Method for preparing sodium electric hard carbon negative electrode by multistage oxidation of asphalt and application of sodium electric hard carbon negative electrode
Through multi-stage crushing and oxidation treatment methods, combined with dynamic stirring and airflow purge, the plate bonding and foaming problems during large-scale asphalt oxidation are solved, the sufficient oxidation and structural improvement of hard carbon materials are achieved, and the electrochemical performance of sodium batteries is improved.
Patent Information
- Application Number
- CN202510738635.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-04
- Publication Date
- 2025-08-12
AI Technical Summary
During the oxidation process of large-scale asphalt, there is easy to cause insufficient reactivity of plate bonding, foaming and oxygen contact, which makes it difficult to industrialize the preparation of hard carbon materials.
Multi-stage crushing and oxidation treatment is adopted, combined with dynamic stirring and airflow purge, the particle size and temperature are gradually controlled, the asphalt and oxygen are fully contacted, and the hard carbon structure is improved through gradient low-temperature carbonization treatment.
It improves the oxidation uniformity and reactivity of asphalt, solves the problems of plate bonding and foaming, and improves the capacity and rate performance of hard charcoal materials.
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Figure CN120463181A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of new energy battery materials, and specifically relates to a method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of asphalt and its application. Background Art
[0002] Sodium-ion batteries (SIBs), owing to their low cost and high safety, have rapidly captured the new energy market and become a focus of attention in both industry and academia. As a key component of SIBs, hard carbon anode materials influence their capacity, rate capability, and cycling properties. Currently, precursors for hard carbon anode materials include biomass, polymers, coal, and asphalt. Asphalt, due to its tunable molecular structure, high carbon content, and low ash content, is considered the most competitive precursor for preparing hard carbon. However, direct heat treatment of asphalt tends to order the polycyclic aromatic hydrocarbons within it, resulting in a soft carbon rather than a hard carbon with a disordered structure. Consequently, many researchers have proposed methods such as liquid-phase oxidation, gas-phase oxidation (air / pure oxygen), and metal oxide / metal compound-modified oxidation to hinder the ordered arrangement of polycyclic aromatic hydrocarbons in asphalt. Gas-phase oxidation is considered the most suitable method for the industrialization of asphalt-based hard carbon, and numerous patents propose oxidation of asphalt using oxygen / air. However, most patents are based on laboratory experiments at the gram-scale, where the asphalt dosage is low, allowing for sufficient oxygen contact and reaction. Increasing the asphalt dosage inevitably increases the thickness of the asphalt reaction, resulting in insufficient oxygen contact and poor reactivity in the underlying asphalt layer, which can lead to asphalt hardening and foaming. Therefore, achieving oxidation of large quantities of asphalt while simultaneously addressing the foaming, hardening, and coking issues associated with increased asphalt dosage is key to advancing the industrialization of asphalt-based hard carbon. Summary of the Invention
[0003] In response to the problems of asphalt compaction, foaming, coking, and insufficient reactivity with oxygen that occur during large-scale asphalt oxidation, the present invention provides a method and application for preparing sodium electric hard carbon negative electrode by multi-stage oxidation of asphalt.
[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0005] A method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch comprises the following steps:
[0006] Step 1: crushing the asphalt with a softening point of 100-150°C in a primary manner, and then performing a primary oxidation treatment to obtain a primary oxidized material;
[0007] Step 2, performing secondary crushing on the primary oxidized material, and then performing secondary oxidation treatment to obtain a secondary oxidized material;
[0008] Step 3, performing tertiary crushing on the secondary oxidized material, and then performing tertiary oxidation treatment to obtain tertiary oxidized material;
[0009] Step 4, subjecting the obtained tertiary oxidation material to a gradient low-temperature carbonization treatment to obtain a low-temperature carbonized material;
[0010] Step 5, then controlling the particle size of the low-temperature carbonized material to obtain fine-particle low-temperature carbonized material;
[0011] Step 6: Finally, the low-temperature carbonized material is subjected to high-temperature carbonization treatment to obtain a sodium electric hard carbon negative electrode material.
[0012] Furthermore, the particle size D50 after the primary crushing in step 1 is controlled to be 300-400 μm;
[0013] The temperature of the primary oxidation treatment in step 1 is controlled at 20-30°C lower than the softening point of asphalt, the reaction airflow is based on the charging amount: air flow = 100g: (20-50) L / min, the shaft stirring rate is 100-500 r / min, the flow ratio of pure oxygen to air in the airflow is (0.1-0.3):1, and the reaction time is 5-10h.
