A road petroleum asphalt-based hard and soft carbon composite material, its preparation method and application

Abstract

This invention provides a road petroleum asphalt-based hard-soft carbon composite material, the raw materials of which include road petroleum asphalt, light component small molecule stabilizer, heavy component small molecule oxidant, activator, and solvent; and the ratio of road petroleum asphalt:solvent:light component small molecule stabilizer:heavy component small molecule oxidant:activator is 1:15-25:0.05-0.2:0.05-0.2:2-5, calculated in g / mL / g / g / g. Furthermore, this invention also provides a method for preparing the aforementioned hard-soft carbon composite material, which includes the following steps: crosslinking treatment of the light component, crosslinking treatment of the heavy component, activation, and carbonization. This invention solves the problem in the prior art where the high price or low carbon yield of hard carbon precursors, high cost of oxidants, or complex overall formulations lead to high costs for the prepared asphalt-based sodium-ion battery anode carbon materials. The hard-soft carbon composite material of this invention not only has a lower cost but also combines the advantages of both hard and soft carbon, exhibiting high sodium storage capacity, high reversible specific capacity, high initial charge-discharge efficiency, and good cycle performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a road petroleum asphalt-based hard and soft carbon composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of new energy technologies, higher demands are being placed on energy conversion and storage devices. Sodium-ion batteries, due to the abundance, availability, and low cost of sodium resources, show great potential in large-scale energy storage systems. Because sodium ions have a relatively large radius, suitable sodium-containing positive and negative electrode materials are one of the key issues for the practical application of sodium-ion batteries. The sodium-containing negative electrode material is a crucial component, playing a vital role in loading and releasing sodium ions (i.e., sodium ion insertion / extraction). Currently, sodium-ion battery negative electrode materials are mainly divided into five types: carbon-based materials, titanium-based materials, alloy materials, organic compounds, and other systems. Among these, carbon-based materials have the highest technological maturity and abundant resources, and are expected to be the first to achieve industrialization.

[0003] Based on the microstructure of carbon atoms, carbon-based anode materials are classified into graphite-based materials, amorphous carbon materials, and nano-carbon materials. Among them, amorphous carbon materials have a high sodium storage capacity and are currently the anode materials closest to industrialization. According to the ease of graphitization during heat treatment, they are divided into soft carbon and hard carbon. Soft carbon can be graphitized at temperatures above 2500℃, while hard carbon is difficult to graphitize and is generally obtained through heat treatment in the range of 800-1400℃. The difference between soft and hard carbon lies in the cross-linking interaction of carbon layers in the microstructure, which fundamentally depends on the structure and shape of the carbonization precursor used. Generally speaking, thermoplastic precursors (petrochemical raw materials and by-products, such as coal tar pitch or high-temperature pitch, commonly used soft carbon precursors) easily form soft carbon, while thermosetting precursors (biomass, organic polymers, polymer materials, etc.) easily form hard carbon.

[0004] The microstructure of hard carbon consists of short-range ordered microregions formed by the stacking of curved graphite-like sheets. The random and disordered stacking of these microregions leaves numerous nanopores. It possesses a large carbon interlayer spacing (typically greater than 0.37 nm), abundant pore structure, and numerous defect sites, allowing it to store a large amount of sodium ions and exhibiting a high charge-discharge specific capacity. Furthermore, due to its large carbon interlayer spacing, its volume expansion during sodium ion insertion / extraction is minimal. Combined with its inherent lattice stability, it maintains good structural stability during high-temperature carbonization and battery use, which in turn ensures a certain degree of cycle stability. However, hard carbon exhibits low initial charge-discharge efficiency, and its performance is highly dependent on the precursors and processing techniques used. Although precursors are widely available, their low carbon yield or high cost increases the cost of hard carbon, hindering its application in large-scale energy storage.

[0005] In comparison, soft carbon has a higher degree of graphitization and a highly ordered carbon layer structure, which is not conducive to the storage of sodium ions, resulting in a lower charge-discharge specific capacity. However, it has higher electronic conductivity and a lower specific surface area and surface defect degree, which can reduce the formation of solid electrolyte interphase (SEI) film (i.e., soft carbon has better electrolyte compatibility), which helps to improve the first charge-discharge efficiency. In addition, the manufacturing cost of soft carbon is also lower and the process is easier to control.

