A method for the synchronous synthesis of porous carbon based on nitrile resin / graphene nanosheets and the porous carbon material

Abstract

The present invention relates to a method for synchronously synthesizing and preparing porous carbon based on nitrile resin / graphene nanosheets and a porous carbon material. By means of a ball milling process, the synthesis of nitrile resin and the dispersion of graphene nanosheets are synchronously achieved. Using the synthesized nitrile resin as a carbon source and graphene nanosheets as a conductive enhancer, porous carbon doped with nitrile resin and graphene nanosheets is prepared according to a certain component ratio and a certain heat treatment procedure. Based on the synchronous synthesis of nitrile resin / graphene nanosheets, the present invention realizes the functional utilization of nitrile resin and graphene; by using the high char yield of nitrile resin and the high conductivity of graphene, the electrochemical performance after preparing porous carbon is improved. The obtained nitrile resin / graphene porous carbon has excellent electrochemical performance, is synthesized in one pot, not only integrates and optimizes the process, but also has the effect of "1 + 1 > 2", and has the prospect of industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of porous carbon, and particularly relates to a method for synchronous synthesis of nitrile resin / graphene nanosheets and preparation of porous carbon therefrom. Background Art

[0002] Supercapacitors have the capabilities of rapid charge and discharge, a wide operating temperature range, high power density, and long service life, and are important electrochemical energy storage devices. Supercapacitors mainly consist of electrodes, separators, electrolytes, and current collectors, among which the electrode materials play a crucial role in electrochemical performance. Porous carbon materials have received much attention due to their rich preparation methods, excellent chemical stability, high specific surface area, adjustable pore size, and excellent electrical conductivity. It has been widely recognized as a preferred electrode material in energy storage and conversion devices such as supercapacitors, batteries, and fuel cells. In addition, porous carbon also shows its application potential in the field of environmental engineering, including the adsorption of carbon dioxide, water purification, and as a carrier for catalytic reactions. The realization of these applications benefits from its unique physical and chemical properties, making it have broad application prospects in the fields of environmental governance and energy conversion.

[0003] Regarding the carbon sources of resin-based porous carbon, there are currently mainly two types: bio-based and petroleum-based. Patent CN110745823A discloses a method for preparing porous carbon using furfural resin as a carbon source. Although its carbon source is obtained from plants containing pentosan through a series of treatments and is widely present in many natural compounds, bio-based porous carbon still has problems such as large influence of the carbon precursor source by regional differences, insufficient specific capacitance of the carbon material, and poor cycle stability.

[0004] In summary, there is a need to continue to provide a new method for preparing porous carbon materials that can improve the deficiencies of insufficient specific capacitance and poor long-term cycle stability of bio-based porous carbon materials in the above-related technologies. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for synchronous synthesis of nitrile resin / graphene nanosheets and preparation of porous carbon therefrom, which can improve the deficiencies of insufficient specific capacitance and poor long-term cycle stability of bio-based porous carbon materials.

[0006] In the first aspect, the present invention provides a method for synchronous synthesis of nitrile resin / graphene nanosheets and preparation of porous carbon therefrom, comprising the following preparation steps:

[0007] S1. Reactive ball milling: Weigh a phenolic source, a halogenated phthalonitrile, a weak base salt, a polar solvent, expanded graphite, and grinding balls, add them to a ball milling tank, and perform a ball milling reaction to obtain a reaction solution;

[0008] S2. Filtration and Washing: Filter and precipitate the reaction solution, collect the filtrate mixture, add dilute hydrochloric acid to neutralize the weak basic salt, and then dry it to prepare a mixture of nitrile resin / graphene nanosheets / halide salt;

[0009] S3. High-temperature Carbonization: Weigh the nitrile resin / graphene nanosheets / halide salt, weak basic salt, and nitrile resin curing agent according to the ratio and mix them to obtain a mixture. Calcinate the mixture at a high temperature of 500 - 1000 °C, wash it with water and dry it after calcination to prepare porous carbon.