[0014] Furthermore, the particle size D50 after secondary crushing in step 2 is controlled at 100-200 μm;
[0015] The temperature of the secondary oxidation treatment in step 2 is controlled at 150°C~200°C, the reaction airflow is based on the charging amount: air flow = 100g: (10~20) L / min, the shaft stirring rate is 100~500r / min, the flow ratio of pure oxygen to air in the airflow is (0.3~0.5):1, and the reaction time is 3~5h.
[0016] Furthermore, the particle size D50 after the tertiary crushing in step 3 is controlled to be 20-50 μm;
[0017] The temperature of the tertiary oxidation treatment in step 3 is controlled at 250°C to 350°C, the reaction airflow is based on the charge amount: air flow = 100g: (2~10) L / min, the shaft stirring rate is 100~500r / min, the flow ratio of pure oxygen to air in the airflow is (0.5~1.0):1, and the reaction time is 0.5~3h.
[0018] Furthermore, the specific process conditions of the gradient low-temperature carbonization treatment in step 4 are as follows: in an inert gas atmosphere, heating to 250°C~350°C at a rate of 2~10°C / min, maintaining the temperature for 0.5h~2.0h, and then heating to 600~650°C at a rate of 2~10°C / min, and maintaining the temperature for 1.0h~2.0h.
[0019] Furthermore, the particle size control in step 5 is specifically to crush the low-temperature carbonized material to D50 = 5~8um.
[0020] Furthermore, in step 6, the temperature of the high-temperature carbonization treatment is 1200-1400° C., the carbonization time is 1-5 hours, and the heating rate is 2-10° C. / min.
[0021] A sodium electric hard carbon negative electrode material prepared by the preparation method according to any one of claims 1 to 7.
[0022] A pitch-based hard carbon negative electrode plate, comprising a pitch-based hard carbon material prepared by the preparation method according to any one of claims 1 to 7.
[0023] A sodium ion battery, comprising the negative electrode sheet according to claims 1 to 7.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] (1) By performing multi-stage crushing and multi-stage oxidation on the asphalt, the formed surface passivation layer can be destroyed and a new oxidizable surface can be exposed, thereby increasing the reactivity of the polycyclic aromatic hydrocarbon structure in the asphalt with oxygen, and solving the problem of internal softening of the asphalt caused by inconsistent internal and external temperature differences. At the same time, during the oxidation process, auxiliary dynamic stirring and lower air flow purge are used to achieve full contact between the asphalt and the oxygen-containing gas. With the condition that the smaller the particle size, the higher the oxygen concentration, the more complete and uniform the oxidation of the asphalt is, and the problems of thermal storage foaming and poor stability between batches of materials caused by the large thickness of the asphalt oxidation are solved.
[0026] (2) By subjecting the tertiary oxidized material to a gradient low-temperature carbonization treatment, the native hydroxyl functional groups in the oxidized asphalt can be converted into CO groups, thereby causing the hard carbon microchip layer to accumulate in a "house of cards" type, thereby improving the capacity and rate properties of the sodium-electrochemical hard carbon. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.
[0028] Figure 1 It is a schematic flow diagram of the method of the present invention;
[0029] Figure 2 It is the SEM image of the sodium-ion hard carbon negative electrode;
[0030] Figure 3This is the charge and discharge curve of the sodium-ion hard carbon negative electrode. DETAILED DESCRIPTION
[0031] To gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description thereof. However, the present invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a comprehensive understanding of the present disclosure.
[0032] Example 1
[0033] This embodiment provides a method and application for preparing sodium electric hard carbon negative electrode by multi-stage oxidation of asphalt. The process flow chart is as follows: Figure 1 As shown, the preparation method comprises the following steps:
[0034] Step 1: Coal liquefaction residue asphalt with a softening point of 135°C is coarsely crushed to obtain a primary crushed material with a particle size D50 of 350 μm. The primary crushed material is charged into an axially agitated oxidation furnace and subjected to a primary oxidation reaction at a reaction temperature of 110°C, a gas flow rate of 100 g:35 L / min, an axial agitation rate of 300 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.2:1, and a reaction time of 7 hours. After completion of the reaction, the primary oxidized material is obtained.
