Preparation method of waste asphalt carbon with microcrystalline vortex structure as ion battery material

Abstract

The invention provides a preparation method of waste asphalt carbon with a microcrystalline vortex structure as an ion battery material, which comprises the following steps: mixing a waste asphalt solution with magnesium oxide powder, heating and evaporating to dryness, pre-carbonizing, ball-milling and screening, pickling to remove a template, secondarily carbonizing at high temperature and the like to prepare a carbon negative electrode material with a semi-disordered microcrystalline cross-linked structure. According to the material, carbon layer spacing and a pore structure are regulated and controlled through a magnesium oxide template and two-time carbonization processes, a vortex-shaped space is formed, the storage capacity and the first coulombic efficiency of alkali metal ions are remarkably improved, high-added-value utilization of waste asphalt is achieved, and both environmental benefits and economic benefits are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to a preparation method of using waste asphalt carbon with a microcrystalline eddy structure as an ion battery material. Background Art

[0002] As a large amount of solid waste, waste asphalt mixture has a slow degradation rate, a large accumulation volume, and occupies a wide space. If it is not effectively treated, it will have an adverse impact on the environment. If the waste asphalt in the waste asphalt mixture can be converted into a battery material with high added value, turning waste into treasure, it can bring extremely high economic and environmental benefits. However, the chemical composition of waste asphalt is significantly different from that of new asphalt, and its physical and chemical properties such as softening point, viscosity, and ductility have large variations, resulting in different directional changes during the process of converting it into carbon materials.

[0003] For example, during the thermal-oxidative aging process of waste asphalt, the content of oxygen-containing functional groups increases, which makes the group composition of the carbon-based material obtained after its conversion different from that of new asphalt. At the same time, the sulfur content of waste asphalt is also higher than that of new asphalt, which leads to a large difference in the microcrystalline composition of its carbon layer from that of new asphalt. Simply modifying the carbon microcrystalline structure by introducing heteroatoms can provide more storage sites and increase the storage capacity, but it will also result in a larger specific surface area, form more SEI films, and cause a higher initial irreversible capacity loss. Therefore, how to effectively control the carbonization process of waste asphalt at high temperature and reasonably regulate the microcrystalline eddy structure of waste asphalt carbon to make it suitable for the storage of alkali metal ion batteries is still a major challenge. Summary of the Invention

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

[0005] The technical solution adopted by the present invention is a preparation method of using waste asphalt carbon with a microcrystalline eddy structure as an ion battery material, including the following steps: Step S1, extracting waste asphalt from retired asphalt roads and mixing the waste asphalt solution evenly with magnesium oxide powder; Step S2, heating the mixed solution in S1 until the solvent is evaporated to dryness to obtain a waste asphalt and magnesium oxide composite precursor; Step S3, pre-carbonizing the waste asphalt and magnesium oxide composite precursor obtained in S2; Step S4, ball-milling the pre-carbonized product into powder and screening it through a sieve; Step S5, performing acid washing on the screened product to wash away the magnesium oxide template and drying it; Step S6: Subject the product dried in S5 to secondary high-temperature carbonization to obtain the waste asphalt carbon negative electrode material.

[0006] Further, in the step S1, the softening point of the waste asphalt is 40 - 70 °C, and the waste asphalt solution and the magnesium oxide powder are mixed evenly at a mass ratio of (4.3 - 8.6):1.

[0007] Further, in the step S2, heat the mixed solution to 100 - 200 °C, and continuously stir it with a magnetic stirrer during the heating process of the solution.

[0008] Further, in the step S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in one or more of 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.

[0009] Further, in the step S5, soak the sieved product in one or more mixtures of 1 - 4 mol / L hydrochloric acid solution, sulfuric acid solution, and nitric acid solution for 5 - 12 h.

[0010] Further, in the step S6, the dried product is subjected to secondary high-temperature carbonization in an inert gas atmosphere. The temperature is 800 - 1600 °C, the flow rate of the inert atmosphere is 20 - 100 mL / min, the carbonization time is 1 - 3 h, and it is cooled to room temperature to obtain the waste asphalt carbon negative electrode material.

