, and the rubber content of the rubber asphalt is ≥15%.

[0042] 3. The coking reaction stage is a variable temperature and pressure process;

[0043] The specific process steps include: the total coking reaction cycle is 24-48 hours; low-temperature and high-pressure coking is used in the early stage of the reaction.

[0044] In the early stage of the reaction, a low-temperature and high-pressure coking method is adopted, with a coking temperature of 460-480℃, a reaction pressure of 0.5-1MPa, and a reaction time of 5-12h.

[0045] In the later stages of the reaction, the reaction temperature is gradually increased to 480-520℃, and the reaction pressure is reduced to 0-0.6MPa.

[0046] 4. High-temperature oil and gas are used for coking during the steam blowing and coking stage;

[0047] The specific process steps include: the coking cycle is 6-24h, the steam coking temperature is 470-550℃, the steam coking oil and gas volume is 10-35t / h, the oil and gas ratio is 10-30t / h, the steam volume ratio is 0-10t / h, and the pressure during the steam coking stage is 0.1-1MPa.

[0048] 5. The obtained needle coke is processed through crushing, shaping and grading to obtain a negative electrode material precursor with a D50 of 14-16μm.

[0049] The needle-shaped fossils obtained through the above operations, after processing, were observed using a polarizing microscope. Figure 1 .from Figure 1 It can be seen that the obtained needle coke has a high proportion of fibrous and domain structures, good interphase fusion effect, regular arrangement, and dense internal structure, which is conducive to obtaining needle coke with good processing performance, high capacity and high graphitization degree.

[0050] To more intuitively demonstrate the technological advantages of this invention, a comparison is made between the preparation method of the high-processability and high-capacity anode material precursor of this invention and a method using equivalent substitution in the same process.

[0051] Comparative Example 1:

[0052] The preparation method is the same as in Example 1, except that: in the preparation process of this comparative example, after the coking is completed, the coke is not pulled out, and the oil and gas in the coke are blown out by a large amount of steam.

[0053] Specifically:

[0054] The raw materials used in this comparative example are the same as those in Comparative Example 1. The mass fractions of refined product oil, compounding agent, and accelerator are 30%-90%, 5%-50%, and 5%-30%, respectively.

[0055] In the coking reaction stage, variable temperature and pressure operation is adopted. In the early stage of the reaction, a low-temperature and high-pressure coking method is used, with a coking temperature of 460-480℃ and a reaction pressure of 0.5-1MPa to improve the fusion effect of the mesophase. In the later stage of the reaction, the reaction temperature is gradually increased to 480-520℃ and the reaction pressure is reduced to 0-0.6MPa. The coking cycle is 24-48 hours. After coking is completed, coke pulling is not performed, and oil and gas in the coke are blown out by large-volume steam blowing.

[0056] Comparative Example 2

[0057] The preparation method is the same as in Example 1, except that the coking stage in this comparative example is carried out under constant temperature and pressure.

[0058] Specifically: During the coking reaction stage, constant temperature and pressure operation is adopted, with a coking reaction temperature of 480-520℃, a reaction pressure of 0.1-1MPa, and a coking cycle of 24-48h.

[0059] Comparative Example 3

[0060] The preparation method is the same as in Example 1, except that no compounding agent or accelerator was added to the refined product oil during the preparation process of this comparative example.

[0061] Specifically: Catalytic cracking slurry is used as raw material. After vacuum cutting, light components and impurity components are removed to obtain intermediate high-quality aromatic oil. After hydrorefining, the sulfur content of the aromatic oil is reduced to ≤0.5% to obtain refined product oil. The refined product oil is used as raw material for coking reaction. The proportion of compounding agent and accelerator is 0%.

[0062] Comparative Example 4

[0063] The preparation method is the same as in Example 1, except that no compounding agent or accelerator is added to the refined product oil during the preparation process of this comparative example; and constant temperature and pressure operation is adopted in the coking stage.

[0064] Specifically:

[0065] Catalytic cracking slurry oil is used as feedstock. After vacuum cutting, light and impurity components are removed to obtain intermediate high-quality aromatic oil. This aromatic oil is then hydrorefined to reduce its sulfur content to ≤0.5%, yielding refined product oil. This refined product oil is used as feedstock for the coking reaction, with both compounding agents and accelerators accounting for 0% of the total.