[0006] The above analysis shows that both soft and hard carbon have certain shortcomings in the practical application of sodium-ion battery anode materials. Current technologies typically involve mixing oxidants into the soft carbon precursor to pre-oxidize it, thereby increasing the disorder of the carbon layers and thus improving its sodium storage capacity; or mixing soft and hard carbon precursors to prepare soft-hard carbon composite materials, thus combining the advantages of both to improve material performance. For example:

[0007] Patent CN116314773A discloses a pre-oxidized pitch-based sodium-ion battery anode material. It utilizes graphene oxide as a modifier to improve the conductivity of the prepared pitch-based anode material. Specifically, graphene oxide is reduced to graphene after carbonization. The high conductivity and uniform distribution of graphene enable the formation of a high-speed conductive network between the sodium-ion battery anode and the current collector, thereby effectively improving the material's conductivity. The pitch is derived from coal tar pitch, petroleum pitch, and synthetic pitch. Although the patent formulation is simple, requiring only one precursor and one oxidation modifier, the use of graphene oxide as the oxidation modifier significantly increases the cost.

[0008] Patent CN116675215A discloses a soft carbon-hard carbon composite material, whose raw materials are a soft carbon precursor (selected from coal tar pitch, petroleum pitch, ethylene tar pitch, and heavy aromatic hydrocarbon pitch), an organic oxidation accelerator, a catalyst, and a hard carbon precursor (selected from sucrose, glucose, starch, cellulose, lignin, phenolic resin, epoxy resin, and polyfurfuryl alcohol). The soft carbon precursor is first pre-oxidized by the organic oxidation accelerator, then the catalyst and hard carbon precursor are mixed with the pre-oxidized soft carbon precursor for polymerization, followed by coking and carbonization to obtain the composite carbon material. Although this composite carbon material combines the advantages of soft and hard carbon, the fact that the soft and hard carbon are derived from two different substances complicates the formulation. Furthermore, as mentioned earlier, the hard carbon precursor is not only expensive but also has a low carbon yield, further increasing the cost of hard carbon, thus leading to a complex overall process and increased costs.

[0009] It is known that existing technologies typically use asphalt as a soft carbon precursor, and incorporate oxidants to oxidize and modify the asphalt or mix in hard carbon precursors to combine the advantages of both soft and hard carbon, thereby improving the performance of asphalt-based carbon materials as anode materials for sodium-ion batteries. Although asphalt as a soft carbon precursor is cheap, readily available, and has a high carbon content, hard carbon precursors are often expensive or have low carbon yield. In addition, asphalt-based carbon materials prepared in this way often have the disadvantages of high oxidant costs or complex formulations, which need to be improved. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a road petroleum asphalt-based hard and soft carbon composite material, which solves the problems of high cost of hard carbon precursors or low carbon yield, high cost of oxidants or complex overall formulation in existing technologies, resulting in high cost of asphalt-based sodium-ion battery anode carbon materials.

[0011] According to an embodiment of the present invention, a road petroleum asphalt-based hard and soft carbon composite material is provided, the raw materials of which include road petroleum asphalt, light component small molecule stabilizer, heavy component small molecule oxidant, activator and solvent; and the ratio of road petroleum asphalt: solvent: light component small molecule stabilizer: heavy component small molecule oxidant: activator is 1:15-25:0.05-0.2:0.05-0.2:2-5, calculated in g / mL / g / g / g.

[0012] On the other hand, according to an embodiment of the present invention, the preparation method of a road petroleum asphalt-based hard and soft carbon composite material includes the following steps:

[0013] S1, Preparation of composite slurry: Road petroleum asphalt, solvent, light component small molecule stabilizer and heavy component small molecule oxidant are mixed in proportion, and then ultrasonically treated for 20-40 min to obtain composite slurry.

[0014] S2, Crosslinking treatment of light components: Under an inert gas atmosphere, the composite slurry is heated to 160-180℃ and then stirred at a constant temperature for 1-2 hours to obtain the first modified asphalt composite.

[0015] S3, Crosslinking treatment of heavy components: Under an inert gas atmosphere, the first modified asphalt composite is heated to 300-500℃ and then kept at a constant temperature for 1-2 hours to obtain the second modified asphalt composite.

[0016] S4, Activation: Add an activator to the second modified asphalt composite, then heat to 800℃ in an inert gas atmosphere, and then keep at the temperature for 1-2 hours for activation treatment;

[0017] S5, Carbonization: Under an inert gas atmosphere, the activated second modified asphalt composite is heated to 1000-1400℃ and then kept at a constant temperature for 2-3 hours for carbonization treatment, thus obtaining a road petroleum asphalt-based hard and soft carbon composite material.

[0018] In another aspect, according to embodiments of the present invention, a sodium-ion battery negative electrode sheet is also provided, which includes the aforementioned road petroleum asphalt-based hard and soft carbon composite material.

[0019] Finally, according to embodiments of the present invention, a sodium-ion battery is also provided, which includes the aforementioned sodium-ion battery negative electrode sheet.

