Modified pitch-based mesoporous carbon and a method for preparing the same

Abstract

This invention provides a modified pitch-based mesoporous carbon and its preparation method. The method uses pitch as the sole carbon source, mixes it with a surfactant, and then adds an acid catalyst at 10%–60% of the total mass of the pitch and surfactant. The mixture undergoes acid-catalyzed crosslinking, self-assembly, curing, and carbonization to obtain mesoporous carbon. This material possesses an ordered mesoporous structure, a specific surface area of ​​400–550 m² / g, and a pore size of 2–10 nm. This invention features a simple process, low cost, and eliminates the need for template removal, making it suitable for high-performance energy storage devices.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a modified pitch-based mesoporous carbon and its preparation method. Background Technology

[0002] Mesoporous carbon materials, due to their high specific surface area, tunable pore structure, and good electrical conductivity, have significant application value in electrochemical energy storage, heterogeneous catalysis, and adsorption separation. Asphalt, as a widely available and inexpensive soft carbon precursor, is an ideal raw material for preparing low-cost carbon materials. However, asphalt is prone to melting and significant volume shrinkage during high-temperature carbonization, leading to common problems in mesoporous carbon materials prepared using it as a single precursor via template methods, such as easily collapsing pore structures, low specific surface area, and poor stability. These issues severely restrict their application in high-performance fields.

[0003] Currently, the mainstream technical approach to improve the structural stability of asphalt-based mesoporous carbon is to introduce hard carbon precursors such as phenolic resins into the composite, utilizing the rigid framework of the hard carbon component to suppress overall shrinkage. While this method can partially improve performance, it does not fundamentally solve the structural defects of asphalt itself, and the cost advantage of asphalt is lost due to the introduction of high-priced components. Furthermore, the process often involves complex steps such as template removal.

[0004] Therefore, developing a method to directly obtain high-performance, low-cost mesoporous carbon materials by chemically modifying the asphalt precursor itself without relying on external rigid components, thereby fundamentally improving its structural stability during the carbonization process, is of great scientific significance and application value. Summary of the Invention

[0005] This invention addresses the problems of poor structural stability and high cost due to reliance on phenolic resin composites in existing pitch-based mesoporous carbon materials. It aims to provide a novel modified pitch-based mesoporous carbon and its preparation method. This method achieves significant enhancement of the mesoporous framework and fundamental improvement in the pore's resistance to collapse without introducing high-valent hard carbon precursors through in-situ acid-catalyzed crosslinking and structural regulation of pitch. Simultaneously, it maintains a simple process and low raw material costs, thereby promoting the large-scale application of this material in high-end fields such as energy storage and catalysis.

[0006] This invention provides a method for preparing modified pitch-based mesoporous carbon, characterized by comprising the following steps:

[0007] (1) Mix asphalt with surfactants to form a precursor mixture system;

[0008] (2) Add concentrated nitric acid to the precursor mixture, and after solvent evaporation and self-assembly, dry and solidify;

[0009] (3) The solidified product is subjected to carbonization treatment to obtain the modified asphalt-based mesoporous carbon.

[0010] In some embodiments, the surfactant is selected from at least one of Pluronic F127, Pluronic P123, PS-b-PEO, and PCS-b-PMMA.

[0011] In some embodiments, the surfactant is Pluronic F127.

[0012] In some embodiments, the softening temperature of the asphalt is 30–300°C.

[0013] In some embodiments, the amount of concentrated nitric acid added is 10% to 60% of the total mass of asphalt and surfactant.

[0014] In some embodiments, the amount of concentrated nitric acid added is 10% to 20% or 40% to 60% of the total mass of asphalt and surfactant.

[0015] In some embodiments, when the softening temperature is 150°C, the amount of concentrated nitric acid added is 10% to 15% of the total mass of the asphalt and surfactant.

[0016] In some embodiments, when the softening temperature is 45°C, 200°C, or 280°C, the amount of concentrated nitric acid added is 50% to 60% of the total mass of the asphalt and surfactant.

[0017] In some implementations, the mass ratio of the asphalt to the surfactant is 1:0.8~1.7.

[0018] In some implementations, the mass ratio of the asphalt to the surfactant is 1:1.2.

[0019] This invention provides a modified pitch-based mesoporous carbon prepared by the method described above.

[0020] In this invention, the modified pitch-based mesoporous carbon has a specific surface area of ​​400–550 m² / g and a pore size distribution of 2–10 nm.