[0011] The beneficial effects of the present invention are as follows: 1. Based on the different physical and chemical properties of waste asphalt, the present invention effectively improves the interlayer spacing, pores, and cross-linking composition mode of the waste asphalt carbon microcrystals by converting waste asphalt into a carbon microcrystal vortex structure, thereby significantly increasing the storage capacity of the waste asphalt carbon material.

[0012] 2. The present invention can improve the carbon element and functional group composition of waste asphalt, making the material more suitable for the storage of alkali metal ions and increasing the first Coulombic efficiency of waste asphalt carbon.

[0013] 3. The present invention provides a high-value-added reuse method for waste asphalt, which not only improves the utilization rate of waste asphalt, but also helps to reduce environmental pollution and resource waste, and promotes the development of circular economy.

[0014] 4. By increasing the first Coulombic efficiency and overall performance of the waste asphalt carbon material, the present invention provides new ideas and technical support for the research and development of negative electrode materials for alkali metal ion batteries, and helps to promote the practical application and development of battery technology. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0016] Figure 1 It is the TEM image of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0017] Figure 2 It is the N2 adsorption / desorption isotherm curve of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0018] Figure 3 It is the pore size distribution curve of the waste asphalt carbon material prepared in Example 1 of the present invention.

[0019] Figure 4 It is the first charge-discharge curve of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Example 1 of the present invention at a current density of 0.1 C.

[0020] Figure 5 It is the cycling performance graph of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Example 1 of the present invention at a current density of 0.1 C.

[0021] Figure 6 It is the Raman spectrum of the waste asphalt carbon material prepared in Example 2 of the present invention.

[0022] Figure 7 It is the XRD spectrum of the waste asphalt carbon material prepared in Example 2 of the present invention.

[0023] Figure 8 It is the first charge-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.

[0024] Figure 9 It is the cycling performance graph 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.

[0025] Figure 10 It is the SEM image of the waste asphalt carbon material prepared in Example 3 of the present invention.

[0026] Figure 11 It is the first charge-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.

[0027] Figure 12It is the cycling performance graph 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.

[0028] Figure 13 It is the first charge-discharge curve of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Example 4 of the present invention at a current density of 0.1 C.

[0029] Figure 14 It is the cycling performance graph of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Example 4 of the present invention at a current density of 0.1 C.

[0030] Figure 15 It is the first charge-discharge curve of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Comparative Example 1 of the present invention at a current density of 0.1 C.

[0031] Figure 16 It is the cycling performance graph of the sodium-ion battery assembled with the waste asphalt carbon material prepared in Comparative Example 1 of the present invention at a current density of 0.1 C. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0033] As Figures 1 - 16 shown, the embodiments of the present invention provide a preparation method of waste asphalt carbon with a microcrystalline eddy structure as an ion battery material. The specific preparation steps are as follows: Step S1: Mix a waste asphalt solution with a softening point of 40-70 °C and magnesium oxide powder evenly at a mass ratio of (4.3-8.6):1. Step S2: Heat the mixed solution in S1 to 100-200 °C, and continuously stir it with a magnetic stirrer during the heating process of the solution until the solvent is evaporated to obtain a waste asphalt and magnesium oxide composite precursor. Step S3: Pre-carbonize the waste asphalt and magnesium oxide composite precursor obtained in S2 in one or more of 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. Step S4: Grind the pre-carbonized product into powder and screen it through a sieve. Step S5: Immerse the sieved product in one or a mixture of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution with a concentration of 1 - 4 mol / L for 5 - 12 h, then stir to wash away the magnesium oxide template and dry it. Step S6: Perform secondary high-temperature carbonization on the product dried in S5 in an inert gas atmosphere. The carbonization temperature is 800 - 1600 °C, the flow rate of the inert atmosphere is 20 - 100 mL / min, the carbonization time is 1 - 3 h, and then cool it to room temperature to obtain the waste asphalt carbon anode material.