[0020] The technical principle of this invention is as follows:

[0021] The road petroleum asphalt used in this invention differs from coal tar pitch and other high-temperature asphalts. It has a lower softening point and contains a higher proportion of light components (approximately 65%), with the remaining components being heavy components (approximately 35%). The light components consist of saturated and aromatic compounds, while the heavy components are resins and asphaltenes. The carbon content in both the light and heavy components is as high as 87%, and the light components are generally considered to produce hard carbon, while the heavy components are generally considered to produce soft carbon. However, due to their lower molecular weight, the light components have weaker intermolecular forces and lower polarity, resulting in poor thermal stability during high-temperature carbonization and greater volatility. This leads to lower carbon production in the asphalt, and after high-temperature carbonization, it exhibits more soft carbon properties and poor sodium storage capacity. Therefore, the main idea of ​​this invention is as follows: Light-component small-molecule stabilizers are used to enhance the high-temperature stability of light components in road petroleum asphalt to prevent its volatilization, thus using road petroleum asphalt as a precursor for both soft and hard carbon. Then, heavy-component small-molecule oxidants are used to oxidize and modify the heavy components, increasing the sodium storage capacity of the soft carbon derived from the heavy components. Simultaneously, the prepared soft carbon and hard carbon are cross-linked to form a hard-soft carbon composite material. This allows the soft carbon derived from the heavy components to further combine with the advantages of high sodium storage and good cycle stability of hard carbon. Furthermore, the good electrical conductivity and good electrolyte compatibility of the soft carbon in the composite material significantly improve the initial charge-discharge efficiency of the material. Specifically:

[0022] The light component small molecule stabilizer cross-links with the light component, while the heavy component small molecule oxidant, possessing highly oxidizing functional groups, also cross-links with the heavy component. In this way, the light and heavy components in road petroleum asphalt each act as target components, with the light component small molecule stabilizer and the heavy component small molecule oxidant playing a bridging role. This promotes the reconstruction and modification of the light / heavy components, establishing a covalently cross-linked network structure within the modified asphalt. This enhances the intermolecular and interaction forces, preventing the volatilization of the light and heavy components during subsequent carbonization. Furthermore, it strengthens the interfacial bonding between the hard carbon derived from the light component and the soft carbon derived from the heavy component during subsequent high-temperature carbonization, resulting in a hard-soft carbon composite material. This hard-soft carbon composite material combines the advantages of both hard and soft carbon, possessing both the high sodium storage and structural stability of hard carbon and the high conductivity and good electrolyte compatibility of soft carbon, thereby improving the overall performance of the material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Low cost. First, this invention uses road petroleum asphalt as a precursor for both hard and soft carbon. On the one hand, road petroleum asphalt itself is inexpensive, readily available, and has a high carbon content, avoiding the introduction of other hard carbon precursors that are expensive and have low carbon yield, thus significantly reducing costs. On the other hand, under the action of the light component small molecule stabilizer and the heavy component small molecule oxidant, both light and heavy components are not easily volatilized during high-temperature carbonization, especially the more abundant light components, which volatilize less. This not only greatly increases the carbon yield of the light component portion as a hard carbon precursor but also improves the carbon yield of the heavy component portion as a soft carbon precursor, thereby significantly improving the carbon utilization rate in road petroleum asphalt and greatly reducing costs. Second, the hard and soft carbon precursors of this invention are derived from the same substance, simplifying the formulation and laying the foundation for a simplified process, thus reducing costs. Finally, the light component small molecule stabilizer and the heavy component small molecule oxidant of this invention can both be common chemical reagents, readily available, of stable quality, and with controllable prices, based on the characteristics of the light and heavy components, increasing the cost reduction potential of the hard and soft carbon composite materials of this invention.

[0025] 2. Excellent electrochemical performance. This invention achieves crosslinking of the light component with a small molecule modifier and the heavy component with a small molecule oxidant, ultimately combining the advantages of both hard and soft carbon in the prepared hard-soft carbon composite material. The hard carbon provides higher charge-discharge specific capacity and better structural stability, while the soft carbon ensures high conductivity and good electrolyte compatibility, resulting in high sodium storage capacity, high reversible specific capacity, high initial charge-discharge efficiency, and good cycle performance.

[0026] 3. Environmentally friendly. This invention uses low-softening-point road petroleum asphalt as a precursor for hard-soft carbon composite materials, and fixes a large number of light components that are easily volatile during high-temperature carbonization, thus deriving a hard carbon structure. This not only avoids the pollution caused by the volatilization of light components, but also provides new ideas and directions for the application of low-softening-point road petroleum asphalt in the field of new energy.