[0010] Optionally, in step S1, the phenol source includes at least one of bisphenol A, bisphenol S, bisphenol F, catechol, hydroquinone, resorcinol, biphenol, 2-aminophenol, 3-aminophenol, 4-aminophenol, and phloroglucinol; and / or,

[0011] The halo-phthalonitrile includes at least one of 2-chlorophthalonitrile, 2-bromophthalonitrile, 2-fluorophthalonitrile, 2-iodophthalonitrile, 3-chlorophthalonitrile, 3-bromophthalonitrile, 3-fluorophthalonitrile, 3-iodophthalonitrile, 4-chlorophthalonitrile, 4-bromophthalonitrile, 4-fluorophthalonitrile, and 4-iodophthalonitrile; and / or,

[0012] The weak basic salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or,

[0013] The polar solvent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0014] Optionally, in step S1, the ball-milling reaction is carried out at 1000 - 9000 rpm for 10 - 120 h.

[0015] Optionally, in step S1, based on 1 unit mole of phenolic hydroxyl groups, 1 - 2 unit moles of halo-phthalonitrile and 1 - 2 unit moles of weak basic salt are used correspondingly, and the amount of the polar solvent is 1 - 3 times the total mass of phenols, halo-phthalonitrile, and weak basic salt.

[0016] Optionally, in step S3, the weak basic salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or,

[0017] The curing agent of the nitrile resin includes at least one of 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 4-(4-aminophenoxy)phthalonitrile, and 1,3-bis(4'-aminophenoxy)benzene.

[0018] Optionally, in step S3, the mass ratio of the nitrile resin / graphene nanosheet / halide salt, the weak base salt, and the nitrile resin curing agent is 1:(0.01 - 0.1):(0.2 - 5):(0.2 - 5):(0.01 - 0.1).

[0019] Optionally, the pore structure of the porous carbon includes macropores, mesopores, and micropores.

[0020] Optionally, the macropores have a pore diameter of 1 - 10 μm, the mesopores have a pore diameter of 2 - 10 nm, and the micropores have a pore diameter of less than 2 nm.

[0021] Optionally, the specific surface area of the pore structure is 2500 m 2 ·g -1 or more, the pore volume is 1.5 cm 3 ·g -1 or less, and the average pore diameter is 1.5 nm or less.

[0022] Optionally, the nitrogen content of the porous carbon is 2% or more, and the nitrogen and oxygen hetero - element content reaches 22% or more.

[0023] In a second aspect, the present invention provides a porous carbon material obtained by the method for preparing porous carbon by synchronous synthesis based on nitrile resin / graphene nanosheet as described above.

[0024] In summary, the present invention has at least one of the following beneficial effects:

[0025] 1. The present invention adopts a one - pot synthesis method to simultaneously achieve the synthesis of nitrile resin monomers and the fragmentation and dispersion of graphene nanosheets, which kills two birds with one stone. The prepared nitrile resin / graphene nanosheet porous carbon material has a high specific surface area, rich and uniform hetero - elements. For the phthalonitrile resin - based porous carbon material prepared by the present invention, the specific surface area of the pore structure is 2500 m 2 ·g -1 or more, the pore volume is 1.5 cm 3 ·g -1 or less, the average pore diameter is 1.5 nm or less, the maximum specific surface area is 2579 m 2 / g, the pore volume is 1.4 cm 3 / g, the highest nitrogen content can reach 2.25%, and the highest hetero - element content can reach 22.69%.

[0026] 2. The nitrile resin / graphene nanoplatelet porous carbon material prepared by the present invention can be used to prepare supercapacitor electrode materials, has excellent electrochemical performance, has a maximum specific capacitance of more than 300 F / g (1 A / g) in a three-electrode test, preferably more than 320 F / g (1 A / g), and can reach up to 360 F / g (1 A / g) at most. It has excellent cycling performance, and after 10,000 cycles, the specific capacitance retention rate is more than 96% at 10 A / g.

[0027] 3. The preparation process of the nitrile resin / graphene nanoplatelet porous carbon material of the present invention is simple, and the equipment cost is low, having broad industrial application prospects. Description of the Drawings

[0028] Figure 1 It is the infrared spectrum of the bisphenol A type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 1.

[0029] Figure 2 It is the SEM image of the bisphenol A type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 1.