[0034] Example 1 S1: Mix the waste asphalt solution with a softening point of 50 °C and magnesium oxide powder evenly at a mass ratio of 6:1. S2: Heat the mixed solution to 140 °C and stir it while heating with a magnetic stirrer until the solvent evaporates completely to obtain the waste asphalt and magnesium oxide composite precursor. S3: Perform pre-carbonization on the obtained waste asphalt and magnesium oxide composite precursor in an inert gas. The pre-carbonization temperature is 500 °C, the flow rate of the inert atmosphere is 25 mL / min, and the pre-carbonization time is 3 h. S4: Grind the pre-carbonized product into powder and sieve it through a sieve. S5: Immerse the sieved product in 2 mol / L hydrochloric acid solution for 8 h, stir to wash away the magnesium oxide template and dry it. S6: Perform secondary high-temperature carbonization on the dried product in an inert gas atmosphere. The carbonization temperature is 900 °C, the flow rate of the inert atmosphere is 25 mL / min, the carbonization time is 2 h, and then cool it to room temperature to obtain the waste asphalt carbon anode material.

[0035] 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, thus providing more storage sites. Assemble the waste asphalt carbon material prepared in this example into a sodium-ion battery for electrochemical testing. The first charge-discharge curve at a current density of 0.1 C is as Figure 4 shown, and the cycling performance graph is as Figure 5 shown. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon anode material in this example is ≧280 mAh g -1 , the first Coulombic efficiency is ≧85%, and the capacity retention rate after 50 cycles is ≧95%.

[0036] Example 2 S1: Mix the waste asphalt solution with a softening point of 40 °C and magnesium oxide powder evenly at a mass ratio of 6:1. S2. Heat the mixed solution to 100 °C and stir it while heating with a magnetic stirrer until the solvent is completely evaporated to obtain a composite precursor of waste asphalt and magnesium oxide. S3. Pre-carbonize the obtained composite precursor of waste asphalt and magnesium oxide in an oxygen gas atmosphere at a pre-carbonization temperature of 400 °C, with an inert gas flow rate of 40 mL / min and a pre-carbonization time of 3 h.

[0037] S4. Grind the pre-carbonized product into powder and sieve it through a sieve. S5. Immerse the sieved product in a 1 mol / L nitric acid solution for 6 h, stir to wash away the magnesium oxide template and then dry it. S6. Perform secondary high-temperature carbonization on the dried product in an inert gas atmosphere at a carbonization temperature of 1400 °C, with an inert gas flow rate of 25 mL / min and a carbonization time of 2 h. Cool it to room temperature to obtain a waste asphalt carbon negative electrode material.

[0038] Assemble the waste asphalt carbon material prepared in this example into a sodium-ion battery for electrochemical testing. The first charge-discharge curve at a current density of 0.1 C is as Figure 8 shown, and the cycling performance graph is as Figure 9 shown. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon negative electrode material in this example is ≧270 mAh g -1 , the first Coulombic efficiency is ≧80%, and the capacity retention rate after 50 cycles is ≧94%. In this example, pre-carbonization is carried out in an oxygen atmosphere using waste asphalt with a lower softening point as the raw material, and then oxygen-containing groups are removed at a higher temperature during the secondary carbonization process. The introduction of oxygen during the pre-carbonization process can form sufficient oxygen-containing groups between carbon materials, and at the same time, combined with the three-dimensional space formed by magnesium oxide, the oxygen-containing group elements can easily overflow during the further carbonization process, further disturbing the carbon microcrystal structure, making the carbon material have more vortex structures, and thus improving the reversible specific capacity of the battery.