[0066] Furthermore, constant temperature and pressure operation is adopted in the coking reaction stage, with a coking reaction temperature of 480-520℃, a reaction pressure of 0.1-1MPa, and a coking cycle of 24-48h.

[0067] Comparative Example 5

[0068] The preparation method is the same as in Example 1, except that no compounding agent or accelerator was added to the refined product oil during the preparation process of this comparative example; and the steam blowing and coking stage process is different.

[0069] Specifically:

[0070] Catalytic cracking slurry oil is used as feedstock. After vacuum cutting, light and impurity components are removed to obtain intermediate high-quality aromatic oil. This aromatic oil is then hydrorefined to reduce its sulfur content to ≤0.5%, yielding refined product oil. This refined product oil is used as feedstock for the coking reaction, with both compounding agents and accelerators accounting for 0%.

[0071] Furthermore, high-temperature oil and gas are used for coking during the steam blowing and coking stage, with a coking cycle of 6-24 hours, a steam blowing and coking temperature of 470-550℃, and high-temperature steam is used for coking, with a pressure of 0.1-1MPa during the steam blowing and coking stage.

[0072] The true density of the oil-based needle coke prepared by the above process was determined using the kerosene displacement method. The results are detailed in the table below:

[0073] Table 1: Detection Indicators of Needle Coke Products Prepared by Different Processes

[0074] True density Volatile components Sulfur content Nitrogen content 1 Example 1 1.386 5.7 0.4 0.46 2 Comparative Example 1 1.37 6.7 0.39 0.48 3 Comparative Example 2 1.372 6.3 0.4 0.49 4 Comparative Example 3 1.362 6.5 0.4 0.48 5 Comparative Example 4 1.358 6.8 0.38 0.47 6 Comparative Example 5 1.36 6.3 0.39 0.45

[0075] Table 2: Comparison of Process Conditions for Preparing Products Under Different Process Conditions

[0076]

[0077] Analysis of the data in Tables 1 and 2 shows that:

[0078] (1) A comparison between Example 1 and Comparative Example 1 shows that:

[0079] The needle-shaped fossil obtained in Comparative Example 1 was processed and observed using a polarizing microscope. Figure 2 ;from Figure 2 It can be seen that the obtained needle-like char has a roughly equal proportion of fibrous and domain-like structures, with slightly more domain-like structures.

[0080] It is possible that because Comparative Example 1 used large-volume blowing to remove oil and gas from the coke, some materials in the upper part of the coke tower did not react fully, resulting in some mesophase spheres not being completely fused together and some plate-like structures not being transformed into fibrous structures. As a result, the volatile matter content of the needle coke was slightly higher and the true density was slightly lower.

[0081] (2) A comparison between Example 1 and Comparative Example 2 shows that:

[0082] The needle-shaped fossils were obtained using the operation in Comparative Example 2, and after processing, they were observed using a polarizing microscope. Figure 3 ;from Figure 3 It can be seen that the obtained needle coke has a low proportion of fibrous and domain structures, few streamlined structures, slightly more isotropic structures, and poor interfacial fusion effect.

[0083] It's possible that Comparative Example 2 did not undergo temperature and pressure regulation during the coking stage, resulting in insufficient development and growth of the mesophase microspheres. Under constant temperature and pressure, the mesophase microspheres solidified rapidly, leading to a slightly higher proportion of isotropic structures. During gas escape, the gas passed through the colloidal layer, forming pores and resulting in numerous, loose needle-like coke pores. Even subsequent high-temperature steam coking could not change the pore structure or achieve satisfactory results.

[0084] (3) A comparison between Example 1 and Comparative Example 3 shows that:

[0085] Needle-shaped fossils were obtained using the operation in Comparative Example 3. After processing, they were observed using a polarizing microscope. Figure 4 ;from Figure 4 It can be seen that the obtained needle-like coke has a low proportion of fibrous and domain-like structures, and poor fiber structure orientation.

[0086] It is possible that because no compounding agent and accelerator were added to Comparative Example 3, the coking raw material had a low specific gravity and contained some unfavorable components. During the coking process, these components disturbed the fusion of the mesophase, resulting in some coarse mosaic structures. Consequently, the processing performance of the needle coke was poor, and its true density was slightly lower.

[0087] (4) A comparison between Example 1 and Comparative Example 4 shows that:

[0088] The needle-shaped fossils were obtained using the operation in Comparative Example 4, and after processing, they were observed using a polarizing microscope. Figure 5 .from Figure 5 It can be seen that the obtained needle-like coke has a low proportion of fibrous and domain structures, poor fiber structure orientation, and an increase in isotropic structures.

