Asphalt-based derivative hard carbon material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of energy storage, in particular to an asphalt-based derivative hard carbon material as well as a preparation method and application thereof, and the preparation method comprises the following steps: pretreating asphalt by adopting a mixed acid treatment method or a solvent heat treatment method to obtain pretreated asphalt; carrying out carbonization treatment on the pre-treated asphalt to obtain the asphalt-based derivative hard carbon material; wherein a reagent used in the mixed acid treatment method is a mixed solution of concentrated sulfuric acid, concentrated nitric acid and ammonium persulfate; in the solvent heat treatment method, a used reagent is an oxidizing structure regulating agent which comprises any one of a nitric acid solution and a hydrogen peroxide solution. The asphalt is subjected to oxidative pretreatment through mixed acid or oxidative solvent heat treatment, oxygen-containing functional groups (such as-OH,-COOH, C = O and the like) are introduced into the asphalt, the functional groups are easy to decompose in the asphalt carbonization process, and a large number of defects and micropores are generated, so that the graphitization process is inhibited, and a disordered playing card house structure is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a pitch-based derived hard carbon material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous growth of global energy demand, the finiteness of traditional fossil energy and the environmental pollution problems caused by it are increasingly prominent, which promotes the exploration of sustainable and environmentally friendly new energy storage technologies. Lithium-ion batteries (LIBs) dominate in the fields of electric vehicles and portable electronic devices due to their high energy density and mature industrial chain. However, the uneven global distribution, limited reserves and high exploitation cost of lithium resources limit their widespread application in large-scale energy storage. In addition, lithium-ion batteries have the risk of thermal runaway, and the safety problem needs to be solved. In contrast, sodium-ion batteries (SIBs) are an ideal alternative for large-scale energy storage systems due to their abundant raw material reserves (the content of sodium in the earth's crust is about 2.3%, much higher than the 0.0017% of lithium), low cost and environmental friendliness.

[0003] Among the negative electrode materials of sodium-ion batteries, hard carbon is of great concern due to its excellent sodium storage performance and structural stability. Pitch-based derived hard carbon is considered as a highly potential sodium battery negative electrode material due to its wide raw material sources, high carbon yield and low cost. However, unmodified pitch is prone to form highly graphitized soft carbon structure during high-temperature pyrolysis, and its interlayer spacing is small (usually <0.37 nm), which is not conducive to the insertion / extraction of sodium ions, resulting in poor reversible capacity and rate performance. Therefore, how to effectively modify the pitch to inhibit the graphitization trend and improve its sodium storage capacity has become one of the key problems in current research.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of pitch-based derived hard carbon material, which can significantly improve the rate performance, reversible capacity and cycle stability of the material.

[0006] The present application provides a preparation method of pitch-based derived hard carbon material, comprising the following steps: S1, pretreating pitch by using a mixed acid treatment method or a solvothermal treatment method to obtain pretreated pitch; S2, carbonizing the pretreated pitch to obtain pitch-based derived hard carbon material; In the mixed acid treatment method, the reagent used is a mixed solution of concentrated sulfuric acid, concentrated nitric acid and ammonium persulfate; In the solvothermal treatment method, the reagent used is an oxidative structure regulator, including any one of nitric acid solution and hydrogen peroxide solution.

[0007] The present application introduces oxygen-containing functional groups (such as -OH, -COOH, C=O, etc.) into the pitch by acid or oxidative solvent thermal treatment for oxidative pretreatment, which are easy to decompose during the carbonization process of pitch and generate a large number of defects and micropores, thereby inhibiting the graphitization process and forming a disordered "card house" structure.

[0008] Studies have shown that the increase in disordered structure caused by the oxidative pretreatment of the present application can increase the carbon layer spacing, thereby facilitating the rapid insertion and extraction of sodium / lithium ions and improving the sodium / lithium storage capacity. In addition, the increase in micropores and defect structures can increase the specific surface area of the material and improve the reversible capacity. Furthermore, the oxygen element introduced by the oxidative pretreatment of the present application can form a mixed carbon structure with better electrical conductivity after carbonization, thereby improving the electron transport rate, and the "card house" structure formed can provide a shorter ion diffusion path and reduce the charge transfer resistance. Moreover, the oxidative pretreatment method of the present application is also helpful for the formation of a stable carbon skeleton, thereby reducing the volume shrinkage during the carbonization process and making the material structure more stable. In addition, the "card house" structure formed by the present application also has better mechanical strength, which can buffer the volume change during the charging and discharging process and reduce the occurrence of cracks.