[0039] Example 3 S1. Mix a waste asphalt solution with a softening point of 50 °C and magnesium oxide powder evenly at a mass ratio of 5:1. S2. Heat the mixed solution to 150 °C and stir it while heating with a magnetic stirrer until the solvent is completely evaporated to obtain a composite precursor of waste asphalt and magnesium oxide. S3. Pre-carbonize the obtained composite precursor of waste asphalt and magnesium oxide in an inert gas atmosphere at a pre-carbonization temperature of 400 °C, with an inert gas flow rate of 20 mL / min and a carbonization time of 3 h. S4. Grind the pre-carbonized product into powder and sieve it through a sieve. S5. Immerse the sieved product in a 1 mol / L sulfuric acid solution for 12 h, stir to wash away the magnesium oxide template, and then dry it. S6. Subject the dried product to secondary high-temperature carbonization in an inert gas atmosphere. The carbonization temperature is 800 °C, the flow rate of the inert atmosphere is 25 mL / min, and the carbonization time is 3 h. Cool it to room temperature to obtain the pore-formed waste asphalt carbon negative electrode material.

[0040] Assemble the waste asphalt carbon material prepared in this example into a sodium-ion battery for electrochemical testing. The first charge-discharge curve at a current density of 0.1 C is as Figure 11 shown, and the cycling performance graph is as Figure 12 shown. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 260 mAh g -1 , the first Coulombic efficiency is ≥ 86%, and the 50-cycle capacity retention rate is ≥ 93%. In this example, with a higher proportion of magnesium oxide, the formed three-dimensional pores are richer, and more vortex structures with cross-linked structures are transformed into larger cavity structures. This cavity structure can provide more storage space, slightly increasing the reversible specific capacity of the battery, but the material is more prone to attenuation.

[0041] Example 4 The difference from Example 1 is that in S1, the waste asphalt solution and magnesium oxide powder are mixed evenly at a mass ratio of 8.6:1.

[0042] The remaining steps are the same as those in Example 1.

[0043] Assemble the waste asphalt carbon material prepared in this example into a sodium-ion battery for electrochemical testing. The first charge-discharge curve at a current density of 0.1 C is as Figure 13 shown, and the cycling performance graph is as Figure 14 shown. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon negative electrode material in this example 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 lower degree of magnesium oxide cross-linking and a slightly lower reversible specific capacity of the battery.

[0044] Example 5 The difference from Example 1 is that in S1, the waste asphalt solution and magnesium oxide powder are mixed evenly at a mass ratio of 4.3:1.

[0045] The remaining steps are the same as those in Example 1.

[0046] Assemble the waste asphalt carbon material prepared in this example into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 275 mAh g-1 , the initial Coulombic efficiency is ≥ 82%, and the capacity retention rate after 50 cycles is ≥ 91%. The magnesia crosslinking of the waste asphalt carbon anode material in this example is sufficient, but excessive magnesia may lead to relatively large internal pores and a slight decrease in the initial Coulombic efficiency.

[0047] Example 6 The difference from Example 1 is that the softening point of the waste asphalt in S1 is 70 °C.

[0048] The remaining steps are the same as those in Example 1.

[0049] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 240 mAh g -1 , the initial Coulombic efficiency is ≥ 82%, and the capacity retention rate after 50 cycles is ≥ 85%. For the waste asphalt carbon anode material in this example, due to the relatively high softening point, the oxygen-containing components are tightly combined with carbon elements, the binding effect between asphalt molecules is stronger, and the crosslinking of magnesia and asphalt is not fully complete, resulting in a slightly lower reversible specific capacity of the battery.

[0050] Example 7 The difference from Example 1 is that in S3, the temperature for pre-carbonization of the waste asphalt and magnesia composite precursor in an inert gas is 600 °C, and the carbonization time is 2 h.

[0051] The remaining steps are the same as those in Example 1.

[0052] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 275 mAh g -1 , the initial Coulombic efficiency is ≥ 85%, and the capacity retention rate after 50 cycles is ≥ 91%. For the waste asphalt carbon anode material obtained in this example, the crosslinking is sufficient, the carbon layers begin to integrate, and the change in the reversible specific capacity of the battery is not obvious.