[0030] Figure 3 It is the constant current charge / discharge curve graph (GCD) of the bisphenol A type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 1.

[0031] Figure 4 It is the BET result graph of the resorcinol type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 2.

[0032] Figure 5 It is the X-ray photoelectron spectroscopy (XPS) graph of the resorcinol type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 2.

[0033] Figure 6 It is the three-electrode system cycling stability of the resorcinol type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 2.

[0034] Figure 7 It is the specific capacitance broken line graph of the resorcinol type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 2 and the resorcinol type nitrile resin porous carbon material prepared in Comparative Example 1.

[0035] Figure 8 It is the specific capacitance broken line graph of the bisphenol F type nitrile resin / graphene nanoplatelet porous carbon material prepared in Example 3. Detailed Embodiments

[0036] The present invention provides a method for the synchronous synthesis of a nitrile-based resin / graphene nanosheet and the preparation of porous carbon therefrom. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Through long-term research, it has been found that nitrile-based resins have become ideal candidate materials for the manufacture of nitrogen-doped porous carbon due to their unique structure. The nitrile-based resin is characterized by having two adjacent cyano groups on the benzene ring, which can be addition-cured into highly conjugated rigid nitrogen-rich heteroaromatic products, including phthalocyanine rings and triazine rings. These covalent heteroaromatic frameworks endow the nitrile-based resin with a high char yield, excellent thermal stability and thermal oxidation stability, excellent flame retardancy, good resistance to strong acids / alkalis, and a high mechanical property retention rate at high temperatures / after high temperatures. Therefore, the nitrile-based resin is an ideal matrix for realizing advanced porous materials. In addition, graphene has extremely excellent electrical conductivity. Applying it to porous carbon materials will improve the rapid charge transfer ability, endow it with more excellent electrical conductivity and electrochemical activity. Therefore, the one-pot synthesis of nitrile-based resin and graphene nanosheets not only shortens the process cycle but also has performance gains. The present invention adopts a one-pot synthesis method to simultaneously realize the synthesis of nitrile-based resin monomers and the fragmentation and dispersion of graphene nanosheets, which serves two purposes at once. The prepared nitrile-based resin / graphene nanosheet porous carbon material has a high specific surface area, rich and uniform heteroelements, and has a high maximum specific capacitance and excellent long-cycle stability in three-electrode tests. The present invention is obtained based on this research.

[0038] In some embodiments of the present invention, a method for the synchronous synthesis of a nitrile-based resin / graphene nanosheet to prepare porous carbon is provided, including the following preparation steps:

[0039] S1. Reactive ball milling: Weigh a phenol source, 4-nitrophthalonitrile or halogenated phthalonitrile, a weak basic salt, a polar solvent, expanded graphite, and grinding balls and add them to a ball milling tank for ball milling reaction to obtain a reaction solution;

[0040] S2. Filtration and washing: Filter the reaction solution by precipitation, collect the filtrate mixture, add dilute hydrochloric acid to neutralize the weak basic salt, and then dry it to prepare a nitrile-based resin / graphene nanosheet / halide salt mixture;

[0041] S3. High-temperature carbonization: Weigh the cyanate resin / graphene nanosheet / halide salt, weak base salt, and cyanate resin curing agent according to the ratio to obtain a mixture. Calcinate the mixture at a high temperature for carbonization. The calcination temperature is 500 - 1000 °C. After calcination, wash with water and dry to prepare porous carbon. Preferably, the calcination temperature is 550 - 850 °C. More preferably, the calcination temperature is 600 - 800 °C. The calcination time is 0.5 - 10 h, preferably 1 - 4 h. The heating rate is 5 - 40 °C / min, and the flow rate of argon is 50 - 200 ml / min.

