Preparation method of asphalt-based porous carbon material induced by fused salt confinement, porous carbon material and application of porous carbon material

Abstract

The invention discloses a molten salt confinement induced asphalt-based porous carbon material preparation method, a porous carbon material and application thereof, and belongs to the technical field of petrochemical engineering byproduct resource utilization and functional carbon materials. According to the method, coal tar pitch is taken as a carbon source, a low-melting-point AlCl3NaCl molten salt system is taken as a reaction medium, and the porous carbon material with high specific surface area, rich mesoporous structures and fibrous morphology is prepared through two-step reaction of constant-temperature pretreatment and high-temperature carbonization under the synergistic effects of confinement, heat conduction and catalysis of molten salt. The method has obvious low-carbon and large-scale manufacturing advantages, the carbon source comes from low-value or by-product asphalt, the raw material source is wide, and the cost is low; the process temperature is obviously lower than that of a traditional high-temperature graphitization route, and the method has more advantages in the aspects of energy consumption and equipment threshold; meanwhile, the molten salt medium can be removed through water washing and the like and has the recycling potential, the process is relatively simplified, the comprehensive manufacturing cost is reduced, and the green manufacturing attribute is improved.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical by-product resource utilization and functional carbon material preparation technology, specifically involving a preparation technology that uses molten salt confined induced heat treatment to convert asphalt-like by-products into porous carbon materials suitable for electrochemical energy storage devices. Background Technology

[0002] The total amount of chemical asphalt by-products generated annually by my country's petrochemical and coal chemical systems exceeds ten million tons. Representative substances include coal tar pitch (CTP) and catalytic cracking slurry, which share common characteristics such as high viscosity, complex composition, high impurity (S / N / metal) content, and difficulty in stabilization and disposal. Currently, engineering disposal mainly relies on landfill, incineration, or low-value-added utilization (road asphalt, waterproofing materials, etc.), resulting in the long-term "locking" of resource value and accompanied by significant environmental burden and carbon emission pressure. Under the existing utilization pattern, the proportion of high-value utilization is still less than 10%. How to transform these low-value, difficult-to-treat by-products into high-value-added materials that can be exported on a large scale has become a key requirement for the green upgrading of the petrochemical industry chain.

[0003] In the field of electrochemical energy storage, carbon materials (such as hard carbon, porous carbon, graphene, and graphite-like carbon) are widely used as electrode materials for lithium / sodium-ion batteries and have been extended to emerging molten salt battery systems due to their good chemical stability and structural designability. This trend is further influenced by the migration of systems from small ions to strongly coordinated, larger ion clusters (such as AlCl4 in aluminum ion aluminochloride systems). - The structural requirements for electrode carbon materials have significantly increased: a continuous conductive framework is needed to reduce ohmic impedance, while open and interconnected channels (especially a certain proportion of mesoporous networks) are required to ensure rapid ion diffusion and suppress polarization. However, at present, commercial carbon materials still mainly rely on traditional carbon sources such as petroleum coke, natural graphite, and mesophase carbon microspheres. Their performance improvement often comes at the cost of high energy consumption and long processes—to obtain higher conductivity and structural order, high-temperature heat treatment or even graphitization (temperatures often need to be >2500℃) is usually required. This not only increases manufacturing costs and carbon emission intensity but also raises the equipment and operation threshold. At the same time, in order to increase the specific surface area and introduce usable pore structures, common practices require chemical activation or template construction, which can easily lead to engineering problems such as consumption of corrosive reagents, waste liquid treatment burden, and insufficient consistency and controllability of pore structure. More importantly, under the established process framework, there is often an unavoidable synergistic contradiction between conductivity and pore structure: when the structure tends to be ordered, the pores are prone to shrinkage and collapse, and the specific surface area decreases. On the other hand, excessive pore formation may introduce too many defects and higher internal resistance, making it difficult for the material to simultaneously meet the comprehensive requirements of "low polarization-fast mass transfer-stable structure" for high-rate and long-life energy storage devices.