[0009] As preferred in the present technical solution, in the acid treatment method of the present application, the reagents used include A solution and B solution, wherein the A solution is a mixed solution of concentrated sulfuric acid and concentrated nitric acid, and the concentrated sulfuric acid mainly acts as a strong dehydrating agent and sulfonating agent, which can introduce -SO3H groups on the aromatic ring, enhance the polarity of the pitch molecule, and promote the permeability and uniformity of the subsequent oxidation reaction. The concentrated nitric acid not only can preliminarily oxidize the aliphatic chains and weak bonds in the pitch to generate carboxyl and hydroxyl groups, laying a foundation for subsequent deep oxidation, but also can nitrate the aromatic ring in the pitch to generate nitroaromatics, which decompose to form nitrogen-doped sites (N-C) during subsequent carbonization, thereby improving the electronic conductivity. Therefore, the A solution of the present application can not only introduce oxygen / sulfur-containing functional groups in the pitch to inhibit the graphitization tendency during carbonization, but also increase the pitch molecular spacing to form a more loose carbon layer structure after carbonization. The B solution is a mixed solution of ammonium persulfate and concentrated sulfuric acid, wherein the ammonium persulfate can generate SO4· and ·OH free radicals under the acidic conditions provided by the concentrated sulfuric acid, which can deeply oxidize the pitch, break the macromolecular aromatic ring structure, and form more small molecular fragments and edge defects. At the same time, the free radicals can also attack the pitch molecular chain to induce intermolecular crosslinking reactions and build a three-dimensional network structure, which can form a stable "card house" accumulation after carbonization. In addition, part of the -SO3H groups can be converted into stable C-S-C bonds during carbonization, providing additional sodium storage active sites. Therefore, the acid treatment method of the present application not only realizes the efficient modification of pitch, but also provides a new strategy for the microstructure regulation of hard carbon materials. - and ·OH free radicals, which can deeply oxidize the pitch, break the macromolecular aromatic ring structure, and form more small molecular fragments and edge defects. At the same time, the free radicals can also attack the pitch molecular chain to induce intermolecular crosslinking reactions and build a three-dimensional network structure, which can form a stable "card house" accumulation after carbonization. In addition, part of the -SO3H groups can be converted into stable C-S-C bonds during carbonization, providing additional sodium storage active sites. Therefore, the acid treatment method of the present application not only realizes the efficient modification of pitch, but also provides a new strategy for the microstructure regulation of hard carbon materials.

[0010] In this technical solution, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in solution A is 1:(0.8-1.2), and preferably 1:1; in solution B, the amount of concentrated sulfuric acid required for each 1g of ammonium persulfate is 3-4mL, and preferably, the amount of concentrated sulfuric acid required for each 1g of ammonium persulfate is 3.3mL.

[0011] In a preferred embodiment of this technical solution, in the mixed acid treatment method, the required volumes of solution A and solution B for each 1g of asphalt are 6-7mL and 3-4mL, respectively.

[0012] Further optimization is that the required volumes of solution A and solution B for each 1g of asphalt are 6.5mL and 3.3mL, respectively.

[0013] In a preferred embodiment of this technical solution, the mixed acid treatment method involves uniformly mixing asphalt with solution A and solution B, stirring at 60-90℃ for 4-8 hours, cooling to room temperature after the reaction is complete, filtering, and vacuum drying to obtain pretreated asphalt.

[0014] As a preferred embodiment of this technical solution, in the solvothermal treatment method, nitric acid mainly modifies asphalt in the following way: nitric acid decomposes at high temperature to generate NO2. + Nitric acid and ·OH radicals attack aromatic rings and aliphatic chains in asphalt, causing them to oxidize and break bonds, forming oxygen-containing functional groups (-COOH, -OH, -C=O). The introduction of these oxygen-containing functional groups helps suppress graphitization during carbonization, forming a disordered "house of cards" structure. Nitric acid can also nitrate aromatic rings (introducing -NO2), and during subsequent carbonization, -NO2 decomposes to form nitrogen-doped carbon (NC), improving electronic conductivity and reducing charge transfer resistance. Compared to nitric acid, hydrogen peroxide exhibits milder but more uniform oxidation characteristics, forming mesoporous structures in asphalt rather than micropores caused by excessive corrosion, which is beneficial for ion transport.

