A method for preparing waste asphalt carbon with microcrystalline vortex structure as ion battery material

Abstract

This invention provides a method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material. The method involves mixing a waste asphalt solution with magnesium oxide powder, heating and evaporating it to dryness, pre-carbonizing it, ball milling and screening it, acid washing to remove the template, and then performing a secondary high-temperature carbonization process to produce a carbon negative electrode material with a semi-disordered microcrystalline cross-linked structure. This material utilizes the magnesium oxide template and two carbonization processes to control the carbon interlayer spacing and pore structure, forming a vortex-like space. This significantly increases the alkali metal ion storage capacity and initial coulombic efficiency, achieving high-value-added utilization of waste asphalt with both environmental and economic benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and in particular relates to a method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material. Background Art

[0002] Asphalt waste, a major solid waste, degrades slowly, accumulates in large volumes, and occupies extensive space. Without effective treatment, it can negatively impact the environment. Converting the waste asphalt in asphalt waste into high-value-added battery materials, turning waste into treasure, could bring significant economic and environmental benefits. However, waste asphalt differs significantly from new asphalt in chemical composition, with significant variations in its physicochemical properties, such as softening point, viscosity, and ductility. This results in different transformations during its conversion into carbon materials.

[0003] For example, during the thermal oxidative aging process, waste asphalt increases its oxygen functional groups, which results in a different group composition from new asphalt after conversion to carbon-based materials. Furthermore, the sulfur content of waste asphalt is higher than that of new asphalt, which results in a significant difference in the composition of its carbon layer crystallites from that of new asphalt. While simply modifying the carbon crystallite structure by introducing heteroatoms can provide more storage sites and increase storage capacity, it also leads to a larger specific surface area, forming more SEI films and causing a higher initial irreversible capacity loss. Therefore, effectively controlling the carbonization process of waste asphalt at high temperatures and rationally regulating the vortex structure of waste asphalt carbon crystallites to make them suitable for storage in alkali metal ion batteries remains a major challenge. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material. Based on the basic properties of waste asphalt, the first coulombic efficiency and structural stability of waste asphalt as a negative electrode material are improved by adjusting the microcrystalline vortex structure of waste asphalt carbon.

[0005] The technical solution adopted by the present invention is a method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material, comprising the following steps:

[0006] Step S1, extracting waste asphalt from decommissioned asphalt roads, and uniformly mixing the waste asphalt solution with magnesium oxide powder;

[0007] Step S2, heating the mixed solution in S1 until the solvent is evaporated to dryness, thereby obtaining a composite precursor of waste asphalt and magnesium oxide;

[0008] Step S3, pre-carbonizing the waste asphalt obtained in S2 and the magnesium oxide composite precursor;

[0009] Step S4, ball-milling the pre-carbonized product into powder, and sieving it through a sieve;

[0010] Step S5, pickling the screened product to remove the magnesium oxide template and drying;

[0011] Step S6, subjecting the product dried in S5 to secondary high-temperature carbonization to obtain waste asphalt carbon negative electrode material.

[0012] Furthermore, in step S1, the softening point of waste asphalt is 40-70°C, and the waste asphalt solution and magnesium oxide powder are uniformly mixed at a mass ratio of (4.3-8.6):1.

[0013] Furthermore, in step S2, the mixed solution is heated to 100-200° C., and is continuously stirred using a magnetic stirrer during the heating process.

[0014] Furthermore, in step S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in one or more of an inert gas, air, and oxygen, the pre-carbonization temperature is 400-700°C, the gas flow rate is 20-100 mL / min, and the pre-carbonization time is 1-3 h.

[0015] Furthermore, in step S5, the sieved product is soaked in a mixture of one or more of a 1-4 mol / L hydrochloric acid solution, a sulfuric acid solution, and a nitric acid solution for 5-12 hours.

[0016] Furthermore, in step S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a temperature of 800-1600°C, a flow rate of the inert atmosphere of 20-100 mL / min, a carbonization time of 1-3 h, and cooled to room temperature to obtain a waste asphalt carbon negative electrode material.