[0053] Example 8 The difference from Example 2 is that in S3, the temperature for pre-carbonization of the waste asphalt and magnesia composite precursor in an inert gas is 700 °C, and the carbonization time is 2 h.

[0054] The remaining steps are the same as those in Example 2.

[0055] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 248 mAh g -1, the initial Coulombic efficiency ≥ 80%, and the capacity retention rate after 50 cycles ≥ 93%. For the waste asphalt carbon negative electrode material obtained in this example, the cross-linking is sufficient, but the carbon layer development is hooked, making it difficult to completely remove magnesium oxide in subsequent steps, resulting in a decrease in the reversible specific capacity of the battery.

[0056] Example 9 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.

[0057] The remaining steps are the same as those in Example 3.

[0058] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example ≥ 275 mAh g -1 , the initial Coulombic efficiency ≥ 86%, and the capacity retention rate after 50 cycles ≥ 95%. For the waste asphalt carbon negative electrode material obtained in this example, due to the introduction of sufficient oxygen groups by longer-term nitric acid treatment, the reversible specific capacity of the battery is slightly higher.

[0059] Example 10 The difference from Example 3 is that in S5, the sieved product is soaked in 3 mol / L hydrochloric acid solution for 5 h, stirred to wash away the magnesium oxide template, and then dried.

[0060] The remaining steps are the same as those in Example 3.

[0061] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example ≥ 260 mAh g -1 , the initial Coulombic efficiency ≥ 80%, and the capacity retention rate after 50 cycles ≥ 94%. For the waste asphalt carbon negative electrode material obtained in this example, due to the introduction of some chloride ions by hydrochloric acid treatment, the initial Coulombic efficiency decreases.

[0062] Example 11 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.

[0063] The remaining steps are the same as those in Example 3.

[0064] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example ≥ 260 mAh g -1, the initial Coulombic efficiency is ≥ 79%, and the capacity retention rate after 50 cycles is ≥ 92%. For the waste asphalt carbon anode material obtained in this example, since more oxygen groups are introduced by stronger nitric acid and it is difficult to completely remove them during subsequent carbonization, the initial Coulombic efficiency decreases.

[0065] Example 12 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.

[0066] The remaining steps are the same as those in Example 3.

[0067] The waste asphalt carbon material prepared in this example is assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 260 mAh g -1 , the initial Coulombic efficiency is ≥ 81%, and the capacity retention rate after 50 cycles is ≥ 90%. For the waste asphalt carbon anode material obtained in this example, since more sulfur groups are introduced, the initial Coulombic efficiency decreases.

[0068] Example 13 The difference from Example 1 is that in S6, the temperature of the secondary high-temperature carbonization of the dried product in an inert gas atmosphere is 1000 °C, and the carbonization time is 2 h.

[0069] The remaining steps are the same as those in Example 1.

[0070] The waste asphalt carbon material prepared in this example is assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 250 mAh g -1 , the initial Coulombic efficiency is ≥ 85%, and the capacity retention rate after 50 cycles is ≥ 92%. For the waste asphalt carbon anode material obtained in this example, the arrangement of the carbon layers changes to be more regular and orderly, destroying the original vortex structure, and the reversible specific capacity is slightly lower.

[0071] Example 14 The difference from Example 1 is that in S6, the temperature of the secondary high-temperature carbonization of the dried product in an inert gas atmosphere is 1200 °C, and the carbonization time is 2 h.

[0072] The remaining steps are the same as those in Example 1.

[0073] The waste asphalt carbon material prepared in this example is assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the sodium-ion battery made of the waste asphalt carbon anode material in this example is ≥ 275 mAh g -1, the initial Coulombic efficiency ≥ 85%, and the capacity retention rate after 50 cycles ≥ 93%. For the waste asphalt carbon anode material obtained in this example, the carbon layer arrangement is relatively orderly, the layer spacing narrows, but the impurity atoms decrease, and the change in the reversible specific capacity of the battery is not obvious.