[0015] Specifically, the required volume of oxidizing structure modifier is 40-60 mL per 1 g of asphalt, wherein the concentration of nitric acid solution is 0.5-2 mol / L. -1 The concentration of the hydrogen peroxide solution is 20-40 wt.%.

[0016] In a preferred embodiment of this technical solution, the solvothermal treatment method involves placing the asphalt in a liner containing an oxidizing structure modifier and reacting it with a solvothermal agent at 150-200°C for 20-30 hours. After the reaction is completed, the asphalt is cooled to room temperature, filtered, and then vacuum dried to obtain the pretreated asphalt.

[0017] The high temperature and high pressure environment of the solvent reaction heat can promote the penetration of oxidative structure modifiers into the interior of the asphalt, achieve uniform bulk phase modification, and avoid local excessive oxidation of the surface; while the longer solvothermal reaction time can ensure that the oxidation reaction is fully carried out, forming a stable cross-linked structure, and the hard carbon after carbonization has higher mechanical strength.

[0018] As a preferred embodiment of this technical solution, during the carbonization process, the pretreated asphalt is placed in a ceramic boat and heated at 1-3°C for 1 minute under a nitrogen atmosphere. -1 The temperature is increased to 900-1500℃ and then held for 2-4 hours to obtain pitch-based derived hard carbon materials.

[0019] As a preferred embodiment of this technical solution, a segmented carbonization method can be further adopted during the carbonization process. For example, pre-carbonization can be carried out at 300-500℃ to allow the oxidized asphalt to initially cross-link and form a stable skeleton; then high-temperature carbonization can be carried out at 800-1500℃ to suppress the growth of graphite microcrystals through precise temperature control and strengthen the "house of cards" structure.

[0020] As a preferred embodiment of this technical solution, during the carbonization process, ZnCl2 can also be used to chemically activate the pretreated asphalt. The chemical activation method can further construct a microporous-mesoporous hierarchical structure on the material surface, thereby enhancing the adsorption capacity for ions.

[0021] Specifically, for asphalt pretreated by mixed acid treatment or solvent heat treatment, the pretreated asphalt and ZnCl2 are taken at a mass ratio of 1:1, thoroughly ground and mixed evenly, placed in a porcelain boat, and heated at 1-3℃ for 1 minute under a nitrogen atmosphere. -1 The material is heated to 900-1500℃ at a certain heating rate and then held at that temperature for 2-4 hours for carbonization, or the above-mentioned segmented carbonization method is used to obtain asphalt-based derived hard carbon materials.

[0022] Secondly, the present invention also discloses asphalt-based derived hard carbon materials prepared by the above method, which should also fall within the protection scope of the present invention.

[0023] Thirdly, the present invention also discloses the application of pitch-based derived hard carbon materials in the preparation of energy storage devices, which should also fall within the scope of protection of the present invention.

[0024] Fourthly, the present invention also discloses an energy storage device whose working electrode includes the above-mentioned pitch-based derived hard carbon material, which should also fall within the protection scope of the present invention.

[0025] The method for preparing pitch-based derived hard carbon materials of the present invention has at least the following beneficial effects: This invention employs a mixed acid or oxidizing solvent heat treatment to perform an oxidative pretreatment on asphalt, introducing oxygen-containing functional groups (such as -OH, -COOH, C=O, etc.) into the asphalt. These functional groups are easily decomposed during asphalt carbonization, generating numerous defects and micropores, thereby inhibiting the graphitization process and forming a disordered "house of cards" structure. Firstly, the increased disordered structure increases the interlayer spacing of carbon layers, facilitating the rapid insertion and extraction of sodium / lithium ions and enhancing sodium / lithium storage capacity. The increased micropores and defects increase the specific surface area of ​​the material, improving reversible capacity. Furthermore, the oxygen elements introduced by the oxidative pretreatment form a mixed carbon structure with better conductivity after carbonization, thereby improving electron transport rate. The "house of cards" structure also provides shorter ion diffusion paths, reducing charge transfer impedance. Moreover, the stable carbon framework formed by the oxidative pretreatment reduces volume shrinkage during carbonization, making the material structure more stable. Additionally, the "house of cards" structure exhibits better mechanical strength, buffering volume changes during charge and discharge processes and reducing cracking. Therefore, compared to traditional graphite anodes that are only suitable for lithium batteries, the pitch-based derived hard carbon material of this invention has an open carbon layer structure, which can be adapted to various ion batteries such as sodium, lithium and potassium, and has broad market prospects in multiple fields such as electric vehicles, energy storage power stations, and consumer electronics batteries. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific 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 from these drawings without creative effort.

