Coal tar-based capacitor carbon, and preparation method and application thereof

Abstract

The invention belongs to the technical field of capacitor carbon preparation, and particularly relates to coal tar-based capacitor carbon and a preparation method and application thereof. Comprising the following steps: by taking coal tar as a carbon source, carrying out Friedel-Crafts reaction under the action of a cross-linking agent and a catalyst to obtain a tar-based cross-linked polymer; and carbonizing the tar-based cross-linked polymer at 600-900 DEG C in a protective gas atmosphere to obtain the coal tar-based capacitor carbon. The coal tar is used as a carbon source, the coal tar is subjected to Friedel-Crafts reaction to obtain the coal tar-based hypercrosslinked polymer, the hypercrosslinked polymer can be directly subjected to one-step high-temperature carbonization without any activating agent to obtain the high-performance coal tar-based capacitor carbon, the method is simple, the cost is low, the carbon yield is high, and the method is suitable for industrial production. The prepared capacitor carbon has a high specific surface area, abundant micropores and a disordered structure, is applied to a supercapacitor as an electrode material, and shows excellent electrochemical performance and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of capacitor carbon, and particularly relates to a coal-tar-based capacitor carbon, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the increasing energy demand has led to the rapid depletion of fossil energy and the increasingly deteriorating environmental conditions, which have promoted the rapid development of renewable clean energy (solar energy, hydropower, electricity). Therefore, developing advanced energy storage devices and materials is an effective way to utilize renewable energy effectively. As an important energy storage device, supercapacitors have received extensive attention due to their high power density, fast charge and discharge speed, long cycle life and other advantages. A supercapacitor consists of an electrode material, a separator and an electrolyte, and the electrode material is crucial for the performance of the supercapacitor. Porous carbon materials have become the most widely used electrode materials due to their low synthesis cost and rich raw materials. Therefore, suitable carbon precursors and optimized preparation methods of materials are the focus of current research on supercapacitor electrode materials.

[0003] Coal tar is a common liquid by-product in coal chemical industry, and its main components are polycyclic aromatic hydrocarbons, heterocyclic compounds and a small amount of alkanes. Due to the advantages of high carbon content, low price and good plasticity, coal tar is an excellent precursor for preparing porous carbon materials. At present, in the methods of preparing porous carbon from coal tar, researchers have used zinc acetate (Chen Zhang, Weihao Zhang, Moxin Yu*, Kemeng Ning, Li Zhang, Xiaoting Wang, Xiaojun He, J. Porous Mater, 2017, 24, 1289-1293), ionic liquids (Xiaoyu Xie, Xiaojun He, Hanfang Zhang, Feng Wei, Nan Xiao, Jieshan Qiu, Chem. Eng. J. 2018, 350, 49-56), molten salts (Huichao Liu, Hua Song, Wenjing Hou, Yunzhen Chang, Ying Zhang, Yanping Li, Yun Zhao, Gaoyi Han, Mater. Chem. Phys, 2021, 265, 124491.) as templates respectively to prepare a series of porous carbon materials and used them as electrode materials for supercapacitors. However, there are still many challenges in the preparation of coal tar-based porous carbon materials. Especially, the coal tar precursor is volatile and prone to foaming during the carbonization process, which inhibits the formation of a stable carbon network structure during carbonization, and the yield is extremely low, with the carbon yield between 15% and 25%. Moreover, a large amount of corrosive activators need to be added during the activation process of such carbon materials, and a large amount of water is consumed in the post-treatment, which is easy to cause environmental pollution and waste of water resources. Therefore, it has become the focus of research to seek more efficient synthesis strategies to reduce or avoid the use of activators while increasing the carbon yield of coal tar-based porous carbon materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a coal tar-based capacitive carbon and its preparation method and application. To solve the problems of low carbon yield and large amount of activator used when coal tar is used as a precursor, using coal tar as a carbon source, through the Friedel-Crafts reaction, the coal tar-based ultra-high cross-linked polymer is obtained by the Friedel-Crafts reaction of coal tar. The ultra-high cross-linked polymer can directly obtain high-performance coal tar-based capacitive carbon through one-step high-temperature carbonization without any activator. The method is simple, low-cost and has a high carbon yield. The prepared capacitive carbon has a high specific surface area, abundant micropores and a disordered structure, and is used as an electrode material in supercapacitors. This material exhibits excellent electrochemical performance and stability.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] One of the objectives of the present invention is to provide a preparation method of coal-tar-based capacitive carbon, comprising the following steps: S1. Using coal tar as a carbon source, under the action of a crosslinking agent and a catalyst, a Friedel-Crafts reaction is carried out to obtain a tar-based crosslinked polymer.