[0004] Existing technologies for preparing carbon materials for electrochemical energy storage from asphalt byproducts (such as coal tar pitch and slurry) mainly include direct carbonization in an inert atmosphere, chemical activation, template method, and high-temperature structural rearrangement / graphitization. These methods generally suffer from several common shortcomings in terms of engineering feasibility and performance synergy: Firstly, asphalt raw materials themselves are characterized by high viscosity, complex composition, high impurity content, and low thermal conductivity, leading to uneven heating, localized overheating and underheating, and large fluctuations in product structure during conventional solid-phase heating processes. Secondly, existing methods often require higher temperatures, more corrosive pore-forming processes, or more complex template removal steps to improve specific surface area or conductivity, resulting in increased energy consumption, cost, and environmental burden. Furthermore, achieving stable synergy between pore structure, conductive framework, and cycle stability remains difficult. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing pitch-based porous carbon materials by molten salt confinement induction, which addresses the shortcomings of the prior art. This method significantly reduces the carbonization process temperature and energy consumption, avoids the high temperature (>1200℃) process required for traditional pitch carbonization, and constructs a high thermal conductivity, low melting point AlCl3-NaCl molten salt system to directionally prepare fibrous carbon with high specific surface area and porous structure, similar to needle coke, in the medium temperature range of 500~700℃.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing pitch-based porous carbon materials induced by molten salt confinement, the process of which is as follows: Coal tar pitch was used as the primary carbon source, and AlCl3 and NaCl were mixed evenly after vacuum drying to form a molten salt system. The original carbon source is mixed with the molten salt system and reacted at an inert atmosphere at a constant temperature to obtain the mixture; The mixture undergoes a high-temperature carbonization reaction under inert gas protection. The resulting carbon material is then washed with water and vacuum dried to obtain a porous carbon material.

[0007] As a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the coal tar pitch has a softening point of 140~160℃, ash content ≤15%, coking value ≥50%, and fixed carbon ≥40%. As a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the molten salt system consists of 36-9 parts AlCl3 and 1-4 parts NaCl by mass.

[0008] In a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in this invention, the vacuum drying temperature of AlCl3 and NaCl is 100~140℃.

[0009] As a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the original carbon source and the molten salt system are mixed at a mass ratio of 1:(8~10).

[0010] As a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the reaction temperature of the isothermal reaction is 150~300℃ and the reaction time is 0.5~3h.

[0011] In a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the high-temperature carbonization reaction is carried out at a temperature of 500~700℃ for 1~5h. Further, the mixture is heated from room temperature to the high-temperature carbonization reaction temperature at a rate of 2~10℃ / min under inert gas protection.

[0012] As a preferred embodiment of the method for preparing pitch-based porous carbon materials induced by molten salt confinement according to the present invention, the vacuum drying temperature of the carbon material is 65~75℃ and the time is 10~14h.

[0013] The pitch-based porous carbon material prepared by the above method can be used as a negative electrode material for aluminum-ion batteries.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention significantly reduces the carbonization process temperature and energy consumption, avoiding the high-temperature (>1200℃) process required for traditional asphalt carbonization. Instead, it significantly improves the pyrolysis uniformity and reaction rate by constructing an AlCl3-NaCl molten salt system with high thermal conductivity and low melting point, thereby significantly reducing energy consumption and equipment requirements.

[0015] 2. This invention achieves precise and controllable construction of carbon material structures, solving the problems of disordered product structure and uneven pore distribution in traditional methods. It can directionally prepare fibrous carbon with high specific surface area and porous structure, similar to needle coke, without the need for pore-forming agents.

[0016] 3. This invention can efficiently process and utilize impurities in asphalt, converting impurity elements such as nitrogen into beneficial functional dopant components, while effectively suppressing the adverse effects of metallic impurities and improving the electrochemical stability of the material.

[0017] 4. The pitch-based porous carbon material prepared by this invention is used as an anode material for aluminum-ion batteries. It has the advantages of high specific capacity (100 mAh / g), long life (more than 10,000 cycles), high rate response (stable cycling under different current densities) and low impedance characteristics, which improves the electrochemical performance of carbon materials in aluminum batteries and meets the comprehensive requirements of high-performance energy storage applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process for preparing porous carbon materials by inducing asphalt through molten salt confinement according to the present invention.

[0020] Figure 2 This is a SEM image of CTP-600-C obtained in Example 1 of the present invention.

[0021] Figure 3 The images show the XRD patterns of the carbon materials prepared in Examples 1 to 3 and Comparative Example 1 of this invention.

[0022] Figure 4 The images show the Raman diagrams of the carbon materials prepared in Examples 1 to 3 and Comparative Example 1 of this invention.

[0023] Figure 5 The images show the specific surface area and pore size distribution of the carbon material prepared in Example 1 of this invention; where (a) is the specific surface area and (b) is the pore size distribution.