[0021] This invention also provides the application of the above-mentioned modified pitch-based mesoporous carbon in the preparation of sodium-ion battery anode materials.

[0022] The beneficial effects of this invention are:

[0023] (1) Achieving a breakthrough in low cost and high performance: By cross-linking and curing asphalt molecules and controlling confined pore formation, the structural stability of the mesoporous framework is significantly enhanced while retaining its high conductivity, fundamentally overcoming the problems of shrinkage, pore collapse and performance degradation of single asphalt precursor materials during long-term use. The mesoporous carbon prepared by this invention has ordered pore structure, high specific surface area and excellent stability, while the raw material cost is only about 1 / 130 of that of the traditional phenolic resin composite route.

[0024] (2) Excellent electrochemical stability: When the obtained material is used as the negative electrode of sodium-ion battery, it exhibits high reversible capacity (about 320 mAh·g⁻¹) and nearly 100% coulombic efficiency. The electrode structure is stable and there are few interfacial side reactions during cycling.

[0025] (3) It has the potential for industrialization and promotion: the preparation process is simple and efficient, no template removal step is required, and the raw materials used are cheap and readily available, providing a practical and feasible technical path for the commercial application of high-performance mesoporous carbon materials in the field of large-scale energy storage. Attached Figure Description

[0026] Figure 1 This is a transmission electron microscope (TEM) image of pitch-based disordered mesoporous carbon obtained in Example 1 of the present invention.

[0027] Figure 2 This is a transmission electron microscope (TEM) image of pitch-based disordered mesoporous carbon obtained in Example 2 of the present invention.

[0028] Figure 3 This is a transmission electron microscope (TEM) image of the pitch-based ordered mesoporous carbon obtained in Example 3 of the present invention.

[0029] Figure 4 The isotherm of asphalt-based ordered mesoporous carbon and nitrogen gas adsorption-desorption obtained in Example 3 of the present invention;

[0030] Figure 5 This is a pore size distribution diagram of the asphalt-based ordered mesoporous carbon obtained in Example 3 of the present invention;

[0031] Figure 6 This is a transmission electron microscope (TEM) image of pitch-based disordered mesoporous carbon obtained in Example 4 of the present invention.

[0032] Figure 7 This is a transmission electron microscope (TEM) image of pitch-based disordered mesoporous carbon obtained in Example 5 of the present invention.

[0033] Figure 8 This is a transmission electron microscope (TEM) image of the asphalt-based ordered mesoporous carbon obtained in Example 6 of the present invention.

[0034] Figure 9 This is a transmission electron microscope (TEM) image of the asphalt-based ordered mesoporous carbon obtained in Example 7 of the present invention.

[0035] Figure 10 This is a transmission electron microscope (TEM) image of the asphalt-based ordered mesoporous carbon obtained in Example 8 of the present invention.

[0036] Figure 11 This is a comparison chart of the raw material costs of asphalt and phenolic resin in an embodiment of the present invention;

[0037] Figure 12 The cycling performance of the mesoporous carbon prepared in this embodiment of the invention as a negative electrode in a sodium-ion battery is shown in the figure. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] 0.6 g of asphalt with a softening point of 150 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; the two solutions were mixed, and 0.1 g of concentrated nitric acid (~67%) was added. The mixture was dried at room temperature for 1–4 h using solvent evaporation-induced self-assembly (EISA), placed in a 50 °C oven for 24 h, then in a 100 °C oven for 24 h, and subsequently calcined at 650 °C for 3 h under an inert atmosphere to obtain disordered mesoporous carbon materials (such as…). Figure 1 ).

[0041] Example 2

[0042] 0.6 g of asphalt with a softening point of 150 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.3 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain disordered mesoporous carbon materials (such as...). Figure 2 ).

[0043] Example 3

[0044] 0.6 g of asphalt with a softening point of 150 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.15 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain ordered mesoporous carbon materials (such as...). Figure 3 BET has a specific surface area of ​​500 m² / g and a pore size of 7 nm (e.g., Figure 4 , Figure 5 ).

[0045] Example 4

[0046] 1.0 g of asphalt with a softening point of 150 °C was dissolved in tetrahydrofuran; 1.0 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.5 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain disordered mesoporous carbon materials (such as...). Figure 6 ).

[0047] Example 5

[0048] 0.6 g of asphalt with a softening point of 150 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant PS-b-PEO was dissolved in tetrahydrofuran; after mixing, 0.15 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C in an inert atmosphere for 3 h to obtain disordered mesoporous carbon material (such as... Figure 7 ).