[0089] The poor results in Comparative Example 4, possibly due to the absence of mixing agents and accelerators, resulted in fewer beneficial components for coking and poor mesophase fusion during the coking process. The use of a fixed reaction pressure also hindered the formation of a well-developed needle-like streamline structure during coking. Furthermore, the high initial reaction temperature prevented the mesophase microspheres from fusion and solidified into nuclei in time, leading to some embedded structures. The high reaction temperature also resulted in high hardness and poor processing performance of the needle-like coke.

[0090] (5) A comparison between Example 1 and Comparative Example 5 shows that:

[0091] The needle-shaped fossils obtained through the above operations, after processing, were observed using a polarizing microscope. Figure 6 .from Figure 6 It can be seen that the resulting needle coke has a low proportion of fibrous and domain-like structures, and poor fiber orientation. Due to the absence of compounding agents and accelerators, some gases generated during the coking process disturb the coalescence of the mesophase, resulting in poor fiber orientation. Furthermore, the use of high-temperature steam during the coking stage leads to numerous pores in the needle coke, resulting in low true density.

[0092] When using it, the specific operation is as follows:

[0093] In summary:

[0094] This invention creatively incorporates a compounding agent and an accelerator, thereby improving the fibrous and domain structure of needle coke, increasing its true density, and enhancing its capacity and degree of graphitization after pulverization and graphitization.

[0095] Based on the coking principle of needle coke, this invention employs variable temperature and pressure operation during the coking stage to ensure better fusion of the mesophase, improve its true density, retain a certain amount of volatile matter, ensure good processing performance, improve the yield in the pulverization stage, and reduce the processing costs of anode manufacturers.

[0096] In this invention, high-temperature oil and gas coking is used in the coking stage, which improves the fiber structure of needle coke, reduces porosity, increases fiber content, ensures the uniformity of samples in the upper, middle and lower parts of the coke tower, and ensures the stability and consistency of raw materials for anode material enterprises.

Claims

1. A method for preparing a high-processing-performance and high-capacity anode material precursor, comprising an oil slurry pretreatment stage, a heavy mixed oil preparation stage, a coking reaction stage, and a steam blowing and coking stage, characterized in that: The oil slurry pretreatment stage includes: using catalytic cracking oil slurry as raw material, removing light components and impurity components through vacuum cutting to obtain intermediate high-quality component aromatic oil, and after hydrorefining, reducing its sulfur content to ≤0.5% to obtain refined product oil; The preparation stage of the heavy mixed oil: the refined product oil is mixed with accelerator and compounding agent in a certain proportion to obtain heavy mixed oil, and needle coke is obtained by using the heavy mixed oil through the coking reaction stage and the steam blowing and coking stage. The accelerator is one of the following: cycloalkane-rich oil, raffinate oil, hydrotreated tail oil, and naphthenic crude oil; The mixing agent is one of the following: bottom oil from primary distillation column, vacuum residue, rubber asphalt, ethylene tar asphalt, and refined coal tar asphalt; The coking reaction stage is a variable temperature and pressure process; the total coking reaction cycle is 24-48 hours; in the early stage of the reaction, a low temperature and high pressure coking method is adopted, with a coking temperature of 460-480℃, a reaction pressure of 0.5-1MPa, and a reaction time of 5-12 hours. In the later stages of the reaction, the reaction temperature was gradually increased to 480-520℃, and the reaction pressure was reduced to 0-0.6MPa. The steam blowing and coking stage uses high-temperature oil and gas for coking. The coking cycle of the steam blowing stage is 6-24 hours, the steam blowing temperature is 470-550℃, the steam blowing oil and gas volume is 10-35 t / h, the oil and gas ratio is 10-30 t / h, the steam volume ratio is 0-10 t / h, and the pressure of the steam blowing stage is 0.1-1 MPa.

2. The method for preparing a high-processability and high-capacity anode material precursor according to claim 1, characterized in that... The mass fractions of the refined product oil, compounding agent, and accelerator are 30%-90%, 5%-50%, and 5%-30%, respectively.

3. The method for preparing a high-processability and high-capacity anode material precursor according to claim 1 or 2, characterized in that... The obtained needle coke is processed through crushing, shaping, and grading to obtain anode material precursors with a D50 of 14-16 μm.

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