[0007] S2. Under an atmosphere of a protective gas, the tar-based crosslinked polymer is carbonized at 600 °C to 900 °C to obtain coal-tar-based capacitive carbon.

[0008] Further, the crosslinking agent is one of a halogenated aliphatic compound, a halogenated hydrocarbon compound, an acyl halide compound, an alkyl alcohol compound, an alkyl ether compound, an epoxy compound, a nitro compound, an acid anhydride compound, a carboxylic acid compound or CS2.

[0009] Further, the dosage of the crosslinking agent is 1 to 4 times the mass of the coal tar.

[0010] Further, the crosslinking agent is a Lewis acid or a protonic acid.

[0011] Further, the dosage of the catalyst is 20 wt.% to 120 wt.% of the mass of the coal tar.

[0012] Further, the temperature of the Friedel-Crafts reaction is 25 °C to 100 °C, and the reaction time is 4 h to 24 h.

[0013] Further, the heating rate of the carbonization is 1 °C / min to 10 °C / min, the heat preservation time is 0.5 h to 4 h, and the protective gas is nitrogen.

[0014] Another objective of the present invention is to provide a coal-tar-based capacitive carbon prepared by the above preparation method.

[0015] Another objective of the present invention is to provide the application of the above coal-tar-based capacitive carbon in a supercapacitor.

[0016] The present invention has the following beneficial effects compared with the prior art: The present invention uses coal tar as a carbon source. Through the Friedel-Crafts reaction, the coal tar undergoes a Friedel-Crafts reaction to obtain a coal-tar-based ultra-high crosslinked polymer. This ultra-high crosslinked polymer can directly obtain high-performance coal-tar-based capacitive carbon through one-step high-temperature carbonization without any activator. The method is simple, has low cost and high carbon yield. The prepared capacitive carbon has a high specific surface area, rich micropores and a disordered structure. When used as an electrode material in a supercapacitor, this material exhibits excellent electrochemical performance and stability. Description of the Drawings

[0017] Figure 1 It is a physical diagram of the coal-tar-based capacitive carbon prepared in Example 1 of the present invention.

[0018] Figure 2 This is the microstructural diagram of the coal-tar-based capacitive carbon prepared in Example 1 of the present invention. Figure 2 In [the figure], a is the scanning electron microscope image and b is the transmission electron microscope image.

[0019] Figure 3 This is the Raman spectrum diagram of the coal-tar-based capacitive carbon prepared in Example 1 of the present invention.

[0020] Figure 4 This is the X-ray photoelectron spectroscopy spectrum diagram of the coal-tar-based capacitive carbon prepared in Example 1 of the present invention.

[0021] Figure 5 This is the specific surface area diagram of the coal-tar-based capacitive carbon prepared in Example 1 of the present invention.

[0022] Figure 6 This is the thermogravimetric analysis diagram of the coal-tar-based capacitive carbon and coal tar prepared in Example 1 of the present invention.

[0023] Figure 7 This is the charge-discharge test result diagram under the condition of constant current charge and discharge of the coal-tar-based capacitive carbon and commercial activated carbon in Example 1 of the present invention. Detailed implementation manners

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0025] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the following embodiments of the present invention can be obtained through the market or prepared by existing methods.

[0026] Currently, in the method of preparing porous carbon using coal tar as a raw material, due to the easy volatilization of the coal tar precursor and the easy foaming during the carbonization process, the formation of a stable carbon network structure during the carbonization process is inhibited, and the yield is extremely low. Moreover, a large amount of corrosive activators need to be added during the activation process, and the post-treatment is complex and prone to cause environmental pollution and waste of water resources. Therefore, it has become the focus of research to seek a more efficient synthesis strategy to reduce or not use activators while increasing the carbon yield of coal-tar-based porous carbon materials.

[0027] Based on this, the present invention provides a preparation method of a coal-tar-based capacitive carbon, including the following steps: S1. Using coal tar as a carbon source, under the action of a crosslinking agent and a catalyst, a Friedel-Crafts reaction is carried out to obtain a tar-based crosslinked polymer.