[0035] Step 2: The primary oxidized material is subjected to secondary crushing to obtain a secondary crushed material with a particle size D50 of 150 μm. The secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a secondary oxidation reaction at a reaction temperature of 180° C., a gas flow rate of 100 g:15 L / min, an axial stirring rate of 350 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.4:1, and a reaction time of 4 h. After the reaction is completed, a secondary oxidized material is obtained;
[0036] Step 3, the secondary oxidation material is subjected to tertiary crushing to obtain a secondary crushed material with a particle size D50 of 35um, and the secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a tertiary oxidation reaction at a reaction temperature of 300°C, a gas flow rate of 100g:6L / min, an axial stirring rate of 400r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.8:1, and a reaction time of 1.5h. After the reaction, a tertiary oxidation material is obtained.
[0037] Step 4: The tertiary oxidation material is subjected to a heat treatment program of increasing the temperature to 300° C. at 5° C. / min and holding the temperature for 1.0 h in a nitrogen atmosphere, and then increasing the temperature to 630° C. at 5° C. / min and holding the temperature for 1 h to obtain a low-temperature carbonized material;
[0038] Step 5: The obtained low-temperature carbonized material is subjected to air flow pulverization treatment to obtain a pulverized material with a particle size D50 of 7 μm;
[0039] In step 6, the low-carbon crushed material is then subjected to high-temperature carbonization treatment at a heating rate of 5°C / min, a final reaction temperature of 1300°C, and a reaction time of 1.5h to obtain a pitch-based hard carbon negative electrode after the reaction is completed.
[0040] Example 2
[0041] This embodiment provides a method and application for preparing sodium electric hard carbon negative electrode by multi-stage oxidation of asphalt. The process flow chart is as follows: Figure 1 As shown, the preparation method comprises the following steps:
[0042] In step 1, the oil-based coated asphalt with a softening point of 150°C is coarsely crushed to obtain a primary crushed material with a particle size D50 of 400 μm. The primary crushed material is charged into an axially stirred oxidation furnace and subjected to a primary oxidation reaction at a reaction temperature of 120°C, a gas flow rate of 100 g:20 L / min, an axial stirring rate of 100 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.1:1, and a reaction time of 10 hours. After completion of the reaction, the primary oxidized material is obtained.
[0043] Step 2: The primary oxidized material is subjected to secondary crushing to obtain a secondary crushed material with a particle size D50 of 100 μm. The secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a secondary oxidation reaction at a reaction temperature of 200° C., a gas flow rate of 100 g:10 L / min, an axial stirring rate of 100 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.3:1, and a reaction time of 5 h. After the reaction, a secondary oxidized material is obtained;
[0044] Step 3, the secondary oxidation material is subjected to tertiary crushing to obtain a secondary crushed material with a particle size D50 of 50 μm, and the secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a tertiary oxidation reaction at a reaction temperature of 250° C., a gas flow rate of 100 g:10 L / min, an axial stirring rate of 500 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.5:1, and a reaction time of 3 h. After the reaction, a tertiary oxidation material is obtained;
[0045] Step 4: The tertiary oxidation material is subjected to a heat treatment program of increasing the temperature to 350°C at 10°C / min and holding the temperature for 0.5h in a nitrogen atmosphere, and then increasing the temperature to 600°C at 10°C / min and holding the temperature for 1h to obtain a low-temperature carbonized material;
[0046] Step 5: The obtained low-temperature carbonized material is subjected to air flow pulverization treatment to obtain a pulverized material with a particle size D50 of 8 μm;
[0047] In step 6, the low-carbon crushed material is then subjected to high-temperature carbonization treatment at a heating rate of 10°C / min, a final reaction temperature of 1200°C, and a reaction time of 5 hours to obtain a pitch-based hard carbon negative electrode after the reaction is completed.
[0048] Example 3
[0049] This embodiment provides a method and application for preparing sodium electric hard carbon negative electrode by multi-stage oxidation of asphalt. The process flow chart is as follows: Figure 1 As shown, the preparation method comprises the following steps:
[0050] Step 1: Coarsely crush the modified coal tar pitch with a softening point of 115°C to obtain a primary crushed material with a particle size D50 of 300 μm. The primary crushed material is charged into an axially stirred oxidation furnace and subjected to a primary oxidation reaction at a reaction temperature of 95°C, a gas flow rate of 100 g:50 L / min, an axial stirring rate of 500 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.3:1, and a reaction time of 5 hours. After completion of the reaction, the primary oxidized material is obtained.