[0017] The beneficial effects of the present invention are:

[0018] 1. Based on the different physical and chemical properties of waste asphalt, the present invention converts waste asphalt into a carbon microcrystal vortex structure, effectively improving the interlayer spacing, pores and cross-linking composition of waste asphalt carbon microcrystals, thereby significantly improving the storage capacity of waste asphalt carbon materials.

[0019] 2. The present invention can improve the elemental and functional group composition of waste asphalt carbon, making the material more suitable for the storage of alkali metal ions and improving the initial coulombic efficiency of waste asphalt carbon.

[0020] 3. The present invention provides a high-value-added recycling approach for waste asphalt, which not only improves the utilization rate of waste asphalt, but also helps reduce environmental pollution and resource waste, and promotes the development of a circular economy.

[0021] 4. The present invention improves the initial coulombic efficiency and overall performance of waste asphalt carbon materials, provides new ideas and technical support for the research and development of negative electrode materials for alkali metal ion batteries, and helps promote the practical application and development of battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a TEM image of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0024] Figure 2 This is the N2 adsorption / desorption isotherm curve of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0025] Figure 3 1 is the pore size distribution curve of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0026] Figure 4 This is the first cycle charge and discharge curve of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 1 of the present invention at a current density of 0.1 C.

[0027] Figure 5 This is a cycle performance diagram of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 1 of the present invention at a current density of 0.1 C.

[0028] Figure 6 This is the Raman spectrum of the waste asphalt carbon material prepared in Example 2 of the present invention.

[0029] Figure 7 This is the XRD pattern of the waste asphalt carbon material prepared in Example 2 of the present invention.

[0030] Figure 8 This is the first cycle charge and discharge curve of the sodium ion battery assembled with the waste asphalt carbon material prepared in Example 2 of the present invention at a current density of 0.1 C.

[0031] Figure 9 This is a cycle performance diagram of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 2 of the present invention at a current density of 0.1 C.

[0032] Figure 10 This is an SEM image of the waste asphalt carbon material prepared in Example 3 of the present invention.

[0033] Figure 11 This is the first cycle charge and discharge curve of the sodium ion battery assembled with the waste asphalt carbon material prepared in Example 3 of the present invention at a current density of 0.1 C.

[0034] Figure 12 This is a cycle performance diagram of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 3 of the present invention at a current density of 0.1 C.

[0035] Figure 13 This is the first cycle charge and discharge curve of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 4 of the present invention at a current density of 0.1 C.

[0036] Figure 14 This is a cycle performance diagram of a sodium ion battery assembled from waste asphalt carbon material prepared in Example 4 of the present invention at a current density of 0.1 C.

[0037] Figure 15 This is the first cycle charge and discharge curve of a sodium ion battery assembled with waste asphalt carbon material prepared in Comparative Example 1 of the present invention at a current density of 0.1 C.

[0038] Figure 16 This is a cycle performance diagram of a sodium ion battery assembled from waste asphalt carbon material prepared in Comparative Example 1 of the present invention at a current density of 0.1 C. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] like Figures 1 to 16 As shown, an embodiment of the present invention provides a method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material, and the specific preparation steps are as follows:

[0041] Step S1, mixing waste asphalt solution with a softening point of 40-70°C and magnesium oxide powder at a mass ratio of (4.3-8.6):1;

[0042] Step S2, heating the mixed solution in S1 to 100-200° C. and continuously stirring the solution with a magnetic stirrer during the heating process until the solvent is evaporated to obtain a composite precursor of waste asphalt and magnesium oxide;

[0043] Step S3: pre-carbonizing the waste asphalt obtained in S2 and the magnesium oxide composite precursor in one or more of an inert gas, air, and oxygen. The pre-carbonization temperature is 400-700° C., the gas flow rate is 20-100 mL / min, and the pre-carbonization time is 1-3 h.