[0028] S2. Under an inert gas atmosphere, the tar-based crosslinked polymer is carbonized at 600 °C to 900 °C to obtain coal tar-based capacitive carbon.

[0029] In the present invention, coal tar is used as a carbon source. By adopting the Friedel-Crafts reaction, coal tar first obtains a coal tar-based ultra-high crosslinked polymer through the Friedel-Crafts reaction. This ultra-high crosslinked polymer can directly obtain high-performance coal tar-based capacitive carbon through one-step high-temperature carbonization without any activator. The method is simple, has low cost and high carbon yield. The prepared capacitive carbon has a high specific surface area, abundant micropores and a disordered structure. When used as an electrode material in supercapacitors, this material exhibits excellent electrochemical performance and stability.

[0030] In some specific embodiments, the crosslinking agent is one of halogenated hydrocarbon compounds, acyl halide compounds, alkyl alcohol compounds, alkyl ether compounds, epoxy compounds, nitro compounds, acid anhydride compounds, carboxylic acid compounds, and CS2. It should be noted that different crosslinking agents have an impact on the structure of the prepared coal tar-based capacitive carbon. The pore sizes in the structure of the coal tar-based capacitive carbon are different, which affects the graphitization degree of the coal tar-based capacitive carbon, and further affects the electrochemical performance and stability of the coal tar-based capacitive carbon. In the present invention, the halogenated hydrocarbon compound can be a C1-C6 halogenated hydrocarbon compound. In some preferred embodiments, the halogenated hydrocarbon compound is one of CH2Cl2, CHCl3, CCl4, C2H4Br2, or C6H4Cl2; the acyl halide compound can be a C2-C5 acyl halide compound. In some preferred embodiments, the acyl halide compound is one of acetyl chloride, oxalyl chloride, or chloroacetyl chloride; the alkyl alcohol compound can be a C1-C5 alkyl alcohol compound. In some preferred embodiments, the alkyl alcohol compound is one of propylene glycol (C3H8O2), CH3OH, or glycerol; the alkyl ether compound can be a C2-C5 alkyl ether compound. In some preferred embodiments, the alkyl ether compound can be methyl tert-butyl ether or ethylene glycol dimethyl ether; the nitro compound can be one of nitrobenzene and its derivatives or nitroalkane compounds. In a preferred embodiment, the nitro compound is nitrobenzene or CH3NO2; in a preferred embodiment, the acid anhydride compound is acetic anhydride or maleic anhydride; in a preferred embodiment, the carboxylic acid compound is oxalic acid, malonic acid, or citric acid.

[0031] In some specific embodiments, the dosage of the crosslinking agent is 1 to 4 times the mass of the coal tar. It should be noted that the dosage of the crosslinking agent has an important influence on the specific surface area and pore structure of the prepared coal tar-based capacitive carbon. When the dosage of the crosslinking agent increases, the crosslinking density increases, resulting in a reduction in internal pores and a decrease in the specific surface area, thereby affecting the adsorption capacity and ion transport performance of the capacitive carbon.

[0032] In some specific embodiments, the catalyst is a Lewis acid or a protonic acid. In the present invention, the Lewis acid includes, but is not limited to, AlCl3, FeCl3, SnCl4, BF3, TiCl4, or ZnCl2; the protonic acid includes, but is not limited to, HF, H2SO4, or H3PO4. During the Friedel-Crafts reaction, the Lewis acid or the protonic acid acts as a catalyst to achieve the alkylation or acylation of the aromatic ring and form a coal tar-based ultra-high crosslinked polymer by activating the electrophilic reagent, stabilizing the intermediate, and promoting electrophilic substitution.

[0033] In some specific embodiments, the dosage of the catalyst is 20 wt.% to 120 wt.% of the mass of the coal tar.

[0034] In some specific embodiments, the temperature of the Friedel-Crafts reaction is 25°C to 100°C, and the reaction time is 4 h to 24 h.

[0035] In some specific embodiments, the heating rate of carbonization is 1°C / min to 10°C / min, the holding time is 0.5 h to 4 h, and the protective gas is nitrogen.

[0036] The following is further illustrated by specific examples.