[0027] Figure 1 This is a scanning electron microscope image of the pitch-based derived hard carbon material obtained in Example 1 of the present invention; Figure 2 This is a transmission electron microscope (TEM) image of the pitch-based derived hard carbon material obtained in Example 1 of the present invention. Figure 3 The GCD curves of the pitch-based derived hard carbon material obtained in Example 1 of this invention are shown for the first 5 cycles at 0.1 A / g. Figure 4 This is a graph showing the cycling performance of the asphalt-based derived hard carbon material and ordinary asphalt material obtained in Example 1 of the present invention after carbonization at 2 A / g; Figure 5 This is a comparison chart of the rate performance of the asphalt-based derived hard carbon material and ordinary asphalt material after carbonization, obtained in Example 1 of this invention. Figure 6 The GCD curve of the pitch-based derived hard carbon material obtained in Example 4 of this invention is shown for the first 5 cycles at 0.1 A / g. Figure 7 This is a graph showing the cycling performance of the asphalt-based derived hard carbon material and ordinary asphalt material obtained in Example 4 of the present invention after carbonization at 2A / g. Figure 8 This is a comparison chart of the carbonization performance of the asphalt-based derived hard carbon material and the ordinary asphalt material obtained in Example 4 of the present invention. Figure 9 This is a transmission electron microscope (TEM) image of the pitch-based derived hard carbon material obtained in Example 7 of the present invention. Figure 10 The isothermal adsorption curves of the asphalt-based derived hard carbon materials obtained in Examples 4 and 8 of this invention are shown. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] 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.

[0031] Example 1 S1. Mix 3 g asphalt with solution A (10 mL concentrated sulfuric acid + 10 mL concentrated nitric acid) and solution B (3 g ammonium persulfate + 10 mL concentrated sulfuric acid) evenly, stir at 80 ℃ for 6 h, cool to room temperature after the reaction is complete, filter and vacuum dry to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt and place it in a ceramic boat. Under a nitrogen atmosphere, incubate at 2 °C for min. -1 The material was heated to 900 °C at a heating rate and held for 3 h to obtain asphalt-based derived hard carbon material.

[0032] Example 2 S1. Mix 3 g asphalt with solution A (8 mL concentrated sulfuric acid + 12 mL concentrated nitric acid) and solution B (3 g ammonium persulfate + 12 mL concentrated sulfuric acid) evenly, stir at 60 ℃ for 8 h, cool to room temperature after the reaction is complete, filter and vacuum dry to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt and place it in a ceramic boat. Under a nitrogen atmosphere, incubate at 2 °C for min. -1 The material was heated to 1200 °C at a certain heating rate and then held for 3 h to obtain asphalt-based derived hard carbon material.

[0033] Example 3 S1. Mix 3 g asphalt with solution A (10 mL concentrated sulfuric acid + 8 mL concentrated nitric acid) and solution B (3 g ammonium persulfate + 9 mL concentrated sulfuric acid) evenly, stir at 90 ℃ for 3 h, cool to room temperature after the reaction is complete, filter and vacuum dry to obtain pretreated asphalt; S2. Take 0.5 g of pretreated asphalt and place it in a ceramic boat. Under a nitrogen atmosphere, incubate at 2 °C for min. -1 The material was heated to 1500 °C at a heating rate and held for 2 h to obtain asphalt-based derived hard carbon material.

[0034] Example 4 S1. Place 0.6 g of asphalt into a container containing 50 mL of 1 mol / L... -1 The sample was lining with nitric acid solution and reacted solvothermically in an oven at 180°C for 24 h. After cooling to room temperature, it was filtered until neutral and then vacuum dried to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt in a ceramic boat and, under a nitrogen atmosphere, incubate at 2 ℃ for min. -1 The material was heated to 900 °C at a heating rate and held for 3 h to obtain asphalt-based derived hard carbon material.