[0074] Example 15 The difference from Example 1 is that in S6, the temperature of the secondary high-temperature carbonization of the dried product in an inert gas atmosphere is 1600 °C, and the carbonization time is 2 h.

[0075] The remaining steps are the same as those in Example 1.

[0076] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon anode material in this example ≥ 250 mAh g -1 , the initial Coulombic efficiency ≥ 85%, and the capacity retention rate after 50 cycles ≥ 91%. For the waste asphalt carbon anode material obtained in this example, the carbon layer spacing further narrows, and the reversible specific capacity of the battery decreases.

[0077] Example 16 The difference from Example 2 is that in S3, pre-carbonization is carried out in an air atmosphere.

[0078] The remaining steps are the same as those in Example 2.

[0079] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon anode material in this example ≥ 249 mAh g -1 , the initial Coulombic efficiency ≥ 80%, and the capacity retention rate after 50 cycles ≥ 95%. For the waste asphalt carbon anode material obtained in this example, fewer oxygen groups are generated during the pre-carbonization stage compared to pure oxygen, and the reversible specific capacity of the battery is slightly lower, but the cost is lower compared to pure oxygen.

[0080] Example 17 The difference from Example 2 is that the flow rate of the atmosphere in S3 is 100 mL / min.

[0081] The remaining steps are the same as those in Example 2.

[0082] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon anode material in this example ≥ 265 mAh g -1 , the initial Coulombic efficiency ≥ 80%, and the capacity retention rate after 50 cycles ≥ 89%. For the waste asphalt carbon anode material obtained in this example, due to the high flow rate of the atmosphere, the gaseous hydrocarbons generated by the decomposition of the material are more easily carried out with the gas, and the reversible specific capacity of the battery decreases.

[0083] Example 18 The difference from Example 2 is that: the flow rate of the atmosphere in S3 is 20 mL / min.

[0084] The remaining steps are the same as those in Example 2.

[0085] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 250 mAh g -1 , the initial Coulombic efficiency is ≥ 80%, and the capacity retention rate after 50 cycles is ≥ 88%. For the waste asphalt carbon negative electrode material obtained in this example, due to the low flow rate of the atmosphere, it is difficult for the gas generated by the decomposition of the material to be carried out, which affects the combination of oxygen groups and magnesium oxide asphalt, resulting in a decrease in the reversible specific capacity of the battery.

[0086] Example 19 The difference from Example 2 is that: the carbonization temperature in S6 is 800 °C.

[0087] The remaining steps are the same as those in Example 2.

[0088] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 270 mAh g -1 , the initial Coulombic efficiency is ≥ 75%, and the capacity retention rate after 50 cycles is ≥ 90%. For the waste asphalt carbon negative electrode material obtained in this example, the temperature of the second carbonization decreases, and the oxygen groups introduced during the pre-carbonization process may be difficult to completely remove, resulting in a decrease in the initial Coulombic efficiency.

[0089] Example 20 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 to dryness.

[0090] The remaining steps are the same as those in Example 3.

[0091] The waste asphalt carbon material prepared in this example was assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 260 mAh g -1 , the initial Coulombic efficiency is ≥ 80%, and the capacity retention rate after 50 cycles is ≥ 92%. For the waste asphalt carbon negative electrode material obtained in this example, it is evaporated to dryness more quickly before carbonization, but the high temperature causes oxygen groups to be initially introduced on the surface of the material, resulting in a decrease in the initial Coulombic efficiency.

[0092] Example 21 The difference from Example 3 is that in S1, the waste asphalt solution and magnesium oxide powder are uniformly mixed at a mass ratio of 4.3:1.

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

[0094] The waste asphalt carbon materials prepared in this example are assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 260 mAh g -1 , the initial Coulombic efficiency is ≥ 86%, and the capacity retention rate after 50 cycles is ≥ 70%. For the waste asphalt carbon negative electrode material obtained in this example, the proportion of magnesium oxide is higher, but there are more pore cavities, the material is prone to collapse, and it is more likely to decay.