[0042] In some embodiments of the present invention, in step S1, the phenol source includes at least one of bisphenol A, bisphenol S, bisphenol F, catechol, hydroquinone, resorcinol, biphenol, 2-aminophenol, 3-aminophenol, 4-aminophenol, and phloroglucinol; preferably bisphenol A, bisphenol F, and resorcinol; more preferably resorcinol; and / or,

[0043] The halo-phthalonitrile includes at least one of 2-chlorophthalonitrile, 2-bromophthalonitrile, 2-fluorophthalonitrile, 2-iodophthalonitrile, 3-chlorophthalonitrile, 3-bromophthalonitrile, 3-fluorophthalonitrile, 3-iodophthalonitrile, 4-chlorophthalonitrile, 4-bromophthalonitrile, 4-fluorophthalonitrile, and 4-iodophthalonitrile; and / or,

[0044] The weak base salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or,

[0045] The polar solvent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0046] In some embodiments of the present invention, in step S1, the ball-milling reaction is carried out at 1000 - 9000 rpm for 10 - 120 h; preferably, the ball-milling speed is 2000 - 8000 rpm, more preferably 5000 - 8000 rpm; the ball-milling time is preferably 15 - 80 h, more preferably 20 - 50 h.

[0047] In some embodiments of the present invention, in step S1, based on 1 unit mole of phenolic hydroxyl groups, 1 - 2 unit moles of 4-nitrophthalonitrile or halo-phthalonitrile and 1 - 2 unit moles of the weak base salt are used correspondingly. The amount of the polar solvent is 1 - 3 times the total mass of the phenols, 4-nitrophthalonitrile or halo-phthalonitrile, and the weak base salt.

[0048] In some embodiments of the present invention, in step S3, the weak base salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or,

[0049] The curing agent of the nitrile resin includes at least one of 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 4-(4-aminophenoxy)phthalonitrile, and 1,3-bis(4'-aminophenoxy)benzene.

[0050] In some embodiments of the present invention, in step S3, the mass ratio of the nitrile resin / graphene nanosheets / halide salt, the weak base salt, and the nitrile resin curing agent is 1:(0.01 - 0.1):(0.2 - 5):(0.2 - 5):(0.01 - 0.1); preferably 1:(0.01 - 0.04):(0.5 - 2):(0.2 - 5):(0.01 - 0.04); more preferably 1:(0.01 - 0.03):(0.5 - 2):(0.2 - 4):(0.01 - 0.04).

[0051] In some embodiments of the present invention, the pore structure of the porous carbon includes macropores, mesopores, and micropores. The macropores have a pore diameter of 1 - 10 μm, the mesopores have a pore diameter of 2 - 10 nm, and the micropores have a pore diameter of less than 2 nm. The specific surface area of the pore structure is 2500 m 2 ·g -1 or more, and the pore volume is 1.5 cm 3 ·g -1 or less, and the average pore diameter is 1.5 nm or less.

[0052] In some embodiments of the present invention, the nitrogen content of the porous carbon is 2% or more, and the nitrogen and oxygen heteroatom content reaches 22% or more.

[0053] The following further elaborates on the present invention in detail with specific embodiments and accompanying drawings.

[0054] Example 1: Example 1 provides a method for synchronously synthesizing porous carbon based on bisphenol A type nitrile resin / graphene nanosheets, including the following preparation steps:

[0055] S1. Reactive ball milling: At room temperature, N-methylpyrrolidone (190 g), bisphenol A (18.05 g), potassium carbonate (23.75 g), 4-nitrophthalonitrile (27.39 g), expanded graphite (2 g), and zirconia microspheres (with diameters of 0.2 mm and 2 mm, each 33.33 g) are sequentially added to the ball milling tank. Under high-speed stirring (7000 rpm), they are mixed for 36 h to obtain a reaction solution;

[0056] S2. Filtration and Washing: Pour the reaction solution into a sieve, precipitate, filter, collect the filtrate mixture, recycle and wash the zirconia microspheres for the next use. Adjust the pH of the filtrate mixture to 6 - 7 with 1 mol / L dilute hydrochloric acid, and then dry the filtrate mixture to obtain a bisphenol A type nitrile resin / graphene nanosheet / potassium chloride mixture. According to the ratio, the mass ratio of bisphenol A type nitrile resin: graphene nanosheet: potassium chloride is 1:0.02:1;

[0057] S3. High-temperature Carbonization: Take a mixture with a mass ratio of bisphenol A type nitrile resin: graphene nanosheet: potassium chloride: potassium carbonate: DDS (4,4'-diaminodiphenyl sulfone) = 1:0.02:1:2:0.02, mix and grind for 30 min. Then place the ground mixture in a quartz tube and put it into a tube furnace. The calcination temperature is 600 °C, the calcination time is 2 h, the heating rate is 10 °C / min, and the argon flow rate is 100 ml / min. After the calcined sample is rinsed with a certain amount of deionized water until the pH of the washing solution is about 7, dry it at 80 °C for 12 h to obtain a bisphenol A type nitrile resin / graphene nanosheet porous carbon material.