[0024] Figure 6 The electrochemical performance test results of the carbon material prepared in Example 1 of this invention are shown in the figure; where (a) is 1A g. -1 (a) shows the long-cycle plots at different current densities, and (b) shows the charge-discharge curves at different current densities. (c) shows the plots at 10 A g. -1 Long cycle plot at current density. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Unless otherwise specified, all raw materials used in this invention are commercially available in the art. Among them, the coal tar pitch, also known as coal pitch powder, has a softening point of 140-160℃, ash content ≤15%, coking value ≥50%, and fixed carbon ≥40%, and is used as a primary carbon source.

[0028] Example 1 Reference Figure 1 This embodiment provides a method for preparing pitch-based porous carbon materials induced by molten salt confinement, specifically: 1) Use coal tar pitch as the primary carbon source; 2) Weigh out AlCl3 and NaCl inorganic salts at a mass ratio of 77:23, mix them, and then vacuum dry them at 120℃ for 5 hours to remove adsorbed moisture and obtain a uniformly dried molten salt system. 3) The original carbon source, coal tar pitch, and the dried molten salt system are mixed in a ceramic boat at a mass ratio of 1:10 and placed in a closed muffle furnace with an inert atmosphere for 1 hour at a constant temperature of 200°C. This temperature is significantly lower than the pyrolysis temperature of pitch, and the fluidity of the pitch allows the pitch components to be uniformly dispersed in the molten salt to obtain a mixture.

[0029] 4) The above mixture is heated to 600℃ at a heating rate of 5℃ / min and held at this temperature for 3 hours to achieve carbonization, yielding carbon material. During this process, pitch molecules polymerize into planar macromolecules, which then precipitate from the molten salt under surface tension, forming liquid pitch microspheres. Finally, due to the vigorous volatilization of AlCl3 in the molten salt, the molten salt flows, causing the precipitated liquid pitch microspheres to elongate and form fibers, resulting in fibrous carbon similar to needle coke, possessing a high specific surface area and porous structure. Figure 2 The SEM image shows that its surface has a porous, fibrous morphology. The obtained carbon material was thoroughly washed with deionized water to remove residual molten salt, and then dried in a vacuum drying oven at 70°C for 12 hours. The resulting pitch-based porous carbon material was named CTP-600-C.

[0030] Example 2 The difference between this embodiment and embodiment 1 is that the carbonization temperature in step 4) is adjusted to 500℃, while the remaining steps are the same as in embodiment 1, resulting in the asphalt-based porous carbon material of this embodiment, named CTP-500-C.

[0031] Example 3 The difference between this embodiment and embodiment 1 is that the carbonization temperature in step 4) is adjusted to 700℃, while the remaining steps are the same as in embodiment 1, resulting in the asphalt-based porous carbon material of this embodiment, named CTP-700-C.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that, without adding molten salt, the coal tar pitch was directly subjected to carbonization pyrolysis treatment at 600°C, resulting in coke with a low specific surface area, which was named CTP-600-D.

[0033] The carbon materials of Examples 1 to 3 and Comparative Example 1 were characterized, and the results are as follows: Figure 3 , Figure 4 As shown, Figure 3 Here are the XRD patterns for each carbon material. Figure 4 The Raman diagrams of the various carbon materials show that the carbon materials prepared in the embodiments of the present invention have structural features that are significantly better than those of conventional pyrolytic carbon (Comparative Example 1). The interlayer spacing is reduced, and XRD analysis shows that the (002) diffraction peak is close to the graphite standard 26.5°. The D / G peak intensity ratio in the Raman spectrum is significantly reduced (compared to CTP-600-D at the same carbonization pyrolysis treatment temperature CTP-600-C), indicating that it has a high degree of carbon atom order and good electrical conductivity.

[0034] At the same time, combined Figure 2 and 5 It can be seen that the carbon material prepared in Example 1 has a BET specific surface area as high as 1205.1 m². 2 / g, possessing an internally penetrating mesoporous network (2–50 nm), with mesopore sizes mainly in the 2–20 nm range, and the most probable pore size (the pore size with the highest pore volume ratio) approximately 3.47 nm. This mesoporous network consists of bulky aluminum coordination ions (such as AlCl4). - It provides an unobstructed, rapid diffusion channel, greatly alleviating the bottleneck of ion diffusion and enabling fast charging and discharging.