[0044] Step S4, ball-milling the pre-carbonized product into powder, and sieving it through a sieve;

[0045] Step S5: soak the sieved product in a mixture of one or more of a 1-4 mol / L hydrochloric acid solution, a sulfuric acid solution, and a nitric acid solution for 5-12 hours, then stir to wash away the magnesium oxide template and dry.

[0046] Step S6: subjecting the product dried in S5 to secondary high-temperature carbonization in an inert gas atmosphere at a carbonization temperature of 800-1600°C, a flow rate of the inert atmosphere of 20-100 mL / min, and a carbonization time of 1-3 h, and cooling to room temperature to obtain a waste asphalt carbon negative electrode material.

[0047] Example 1

[0048] S1, mixing waste asphalt solution with a softening point of 50°C and magnesium oxide powder at a mass ratio of 6:1;

[0049] S2, heating the mixed solution to 140° C. and stirring with a magnetic stirrer until the solvent is evaporated to dryness, thereby obtaining a composite precursor of waste asphalt and magnesium oxide;

[0050] S3, pre-carbonizing the waste asphalt and magnesium oxide composite precursor obtained above in an inert gas at a pre-carbonization temperature of 500°C, a flow rate of the inert atmosphere of 25 mL / min, and a pre-carbonization time of 3 h;

[0051] S4, ball-milling the pre-carbonized product into powder and sieving it through a sieve;

[0052] S5, soaking the sieved product in 2 mol / L hydrochloric acid solution for 8 h, stirring to wash away the magnesium oxide template and drying;

[0053] S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a carbonization temperature of 900°C, a flow rate of the inert atmosphere of 25 mL / min, and a carbonization time of 2 h. It is then cooled to room temperature to obtain a waste asphalt carbon negative electrode material.

[0054] The carbon material obtained in this example has a semi-disordered microcrystalline cross-linked structure, which is the cross-linking modification introduced by magnesium oxide in the first carbonization stage. This semi-disordered microcrystalline cross-linked structure is manifested as the formation of more vortex-shaped spaces, thereby providing more storage sites. The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The first cycle charge and discharge curve at a current density of 0.1 C is shown in FIG. Figure 4 As shown, the cycle performance diagram is as follows Figure 5 As shown in the figure, after testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment is ≥280 mAh g -1 The first coulombic efficiency is ≥85%, and the 50-cycle capacity retention rate is ≥95%.

[0055] Example 2

[0056] S1, mixing waste asphalt solution with a softening point of 40°C and magnesium oxide powder at a mass ratio of 6:1;

[0057] S2, heating the mixed solution to 100° C. and stirring with a magnetic stirrer until the solvent is evaporated to dryness, thereby obtaining a composite precursor of waste asphalt and magnesium oxide;

[0058] S3, pre-carbonizing the waste asphalt and magnesium oxide composite precursor obtained above in oxygen gas, with the pre-carbonization temperature being 400°C, the flow rate of the inert atmosphere being 40 mL / min, and the pre-carbonization time being 3 h.

[0059] S4, ball-milling the pre-carbonized product into powder and sieving it through a sieve;

[0060] S5, soaking the sieved product in 1 mol / L nitric acid solution for 6 h, stirring to wash away the magnesium oxide template and drying;

[0061] S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a carbonization temperature of 1400°C, a flow rate of the inert atmosphere of 25 mL / min, and a carbonization time of 2 h. The product is cooled to room temperature to obtain a waste asphalt carbon negative electrode material.

[0062] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The first cycle charge and discharge curve at a current density of 0.1 C was as follows: Figure 8 As shown, the cycle performance diagram is as follows Figure 9 As shown in the figure, after testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment is ≥270 mAh g -1, initial coulombic efficiency ≥ 80%, and 50-cycle capacity retention ≥ 94%. This embodiment performs pre-carbonization in an oxygen atmosphere, using waste asphalt with a relatively low softening point as the raw material. A higher temperature is then used during the secondary carbonization process to remove oxygen groups. The introduction of oxygen during the pre-carbonization process allows for the formation of sufficient oxygen groups within the carbon material. Combined with the three-dimensional space created by magnesium oxide, this facilitates the escape of oxygen groups during further carbonization, further disrupting the carbon microcrystal structure and creating more vortex structures in the carbon material, thereby increasing the battery's reversible specific capacity.