[0027] 4. The process is simple, easy to implement, and yields good results, making it worthy of promotion. The formula used in this process is simple, resulting in a simple and easy-to-implement process. The sequential modification of light and heavy components ensures sufficient modification and good results. The reaction temperature and time for the crosslinking treatment are appropriate. Understandably, if the reaction temperature is too low or the time is too short, sufficient crosslinking of the two asphalt components cannot be achieved, affecting the carbon interlayer spacing and disorder of the final sample, thus reducing sodium storage capacity. Conversely, if the reaction temperature is too high or the time is too long, the yield will decrease and the cost will increase. The carbonization temperature and time are also appropriate. Understandably, if the carbonization temperature is too low or the time is too short, volatile matter and heteroatoms cannot be effectively removed, leading to increased defects and irreversible capacity. Conversely, if the carbonization temperature is too high or the time is too long, the carbon interlayer spacing will decrease, the disorder will decrease, and the sodium storage capacity will be reduced.

[0028] 5. Promising application prospects. The formulation of this invention is simple, the cost is low, the process is simple and easy to implement, and the prepared hard and soft carbon composite material has good electrochemical performance, making it an ideal electrode material for sodium batteries and showing potential application prospects.

[0029] Preferably, the light component small molecule stabilizer includes one of phosphoric acid, polyphosphoric acid, and resorcinol.

[0030] Beneficial effects: These three small molecule stabilizers are all common chemical substances that are readily available, of stable quality, and inexpensive. They contain highly active functional groups (such as phenolic hydroxyl groups and phosphate groups), which can easily crosslink with the light components of road petroleum asphalt. In addition, phosphoric acid and polyphosphoric acid provide phosphorus atoms, which can form P=O, PC and other bond types and embed themselves in the carbon layer during the reaction, thereby further expanding the carbon layer spacing and enhancing the absorption capacity of sodium ions.

[0031] Preferably, the heavy component small molecule oxidant includes one of terephthalic acid, benzaldehyde, and terephthaloyl chloride.

[0032] Beneficial effects: These three small molecule oxidants are common chemical substances that are readily available, of stable quality, and inexpensive; they contain highly active functional groups (such as alcohol hydroxyl groups, aldehyde groups, and acyl groups), which can easily cross-link with road petroleum asphalt components.

[0033] Preferably, the activator includes one of potassium hydroxide, sodium hydroxide, and phosphoric acid.

[0034] Beneficial effects: All of them are commonly used chemical activators in the preparation of porous carbon materials, and the selection is relatively flexible.

[0035] Preferably, the solvent is trichloroethylene.

[0036] Preferably, the road petroleum asphalt includes one of AH-90 base asphalt, AH-70 base asphalt, and AH-50 base asphalt.

[0037] Preferably, the inert gas includes either nitrogen or argon.

[0038] Beneficial effects: All are commonly used inert gases, allowing for flexible selection. Detailed Implementation

[0039] The technical solutions of the present invention will be further described below with reference to the embodiments.

[0040] 1. Explanation of the relevant circumstances of the three types of road petroleum asphalt used in Examples 1-13 and Comparative Examples 1-5 of this application:

[0041] (1) Their softening points are as follows:

[0042] AH-90 base asphalt: 42~55℃

[0043] AH-70 base asphalt: 44~57℃

[0044] AH-50 base asphalt: 45~58℃

[0045] The softening point data mentioned above is sourced from: GB / T 15180-2010 Petroleum Asphalt for Heavy Traffic Roads

[0046] (2) The road petroleum asphalt is fresh base asphalt that has not undergone any modification treatment.

[0047] (3) Asphalt Grade Classification: The grade of asphalt is also known as its class. Currently, there are various grading methods internationally. my country uses the penetration grade grading method, which determines the asphalt grade based on the penetration value obtained from the penetration test and according to the grading range. For example, the penetration range of No. 90 asphalt is approximately between 80 and 100. The asphalt grade is related to the properties of the asphalt. It is very important to select the appropriate grade of asphalt based on factors such as regional climate and transportation.

[0048] (4) The definition of road petroleum asphalt and the reasons for selecting the above three types of asphalt in the embodiments and comparative examples of this application are as follows:

[0049] Petroleum asphalt is a byproduct of crude oil extraction into gasoline, kerosene, diesel, and other heavy oils in petrochemical plants. It is further processed or formulated into a building material, a primary material for paving modern highways and urban roads. It is also used to construct waterproofing layers and filler materials for buildings, underground structures, and hydraulic engineering projects. Petroleum asphalt used for highways and urban roads is called road petroleum asphalt. According to the People's Republic of China industry standard "JTG F40-2004 Technical Specification for Construction of Highway Asphalt Pavement," asphalt is classified into seven grades based on its penetration: 160, 130, 110, 90, 70, 50, and 30.