[0035] Application examples Application of pitch-based porous carbon materials as anode materials for aluminum-ion batteries Positive electrode preparation: The porous carbon material, Super P conductive agent and PTFE binder prepared in Example 1 were mixed in a mass ratio of 8:1:1, mixed evenly with isopropanol, pressed and cut into small pieces, and dried under vacuum at 80°C for 12 h. Battery assembly: Using the 12mm aluminum positive and negative electrodes prepared above as positive and negative electrodes respectively, glass fiber membrane (GF / D) as the separator, and quaternary molten salt (LiCl-NaCl-KCl-AlCl3) as the electrolyte, the Swagelok battery is assembled in an argon-protected glove box.

[0036] Electrochemical performance testing verified the results as follows: Figure 6 .like Figure 6 As shown in Figure A, the Swagelok battery assembled from carbon materials prepared in Example 1 can stably cycle 15,000 times at a specific capacity of 100 mAh / g at a current density of 1 A / g, with almost no capacity decay, indicating extremely strong cycle stability and a coulombic efficiency that remains close to 100%. Figure 6As shown in Figure C, at a current density of 10 A / g, it can stably cycle for 15,000 cycles with a specific capacity of 100 mAh / g, maintaining a capacity retention of 97.22%. This indicates that even under high-rate charge-discharge scenarios, the cycle stability remains extremely strong, and there is no rapid capacity decay due to excessive current. Figure 6 As shown in Figure B, at current densities of 1–10 A / g, all curves exhibit an “approximately symmetrical triangular shape,” which is a typical charge-discharge curve for supercapacitors (or capacitive batteries), indicating that the energy storage mechanism is mainly based on double-layer capacitance / pseudocapacitance; as the current density increases from 1 A / g… - ¹ to 10 A g - ¹Increased capacity while maintaining a high specific capacity, demonstrating excellent rate performance and fast charging potential.

[0037] Example 4 A method for preparing pitch-based porous carbon materials induced by molten salt confinement, comprising the following specific steps: 1) Use coal tar pitch as the primary carbon source; 2) Weigh out AlCl3 and NaCl by mass ratio of 6:4, mix them and dry them under vacuum at 120℃ for 5h to remove adsorbed moisture and obtain a uniformly dried molten salt system. 3) The original carbon source, coal tar pitch, and the dried molten salt system were mixed in a ceramic boat at a mass ratio of 1:10 and placed in a closed muffle furnace under an inert atmosphere. The mixture was reacted at a constant temperature of 180°C for 2 hours, and then heated to 580°C at a rate of 5°C / min and held at this temperature for 3 hours to achieve carbonization. Residual molten salt was removed by thorough washing with deionized water. The resulting carbon material was dried in a vacuum drying oven at 75°C for 10 hours. The final material was named CTP-580-C.

[0038] Example 5 A method for preparing pitch-based porous carbon materials induced by molten salt confinement, comprising the following specific steps: 1) Use coal tar pitch as the primary carbon source; 2) Weigh out AlCl3 and NaCl inorganic salts at a mass ratio of 9:1, mix them, and then vacuum dry them at 120℃ for 5 hours to remove adsorbed moisture and obtain a uniformly dried molten salt system. 3) The raw carbon source, coal tar pitch, was mixed with the dried molten salt system at a mass ratio of 1:8 in a ceramic boat and placed in a closed muffle furnace under an inert atmosphere. The mixture was reacted at a constant temperature of 220℃ for 0.5 hours, then heated to 620℃ at a rate of 5℃ / min and held at this temperature for 2 hours to achieve carbonization. Residual molten salt was removed by thorough washing with deionized water. The resulting carbon material was dried in a vacuum drying oven at 65℃ for 14 hours. The final material was named CTP-620-C.

[0039] Under the same conditions as in Example 1, the carbon materials prepared in Examples 4 and 5 were assembled into Swagelok batteries for electrochemical performance testing, and the results are shown in Table 1.

[0040] Table 1

[0041] As can be seen from Table 1, the carbon materials obtained under the schemes of Example 1, Example 4 and Example 5 all have excellent performance, with specific capacity reaching more than 75 mAh / g and capacity retention rate of more than 98% after 1000 cycles, among which Example 1 is the best.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that the molten salt system in step 2) is adjusted to be AlCl3 and NaCl in a mass ratio of 1:1, while the remaining steps are the same as in Example 1.

[0043] The result was that no porous fibrous carbon was formed, and the SEM showed disordered particles. The specific capacity of the prepared carbon material was only 45 mAh / g, and the cycle performance was poor.