[0063] Example 3

[0064] S1, mixing waste asphalt solution with a softening point of 50°C and magnesium oxide powder at a mass ratio of 5:1;

[0065] S2, heating the mixed solution to 150° C. and stirring with a magnetic stirrer until the solvent is evaporated to dryness, thereby obtaining a composite precursor of waste asphalt and magnesium oxide;

[0066] S3, pre-carbonizing the waste asphalt and magnesium oxide composite precursor obtained above in an inert gas at a pre-carbonization temperature of 400°C, a flow rate of the inert atmosphere of 20 mL / min, and a carbonization time of 3 h;

[0067] S4, ball-milling the pre-carbonized product into powder and sieving it through a sieve;

[0068] S5, soaking the sieved product in 1 mol / L sulfuric acid solution for 12 h, stirring to wash away the magnesium oxide template and drying;

[0069] S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a carbonization temperature of 800°C, a flow rate of the inert atmosphere of 25 mL / min, and a carbonization time of 3 h. The product is cooled to room temperature to obtain the pore-forming waste asphalt carbon negative electrode material.

[0070] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The first cycle charge and discharge curve at a current density of 0.1 C was as follows: Figure 11 As shown, the cycle performance diagram is as follows Figure 12 As shown in the figure, after testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment is ≥260 mAh g -1 , first-time coulombic efficiency ≥ 86%, and 50-cycle capacity retention ≥ 93%. This example uses a higher proportion of magnesium oxide to form richer three-dimensional pores, resulting in a more cross-linked structure with more vortex structures that transform into larger cavities. This cavity structure provides more storage space and slightly improves the battery's reversible specific capacity, but the material is more susceptible to degradation.

[0071] Example 4

[0072] The difference from Example 1 is that the waste asphalt solution in S1 and the magnesium oxide powder are evenly mixed at a mass ratio of 8.6:1.

[0073] The remaining steps are the same as those in Example 1.

[0074] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The first cycle charge and discharge curve at a current density of 0.1 C was as follows: Figure 13 As shown, the cycle performance diagram is as follows Figure 14 As shown in the figure, after testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment is ≥245 mAh g -1 The first coulombic efficiency is ≥84%, and the 50-cycle capacity retention rate is ≥92%. The waste asphalt carbon negative electrode material obtained in this example has a low degree of magnesium oxide cross-linking, and the battery reversible specific capacity is slightly lower.

[0075] Example 5

[0076] The difference from Example 1 is that the waste asphalt solution in S1 and the magnesium oxide powder are evenly mixed at a mass ratio of 4.3:1.

[0077] The remaining steps are the same as those in Example 1.

[0078] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 275 mAh g -1 , the first coulombic efficiency ≥ 82%, and the 50-cycle capacity retention rate ≥ 91%. The magnesium oxide in the waste asphalt carbon negative electrode material of this embodiment is fully cross-linked, but excessive magnesium oxide may lead to larger internal pores, slightly reducing the first coulombic efficiency.

[0079] Example 6

[0080] The difference from Example 1 is that the softening point of the waste asphalt in S1 is 70°C.

[0081] The remaining steps are the same as those in Example 1.

[0082] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 240 mAh g -1 , initial coulombic efficiency ≥ 82%, and 50-cycle capacity retention ≥ 85%. The waste asphalt carbon negative electrode material in this example has a high softening point, tight bonding between the oxygen-based components and the carbon element, and stronger bonding between the asphalt molecules. However, the crosslinking between magnesium oxide and asphalt is not fully complete, resulting in a slightly lower reversible specific capacity.