[0051] Step 2: The primary oxidized material is subjected to secondary crushing to obtain a secondary crushed material with a particle size D50 of 200 μm. The secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a secondary oxidation reaction at a reaction temperature of 150° C., a gas flow rate of 100 g:20 L / min, an axial stirring rate of 500 r / min, a flow ratio of pure oxygen to air in the mixed gas of 0.5:1, and a reaction time of 3 h. After the reaction is completed, a secondary oxidized material is obtained;
[0052] Step 3, the secondary oxidation material is subjected to tertiary crushing to obtain a secondary crushed material with a particle size D50 of 20um, and the secondary crushed material is charged into an axially stirred oxidation furnace and subjected to a tertiary oxidation reaction at a reaction temperature of 350°C, a gas flow rate of 100g:2L / min, an axial stirring rate of 100r / min, a flow ratio of pure oxygen to air in the mixed gas of 1:1, and a reaction time of 0.5h. After the reaction, a tertiary oxidation material is obtained.
[0053] Step 4: The tertiary oxidation material is subjected to a heat treatment program of increasing the temperature to 250° C. at 2° C. / min and holding the temperature for 2.0 h in a nitrogen atmosphere, and then increasing the temperature to 650° C. at 2° C. / min and holding the temperature for 2 h to obtain a low-temperature carbonized material;
[0054] Step 5: The obtained low-temperature carbonized material is subjected to air flow pulverization treatment to obtain a pulverized material with a particle size D50 of 5 μm;
[0055] In step 6, the low-carbon crushed material is then subjected to high-temperature carbonization treatment at a heating rate of 2°C / min, a final reaction temperature of 1400°C, and a reaction time of 1 hour to obtain a pitch-based hard carbon negative electrode after the reaction is completed.
[0056] Example 4
[0057] The difference between this embodiment and embodiment 1 is that the coal tar pitch is not subjected to primary oxidation in step 1.
[0058] The rest of the preparation methods and parameters remained the same as in Example 1.
[0059] Example 5
[0060] The difference between this embodiment and embodiment 1 is that the coal tar pitch is not subjected to secondary oxidation in step 2.
[0061] The rest of the preparation methods and parameters remained the same as in Example 1.
[0062] Example 6
[0063] The difference between this embodiment and embodiment 1 is that the coal tar pitch is not subjected to tertiary oxidation in step 3.
[0064] The rest of the preparation methods and parameters remained the same as in Example 1.
[0065] Example 7
[0066] The difference between this embodiment and embodiment 1 is that in step 4, the tertiary oxidized asphalt is not subjected to gradient temperature carbonization, but is directly subjected to temperature-raising low-carbon treatment.
[0067] The rest of the preparation methods and parameters remained the same as in Example 1.
[0068] Comparative Example 1
[0069] The difference between this comparative example and Example 1 is that, under the same asphalt dosage, the comparative experimental group does not perform a multi-stage crushing-multi-stage oxidation process, but performs a one-step three-stage crushing-three-stage oxidation process. The comparison illustrates that most of the current patents and small laboratories prepare hard carbon under the conditions of a large amount of asphalt.
[0070] The rest of the preparation methods and parameters remained the same as in Example 1.
[0071] The pitch-based hard carbon material provided in the above examples and comparative examples was made into a negative electrode sheet, and assembled with a commercial sodium sheet, a separator and an electrolyte to obtain a sodium ion button battery. The specific steps include:
[0072] A slurry prepared by mixing pitch-based hard carbon material, Super P, 1.5% carboxymethyl cellulose (CMC), and 45% styrene-butadiene rubber (SBR) in a mass ratio of 91:2:2:5 was coated onto aluminum foil. A commercial sodium sheet was used as the positive electrode. Glass fiber (Whatman, GF / D) and 1 M NaClF₂ were used as the separator and electrolyte, respectively. CR2032 coin cells were assembled in a glove box (H₂O, O₂ <0.1 ppm). Charge-discharge tests at 0–2 V and cycling stability were performed using a LAND CT2001 battery tester (LAND, Wuhan, China).
[0073] The above sodium ion batteries were subjected to capacity performance tests and cycle stability tests.