[0049] Example 6

[0050] 0.6 g of asphalt with a softening point of 45 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.6 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain ordered mesoporous carbon materials (such as...). Figure 8 ).

[0051] Example 7

[0052] 0.6 g of asphalt with a softening point of 200 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.6 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain ordered mesoporous carbon materials (such as...). Figure 9 ).

[0053] Example 8

[0054] 0.6 g of asphalt with a softening point of 280 °C was dissolved in tetrahydrofuran; 0.5 g of surfactant Pluronic F127 was dissolved in tetrahydrofuran; after mixing, 0.6 g of concentrated nitric acid (~67%) was added, and the mixture was dried by EISA as in Example 1 and calcined at 650 °C under an inert atmosphere for 3 h to obtain ordered mesoporous carbon materials (such as...). Figure 10 ).

[0055] In summary, the preparation method provided by this invention is not only simple in process and controllable in structure, but also has significant advantages in raw material cost and overall performance. From a cost perspective, the unit price of phenolic resin is approximately RMB 1.56 / gram, while that of asphalt is only approximately RMB 0.012 / gram (e.g., ...). Figure 11 The cost difference between the two is approximately 130 times. If calculated based on the same carbon source, phenolic resin would significantly increase raw material and experimental iteration costs, and scaling up to the kilogram level would easily create financial pressure. Asphalt, on the other hand, is widely available, has stable prices, can be purchased on a large scale, and possesses good carbon-forming properties and processability, facilitating large-scale preparation and industrial transformation. Furthermore, asphalt reduces solvent and curing steps, lowering energy consumption and process complexity, resulting in a more significant cost advantage. Therefore, given the performance requirements, prioritizing asphalt is more economical and sustainable.

[0056] In terms of energy storage performance, this material exhibits high and stable sodium storage capacity in sodium-ion batteries. The reversible specific capacity after the first cycle is approximately 320 mAh g⁻¹, subsequently fluctuating slightly within the range of approximately 320–350 mAh g⁻¹ over 35 cycles, showing a gradual upward trend, indicating further improvement in reaction kinetics after electrode wetting and activation (e.g., ...). Figure 12 Meanwhile, the coulombic efficiency remained close to and stable at approximately 99–100%, with almost no significant decay, indicating that side reactions were effectively suppressed and the SEI film was relatively stable. Overall, this material combines high capacity with excellent cycling stability, making it a suitable candidate for a cost-effective carbon-based sodium anode.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing modified pitch-based mesoporous carbon, characterized in that, Includes the following steps: (1) Mix asphalt with surfactants to form a precursor mixture system; (2) Add concentrated nitric acid to the precursor mixture, and after solvent evaporation and self-assembly, dry and solidify; (3) The solidified product is subjected to carbonization treatment to obtain the modified asphalt-based mesoporous carbon.

2. The preparation method according to claim 1, characterized in that, The surfactant is selected from at least one of Pluronic F127, Pluronic P123, PS-b-PEO, and PCS-b-PMMA; further, the surfactant is Pluronic F127.

3. The preparation method according to claim 1, characterized in that, The softening temperature of the asphalt is 30–300℃.

4. The preparation method according to claim 1, characterized in that, The amount of concentrated nitric acid added is 10% to 60% of the total mass of asphalt and surfactant; further, the amount of concentrated nitric acid added is 10% to 20% or 40% to 60% of the total mass of asphalt and surfactant.

5. The preparation method according to claim 3, characterized in that, When the softening temperature is 150°C, the amount of concentrated nitric acid added is 10%~15% of the total mass of asphalt and surfactant.

6. The preparation method according to claim 3, characterized in that, When the softening temperature is 45℃, 200℃, or 280℃, the amount of concentrated nitric acid added is 50% to 60% of the total mass of asphalt and surfactant.

7. The preparation method according to claim 1, characterized in that, The mass ratio of asphalt to surfactant is 1:0.8~1.7; further, the mass ratio of asphalt to surfactant is 1:1.

2.

8. Modified pitch-based mesoporous carbon prepared by the method according to any one of claims 1 to 7.

9. The modified pitch-based mesoporous carbon according to claim 8, characterized in that, The mesoporous carbon has a BET specific surface area of ​​400–550 m² / g and a pore size distribution of 2–10 nm.

10. The application of the modified pitch-based mesoporous carbon as described in claim 8 or 9 in the preparation of sodium-ion battery anode materials.

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