[0037] Example 1 A preparation method of coal tar-based capacitive carbon includes the following steps: S1. Weigh 2.0 g of coal tar, 3.0 g of AlCl3, and 20 mL of C3H8O2, place them in a 50 mL beaker, and stir at 50°C for 24 h for the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0038] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 700°C, the heating rate is 5°C / min, and the holding time is 2 h. After the high-temperature calcination carbonization ends, natural cooling is carried out, then it is washed with distilled water until neutral, and placed in an oven for drying to obtain coal tar-based capacitive carbon, with a yield of 64%.

[0039] Example 2 A preparation method of coal tar-based capacitive carbon includes the following steps: S1. Weigh 2.0 g of coal tar, 2.0 g of SnCl4 and 30 mL of PhNO2, place them in a 50 mL beaker, and stir for 12 h at 60 °C to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0040] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then place it in a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 700 °C, with a heating rate of 2 °C / min, and keep the temperature for 1 h. After the high-temperature calcination carbonization ends, perform natural cooling, then wash it with distilled water until neutral, and place it in an oven for drying to obtain coal tar-based capacitive carbon, with a yield of 58%.

[0041] Example 3 A preparation method of coal tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 1.0 g of FeCl3 and 20 mL of CS2, place them in a 50 mL beaker, and stir for 24 h at 50 °C to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0042] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then place it in a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 600 °C, with a heating rate of 2 °C / min, and keep the temperature for 1 h. After the high-temperature calcination carbonization ends, perform natural cooling, then wash it with distilled water until neutral, and place it in an oven for drying to obtain coal tar-based capacitive carbon, with a yield of 60%.

[0043] Example 4 A preparation method of coal tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 2.0 g of TiCl4 and 20 mL of CH3OCH2OCH3, place them in a 50 mL beaker, and stir for 24 h at 60 °C to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0044] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then place it in a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 800 °C, with a heating rate of 5 °C / min, and keep the temperature for 1 h. After the high-temperature calcination carbonization ends, perform natural cooling, then wash it with distilled water until neutral, and place it in an oven for drying to obtain coal tar-based capacitive carbon, with a yield of 46%.

[0045] Example 5 A preparation method of coal tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 3.0 g of BF3 and 20 mL of CCl4, place them in a 50 mL beaker, and stir at 70 °C for 48 h to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0046] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, carry out high-temperature calcination carbonization of the tar-based crosslinked polymer at 900 °C, with a heating rate of 3 °C / min, and keep the temperature for 1 h. After the high-temperature calcination carbonization ends, carry out natural cooling, then wash with distilled water until neutral, and put it in an oven to dry to obtain coal tar-based capacitive carbon, with a yield of 54%.

[0047] Example 6 A preparation method of coal tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 4.0 g of H3PO4 and 15 mL of CH3NO2, place them in a 50 mL beaker, and stir at 70 °C for 48 h to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0048] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, carry out high-temperature calcination carbonization of the tar-based crosslinked polymer at 850 °C, with a heating rate of 2 °C / min, and keep the temperature for 2.5 h. After the high-temperature calcination carbonization ends, carry out natural cooling, then wash with distilled water until neutral, and put it in an oven to dry to obtain coal tar-based capacitive carbon, with a yield of 38%.

[0049] Example 7 A preparation method of coal tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 3.5 g of HF and 30 mL of C2H4O, place them in a 50 mL beaker, and stir at 70 °C for 48 h to carry out the Friedel-Crafts reaction. After the reaction ends, a tar-based crosslinked polymer is obtained.

[0050] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a magnetic boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, carry out high-temperature calcination carbonization of the tar-based crosslinked polymer at 700 °C, with a heating rate of 5 °C / min, and keep the temperature for 2 h. After the high-temperature calcination carbonization ends, carry out natural cooling, then wash with distilled water until neutral, and put it in an oven to dry to obtain coal tar-based capacitive carbon, with a yield of 43%.

[0051] Example 8 A preparation method of coal-tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 2.0 g of ZnCl2 and 20 mL of C4H2O3, place them in a 50 mL beaker, and stir at 50 °C for 36 h to carry out the Friedel-Crafts reaction. After the reaction is completed, a tar-based crosslinked polymer is obtained.

[0052] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 800 °C, with a heating rate of 3 °C / min, and keep the temperature for 2 h. After the high-temperature calcination carbonization is completed, natural cooling is carried out, then it is washed with distilled water until neutral, and placed in an oven for drying to obtain coal-tar-based capacitive carbon, with a yield of 42%.

