Asphalt-based hard carbon / graphite composite material with nano closed pores and preparation method of asphalt-based hard carbon / graphite composite material

Abstract

The invention discloses an asphalt-based hard carbon / graphite composite material with nano closed pores and a preparation method of the asphalt-based hard carbon / graphite composite material, and belongs to the technical field of secondary battery negative electrode materials. Comprising the following steps: in the presence of a pore-forming agent, catalyzing cross-linking polymerization of asphalt by taking anhydrous metal chloride capable of catalyzing graphitization as an acid catalyst, and regulating and controlling the residual amount of the catalyst in a product by controlling washing and extraction. After carbonization, the pore-forming agent is pyrolyzed to form nanopores in the carbon material, the cross-linked polymer skeleton forms hard carbon, and the residual catalyst causes the carbon nearby to form a graphite micro-area structure. The raw materials are easy to obtain, the process is simple, operation is convenient, and large-scale production is easy to achieve.

Description

Technical Field

[0001] The invention relates to the technical field of secondary battery negative electrode materials, and in particular to an asphalt-based hard carbon / graphite composite material with nano closed pores and a preparation method thereof. Background Art

[0002] As a promising energy storage technology, sodium-ion batteries have attracted much attention due to their abundant resources and low cost. The negative electrode material of sodium-ion batteries has always been one of the key factors limiting the release and improvement of their performance, and the development of high-performance sodium-ion battery negative electrodes has become a research hotspot.

[0003] Soft carbon and hard carbon materials have good performance in different technical applications and directions due to their unique microstructure and advantages. Soft carbon materials generally have low defects and good conductivity, but due to the limitation of their interlayer spacing, it is difficult for sodium ions to embed and escape, which ultimately affects the performance of sodium ion batteries; while hard carbon materials complement their advantages. Hard carbon has a larger interlayer spacing, higher defect points and rich microporous structure, which can provide more sodium storage sites, but its conductivity is poor, which will affect the transmission of sodium ions. Therefore, if soft carbon and hard carbon are combined to prepare a composite material with the advantages of both, the sodium storage performance of the negative electrode material can be significantly improved; for example, patent CN119461319A prepares soft and hard carbon composite materials by mixing asphalt and BC aerogel in a certain proportion in a high temperature and high pressure reactor.

[0004] As researchers delve deeper into negative electrode materials for sodium-ion batteries, they believe that closed-pore structures have a huge impact on the performance of sodium-ion batteries. Studies have shown that closed-pore structures provide additional storage sites for sodium ions, significantly increasing the capacity of the low-voltage platform region, and have unique advantages in improving the initial coulombic efficiency and cycle stability of sodium-ion batteries. For example, patent CN119284882B pre-oxidizes biomass-based fruit shells and then performs a heat treatment, followed by carbonization and vapor deposition of a biomass-based hard carbon structure with a closed-pore structure.

[0005] However, there is no design and regulation method for asphalt-based soft carbon / hard carbon composite nano closed-cell materials, so it is urgent to develop an efficient and feasible preparation method. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a pitch-based hard carbon / graphite composite material with nano-closed pores. In the presence of a pore-forming agent, an anhydrous metal chloride capable of catalyzing graphitization is used as a Lewis acid catalyst to catalyze the cross-linking polymerization of heavy organic matter, and the obtained composite is washed and extracted in a controlled manner to regulate the amount of catalyst residue in the product. During the carbonization process, the pore-forming agent is pyrolyzed to form nanopores in the carbon material, the cross-linked polymer skeleton forms hard carbon, and the residual catalyst causes the carbon near it to form a graphite structure.

[0007] The technical solution of the present invention is as follows:

[0008] A preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores, comprising the following steps:

[0009] (1) Mix heavy organic matter, crosslinking agent, catalyst, pore-forming agent and solvent evenly;

[0010] (2) Heat the mixture obtained in step (1) for reaction. After the reaction ends, immediately quench the reaction with a quenching solvent, then wash with an organic solvent first, and then extract with an organic solvent. After the extraction ends, dry the product to obtain a carbon precursor;

[0011] (3) Place the carbon precursor obtained in step (2) in a high-temperature furnace and perform high-temperature carbonization treatment under an inert gas protection atmosphere to obtain an asphalt-based hard carbon / graphite composite material with nano-closed pores.