[0095] Example 22 The difference from Example 3 is that in S6, the carbonization time is 1 h.

[0096] The remaining steps are the same as those in Example 3.

[0097] The waste asphalt carbon materials prepared in this example are assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 248 mAh g -1 , the initial Coulombic efficiency is ≥ 85%, and the capacity retention rate after 50 cycles is ≥ 91%. For the waste asphalt carbon negative electrode material obtained in this example, the carbonization time is reduced, and the carbon layer in some areas of the material may not be completely transformed, resulting in a decrease in the reversible specific capacity of the battery.

[0098] Example 23 The difference from Example 1 is that in S3, the temperature for pre-carbonization of the waste asphalt and magnesium oxide composite precursor in an inert gas is 400 °C, and the pre-carbonization time is 2 h.

[0099] The remaining steps are the same as those in Example 1.

[0100] The waste asphalt carbon materials prepared in this example are assembled into a sodium-ion battery for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≥ 250 mAh g -1 , the initial Coulombic efficiency is ≥ 84%, and the capacity retention rate after 50 cycles is ≥ 90%. For the waste asphalt carbon negative electrode material in this example, due to the decrease in the pre-carbonization temperature, the cross-linking is not fully complete, and the reversible specific capacity of the battery is slightly lower.

[0101] Comparative Example 1 The difference from Example 1 is that the waste asphalt is directly pre-carbonized in an inert gas.

[0102] The rest are the same as those in Example 1.

[0103] The waste asphalt carbon materials prepared in this comparative example were assembled into sodium-ion batteries for electrochemical testing. The first charge-discharge curve at a current density of 0.1 C is as shown in Figure 8 and the cycling performance graph is as shown in Figure 9 . After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≧180 mAh g -1 , the first Coulombic efficiency is ≧82%, and the capacity retention rate after 50 cycles is ≧85%. For the waste asphalt carbon negative electrode material obtained in this comparative example, the microcrystalline crosslinking is poor, there are not many storage sites, and the reversible specific capacity of the battery is low.

[0104] Comparative Example 2 The difference from Example 1 is that: without going through steps such as pre-carbonization, the waste asphalt was heated to above 2600 °C using a one-step carbonization method.

[0105] The rest are the same as in Example 1.

[0106] The waste asphalt carbon materials prepared in this comparative example were assembled into sodium-ion batteries for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≧190 mAh g -1 , the first Coulombic efficiency is ≧85%, and the capacity retention rate after 50 cycles is ≧87%. For the waste asphalt carbon negative electrode material obtained in this comparative example, the reversible specific capacity of the battery is low and it is difficult to be practical.

[0107] Comparative Example 3 The difference from Example 1 is that: in S1, the waste asphalt solution and magnesium oxide powder were mixed evenly at a mass ratio of 1:1 respectively.

[0108] The rest are the same as in Example 1.

[0109] The waste asphalt carbon materials prepared in this comparative example were assembled into sodium-ion batteries for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example is ≧180 mAh g -1 , the first Coulombic efficiency is ≧73%, and the capacity retention rate after 50 cycles is ≧89%. For the waste asphalt carbon negative electrode material obtained in this comparative example, there are too many open pores. Although the pore structure can provide certain storage sites, its specific surface area is too large, the first Coulombic efficiency is too low, and the attenuation is relatively serious.

[0110] Comparative Example 4 The difference from Example 1 is that: in S1, the waste asphalt solution and magnesium oxide powder were mixed evenly at a mass ratio of 20:1 respectively.

[0111] The rest are the same as in Example 1.

[0112] The waste asphalt carbon materials prepared in this comparative example were assembled into sodium-ion batteries for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥175 mAh g -1 , the initial Coulombic efficiency was ≥85%, and the capacity retention rate after 50 cycles was ≥86%. For the waste asphalt carbon negative electrode material obtained in this comparative example, only a very small proportion was cross-linked with the magnesium oxide material, resulting in an insignificant improvement in the modification of carbon microcrystals and poor capacity.