[0053] Example 9 A preparation method of coal-tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 2.5 g of TiCl4 and 35 mL of HOOCCH2COOH, place them in a 50 mL beaker, and stir at 755 °C for 48 h to carry out the Friedel-Crafts reaction. After the reaction is completed, a tar-based crosslinked polymer is obtained.

[0054] S2. Transfer the tar-based crosslinked polymer obtained in S1 to a boat (6 cm × 3 cm × 2 cm), then put it into a tube furnace, and introduce nitrogen. Under the nitrogen gas atmosphere, the tar-based crosslinked polymer is subjected to high-temperature calcination carbonization at 750 °C, with a heating rate of 55 °C / min, and keep the temperature for 1.5 h. After the high-temperature calcination carbonization is completed, natural cooling is carried out, then it is washed with distilled water until neutral, and placed in an oven for drying to obtain coal-tar-based capacitive carbon, with a yield of 35%.

[0055] Example 10 A preparation method of coal-tar-based capacitive carbon, comprising the following steps: S1. Weigh 2.0 g of coal tar, 3.0 g of PCl5 and 40 mL of CH3OH, place them in a 50 mL beaker, and stir at 60 °C for 48 h to carry out the Friedel-Crafts reaction. After the reaction is completed, a tar-based crosslinked polymer is obtained.

[0056] S2. The tar-based cross-linked polymer obtained in S1 was transferred to a magnetic boat (6cm×3cm×2cm), and then placed in a tubular furnace and introduced with nitrogen. In a nitrogen gas atmosphere, the tar-based cross-linked polymer was subjected to high-temperature calcination and carbonization at 850°C with a heating rate of 4°C / min and kept warm for 3 h. After the high-temperature calcination and carbonization, it was naturally cooled, then washed with distilled water until neutral, and placed in an oven for drying to obtain coal tar-based capacitor carbon with a yield of 55%.

[0057] Coal tar-based capacitor carbons are prepared in Examples 1 to 10 of the present invention, and have similar structures and effects. The coal tar-based capacitor carbon prepared in Example 1 is taken as an example to study and illustrate the advantages of its structure, and the results are as follows.

[0058] Figure 1 This is a physical picture of the coal tar-based capacitor carbon prepared in Example 1 of the present invention. Figure 1 As shown, the prepared coal tar-based capacitor carbon is black fine particles without metallic luster, usually in powder form.

[0059] Figure 2 This is a microstructure diagram of the coal tar-based capacitor carbon prepared in Example 1 of the present invention. Figure 2 a in the figure is a scanning electron microscope image, and b is a transmission electron microscope image. Figure 2 As shown in the SEM image of coal tar-based capacitor carbon, the prepared carbon material is composed of numerous uniform block structures, and these block structure units are surrounded by abundant pores. The transmission electron microscope image further proves the irregular stacking of the block structure of coal tar-based capacitor carbon in three-dimensional space, which increases the disorder of the material and is conducive to the storage of electrolyte ions.

[0060] Figure 3 This is a Raman spectrum of the coal tar-based capacitor carbon prepared in Example 1 of the present invention. Figure 3 As shown, at 1300cm -1 ~1400cm -1 There is an obvious peak near 1500cm, which is usually related to defects, disordered structures and edge carbon atoms in carbon materials. Its appearance is related to the asymmetry of lattice vibration and the Raman active vibration mode caused by defects; -1 ~1600cm -1 There is also an obvious peak at this point, which corresponds to the sp 2 The in-plane stretching vibration of hybridized carbon atoms reflects the degree of graphitization of carbon materials.

[0061] Figure 4 This is the X-ray photoelectron spectrum of the coal tar-based capacitor carbon prepared in Example 1 of the present invention. Figure 4As shown in the figure, there is a strong and sharp peak at a lower binding energy (roughly between 200eV and 300eV), corresponding to the C1s peak; the presence of the C1s peak is a typical feature of carbon materials, indicating that the sample contains a large amount of carbon elements; there is a relatively weak peak at a higher binding energy (roughly between 500eV and 600eV), corresponding to the O1s peak. This means that there may be a certain amount of oxygen-containing functional groups in the sample, such as hydroxyl (-OH), carbonyl (C = O) or carboxyl (-COOH). These oxygen-containing functional groups will affect the chemical properties and surface activity of carbon materials.