[0012] Furthermore, in the step (1), the heavy organic matter is selected from coal tar pitch, petroleum asphalt, and ethylene tar pitch; the crosslinking agent is selected from trioxymethylene, paraformaldehyde, chloroform, and dimethoxymethane; the catalyst is selected from anhydrous ferric chloride, anhydrous cobalt dichloride, and anhydrous nickel dichloride; the pore-forming agent is selected from polyethylene glycol, polyvinyl chloride, and polystyrene microspheres; the solvent is selected from 1,2-dichloroethane, dichloromethane, and chloroform.

[0013] Furthermore, in the step (1), the mass ratio of the heavy organic matter, crosslinking agent, catalyst, pore-forming agent and solvent is 100:50 - 100:200 - 450:0 - 50:2500 - 3500.

[0014] Furthermore, in the step (2), the reaction temperature is 50 - 100 °C, and the reaction time is controlled within 1 - 12 h.

[0015] Furthermore, in the step (2), the quenching solvent is selected from anhydrous methanol and anhydrous ethanol; the organic solvent used for washing is selected from anhydrous methanol and dichloromethane; the organic solvent used for extraction is selected from anhydrous methanol and tetrahydrofuran.

[0016] Furthermore, in the step (2), the number of washing times is 1 - 5 times; the extraction time is 1 - 48 h, the extraction temperature is 50 - 100 °C; the drying temperature is 50 - 150 °C, and the drying time is 1 - 12 h.

[0017] Furthermore, in the step (3), the inert gas is selected from one of nitrogen and argon; the high-temperature carbonization temperature is 800 - 1500 °C, the heating rate is 3 - 10 °C / min, and the holding time is 2 - 4 h.

[0018] One kind of the asphalt-based hard carbon / graphite composite material with nano-closed pores is used for sodium ion batteries.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1) Using asphalt-based heavy organic matter as raw material, through cross-linking reaction, a hard carbon skeleton is obtained after carbonization; the pore-forming agent pyrolyzes to form a closed pore structure; by controlling washing and extraction, the residual catalyst catalyzes the formation of graphite microdomains during carbonization. This composite structure fully combines the advantages of the abundant sodium storage sites of hard carbon, the high conductivity of graphite, and the additional sodium storage space generated by the closed pore structure, which can significantly improve the specific capacity and rate performance of the anode material for sodium ion batteries.

[0021] 2) The raw materials of the present invention are easily available, the preparation process is simple, the operation is convenient, the cost is low, it is easy to realize large-scale production, and it has good industrial application prospects. Description of the Drawings

[0022] Figure 1 XRD spectrum of the nano-closed pore asphalt-based hard carbon / graphite composite material prepared in Example 5.

[0023] Figure 2 Sodium ion storage performance of the nano-closed pore asphalt-based hard carbon / graphite composite materials prepared in Example 5 and Example 6. Detailed Embodiments

[0024] The technical solutions of the present invention are further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0025] Example 1

[0026] Mix petroleum asphalt, paraformaldehyde, anhydrous cobalt dichloride, polyvinyl chloride and 1,2-dichloroethane evenly at a mass ratio of 100:50:200:10:2500, and react at 100 °C for 1 h. After the reaction is completed, immediately quench the reaction with anhydrous methanol, then wash it once with dichloromethane, and then extract it with anhydrous methanol at 100 °C for 1 h. After the extraction is completed, the product is dried at 50 °C for 8 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 5 °C / min, and carry out high-temperature carbonization treatment at 800 °C under a nitrogen gas protection atmosphere. After holding for 4 h, a nano-closed pore asphalt-based hard carbon / graphite composite material is obtained.