[0083] Example 7

[0084] The difference from Example 1 is that in S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in an inert gas at a temperature of 600° C. and a carbonization time of 2 h.

[0085] The remaining steps are the same as those in Example 1.

[0086] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 275 mAh g -1 The first coulombic efficiency was ≥85%, and the 50-cycle capacity retention rate was ≥91%. The waste asphalt carbon negative electrode material obtained in this example was fully cross-linked, the carbon layer began to integrate, and the reversible specific capacity of the battery did not change significantly.

[0087] Example 8

[0088] The difference from Example 2 is that in S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in an inert gas at a temperature of 700° C. and a carbonization time of 2 h.

[0089] The remaining steps are the same as those in Example 2.

[0090] The waste asphalt carbon material prepared in this embodiment was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this embodiment was ≥ 248 mAh g -1 The initial coulombic efficiency was ≥80%, and the 50-cycle capacity retention was ≥93%. The waste asphalt carbon negative electrode material obtained in this example was sufficiently cross-linked, but the carbon layer was interconnected, making it difficult to completely remove the magnesium oxide in subsequent steps, resulting in a reduced reversible specific capacity of the battery.

[0091] Example 9

[0092] The difference from Example 3 is that in S5, the sieved product is soaked in 1 mol / L nitric acid solution for 6 h, stirred to wash away the magnesium oxide template, and then dried.

[0093] The remaining steps are the same as those in Example 3.

[0094] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 275 mAh g -1 The first coulombic efficiency was ≥86%, and the 50-cycle capacity retention rate was ≥95%. The waste asphalt carbon negative electrode material obtained in this example had a slightly higher reversible specific capacity due to the longer nitric acid treatment, which introduced sufficient oxygen groups.

[0095] Example 10

[0096] The difference from Example 3 is that in S5, the sieved product is soaked in a 3 mol / L hydrochloric acid solution for 5 h, stirred to wash away the magnesium oxide template, and then dried.

[0097] The remaining steps are the same as those in Example 3.

[0098] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 260 mAh g -1 , the first coulombic efficiency is ≥80%, and the 50-cycle capacity retention rate is ≥94%. The waste asphalt carbon negative electrode material obtained in this embodiment has a lower first coulombic efficiency due to the introduction of some chloride ions by hydrochloric acid treatment.

[0099] Example 11

[0100] The difference from Example 3 is that in S5, the sieved product is soaked in 4 mol / L nitric acid solution for 5 h, stirred to wash away the magnesium oxide template, and then dried.

[0101] The remaining steps are the same as those in Example 3.

[0102] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 260 mAh g -1 , initial coulombic efficiency ≥ 79%, and 50-cycle capacity retention ≥ 92%. The waste asphalt carbon negative electrode material obtained in this example introduced more oxygen groups due to the more concentrated nitric acid, which were difficult to completely remove during the subsequent carbonization, resulting in a lower initial coulombic efficiency.

[0103] Example 12

[0104] The difference from Example 3 is that in S5, the sieved product is soaked in 1 mol / L sulfuric acid solution for 6 h, stirred to wash away the magnesium oxide template, and then dried.

[0105] The remaining steps are the same as those in Example 3.

[0106] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 260 mAh g -1 , the first coulombic efficiency ≥ 81%, and the 50-cycle capacity retention rate ≥ 90%. The waste pitch carbon negative electrode material obtained in this example has a lower first coulombic efficiency due to the introduction of more sulfur groups.

[0107] Example 13

[0108] The difference from Example 1 is that in S6, the product after drying is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a temperature of 1000° C. and a carbonization time of 2 h.

[0109] The remaining steps are the same as those in Example 1.

[0110] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 250 mAh g -1 The first coulombic efficiency was ≥85%, and the 50-cycle capacity retention rate was ≥92%. The waste asphalt carbon negative electrode material obtained in this example had a regular and orderly carbon layer arrangement, which destroyed the original vortex structure and had a slightly lower reversible specific capacity.