[0044] Comparative Example 3 The difference between this comparative example and Example 1 is that the mixing ratio of the original carbon source coal tar pitch raw material and the molten salt system in step 3) is adjusted to 1:5, while the remaining steps are the same as in Example 1.

[0045] The resulting bulk carbon had an uneven pore size distribution, and the carbon material subsequently prepared had a specific capacity of 60 mAh / g, resulting in a decrease in rate performance.

[0046] Comparative Example 4 The difference between this comparative example and Example 1 is that the molten salt system in step 2) is adjusted to a mass ratio of NaCl and KCl of 1:1, while the remaining steps are the same as in Example 1.

[0047] The carbon source treated under molten salt conditions in this comparative example could not form porous carbon structures during the reaction, resulting in a product with a low specific surface area, a specific capacity of only 54 mAh / g, and a cycle life of only 60%.

[0048] Comparative Example 5 The difference between this comparative example and Example 1 is that the molten salt system in step 2) is adjusted to be AlCl3, NaCl and KCl in a mass ratio of 53:16:31, while the remaining steps are the same as in Example 1.

[0049] The resulting material was a porous carbon material, but it did not exhibit a fibrous structure, and its specific capacity was only 80 mAh / g.

[0050] Existing technologies primarily use nitrates, sulfates, or alkali metal / alkaline earth metal chlorides (such as NaCl and KCl) as molten salts. Their main functions are as physical templates, dispersion media, or to provide dopant elements. They also require additional pore-forming agents (such as ammonium carbonate) or subsequent high-temperature activation to achieve high specific surface area. Furthermore, existing technologies typically employ high temperatures (>1000℃) to achieve thermodynamic rearrangement of carbon atoms or etching reactions using activators such as KOH. This invention utilizes the strong Lewis acidity of AlCl3 to significantly reduce the activation energy for the aromatization and ordered stacking of coal tar pitch molecules. It can induce a high degree of carbon atom order in the mid-temperature range of 500–700℃, resulting in materials with good electrical conductivity without the need for subsequent high-temperature graphitization. Moreover, the vigorous volatilization of AlCl3 at the carbonization temperature creates a unique dynamic microenvironment in the molten salt, not only creating abundant mesoporous channels but also driving the liquid pitch intermediate to be stretched into a fibrous structure, achieving integrated pore-forming and fiber-forming. This volatilization-induced pore-forming / fiber-forming process is a physicochemical coupling process, most significant at 500–700℃. The temperature range of 500~700℃ chosen in this application is a necessary technical feature to match its unique reaction mechanism. This molten salt system of the present invention functions as a catalyst, dynamic template, and pore-forming agent, requiring no additional pore-forming agent or post-activation. The final product can be obtained after a simple washing following one-step carbonization, resulting in a short and environmentally friendly process. Furthermore, the formation of a eutectic mixture between AlCl3 and NaCl lowers the overall melting temperature of the system, allowing the asphalt to be uniformly dispersed under milder conditions.

[0051] In summary, this invention constructs AlCl3 The NaCl binary low-melting-point molten salt system was used to induce the preparation of porous carbon materials with high specific surface area, rich mesoporous structure and fibrous morphology of coal tar pitch at medium temperature. This successfully achieved the efficient conversion of high viscosity and complex composition petrochemical by-products into structurally ordered and highly graphitized carbon materials, overcoming a series of bottleneck problems in the existing technology, such as high pyrolysis temperature, poor performance of carbon materials and uncontrollable structure.

[0052] In terms of low energy consumption and cost, the core carbon source is coal tar pitch, which is a low-value or negative-cost solid waste. The raw material procurement cost is far lower than that of traditional carbon sources such as petroleum coke, graphite, and special polymers, reducing material costs by more than 70%. This technology uses carbonization at 500-700℃, significantly lower than the 2800℃ high-temperature sintering process required for traditional graphite material preparation, reducing energy consumption by more than 90%. Furthermore, the molten salt medium is cost-controllable and recyclable; AlCl3 and NaCl are both bulk industrial chemicals, with prices far lower than many functional salts. In addition, most of the molten salt can be recovered through simple water washing, and wastewater treatment is simple, demonstrating good environmental friendliness.