[0027] Example 2

[0028] Mix ethylene tar pitch, chloroform, anhydrous nickel dichloride, polystyrene microspheres and chloroform evenly at a mass ratio of 100:75:300:25:3000, and react at 75 °C for 6.5 h. Immediately after the reaction is completed, quench the reaction with absolute ethanol, then wash it with absolute methanol three times first, and then extract it with absolute methanol at 75 °C for 24 h. After the extraction is completed, dry the product at 150 °C for 1 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 8 °C / min, and carry out high-temperature carbonization treatment at 1500 °C under an argon gas protection atmosphere. After holding for 2 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0029] Example 3

[0030] Mix petroleum asphalt, trioxane, anhydrous cobalt dichloride, polyvinyl chloride and chloroform evenly at a mass ratio of 100:80:350:30:2800, and react at 50 °C for 12 h. Immediately after the reaction is completed, quench the reaction with absolute ethanol, then wash it with absolute methanol four times first, and then extract it with absolute methanol at 80 °C for 28 h. After the extraction is completed, dry the product at 140 °C for 2 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 6 °C / min, and carry out high-temperature carbonization treatment at 1400 °C under an argon gas protection atmosphere. After holding for 3 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0031] Example 4

[0032] Mix coal tar pitch, dimethoxymethane, anhydrous ferric trichloride, polyethylene glycol and 1,2-dichloroethane evenly at a mass ratio of 100:100:450:50:3200, and react at 80 °C for 6 h. Immediately after the reaction is completed, quench the reaction with absolute ethanol, then wash it with absolute methanol once first, and then extract it with tetrahydrofuran at 85 °C for 12 h. After the extraction is completed, dry the product at 105 °C for 12 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 10 °C / min, and carry out high-temperature carbonization treatment at 1300 °C under an argon gas protection atmosphere. After holding for 4 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0033] Example 5

[0034] Mix petroleum asphalt, trioxane, anhydrous ferric chloride, polyvinyl chloride, and dichloromethane evenly at a mass ratio of 100:100:430:0:3100, and react at 90 °C for 8 h. Immediately quench the reaction with anhydrous methanol after the reaction ends, then wash it with anhydrous methanol 5 times first, and then extract it with tetrahydrofuran at 90 °C for 48 h. After the extraction ends, dry the product at 110 °C for 12 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 4 °C / min, and conduct high-temperature carbonization treatment at 1300 °C under an argon gas protection atmosphere. After holding for 2 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0035] Example 6

[0036] Mix coal tar pitch, dimethoxymethane, anhydrous ferric chloride, polyethylene glycol, and 1,2-dichloroethane evenly at a mass ratio of 100:100:430:20:3350, and react at 100 °C for 10 h. Immediately quench the reaction with anhydrous ethanol after the reaction ends, then wash it with anhydrous methanol 2 times first, and then extract it with tetrahydrofuran at 100 °C for 12 h. After the extraction ends, dry the product at 100 °C for 12 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 3 °C / min, and conduct high-temperature carbonization treatment at 1300 °C under an argon gas protection atmosphere. After holding for 2 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0037] Example 7

[0038] Mix petroleum asphalt, chloroform, anhydrous cobalt dichloride, polyethylene glycol, and 1,2-dichloroethane evenly at a mass ratio of 100:60:250:40:2750, and react at 50 °C for 12 h. Immediately quench the reaction with anhydrous ethanol after the reaction ends, then wash it with anhydrous methanol 2 times first, and then extract it with tetrahydrofuran at 70 °C for 30 h. After the extraction ends, dry the product at 100 °C for 4 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 10 °C / min, and conduct high-temperature carbonization treatment at 850 °C under an argon gas protection atmosphere. After holding for 2 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0039] Example 8

[0040] Mix ethylene tar pitch, paraformaldehyde, anhydrous ferric trichloride, polyvinyl chloride, and dichloromethane evenly at a mass ratio of 100:85:400:45:3500, and react at 85 °C for 9 h. Immediately after the reaction ends, quench the reaction with anhydrous methanol, then wash it twice with anhydrous methanol first, and then extract it with tetrahydrofuran at 95 °C for 10 h. After the extraction ends, dry the product at 100 °C for 5.5 h to obtain a carbon precursor. Place the obtained carbon precursor in a high-temperature furnace, with a heating rate of 10 °C / min, and perform high-temperature carbonization treatment at 850 °C under an argon gas protection atmosphere. After holding for 2 h, an asphalt-based hard carbon / graphite composite material with nano-closed pores is obtained.