[0050] The grade of asphalt used for asphalt pavement should be carefully determined after technical demonstration, taking into account factors such as highway grade, climate conditions, traffic conditions, pavement type, layer placement in the pavement structure, construction methods, and local experience. For expressways, first-class highways, roads with high summer temperatures, prolonged periods of high temperatures, heavy traffic, steep and winding sections in mountainous or hilly areas, parking lots, or slow-moving sections, asphalt with higher consistency, such as No. 70 or No. 50, is recommended. For areas with cold winters, low traffic volume, light loads, or tourist roads, asphalt with lower consistency and higher low-temperature ductility is preferred. When high-temperature and low-temperature requirements conflict, the high-temperature performance requirements should be given priority.

[0051] It is known that when constructing roads on a large scale, the amount of asphalt with a higher consistency is generally selected based on comprehensive conditions. Therefore, and considering the subsequent recycling of a large amount of asphalt (such as using it as a precursor for carbon materials), the embodiments and comparative examples of this application select No. 90, No. 70 and No. 50 road petroleum asphalt with a higher consistency as precursors for carbon materials.

[0052] 2. Explanation of the other raw materials in Examples 1-13 and Comparative Examples 1-5 of this application:

[0053] Trichloroethylene: Maclean, AR, 99.0%, containing 40 ppm diisopropylamine (stabilizer), 131.39 (MW);

[0054] Phosphoric acid: Maclean, density 1.69 g / mL;

[0055] Polyphosphoric acid (H n+2 P n O 3n+1 ): Maclean, content (H3PO4) ≥ 115%;

[0056] Resorcinol: Aladdin, AR, 99.0%;

[0057] terephthalic acid: Maclean, AR, 98.0%;

[0058] Benzaldehyde: Aladdin, AR, ≥98%;

[0059] Terephthaloyl chloride: Aladdin, AR, 99%;

[0060] Potassium hydroxide: Aladdin, AR, 85%;

[0061] Sodium hydroxide: Aladdin, AR, 96%.

[0062] 3. Explanation of terms related to electrochemical performance used in this application:

[0063] (1) Sodium storage capacity (here referring to sodium-ion half-cells; also called sodium storage capacity): the capacity of sodium ions embedded in the anode carbon material during discharge.

[0064] (2) Reversible capacity: The sodium ion capacity that a sodium battery can recover under certain charging / discharging conditions (current density, temperature, voltage, etc.) after a full charge / discharge process, under certain discharge / charging conditions (current density, temperature, voltage).

[0065] (3) Reversible specific capacity: reversible capacity per unit mass.

[0066] (4) 30mA / g reversible specific capacity: refers to the sodium battery capacity that a unit mass of sodium battery can recover during charge-discharge cycles at a current density of 30mA / g.

[0067] (5) Charge and discharge efficiency (for sodium-ion half-cells): The ratio of charge specific capacity (corresponding to sodium removal) to discharge specific capacity (corresponding to sodium insertion).

[0068] (6) First charge and discharge efficiency (here referring to sodium-ion half-cells; also called first coulombic efficiency): refers to the ratio of the first charge specific capacity (corresponding to the first sodium removal) to the first discharge specific capacity (corresponding to the first sodium insertion).

[0069] (7) Irreversible capacity: The sodium ion capacity that a sodium battery cannot release (recover) after a full charge process under certain discharge conditions (discharge rate, temperature, discharge voltage, etc.) and under given discharge conditions (charge rate, temperature, discharge voltage).

[0070] Example 1

[0071] A method for preparing a road petroleum asphalt-based hard and soft carbon composite material includes the following steps:

[0072] S1, Preparation of composite slurry: 5g of AH-70 road petroleum asphalt, 100mL of trichloroethylene, 0.25g of phosphoric acid and 0.25g of terephthalic acid were added to a 500mL three-necked flask and ultrasonically treated for 30min to obtain composite slurry;

[0073] S2, Crosslinking treatment of light components: The composite slurry is transferred to an oil bath and subsequent operations are carried out under N2 protection: heated to 160°C, then stirred at a constant temperature for 1 hour until the solvent evaporates, and the crosslinking reaction of light components is carried out, and then a uniformly mixed first modified asphalt composite is obtained.

[0074] S3, Crosslinking treatment of heavy components: The first modified asphalt composite is transferred to a tube furnace and the subsequent operation is carried out under N2 protection: after heating to 300℃, it is kept at the temperature for 2 hours to carry out the modification and crosslinking reaction of heavy components, and then the second modified asphalt composite is obtained.

[0075] S4, Activation: Weigh 10g of potassium hydroxide and add it to a beaker, then add 50g of deionized water and stir well to prepare a potassium hydroxide aqueous solution; take out the obtained second modified asphalt composite, let it stand and cool, then add it to the prepared potassium hydroxide aqueous solution, stir well and let it stand for 12h, then put the mixture back into the tube furnace and perform activation treatment under N2 protection: heat to 800℃ and then keep it at the temperature for 1h;

[0076] S5, Carbonization: The activated second modified asphalt composite is further processed under N2 protection: heated to 1200℃ and then kept at that temperature for 2 hours for carbonization treatment, resulting in a road petroleum asphalt-based hard and soft carbon composite material.