[0111] Example 14

[0112] The difference from Example 1 is that in S6, the product after drying is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a temperature of 1200° C. and a carbonization time of 2 h.

[0113] The remaining steps are the same as those in Example 1.

[0114] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 275 mAh g -1 The first coulombic efficiency was ≥85%, and the 50-cycle capacity retention rate was ≥93%. The waste asphalt carbon negative electrode material obtained in this example had a relatively orderly carbon layer arrangement and a narrow interlayer spacing, but the number of impurity atoms was reduced, and the reversible specific capacity of the battery did not change significantly.

[0115] Example 15

[0116] The difference from Example 1 is that in S6, the product after drying is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a temperature of 1600° C. and a carbonization time of 2 h.

[0117] The remaining steps are the same as those in Example 1.

[0118] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 250 mAh g -1 , the first coulombic efficiency ≥ 85%, and the 50-cycle capacity retention rate ≥ 91%. The waste asphalt carbon negative electrode material obtained in this example has a further narrowed carbon layer spacing, and the reversible specific capacity of the battery is reduced.

[0119] Example 16

[0120] The difference from Example 2 is that in S3, pre-carbonization is carried out in an air atmosphere.

[0121] The remaining steps are the same as those in Example 2.

[0122] The waste asphalt carbon material prepared in this embodiment was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this embodiment was ≥ 249 mAh g -1 The first coulombic efficiency was ≥80%, and the 50-cycle capacity retention was ≥95%. The waste asphalt carbon negative electrode material obtained in this example produced fewer oxygen groups during the pre-carbonization stage compared to pure oxygen, resulting in a slightly lower reversible specific capacity, but at a lower cost than pure oxygen.

[0123] Example 17

[0124] The difference from Example 2 is that the flow rate of the atmosphere in S3 is 100 mL / min.

[0125] The remaining steps are the same as those in Example 2.

[0126] The waste asphalt carbon material prepared in this embodiment was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this embodiment was ≥ 265 mAh g -1 , initial coulombic efficiency ≥ 80%, and 50-cycle capacity retention ≥ 89%. Due to the high flow rate of the atmosphere, the waste asphalt carbon negative electrode material obtained in this example is more likely to be carried away by the gaseous hydrocarbons produced by the decomposition of the material, resulting in a reduction in the reversible specific capacity of the battery.

[0127] Example 18

[0128] The difference from Example 2 is that the flow rate of the atmosphere in S3 is 20 mL / min.

[0129] The remaining steps are the same as those in Example 2.

[0130] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 250 mAh g -1 The initial coulombic efficiency was ≥80%, and the 50-cycle capacity retention was ≥88%. Due to the low flow rate of the atmosphere, the decomposed gases of the waste asphalt carbon negative electrode material obtained in this example were difficult to remove, affecting the binding of oxygen groups with the magnesium oxide asphalt, resulting in a reduction in the reversible specific capacity of the battery.

[0131] Example 19

[0132] The difference from Example 2 is that the carbonization temperature in S6 is 800°C.

[0133] The remaining steps are the same as those in Example 2.

[0134] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 270 mAh g -1 , the first coulombic efficiency ≥ 75%, and the 50-cycle capacity retention rate ≥ 90%. The waste pitch carbon negative electrode material obtained in this example had a lower temperature during the second carbonization, and the oxygen groups introduced during the pre-carbonization process may be difficult to completely remove, resulting in a lower first coulombic efficiency.

[0135] Example 20

[0136] The difference from Example 3 is that in S2, the mixed solution is heated to 200° C. and continuously stirred by a magnetic stirrer while heating until the solvent is evaporated.

[0137] The remaining steps are the same as those in Example 3.

[0138] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 260 mAh g -1 , initial coulombic efficiency ≥ 80%, and 50-cycle capacity retention ≥ 92%. The waste asphalt carbon negative electrode material obtained in this example was evaporated more quickly before carbonization, but the high temperature initially introduced oxygen groups on the material's surface, reducing the initial coulombic efficiency.