[0041] Application Example

[0042] Use the asphalt-based soft carbon / hard carbon composite nano-closed pore materials prepared in Example 5 and Example 6 as the negative electrode material, use a sodium sheet as the counter electrode, and assemble it in a glove box with the water content and oxygen content both below 0.1 ppm. First, place the positive electrode battery case, drop a drop of electrolyte, then place the negative electrode material and add two drops of electrolyte, place the separator and add an appropriate amount of electrolyte, and then place the cut sodium sheet, gasket, and battery negative case in sequence. Assemble a half-cell and conduct electrochemical tests on it; the electrochemical cycling performance results of the prepared hard carbon are as Figure 2 , the nano-closed pore hard carbon materials prepared in Example 5 and Example 6 have reversible capacities of 135.2 mA g -1 , 257.6 mA g -1 , respectively, and capacity retention rates of 66.7%,, 91.06% after 200 cycles. The asphalt-based soft carbon / hard carbon composite nano-closed pore material obtained in Example 6 exhibits very excellent capacity retention rate and cycling performance.

Claims

1. A preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores, characterized in that, It includes the following steps: (1) Mix heavy organic matter, crosslinking agent, catalyst, pore-forming agent and solvent evenly; (2) Heat the mixture evenly obtained in step (1) for reaction. Immediately after the reaction ends, quench the reaction with a quenching solvent, then wash with an organic solvent first, and then extract with an organic solvent. After the extraction ends, dry the product to obtain a carbon precursor; (3) Place the carbon precursor obtained in step (2) in a high-temperature furnace and carry out high-temperature carbonization treatment under an inert gas protection atmosphere to obtain an asphalt-based hard carbon / graphite composite material with nano-closed pores.

2. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (1), the heavy organic matter is selected from coal tar pitch, petroleum asphalt, ethylene tar pitch; the crosslinking agent is selected from trioxymethylene, paraformaldehyde, chloroform, dimethoxymethane; the catalyst is selected from anhydrous ferric chloride, anhydrous cobalt dichloride, anhydrous nickel dichloride; the pore-forming agent is selected from polyethylene glycol, polyvinyl chloride, polystyrene microspheres; the solvent is selected from 1,2-dichloroethane, dichloromethane, chloroform.

3. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (1), the mass ratio of heavy organic matter, crosslinking agent, catalyst, pore-forming agent and solvent is 100:50 - 100:200 - 450:0 - 50:2500 - 3500.

4. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (2), the reaction temperature is 50 - 100 °C, and the reaction time is controlled within 1 - 12 h.

5. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (2), the quenching solvent is selected from anhydrous methanol, anhydrous ethanol; the organic solvent used for washing is selected from anhydrous methanol, dichloromethane; the organic solvent used for extraction is selected from anhydrous methanol, tetrahydrofuran.

6. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (2), the number of washing times is 1 - 5 times; the extraction time is 1 - 48 h, the extraction temperature is 50 - 100 °C; the drying temperature is 50 - 150 °C, and the drying time is 1 - 12 h.

7. The preparation method of an asphalt-based hard carbon / graphite composite material with nano-closed pores according to claim 1, characterized in that, In the said step (3), the inert gas is selected from one of nitrogen, argon; the high-temperature carbonization temperature is 800 - 1500 °C, the heating rate is 3 - 10 °C / min, and the holding time is 2 - 4 h.

8. The asphalt-based hard carbon / graphite composite material with nano-closed pores prepared by the preparation method according to any one of claims 1 - 7 is used for sodium ion batteries.

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