[0074] The conditions for the capacity performance test are as follows: according to the multi-stage discharge system (first discharge at 60mA / g to 0V and then stand for 10s, then discharge at 45mA / g to 0V and then stand for 10s, discharge at 36mA / g to 0V and then stand for 10s, discharge at 24mA / g to 0V and then stand for 10s, discharge at 18mA / g to 0V and then stand for 10s, discharge at 10mA / g to 0V and then stand for 10s, discharge at 15mA / g to The battery was charged at the following steps: discharge at 0V and then stand for 10s, discharge at 12mA / g to 0V and then stand for 10s, discharge at 9mA / g to 0V and then stand for 10s, discharge at 6mA / g to 0V and then stand for 10s, discharge at 3mA / g to 0V and then stand for 10s, discharge at 20uA / g to 0V and then stand for 10s, discharge at 10uA / g to 0V and then stand for 10s) and one-step 30mA / g current; the voltage window was set to 0~2 V.
[0075] The conditions for the cyclic stability test are: the button is charged and discharged for 3 cycles at a current of 30 mA / g, and then charged and discharged at a current density of 100 mA / g. The current window is set to 0-2 V and the number of cycles is 150.
[0076] The test results are shown in Table 1.
[0077] Table 1
[0078]
[0079] Any matters not described in detail in this specification are prior art known to those skilled in the art. Although the above description of the present invention is based on specific embodiments to facilitate understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the specific embodiments. As long as various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, such modifications will be obvious to those skilled in the art, and all inventions and creations utilizing the concepts of the present invention are protected.
Claims
1. A method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch, characterized in that: The following steps are involved: Step 1: crushing the asphalt with a softening point of 100-150°C in a primary manner, and then performing a primary oxidation treatment to obtain a primary oxidized material; Step 2, performing secondary crushing on the primary oxidized material, and then performing secondary oxidation treatment to obtain a secondary oxidized material; Step 3, performing tertiary crushing on the secondary oxidized material, and then performing tertiary oxidation treatment to obtain tertiary oxidized material; Step 4, subjecting the obtained tertiary oxidation material to a gradient low-temperature carbonization treatment to obtain a low-temperature carbonized material; Step 5, then controlling the particle size of the low-temperature carbonized material to obtain fine-particle low-temperature carbonized material; Step 6: Finally, the low-temperature carbonized material is subjected to high-temperature carbonization treatment to obtain a sodium electric hard carbon negative electrode material.
2. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: The particle size D50 after primary crushing in step 1 is controlled at 300-400 μm; The temperature of the primary oxidation treatment in step 1 is controlled at 20-30°C lower than the softening point of asphalt, the reaction airflow is based on the charging amount: air flow = 100g: (20-50) L / min, the shaft stirring rate is 100-500 r / min, the flow ratio of pure oxygen to air in the airflow is (0.1-0.3):1, and the reaction time is 5-10h.
3. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: The particle size D50 after secondary crushing in step 2 is controlled at 100-200 μm; The temperature of the secondary oxidation treatment in step 2 is controlled at 150°C~200°C, the reaction airflow is based on the charging amount: air flow = 100g: (10~20) L / min, the shaft stirring rate is 100~500r / min, the flow ratio of pure oxygen to air in the airflow is (0.3~0.5):1, and the reaction time is 3~5h.
4. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: The particle size D50 after the tertiary crushing in step 3 is controlled at 20-50 μm; The temperature of the tertiary oxidation treatment in step 3 is controlled at 250°C to 350°C, the reaction airflow is based on the charge amount: air flow = 100g: (2~10) L / min, the shaft stirring rate is 100~500r / min, the flow ratio of pure oxygen to air in the airflow is (0.5~1.0):1, and the reaction time is 0.5~3h.
5. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: The specific process conditions for the gradient low-temperature carbonization treatment in step 4 are as follows: in an inert gas atmosphere, heating to 250°C~350°C at a rate of 2~10°C / min, maintaining the temperature for 0.5h~2.0h, and then heating to 600~650°C at a rate of 2~10°C / min, and maintaining the temperature for 1.0h~2.0h.
6. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: The particle size control in step 5 is specifically to crush the low-temperature carbonized material to D50 = 5~8um.
7. The method for preparing a sodium electric hard carbon negative electrode by multi-stage oxidation of pitch according to claim 1, characterized in that: In step 6, the temperature of the high-temperature carbonization treatment is 1200-1400° C., the carbonization time is 1-5 hours, and the heating rate is 2-10° C. / min.
8. A sodium electric hard carbon negative electrode material prepared by the preparation method according to any one of claims 1 to 7.
9. A pitch-based hard carbon negative electrode plate, characterized in that: The negative electrode plate comprises a pitch-based hard carbon material prepared by the preparation method according to any one of claims 1 to 7.
10. A sodium ion battery, characterized in that: The sodium ion battery comprises the negative electrode sheet according to claims 1 to 7.