[0139] Example 21

[0140] The difference from Example 3 is that in S1, the waste asphalt solution and the magnesium oxide powder are uniformly mixed at a mass ratio of 4.3:1.

[0141] The remaining steps are the same as those in Example 3.

[0142] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 260 mAh g -1 The first coulombic efficiency was ≥86%, and the 50-cycle capacity retention rate was ≥70%. The waste asphalt carbon negative electrode material obtained in this example had a higher proportion of magnesium oxide, but this resulted in more pores and cavities, making the material more prone to collapse and attenuation.

[0143] Example 22

[0144] The difference from Example 3 is that the carbonization time in S6 is 1 h.

[0145] The remaining steps are the same as those in Example 3.

[0146] The waste asphalt carbon material prepared in this embodiment was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this embodiment was ≥ 248 mAh g -1 , initial coulombic efficiency ≥ 85%, 50-cycle capacity retention ≥ 91%. The waste asphalt carbon negative electrode material obtained in this example has a reduced carbonization time, and the carbon layer in some areas of the material may not be fully converted, resulting in a reduced reversible specific capacity of the battery.

[0147] Example 23

[0148] The difference from Example 1 is that in S3, the temperature for pre-carbonizing the waste asphalt and magnesium oxide composite precursor in an inert gas is 400° C., and the pre-carbonization time is 2 h.

[0149] The remaining steps are the same as those in Example 1.

[0150] The waste asphalt carbon material prepared in this example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥ 250 mAh g -1 , the first coulombic efficiency ≥ 84%, and the 50-cycle capacity retention rate ≥ 90%. The waste asphalt carbon negative electrode material in this embodiment has a slightly lower reversible specific capacity due to the low pre-carbonization temperature and incomplete cross-linking.

[0151] Comparative Example 1

[0152] The difference from Example 1 is that the waste asphalt is directly pre-carbonized in an inert gas.

[0153] The rest are the same as in Example 1.

[0154] The waste asphalt carbon material prepared in this comparative example was assembled into a sodium ion battery for electrochemical testing. The first cycle charge and discharge curve at a current density of 0.1 C was as follows: Figure 8 As shown, the cycle performance diagram is as follows Figure 9 As shown in the figure, after testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment is ≥180 mAh g -1 The initial coulombic efficiency was ≥82%, and the 50-cycle capacity retention rate was ≥85%. The waste asphalt carbon negative electrode material obtained in this comparative example had poor microcrystalline cross-linking, lacked many storage sites, and had a low reversible specific capacity.

[0155] Comparative Example 2

[0156] The difference from Example 1 is that the waste asphalt is heated to above 2600° C. using a one-step carbonization method without going through steps such as pre-carbonization.

[0157] The rest are the same as in Example 1.

[0158] The waste asphalt carbon material prepared in this comparative example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment was ≥190 mAh g -1 , the first coulombic efficiency ≥ 85%, and the 50-cycle capacity retention rate ≥ 87%. The waste pitch carbon negative electrode material obtained in this comparative example has a low reversible specific capacity of the battery, making it difficult to use in practice.

[0159] Comparative Example 3

[0160] The difference from Example 1 is that in S1, the waste asphalt solution and the magnesium oxide powder are uniformly mixed in a mass ratio of 1:1.

[0161] The rest are the same as in Example 1.

[0162] The waste asphalt carbon material prepared in this comparative example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment was ≥180 mAh g -1 The waste asphalt carbon negative electrode material obtained in this comparative example has too many open pores. Although the pore structure can provide certain storage sites, its large specific surface area leads to low initial coulombic efficiency and severe attenuation.

[0163] Comparative Example 4

[0164] The difference from Example 1 is that in S1, the waste asphalt solution and the magnesium oxide powder are uniformly mixed at a mass ratio of 20:1.

[0165] The rest are the same as in Example 1.