[0058] Figure 1 is the infrared spectrum of the bisphenol A type nitrile resin / graphene nanosheet porous carbon prepared in Example 1. It can be seen from Figure 1 that for the obtained porous carbon sample, the vibration peak intensity of -CN at 2231 cm -1 is very weak, indicating that the bisphenol A type nitrile resin has been basically cured completely. Furthermore, the appearance of new peaks at 1517 cm -1 and 1355 cm -1 reflects the formation of the triazine ring structure during the polymerization of the bisphenol A type nitrile resin. In addition, it is worth noting that isoindoline (1715 cm -1 ) and phthalocyanine (966 cm -1 ) are also the main products during the polymerization process. The above cured products indicate that there is cured bisphenol A type nitrile resin in the prepared porous carbon.

[0059] Figure 2 is the SEM image of the bisphenol A type nitrile resin / graphene nanosheet porous carbon prepared in Example 1. Figure 2 The smooth part in it is the bisphenol A type nitrile resin, and the framed wrinkled part is the layered graphene sheet. It can be seen that the prepared porous carbon has a macroporous structure with a pore size of 1 - 10 μm.

[0060] To further investigate the electrochemical performance of the bisphenol A-based nitrile resin / graphene nanoplatelet porous carbon material provided in Example 1, it was tested in a three-electrode system: Prepare an N,N-dimethylacetamide solution of polytetrafluoroethylene at 10 mg / ml. Take 80 mg of the dried bisphenol A-based nitrile resin / graphene nanoplatelet porous carbon material from Example 1, 10 mg of acetylene black, and 1 ml of the N,N-dimethylacetamide solution of polytetrafluoroethylene at a concentration of 10 mg / ml, and ultrasonically mix them evenly. Take 25 μl of the turbid liquid and drop it on a carbon paper of 1*1 cm 2 to prepare a porous carbon electrode material by drying at 80 °C for 12 hours. Then, it was tested in a three-electrode system. Using a Hg / HgO electrode as the reference electrode and a platinum electrode as the counter electrode, with 1 M KOH as the electrolyte, the constant current charge / discharge curve (GCD graph) of the porous carbon electrode material was measured on an electrochemical workstation as shown in Figure 3 . It was measured that at a current of 1 A / g, the specific capacitance of the porous carbon electrode material of Example 1 was as high as 300 F / g.

[0061] Example 2: Example 2 provides a method for the synchronous synthesis of porous carbon based on resorcinol-based nitrile resin / graphene nanoplatelets, including the following preparation steps:

[0062] S1. Reactive ball milling: At room temperature, successively add dimethyl sulfoxide (106 g), resorcinol (11 g), potassium carbonate (30 g), 4-chlorophthalonitrile (32.6 g), expanded graphite (2 g), and zirconia microspheres (with diameters of 0.2 mm and 2 mm, 33.33 g each) into the ball milling tank. Mix for 36 h under high-speed stirring (7000 rpm) to obtain a reaction solution;

[0063] S2. Filtration and washing: Pour the reaction solution into a sieve for precipitation and filtration. Collect the filtrate mixture, recycle and wash the zirconia microspheres for the next use. Adjust the pH of the filtrate mixture to 6 - 7 with 1 mol / L dilute hydrochloric acid, and then dry the filtrate mixture to obtain a resorcinol-based nitrile resin / graphene nanoplatelet / potassium chloride mixture. According to the ratio, the mass ratio of resorcinol-based nitrile resin:graphene nanoplatelets:potassium chloride is 1:0.02:1;