[0113] Comparative Example 5 The difference from Example 1 was that the softening point of the waste asphalt in S1 was 200 °C.

[0114] The rest were the same as in Example 1.

[0115] The waste asphalt carbon materials prepared in this comparative example were assembled into sodium-ion batteries for electrochemical testing. After testing, the reversible specific capacity of the ion battery made of the waste asphalt carbon negative electrode material in this example was ≥165 mAh g -1 , the initial Coulombic efficiency was ≥75%, and the capacity retention rate after 50 cycles was ≥80%. For the waste asphalt carbon negative electrode material obtained in this comparative example, it was difficult to cross-link with the asphalt, and the cross-linking effect was poor, resulting in an insignificant improvement in the modification of carbon microcrystals, poor capacity, and relatively serious attenuation.

[0116] The performance of the sodium-ion batteries assembled from the waste asphalt carbon materials prepared in each example and comparative example at a current density of 0.1 C is shown in Table 1: Table 1 Performance of each example and comparative example at a current density of 0.1 C Continued

[0117] In the present invention, magnesium oxide is used to structurally adjust and modify waste asphalt. Through two carbonizations, the carbonization temperature, duration, atmosphere, and flow rate of material treatment are adjusted, and the carbon microcrystal structure of waste asphalt is coordinately modified from multiple angles. Compared with ordinary pore formation, the present invention utilizes the basic structure of waste asphalt carbon to generate a vortex-shaped irregular carbon layer, thereby providing more storage space. Considering the possible changes in oxygen groups and sulfur groups introduced during the process, while not affecting the initial Coulombic efficiency of the material, the degree of disorder of carbon microcrystals of the material is provided, but at the same time, a part of the "incompletely regular" carbon structure is retained, so that the incompletely ordered carbon layer and the vortex structure are cross-linked and unified, and thus a waste asphalt-based carbon material with appropriate performance is obtained.

[0118] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, reference can be made to the partial description of the method embodiment.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A preparation method of waste asphalt carbon with a microcrystalline eddy current structure as an ion battery material, characterized in that, It includes the following steps: Step S1: Extract waste asphalt with a softening point of 40 - 70 °C from retired asphalt roads, and mix the waste asphalt solution and magnesium oxide powder evenly at a mass ratio of (4.3 - 8.6):1; Step S2: Heat the mixed solution in S1 until the solvent evaporates completely to obtain a waste asphalt and magnesium oxide composite precursor; Step S3: Pre-carbonize the waste asphalt and magnesium oxide composite precursor obtained in S2; Step S4: Grind the pre-carbonized product into powder and screen it through a sieve; Step S5: Pickle the screened product to wash away the magnesium oxide template and dry it; Step S6: Perform secondary high-temperature carbonization on the product dried in S5 to obtain a waste asphalt carbon negative electrode material.

2. The preparation method of waste asphalt carbon with a microcrystalline eddy current structure as an ion battery material according to claim 1, characterized in that, In step S2, heat the mixed solution to 100 - 200 °C and continuously stir it with a magnetic stirrer during the heating process of the solution.

3. The preparation method of waste asphalt carbon with a microcrystalline eddy current structure as an ion battery material according to claim 1, characterized in that, In step S3, the waste asphalt and magnesium oxide composite precursor are pre-carbonized in one or more of 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.

4. The preparation method of waste asphalt carbon with a microcrystalline eddy current structure as an ion battery material according to claim 1, characterized in that, In step S5, soak the screened product in one or more mixtures of hydrochloric acid solution, sulfuric acid solution, and nitric acid solution with a concentration of 1 - 4 mol / L for 5 - 12 h.

5. The preparation method of waste asphalt carbon with a microcrystalline eddy current structure as an ion battery material according to claim 1, characterized in that, 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, the flow rate of the inert atmosphere is 20 - 100 mL / min, the carbonization time is 1 - 3 h, and it is cooled to room temperature to obtain a waste asphalt carbon negative electrode material.

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