[0053] Regarding thermal conductivity, compared to conventional inert atmosphere direct pyrolysis, the core advantage of this invention's AlCl3-dominated molten salt system lies in its extremely high ionic conductivity and fluidity. This system converts the energy from the external heat source into intense and uniform ion convection and conduction within the molten salt medium, thereby altering the heating mode of low thermal conductivity asphalt-like raw materials. It transforms the slow, uneven, inward-to-inward permeation heating into a synchronous, rapid, and uniform immersion heating across the entire surface, significantly improving reaction uniformity and enhancing the consistency of the morphology and pore size distribution of the resulting carbon materials. Due to its high thermal efficiency, the same carbonization and graphitization effects can be achieved at relatively lower set temperatures or shorter holding times, thus achieving energy savings. The molten salt system of this invention also enhances structure guidance; the uniform thermal field provides an ideal environment for the structure-guiding effect of the molten salt, making it easier to realize the theoretically designed structure in the macroscopic product.

[0054] In terms of carbon structure construction, the catalytic effect of AlCl3 promotes the formation of more and more stable polycyclic aromatic hydrocarbon structures by asphalt molecules at relatively low temperatures. These structures serve as the initial rigid framework units of carbon materials, laying the foundation for porosity retention. This invention can effectively control the size and volume of pores by controlling the ratio of asphalt to molten salt. The entire reaction takes place within the confinement of liquid molten salt, whose high viscosity provides nanoscale spatial confinement. This confined environment inhibits the unlimited growth of carbon particles and the excessive ordering of graphite crystallites (XRD diffraction peaks close to 26.5°, Raman α). D / I G The minimum BET value can reach 0.6226, allowing the resulting carbon material to maintain abundant defect sites and open pore structures. The resulting carbon material exhibits a rich microporous and mesoporous structure, with a BET specific surface area as high as 1205.1 m². 2 / g provides a large number of active sites, which can store aluminum ions through various mechanisms such as surface adsorption, ion intercalation or conversion reaction, providing ample space and channels for ion storage and rapid transport, and can achieve a high specific capacity.

[0055] Regarding battery performance, the carbon material prepared in this invention, as the cathode material for molten salt aluminum batteries, exhibits significant specific capacity and cycle stability in half-cell tests. At a current density of 1 A / g, it can stably cycle for 15,000 cycles with a specific capacity of 100 mAh / g; at a current density of 10 A / g, it can stably cycle for 15,000 cycles with a specific capacity of 100 mAh / g, with a capacity retention rate of 97.22%, demonstrating excellent rate performance and fast-charging potential. Furthermore, the mesoporous network (2–50 nm) penetrating within the carbon material contains large-volume aluminum coordination ions (such as AlCl4). - It provides an unobstructed, rapid diffusion channel, greatly alleviating the bottleneck of ion diffusion and enabling fast charging and discharging.

[0056] This invention not only surpasses existing technologies in terms of structural control, performance improvement, energy consumption reduction, and resource utilization, but also establishes a new path for solid waste reuse that is highly engineering-adaptable, green, low-carbon, economical, and efficient, with significant technological promotion value and environmental governance significance.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing pitch-based porous carbon materials induced by molten salt confinement, characterized in that: Coal tar pitch is used as the primary carbon source, and AlCl3 and NaCl are mixed evenly to form a molten salt system. The original carbon source was mixed with the molten salt system and reacted at a constant temperature in an inert atmosphere to obtain the mixture; The mixture undergoes a high-temperature carbonization reaction under a protective atmosphere to obtain a pitch-based porous carbon material.

2. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 1, characterized in that: The coal tar pitch has a softening point of 140~160℃, ash content ≤15%, coking value ≥50%, and fixed carbon ≥40%.

3. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 1, characterized in that: The molten salt system consists of 36-9 parts AlCl and 1-4 parts NaCl by mass.

4. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 3, characterized in that: The original carbon source and molten salt system are mixed at a mass ratio of 1:8~10.

5. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 1, characterized in that: The isothermal reaction is carried out at a temperature of 150-300℃ for 0.5-3 hours.

6. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 1, characterized in that: The high-temperature carbonization reaction is carried out at a temperature of 500~700℃ for 1~5 hours.

7. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 1, characterized in that: The mixture is heated from room temperature to the carbonization reaction temperature at a rate of 2~10℃ / min under the protection of an inert gas.

8. The method for preparing pitch-based porous carbon materials induced by molten salt confinement as described in claim 7, characterized in that: The process after high-temperature carbonization includes water washing and vacuum drying. The vacuum drying temperature is 65-75℃ and the time is 10-14 hours.

9. Pitch-based porous carbon materials prepared by any one of the methods described in claims 1 to 8.

10. The application of the pitch-based porous carbon material as described in claim 9 as a negative electrode material for aluminum-ion batteries.

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