[0035] Example 5 S1. Place 0.6 g of asphalt into a liner containing 50 mL of 30 wt.% hydrogen peroxide solution, and react it in an oven at 180 ℃ for 24 h using a solvothermal method. After cooling to room temperature, filter until neutral, and vacuum dry the sample to obtain the pretreated asphalt. S2. Take 0.5 g of pretreated asphalt in a ceramic boat and, under a nitrogen atmosphere, incubate at 2 ℃ for min. -1 The material was heated to 1200 °C at a heating rate and held for 2 h to obtain asphalt-based derived hard carbon material.

[0036] Example 6 S1. Place 0.6 g of asphalt into a container containing 40 mL of 2 mol / L... -1The sample was lining with nitric acid solution and reacted solvothermically in an oven at 150°C for 24 h. After cooling to room temperature, it was filtered until neutral and then vacuum dried to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt in a ceramic boat and, under a nitrogen atmosphere, incubate at 2 ℃ for min. -1 The material was heated to 1300 °C at a heating rate and held for 2 h to obtain pitch-based derived hard carbon material.

[0037] Example 7 S1. Mix 3 g asphalt with solution A (10 mL concentrated sulfuric acid + 10 mL concentrated nitric acid) and solution B (3 g ammonium persulfate + 10 mL concentrated sulfuric acid) evenly, stir at 80 ℃ for 6 h, cool to room temperature after the reaction is complete, filter and vacuum dry to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt and place it in a ceramic boat. Under a nitrogen atmosphere, incubate at 2 °C for min. -1 The material was heated to 400 °C at a heating rate and held at that temperature for 3 hours for pre-carbonization, followed by high-temperature carbonization at 1200 °C for 2 hours to obtain asphalt-based derived hard carbon material.

[0038] Example 8 S1. Place 0.6 g of asphalt into a container containing 50 mL of 1 mol / L... -1 The sample was lining with nitric acid solution and reacted solvothermically in an oven at 180°C for 24 hours. After cooling to room temperature, it was filtered until neutral and then vacuum dried to obtain pretreated asphalt. S2. Take 0.5 g of pretreated asphalt and 0.5 g of ZnCl2, grind and mix them thoroughly, place them in a porcelain boat, and in a nitrogen atmosphere, heat at 2 ℃ for min. -1 The material was heated to 900 °C at a certain heating rate and held for 3 h. Zinc ions were removed by acid washing, followed by water washing and drying to obtain pitch-based derived hard carbon material.

[0039] Test case The asphalt-based derived hard carbon material, acetylene black (conductive agent), and sodium alginate (binder) of the embodiment were mixed evenly in a mass ratio of 7:2:1. An appropriate amount of deionized water was then added to prepare a slurry. The slurry was then evenly coated onto copper foil to form the negative electrode, with a sodium sheet as the positive electrode at a concentration of 1 mol / L. -1 A sodium hexafluorophosphate solution (solvents being dimethyl carbonate, ethylene carbonate, and ethyl methyl carbonate in a 1:1 volume ratio) was used as the electrolyte, and polypropylene paper was used as the separator to assemble a half-cell. The cell was tested at a current density of 1 Ag. -1 Charge and discharge tests were then conducted.

[0040] Figure 1 This is a scanning electron microscope (SEM) image of the pitch-based derived hard carbon material prepared in Example 1 of this invention.Figure 2 This is a transmission electron microscope (TEM) image of the pitch-based derived hard carbon material prepared in Example 1 of this invention. Figure 1 As can be seen, short-range ordered graphite-like domains and vortex-like closed pores formed by their stacking begin to appear on the surface of pitch-based derived hard carbon materials. Figure 2 As can be seen, the bituminous-based derived hard carbon materials exhibit a disordered "house of cards" structure.

[0041] Figure 3 The GCD curves of the pitch-based derived hard carbon material prepared in Example 1 of this invention for the first 5 cycles at 0.1 A / g are shown. Figure 6 This is the GCD curve of the pitch-based derived hard carbon material of Example 4 of the present invention after the first 5 cycles at 0.1 A / g. From... Figure 3 and Figure 6 As can be seen from the data, the charge-discharge curves of the asphalt-based derived hard carbon materials show a relatively long plateau, indicating that both asphalt treated with mixed acid and asphalt treated with solvent heat can be converted into hard carbon materials after high-temperature carbonization.