[0077] Example 2

[0078] A method for preparing a road petroleum asphalt-based hard and soft carbon composite material includes the following steps:

[0079] S1, Preparation of composite slurry: 5g of AH-70 road petroleum asphalt, 75mL of trichloroethylene, 0.5g of polyphosphoric acid and 0.5g of benzaldehyde were added to a 500mL three-necked flask and ultrasonically treated for 30min to obtain composite slurry.

[0080] S2, Crosslinking treatment of light components: The composite slurry is transferred to an oil bath and subsequent operations are carried out under Ar protection: heated to 170°C, then stirred at a constant temperature for 1 hour until the solvent evaporates, and the crosslinking reaction of light components is carried out, and then a uniformly mixed first modified asphalt composite is obtained.

[0081] S3, Crosslinking treatment of heavy components: The first modified bitumen composite was transferred to a tube furnace and the subsequent operation was carried out under Ar protection: After heating to 350°C, it was kept at the temperature for 1.5h to carry out the modification and crosslinking reaction of heavy components, and then the second modified bitumen composite was obtained.

[0082] S4, Activation: Weigh 15g of sodium hydroxide and add it to a beaker, then add 100g of deionized water and stir well to prepare a sodium hydroxide aqueous solution; take out the obtained second modified asphalt composite, let it stand and cool, then add it to the prepared sodium hydroxide aqueous solution, stir well and let it stand for 12h, then put the mixture back into the tube furnace for activation treatment under Ar protection: heat to 800℃ and then keep it at the temperature for 1.5h.

[0083] S5, Carbonization: The activated second modified asphalt composite is further processed under Ar protection: after heating to 1200℃, it is kept at the temperature for 2.5h for carbonization treatment, and then road petroleum asphalt-based hard and soft carbon composite material is obtained.

[0084] Example 3

[0085] A method for preparing a road petroleum asphalt-based hard and soft carbon composite material includes the following steps:

[0086] S1, Preparation of composite slurry: 5g of AH-70 road petroleum asphalt, 125mL of trichloroethylene, 0.75g of resorcinol and 0.75g of terephthaloyl chloride were added to a 500mL three-necked flask and ultrasonically treated for 20min to obtain the composite slurry.

[0087] S2, Crosslinking treatment of light components: The composite slurry is transferred to an oil bath and subsequent operations are carried out under N2 protection: heated to 180°C, then stirred at a constant temperature for 2 hours until the solvent evaporates, and the crosslinking reaction of light components is carried out, and then a uniformly mixed first modified asphalt composite is obtained.

[0088] S3, Crosslinking treatment of heavy components: The first modified asphalt composite is transferred to a tube furnace and the subsequent operation is carried out under N2 protection: after heating to 400℃, it is kept at the temperature for 2 hours to carry out the modification and crosslinking reaction of heavy components, and then the second modified asphalt composite is obtained.

[0089] S4, Activation: Add 40g of deionized water to a beaker, then weigh 20g of phosphoric acid and add it to the deionized water while stirring to dilute the phosphoric acid solution; then take out the obtained second modified asphalt composite, let it stand and cool, add it to the freshly diluted phosphoric acid solution, stir evenly and let it stand for 12h, then put the mixture back into the tube furnace for activation treatment under Ar protection: heat to 800℃ and then keep it at the temperature for 2h;

[0090] S5, Carbonization: The activated second modified asphalt composite is further processed under N2 protection: heated to 1400℃ and then kept at that temperature for 3 hours for carbonization treatment, resulting in a road petroleum asphalt-based hard and soft carbon composite material.

[0091] Example 4

[0092] A method for preparing a road petroleum asphalt-based hard and soft carbon composite material includes the following steps:

[0093] S1, Preparation of composite slurry: 5g of AH-50 road petroleum asphalt, 100mL of trichloroethylene, 1g of phosphoric acid and 1g of terephthalic acid were added to a 500mL three-necked flask and ultrasonically treated for 40min to obtain composite slurry.

[0094] S2, Crosslinking treatment of light components: The composite slurry is transferred to an oil bath and subsequent operations are carried out under N2 protection: heated to 160℃, then stirred at a constant temperature for 1.5h until the solvent evaporates, and the crosslinking reaction of light components is carried out, and then a uniformly mixed first modified asphalt composite is obtained.

[0095] S3, Crosslinking treatment of heavy components: The first modified asphalt composite is transferred to a tube furnace and subsequent operations are carried out under N2 protection: after heating to 450℃, it is kept at the temperature for 1 hour to carry out the modification and crosslinking reaction of heavy components, and then the second modified asphalt composite is obtained.