[0166] The waste asphalt carbon material prepared in this comparative example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment was ≥175 mAh g -1 , first coulombic efficiency ≥ 85%, and 50-cycle capacity retention ≥ 86%. The waste asphalt carbon negative electrode material obtained in this comparative example was only slightly cross-linked with the magnesium oxide material, resulting in little improvement in carbon microcrystal modification and poor capacity.

[0167] Comparative Example 5

[0168] The difference from Example 1 is that the softening point of the waste asphalt in S1 is 200°C.

[0169] The rest are the same as in Example 1.

[0170] The waste asphalt carbon material prepared in this comparative example was assembled into a sodium ion battery for electrochemical testing. The test showed that the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material of this embodiment was ≥165 mAh g -1 The first coulombic efficiency was ≥75%, and the 50-cycle capacity retention was ≥80%. The waste asphalt carbon negative electrode material obtained in this comparative example was difficult to cross-link with asphalt, resulting in poor cross-linking effect, which resulted in little improvement in carbon microcrystal modification, poor capacity, and severe attenuation.

[0171] The performance of the sodium ion batteries assembled from the waste asphalt carbon materials prepared in each embodiment and comparative example at a current density of 0.1 C is shown in Table 1:

[0172] Table 1 Performance of each embodiment and comparative example at 0.1 C current density

[0173] Continued

[0174]

[0175] The present invention uses magnesium oxide to structurally adjust and modify waste asphalt, and through two carbonizations, adjusts the carbonization temperature, duration, atmosphere, and flow rate of material processing, and comprehensively and coordinately modifies the waste asphalt carbon microcrystalline structure from multiple angles. Compared with ordinary pore making, the present invention utilizes the basic structure of waste asphalt carbon to produce a vortex-shaped irregular carbon layer, thereby providing more storage space, and taking into account the possible changes of oxygen groups and sulfur groups introduced in the process, without affecting the initial coulomb efficiency of the material, provides the material carbon microcrystalline disorder, but at the same time retains some "non-completely regular" carbon structure, so that the incompletely ordered carbon layer and the vortex structure are cross-linked and unified, thereby obtaining a waste asphalt-based carbon material with suitable performance.

[0176] Each embodiment in this specification is described in a related manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiment is generally similar to the method embodiment, so the description is relatively simple. For related parts, refer to the description of the method embodiment.

[0177] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material, characterized in that: The following steps are involved: Step S1: extracting waste asphalt with a softening point of 40-70°C from decommissioned asphalt roads, and uniformly mixing the waste asphalt solution with magnesium oxide powder at a mass ratio of (4.3-8.6):1; Step S2, heating the mixed solution in S1 until the solvent is evaporated to dryness, thereby obtaining a composite precursor of waste asphalt and magnesium oxide; Step S3, pre-carbonizing the waste asphalt obtained in S2 and the magnesium oxide composite precursor; Step S4, ball-milling the pre-carbonized product into powder, and sieving it through a sieve; Step S5, pickling the screened product to remove the magnesium oxide template and drying; Step S6, subjecting the product dried in S5 to secondary high-temperature carbonization to obtain a waste asphalt carbon negative electrode material with a microcrystalline vortex structure; In step S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in one or more of an inert gas, air, and oxygen. The pre-carbonization temperature is 400-700° C., the gas flow rate is 20-100 mL / min, and the pre-carbonization time is 1-3 h. In step S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere at a temperature of 800-1600°C, a flow rate of the inert atmosphere of 20-100 mL / min, and a carbonization time of 1-3 h. The product is then cooled to room temperature to obtain a waste asphalt carbon negative electrode material with a microcrystalline vortex structure.

2. The method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material according to claim 1, characterized in that: In step S2, the mixed solution is heated to 100-200° C. and continuously stirred with a magnetic stirrer during the heating process.

3. The method for preparing waste asphalt carbon with a microcrystalline vortex structure as an ion battery material according to claim 1, characterized in that: In step S5, the screened product is soaked in a mixture of one or more of a 1-4 mol / L hydrochloric acid solution, a sulfuric acid solution, and a nitric acid solution for 5-12 hours.

Images