[0064] S3. High-temperature carbonization: Take resorcinol-based nitrile resin: graphene nanosheets: potassium chloride: potassium hydroxide: DDS (4,4'-diaminodiphenyl sulfone) with a mass ratio of 1:0.02:1:2:0.02, mix and grind for 30 min. Then place the ground mixture in a quartz tube and put it into a tube furnace. The calcination temperature is 600 °C, the calcination time is 2 h, the heating rate is 10 °C / min, and the argon flow rate is 100 ml / min. After the calcined sample is rinsed with a certain amount of deionized water until the pH of the washing solution is about 7, it is dried at 80 °C for 12 h to obtain the resorcinol-based nitrile resin / graphene nanosheet porous carbon material.

[0065] Using the same structural test and characterization method as in Example 1, it is measured that the cured resorcinol-based nitrile resin and layered graphene sheets exist in the resorcinol-based nitrile resin / graphene nanosheet porous carbon material prepared in Example 2. The porous carbon prepared in Example 2 has a macroporous structure with a pore size of 1 - 10 μm. Figure 4 It is the BET characterization diagram of the resorcinol-based nitrile resin / graphene nanosheet porous carbon in Example 2. Combining Figure 4 it can be seen that the pore structure of the resorcinol-based nitrile resin / graphene nanosheet porous carbon prepared in Example 2 also includes mesopores and micropores. Micropores are less than 2 nm, and mesopores are greater than 2 nm. Among them, the pore size of micropores is mainly concentrated at about 0.3 - 1.5 nm, while mesopores are concentrated between 2 - 4 nm. The specific surface area of the pore structure is measured to be 2579 m 2 ·g -1 , the pore volume is 1.4 cm 3 ·g -1 , and the average pore size is 1.47 nm.

[0066] The chemical element composition on the surface of the resorcinol-based nitrile resin / graphene nanosheet porous carbon material in Example 2 is tested by XPS. The XPS test results are as Figure 5 shown in the figure. Three peaks are shown at 284.8 eV (C1s), 541.8 eV (O1s), and 400.8 eV (N1s). Through semi-quantitative analysis, the nitrogen content is 2.25%, and the nitrogen and oxygen hetero-element content reaches 22.69%, which has a positive impact on the electrochemical performance to a certain extent.

[0067] To further investigate the electrochemical performance of the resorcinol-based nitrile resin / graphene nanoplatelet porous carbon material provided in Example 2, the same electrochemical performance test method as in Example 1 was used, and the test was carried out in a three-electrode system: Prepare an N,N-dimethylacetamide solution of polytetrafluoroethylene at 10 mg / ml. Take 80 mg of the dried resorcinol-based nitrile resin / graphene nanoplatelet porous carbon material from Example 2, 10 mg of acetylene black, and 1 ml of the N,N-dimethylacetamide solution of polytetrafluoroethylene with a concentration of 10 mg / ml, and mix them evenly by ultrasonic treatment. Take 25 μl of the turbid liquid and drop it onto a carbon paper of 1*1 cm 2 , and bake it at 80 °C for 12 hours to obtain a porous carbon electrode material. Then, it was tested in a three-electrode system. Using a Hg / HgO electrode as the reference electrode and a platinum electrode as the counter electrode, and 1 M KOH as the electrolyte, the constant current charge / discharge curve of the porous carbon electrode material was measured on an electrochemical workstation. As can be seen from Figure 5 , after 10,000 cycles, at 10 A / g, the specific capacitance retention rate of the porous carbon electrode material in Example 2 was above 96%. As can be seen from Figure 6 , at a current of 1 A / g, the specific capacitance of the porous carbon electrode material in Example 2 was as high as 360 F / g.