[0042] Figure 4 This is a graph showing the cycling performance of the asphalt-based derived hard carbon material and ordinary asphalt material prepared in Example 1 of this invention after carbonization at 2A / g. Figure 7 This is a graph showing the cycling performance of the asphalt-based derived hard carbon material and ordinary asphalt material after carbonization in Example 4 of this invention at 2A / g. From... Figure 4 and Figure 7 As can be seen from the data, the capacity of the asphalt-based derived hard carbon material prepared by the present invention remains stable during the cycling process, which further demonstrates that the asphalt material after mixed acid pretreatment and the asphalt material after solvent heat treatment both have better cycling stability.

[0043] Figure 5 This is a comparison chart of the carbonization performance of asphalt-based derived hard carbon material and ordinary asphalt material after carbonization in Example 1 of the present invention. Figure 8 This is a comparison chart of the rate performance of the asphalt-based derived hard carbon material and ordinary asphalt material after carbonization in Example 4 of the present invention. It further illustrates that the asphalt-based derived hard carbon material of the present invention exhibits better rate performance than ordinary asphalt material after carbonization.

[0044] Figure 9 This is a transmission electron microscope (TEM) image of the pitch-based derived hard carbon material obtained in Example 7 of the present invention, for comparison. Figure 2 It is understood that, based on the present invention, further adopting segmented carbonization treatment helps to further strengthen the "House of Cards" structure.

[0045] Figure 10 These are isothermal adsorption curves of the bitumen-based derived hard carbon materials obtained in Examples 4 and 8 of this invention. Figure 10It is known that chemical activation can be used in conjunction with carbonization to further construct a microporous-mesoporous hierarchical structure and improve ion adsorption capacity.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a pitch-based derived hard carbon material, characterized in that, Includes the following steps: S1. Pre-treat the asphalt using a mixed acid treatment method or a solvent heat treatment method to obtain pre-treated asphalt; S2. Carbonize the pretreated asphalt to obtain asphalt-based derived hard carbon materials. In the mixed acid treatment method, the reagent used is a mixed solution of concentrated sulfuric acid, concentrated nitric acid and ammonium persulfate; In the solvothermal treatment method, the reagent used is an oxidizing structure modifier, including either nitric acid solution or hydrogen peroxide solution.

2. The preparation method according to claim 1, characterized in that, In the mixed acid treatment method, the reagents used include solution A and solution B, wherein solution A is a mixed solution of concentrated sulfuric acid and concentrated nitric acid, and solution B is a mixed solution of ammonium persulfate and concentrated sulfuric acid; Preferably, in solution A, the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 1:(0.8-1.2). In solution B, the required volume of concentrated sulfuric acid is 3-4 mL for every 1 g of ammonium persulfate.

3. The preparation method according to claim 2, characterized in that, In the mixed acid treatment method, the required volumes of solution A and solution B for each 1 g of asphalt are 6-7 mL and 3-4 mL, respectively.

4. The preparation method according to claim 2, characterized in that, In the mixed acid treatment method, asphalt is uniformly mixed with solution A and solution B, stirred at 60-90 ℃ for 4-8 h, cooled to room temperature after the reaction is completed, filtered and vacuum dried to obtain pretreated asphalt.

5. The preparation method according to claim 1, characterized in that, In the solvothermal treatment method, the required volume of oxidizing structure modifier is 40-60 mL per 1 g of asphalt, wherein the concentration of nitric acid solution is 0.5-2 mol / L. -1 The concentration of the hydrogen peroxide solution is 20-40 wt.%.

6. The preparation method according to claim 1, characterized in that, In the solvothermal treatment method, the asphalt is placed in a liner containing an oxidizing structure modifier and subjected to a solvothermal reaction at 150-200 °C for 20-30 h. After the reaction is completed, it is cooled to room temperature, filtered, and then vacuum dried to obtain the pretreated asphalt.

7. The preparation method according to claim 1, characterized in that, During the carbonization process, the pretreated asphalt is placed in a ceramic boat and heated at 1-3 °C for 1 minute under a nitrogen atmosphere. -1 After heating to 900-1500 ℃ at a certain heating rate and holding for 2-4 h, pitch-based derived hard carbon materials are obtained.

8. A bitumen-based derived hard carbon material, characterized in that, It is prepared according to any one of claims 1-7.

9. The application of the pitch-based derived hard carbon material according to claim 8 in the preparation of energy storage devices.

10. An energy storage device, characterized in that, It includes a working electrode, the raw material of which includes the pitch-based derived hard carbon material as described in claim 8.

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