[0096] S4, Activation: Weigh 25g of potassium hydroxide and add it to a beaker, then add 200g of deionized water and stir well to prepare a potassium hydroxide aqueous solution; take out the obtained second modified asphalt composite, let it stand and cool, then add it to the prepared potassium hydroxide aqueous solution, stir well and let it stand for 12h, then put the mixture back into the tube furnace and perform activation treatment under N2 protection: heat to 800℃ and then keep it at the temperature for 1.5h;

[0097] S5, Carbonization: The activated second modified asphalt composite is further processed under N2 protection: heated to 1000℃ and then kept at that temperature for 2 hours for carbonization treatment, resulting in a road petroleum asphalt-based hard and soft carbon composite material.

[0098] Example 5

[0099] The difference from Example 1 is the addition of 0.25g of phosphoric acid and 0.5g of terephthalic acid.

[0100] Example 6

[0101] The difference from Example 1 is the addition of 0.25g of phosphoric acid and 1g of terephthalic acid.

[0102] Example 7

[0103] The difference from Example 1 is the addition of 0.5g of phosphoric acid and 0.25g of terephthalic acid.

[0104] Example 8

[0105] The difference from Example 1 is the addition of 0.5g of phosphoric acid and 1g of terephthalic acid.

[0106] Example 9

[0107] The difference from Example 1 is the addition of 1g of phosphoric acid and 0.25g of terephthalic acid.

[0108] Example 10

[0109] The difference from Example 1 is the addition of 1g of phosphoric acid and 0.5g of terephthalic acid.

[0110] Example 11

[0111] The difference from Example 1 is that AH-90 road petroleum asphalt is used.

[0112] Example 12

[0113] The difference from Example 3 is that the crosslinking temperature of the recombinant components is 500°C.

[0114] Example 13

[0115] The difference from Example 4 is that the carbonization temperature is 1200°C.

[0116] Comparative Example 1

[0117] The difference from Example 1 is that phosphoric acid is not added.

[0118] Comparative Example 2

[0119] The difference from Example 1 is that terephthalic acid is not added.

[0120] Comparative Example 3

[0121] The difference from Example 1 is that phosphoric acid and terephthalic acid are not added.

[0122] Comparative Example 4

[0123] The difference from Example 1 is the addition of 2g of phosphoric acid and 2g of terephthalic acid.

[0124] Comparative Example 5

[0125] The difference from Example 1 is the addition of 0.1g of phosphoric acid and 0.1g of terephthalic acid.

[0126] Performance testing

[0127] When the prepared hard-soft carbon composite material is used as a negative electrode material for sodium-ion batteries, the electrode testing conditions are as follows:

[0128] The electrode consists of 80% modified pitch-based sodium-ion battery negative electrode material, 10% by mass of Super P, and 10% by mass of sodium alginate, with deionized water as the diluent. The electrolyte is a solvent with 1 mol of sodium hexafluorophosphate dissolved in a DME ratio of 100 vol%.

[0129] The performance data of the hard and soft carbon composite materials for sodium-ion battery anodes obtained in Examples 1-13 and Comparative Examples 1-5 are summarized in Table 1:

[0130] Table 1. Preparation parameters of Examples 1-13 and Comparative Examples 1-5, and performance test data of the obtained hard and soft carbon composite materials.

[0131]

[0132] In Comparative Example 1, no light component small molecule stabilizer was added during preparation. Its reversible specific capacity of 30 mA / g and initial charge-discharge efficiency (hereinafter referred to as first efficiency) were only 221.8 mAh / g and 65%, respectively. The poor electrochemical performance indicates that only under the action of heavy component small molecule oxidant, the light components in the road petroleum asphalt precursor volatilized and lost a lot during the high-temperature carbonization process, resulting in the prepared carbon material mainly exhibiting soft carbon properties. Since the sodium storage capacity of soft carbon may be improved by oxidation modification, its electrochemical performance is not too bad. However, the improvement effect of the oxidation modification is limited, so the electrochemical performance is not good.

[0133] In Comparative Example 2, no heavy component small molecule oxidant was added during preparation. Its reversible specific capacity of 30 mA / g and first-efficiency were only 203.1 mAh / g and 62%, respectively, indicating poor electrochemical performance. This shows that although the light component in the road petroleum asphalt precursor was fixed under the action of the light component small molecule stabilizer, its heavy component part was not oxidized and modified. It was difficult to organically combine the hard carbon derived from the light component with the soft carbon derived from the heavy component, and thus could not achieve the complementary advantages of hard and soft carbon, resulting in poor electrochemical performance.