[0068] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 provides a method for preparing porous carbon based on resorcinol-based nitrile resin, including the following preparation steps:

[0069] S1. Reactive ball milling: At room temperature, successively add dimethyl sulfoxide (106 g), resorcinol (11 g), potassium carbonate (30 g), 4-chlorophthalonitrile (32.6 g), and zirconia microspheres (with diameters of 0.2 mm and 2 mm, 33.33 g each) into the ball milling tank. Mix them for 36 h under high-speed stirring (7000 rpm) to obtain a reaction solution;

[0070] S2. Filtration and washing: Pour the reaction solution into a sieve, precipitate, filter, collect the filtrate mixture, recycle and wash the zirconia microspheres for the next use. Adjust the pH of the filtrate mixture to 6-7 with 1 mol / L dilute hydrochloric acid, and then dry the filtrate mixture to obtain a resorcinol-based nitrile resin / potassium chloride mixture. According to the ratio, the mass ratio of resorcinol-based nitrile resin: graphene nanoplatelets: potassium chloride is 1:1;

[0071] S3. High-temperature carbonization: Take resorcinol-based nitrile resin: potassium chloride: potassium hydroxide: DDS (4,4'-diaminodiphenyl sulfone) with a mass ratio of 1:1:2:0.02, mix and grind for 30 min. Then place the ground mixture in a quartz tube and put it into a tube furnace. The calcination temperature is 600 °C, the calcination time is 2 h, the heating rate is 10 °C / min, and the argon flow rate is 100 ml / min. After the calcined sample is rinsed with a certain amount of deionized water until the pH of the washing solution is about 7, it is dried at 80 °C for 12 h to obtain the resorcinol-based nitrile resin porous carbon material.

[0072] Using the same method as in Example 2, a porous carbon electrode material was prepared from the resorcinol-based nitrile resin porous carbon material of Comparative Example 1, and using the same test method as in Example 2, the specific capacitance of the porous carbon electrode material of Comparative Example 1 was measured as Figure 6 shown. At a current of 1 A / g, the specific capacitance of the porous carbon electrode material of Comparative Example 1 was 288 F / g. Combining the specific capacitances of the porous carbon electrode materials of Comparative Example 1 and Example 2, it can be seen that the synchronous generation of nitrile resin and graphene nanosheets is of great help in improving the electrochemical performance of porous carbon.

[0073] Example 3: Example 3 provides a method for preparing porous carbon based on the synchronous synthesis of bisphenol F-based nitrile resin / graphene nanosheets, including the following preparation steps:

[0074] S1. Reactive ball milling: At room temperature, successively add N,N-dimethylformamide (120 g), bisphenol F (40 g), sodium bicarbonate (23.75 g), 4-chlorophthalonitrile (32.6 g), expanded graphite (2 g) and zirconia microspheres (with diameters of 0.2 mm and 2 mm, 33.33 g each) into the ball milling tank. Mix for 24 h under high-speed stirring (7000 rpm) to obtain a reaction solution;

[0075] S2. Filtration and washing: Pour the reaction solution into a sieve, precipitate, filter, collect the filtrate mixture, recycle and wash the zirconia microspheres for the next use. Adjust the pH of the filtrate mixture to 6-7 with 1 mol / L dilute hydrochloric acid, and then dry the filtrate mixture to obtain a bisphenol F-based nitrile resin / graphene nanosheet / sodium chloride mixture. According to the ratio, the mass ratio of bisphenol F-based nitrile resin: graphene nanosheet: sodium chloride is 1:0.02:1;

[0076] S3. High-temperature carbonization: Take bisphenol F-based nitrile resin: graphene nanosheets: sodium chloride: potassium hydroxide: DDS (4,4'-diaminodiphenyl sulfone) with a mass ratio of 1:0.02:1:2:0.02, mix and grind for 30 min. Then place the ground mixture in a quartz tube and put it into a tube furnace. The calcination temperature is 700 °C, the calcination time is 2 h, the heating rate is 5 °C / min, and the argon flow rate is 100 ml / min. After the calcined sample is rinsed with a certain amount of deionized water until the pH of the washing liquid is about 7, it is dried at 80 °C for 12 h to obtain the bisphenol F-based nitrile resin / graphene nanosheet porous carbon material.

[0077] Using the same structure testing and characterization method as in Example 1, it is measured that the cured bisphenol F-based nitrile resin and layered graphene sheets exist in the bisphenol F-based nitrile resin / graphene nanosheet porous carbon material prepared in Example 3. The porous carbon prepared in Example 3 has a macroporous structure with a pore size of 1-10 μm.