[0062] Figure 5 This is a graph showing the specific surface area of the coal tar-based capacitor carbon prepared in Example 1 of the present invention. Figure 5 The following is the N2 adsorption-desorption curve of coal tar-based capacitor carbon. The specific surface area of coal tar-based capacitor carbon measured by Brunauer-Emmet-Teller BET method is 766 m 2 ·g -1 .

[0063] Figure 6 The thermal gravimetric analysis diagram of the coal tar-based capacitor carbon and coal tar prepared in Example 1 of the present invention. Figure 6 As shown in the figure, when the temperature is higher than 400°C, the mass of coal tar is almost completely lost, while the mass of coal tar-derived capacitor carbon remains at 85.7%. When the temperature is increased to 700°C, the mass of coal tar-derived capacitor carbon remains at about 65%, indicating that the method provided by the present invention greatly improves the yield of coal tar as a carbon material precursor.

[0064] The coal tar-based capacitor carbon prepared in Examples 1 to 10 was used for supercapacitors, wherein the coal tar-based capacitor carbon was used as the working electrode of the supercapacitor, 6 M KOH was used as the electrolyte, and glass fiber was used as the diaphragm for the preparation of the supercapacitor, and electrochemical charge and discharge tests were performed by an electrochemical workstation. The charge and discharge test results under the conditions of 1A / g and 10A / g constant current charge and discharge are shown in Table 1.

[0065] Table 1 Charge and discharge test results of coal tar based capacitor carbon prepared in Example 1 to Example 10 As shown in Table 1, the coal tar-based capacitor carbons prepared in Examples 1 to 10 have high specific capacitance under the condition of 1 A / g constant current charge and discharge, and the capacity retention rate at 10 A / g (10,000 cycles) can reach more than 94%, showing excellent electrochemical performance and stability.

[0066] Figure 7 The figure is a charge and discharge test result diagram of coal tar-based capacitor carbon and commercial activated carbon under constant current charge and discharge conditions in Example 1 of the present invention.Figure 7 As shown, at a current density of 1 A / g, the discharge time of the coal tar-based capacitive carbon is longer than that of the commercial activated carbon. After calculation, the specific capacitance of the coal tar-based capacitive carbon is 328 F / g, and the specific capacitance of the commercial activated carbon is 225 F / g.

[0067] It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and the two endpoints can be selected. Since the steps and methods adopted are the same as those in the embodiments, in order to prevent redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of coal tar-based capacitor carbon, characterized in that, It includes the following steps: Using coal tar as a carbon source, under the action of a crosslinking agent and a catalyst, a Friedel-Crafts reaction is carried out to obtain a tar-based crosslinked polymer; Under the atmosphere of a protective gas, the tar-based crosslinked polymer is carbonized at 600 °C to 900 °C to obtain coal tar-based capacitive carbon.

2. The preparation method of the coal-tar-based capacitive carbon according to claim 1, wherein, The crosslinking agent is one of a halogenated aliphatic compound, a halogenated hydrocarbon compound, an acyl halide compound, an alkyl alcohol compound, an alkyl ether compound, an epoxy compound, a nitro compound, an acid anhydride compound, a carboxylic acid compound or CS2.

3. The preparation method of the coal tar-based capacitive carbon according to claim 1, characterized in that, The dosage of the crosslinking agent is 1 to 4 times the mass of the coal tar.

4. The preparation method of the coal tar-based capacitive carbon according to claim 1, wherein, The catalyst is a Lewis acid or a protonic acid.

5. The preparation method of the coal tar-based capacitive carbon according to claim 1, characterized in that The dosage of the catalyst is 20 wt.% to 120 wt.% of the mass of the coal tar.

6. The preparation method of the coal tar-based capacitor carbon according to claim 1, characterized in that, The temperature of the Friedel-Crafts reaction is 25 °C to 100 °C, and the reaction time is 4 h to 24 h.

7. The preparation method of the coal-tar-based capacitive carbon according to claim 1, characterized in that, The heating rate of carbonization is 1 °C / min to 10 °C / min, the heat preservation time is 0.5 h to 4 h, and the protective gas is nitrogen.

8. A coal tar-based capacitor carbon, characterized in that, It is prepared by using the preparation method described in any one of claims 1 to 7.

9. Application of the coal tar-based capacitive carbon described in claim 8 in a supercapacitor.

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