[0134] In Comparative Example 3, neither of the two small molecule formulations mentioned above was added during preparation. Its reversible specific capacity of 30 mA / g and first-efficiency were only 157.2 mAh / g and 54%, respectively, and its electrochemical performance was even worse. This indicates that the role of the two small molecule formulations was missing. Not only were the light components not retained in the road petroleum asphalt precursor, but the soft carbon derived from the heavy components was also not oxidatively modified. In other words, the prepared carbon material could only exhibit the properties of soft carbon, and the structure of the soft carbon was not optimized by oxidative modification. Its sodium storage capacity was particularly low, resulting in particularly poor electrochemical performance.

[0135] In Examples 1-13, the electrochemical performance was good, with a reversible specific capacity of 30 mA / g greater than 260 mAh / g and an initial efficiency of greater than 70%. Among them, the reversible specific capacity of 30 mA / g in Examples 1, 4, 5, 7, and 13 was above 275 mAh / g, and the initial efficiency was basically around 80%, with some even exceeding 80%. This indicates that the hard and soft carbon composite materials prepared by this invention have good electrochemical performance when applied to the negative electrode of sodium-ion batteries. This proves that the road petroleum asphalt used in this invention, under the action of the light component small molecule stabilizer and the heavy component small molecule oxidant, has a very good composite effect of hard carbon and soft carbon derived from the light and heavy components, respectively. The composite material achieves the complementary effect of hard and soft carbon.

[0136] Finally, Comparative Example 4 added excessive amounts of light component small molecule stabilizer and heavy component small molecule oxidant. Although its electrochemical test data was also good (slightly lower than the lowest level in Examples 1-7), it resulted in a waste of raw materials. On the other hand, Comparative Example 5 added too little light component small molecule stabilizer and heavy component small molecule oxidant, and its electrochemical test data was even lower than that of Comparative Example 4. This indicates that insufficient light component small molecule stabilizer and heavy component small molecule oxidant leads to incomplete modification of the light / heavy components, and also proves the rationality of the raw material ratio in this application.

[0137] Finally, 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 road petroleum asphalt-based hard and soft carbon composite material, characterized in that, The raw materials used in the hard and soft carbon composite materials include road petroleum asphalt, light component small molecule stabilizers, heavy component small molecule oxidants, activators, and solvents; and the ratio of road petroleum asphalt: solvent: light component small molecule stabilizers: heavy component small molecule oxidants: activators is 1:15-25:0.05-0.2:0.05-0.2:2-5, calculated in g / mL / g / g / g. Among them, the light component small molecule stabilizers include one of phosphoric acid, polyphosphoric acid, and resorcinol; The heavy component small molecule oxidant includes one of terephthalic acid, benzaldehyde, and terephthaloyl chloride; The road petroleum asphalt includes one of AH-90 base asphalt, AH-70 base asphalt, and AH-50 base asphalt.

2. The road petroleum asphalt-based hard and soft carbon composite material as described in claim 1, characterized in that, The activator includes one of potassium hydroxide, sodium hydroxide, or phosphoric acid.

3. The road petroleum asphalt-based hard and soft carbon composite material as described in claim 1, characterized in that, The solvent is trichloroethylene.

4. A method for preparing a road petroleum asphalt-based hard and soft carbon composite material as described in any one of claims 1-3, characterized in that, Includes the following steps: S1, Preparation of composite slurry: Road petroleum asphalt, solvent, light component small molecule stabilizer and heavy component small molecule oxidant are mixed in proportion, and then ultrasonically treated for 20-40 min to obtain composite slurry. S2, Crosslinking treatment of light components: Under an inert gas atmosphere, the composite slurry is heated to 160-180℃ and then stirred at a constant temperature for 1-2 hours to obtain the first modified asphalt composite. S3, Crosslinking treatment of heavy components: Under an inert gas atmosphere, the first modified asphalt composite is heated to 300-500℃ and then kept at a constant temperature for 1-2 hours to obtain the second modified asphalt composite. S4, Activation: Add an activator to the second modified asphalt composite, then heat to 800℃ in an inert gas atmosphere, and then keep at the temperature for 1-2 hours for activation treatment; S5, Carbonization: Under an inert gas atmosphere, the activated second modified asphalt composite is heated to 1000-1400℃ and then kept at a constant temperature for 2-3 hours for carbonization treatment, thus obtaining a road petroleum asphalt-based hard and soft carbon composite material.

5. The method for preparing a road petroleum asphalt-based hard and soft carbon composite material as described in claim 4, characterized in that, Inert gases include either nitrogen or argon.

6. A sodium-ion battery negative electrode sheet, characterized in that, The invention includes a road petroleum asphalt-based hard and soft carbon composite material as described in any one of claims 1-3.

7. A sodium-ion battery, characterized in that, Includes the sodium-ion battery negative electrode sheet as described in claim 6.

Images