[0078] Using the same method as in Example 1, the porous carbon electrode material is prepared with the bisphenol F-based nitrile resin / graphene nanosheet porous carbon material of Example 3, and using the same testing method as in Example 1, the GCD diagram of the porous carbon electrode material of Example 3 is as Figure 7 shown. It is measured that at a current of 1 A / g, the specific capacitance of the porous carbon electrode material of Example 3 is 321 F / g.

[0079] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description. All these improvements and transformations should fall within the protection scope of the appended claims of this application.

Claims

1. A method for preparing porous carbon based on simultaneous synthesis of nitrile resin / graphene nanosheets, characterized in that: The method comprises the following preparation steps: S1. Reaction ball milling: weigh a phenol source, halogenated phthalonitrile, a weakly alkaline salt, a polar solvent, expanded graphite and grinding balls and add them into a ball milling jar for ball milling reaction to obtain a reaction solution; the ball milling reaction is carried out at 1000-9000 rpm for 10-120 hours; S2. Filtration and washing: The reaction solution is filtered for precipitation, the filtrate mixture is collected, and dilute hydrochloric acid is added to neutralize the weakly alkaline salt and then dried to prepare a nitrile resin / graphene nanosheets / halide salt mixture; S3. High-temperature carbonization: weigh the nitrile resin / graphene nanosheets / halide salts and weakly alkaline salts and nitrile resin curing agent according to a ratio and mix them to obtain a mixture, wherein the mass ratio of the nitrile resin / graphene nanosheets / halide salts and the weakly alkaline salts and nitrile resin curing agent is 1:(0.01-0.1):(0.2-5):(0.2-5):(0.01-0.1); subject the mixture to high-temperature calcination and carbonization, the calcination temperature is 500-1000°C, and the mixture is washed with water and dried after calcination to prepare porous carbon; the pore structure of the porous carbon includes macropores, mesopores and micropores; the pore diameter of the macropores is 1-10μm, the pore diameter of the mesopores is 2-10nm, and the pore diameter of the micropores is less than 2nm.

2. The method for preparing porous carbon based on simultaneous synthesis of nitrile resin / graphene nanosheets according to claim 1, characterized in that: In step S1, the phenol source includes at least one of bisphenol A, bisphenol S, bisphenol F, catechol, hydroquinone, resorcinol, biphenol, 2-aminophenol, 3-aminophenol, 4-aminophenol, and trisphenol; and / or, The halogenated phthalonitrile comprises at least one of 2-chlorophthalonitrile, 2-bromophthalonitrile, 2-fluorophthalonitrile, 2-iodophthalonitrile, 3-chlorophthalonitrile, 3-bromophthalonitrile, 3-fluorophthalonitrile, 3-iodophthalonitrile, 4-chlorophthalonitrile, 4-bromophthalonitrile, 4-fluorophthalonitrile and 4-iodophthalonitrile; and / or, The weakly alkaline salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate; and / or, The polar solvent includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, N'N-dimethylformamide, and N'N-dimethylacetamide.

3. The method for preparing porous carbon based on simultaneous synthesis of nitrile resin / graphene nanosheets according to claim 1 or 2, characterized in that: In step S3, the weakly alkaline salt includes at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or, The nitrile-based resin curing agent includes at least one of 4'4-diaminodiphenyl sulfone, 4'4-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 4-(4-aminophenoxy)phthalonitrile and 1,3-bis(4'-aminophenoxy)benzene.

4. The method for preparing porous carbon based on simultaneous synthesis of nitrile resin / graphene nanosheets according to claim 1, characterized in that: The specific surface area of ​​the pore structure is 2500m 2 ·g -1 Above, the pore volume is 1.5cm 3 ·g -1 Below, the average pore diameter is 1.5 nm or less.

5. The method for preparing porous carbon based on simultaneous synthesis of nitrile resin / graphene nanosheets according to claim 1, characterized in that: The porous carbon has a nitrogen content of more than 2%, and a nitrogen and oxygen element content of more than 22%.

6. A porous carbon material obtained by the method for preparing porous carbon by simultaneous synthesis based on nitrile resin / graphene nanosheets according to any one of claims 1 to 5.

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