CN108264046B - Graphene-asphalt-based activated carbon and preparation method and application thereof - Google Patents
Graphene-asphalt-based activated carbon and preparation method and application thereof Download PDFInfo
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- CN108264046B CN108264046B CN201810178696.5A CN201810178696A CN108264046B CN 108264046 B CN108264046 B CN 108264046B CN 201810178696 A CN201810178696 A CN 201810178696A CN 108264046 B CN108264046 B CN 108264046B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/36—Nanostructures, e.g. nanofibres, nanotubes or fullerenes
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Abstract
The invention provides a preparation method of graphene-asphalt-based activated carbon, which comprises the steps of mixing asphalt, graphene and an activating agent to obtain a mixed material; and (3) under a protective atmosphere, carrying out activation treatment on the mixed material at a lower temperature to obtain the high-quality graphene-asphalt-based activated carbon. Compared with the traditional activated carbon preparation process, the method has the advantages that the graphene is added when the activated carbon is prepared by taking the asphalt as the raw material, so that the activation temperature can be reduced by more than 200 ℃, the using amount of the activating agent is reduced by 2-3 times, the carbon conversion rate is improved by 30-40%, and a template agent is not required to be added; and the preparation method is simple, low in production cost and suitable for large-scale production.
Description
Technical Field
The invention relates to the technical field of electrochemical energy storage, in particular to graphene-asphalt-based activated carbon and a preparation method and application thereof.
Background
With the rapid development of economy in China, available natural resources such as fossil fuels cannot maintain the requirements of life and industry for a long time, and the use of a large amount of fossil fuels causes serious environmental pollution, so that the development of clean and efficient new energy is urgent. However, to maximize the utilization of various new energy sources, a suitable energy storage device is critical. Therefore, there is a need to develop advanced electrode materials for improving the performance of energy storage devices that have been put into use in daily life at present. Super capacitors have been used in bus systems due to their high power density, ultra-long cycling stability and the ability to meet fast charge and discharge characteristics. However, the preparation process of the activated carbon electrode material required by the supercapacitor is complex, and the production cost is high, so that the supercapacitor cannot be widely put into daily life, and therefore, the development of safe, efficient, green and clean supercapacitor materials becomes the focus of current research.
Coal tar pitch and petroleum pitch, which are byproducts of coal and petroleum processing and refining processes, are only used in road construction, building waterproofing and other aspects, and most of the pitch is not developed and utilized to the maximum extent. And the coal tar pitch and the petroleum pitch in China have abundant resources, but the deep processing technology is relatively backward, the added value of the product is low, and the maximization of the product value cannot be achieved. Considering the high carbon content, wide distribution and low price of the asphalt, the asphalt is a better choice for preparing the activated carbon by combining economic benefits and environmental benefits.
Although the reports of preparing the activated carbon by using the coal tar pitch exist at present, the activation temperature is basically higher than 800 ℃, a template agent needs to be added, the synthesis process is complex, the production cost is high, and the large-scale production is not suitable.
Disclosure of Invention
The invention aims to provide graphene-asphalt-based activated carbon and a preparation method and application thereof, and the graphene is added when asphalt is used as a raw material to prepare the activated carbon, so that the activation temperature can be reduced, and a template agent is not required to be added; and the preparation method is simple, low in production cost and suitable for large-scale production.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of graphene-asphalt-based activated carbon, which comprises the following steps:
(A) mixing asphalt, graphene and an activating agent to obtain a mixed material;
(B) and (B) under a protective atmosphere, activating the mixed material in the step (A) at 400-650 ℃ for 3-10 h to obtain the graphene-asphalt-based activated carbon.
Preferably, the mass ratio of the asphalt, the graphene and the activating agent in the step (a) is 100: (5.26-52.6): (100-200).
Preferably, the asphalt in step (a) comprises coal tar asphalt or petroleum asphalt, and the petroleum asphalt comprises solid petroleum asphalt or colloidal petroleum asphalt.
Preferably, the coal tar pitch comprises low temperature pitch, medium temperature pitch or high temperature pitch.
Preferably, the petroleum asphalt comprises straight asphalt, solvent deoiled asphalt, oxidized asphalt, blended asphalt, emulsified asphalt or modified asphalt.
Preferably, the coal tar pitch or the solid petroleum pitch is pretreated before use; the pretreatment comprises the steps of crushing, screening, washing and drying which are sequentially carried out.
Preferably, the granularity of the asphalt obtained after crushing is 20-200 meshes; the crushing comprises ball milling crushing, ultrasonic crushing, high-shear dispersion crushing or sanding crushing.
Preferably, when the ball milling crushing is adopted, the ball milling rotating speed is 100-600 r/min, and the ball milling time is preferably 6-72 h; when the ultrasonic crushing is adopted, the ultrasonic frequency is 20-40 kHz, and the ultrasonic time is 0.5-24 h; when the high-shear dispersing crushing is adopted, the shearing rotating speed is 100-3000 r/min, and the shearing time is 2-100 h; when the sanding is adopted for crushing, the sanding rotating speed is 1000-3000 r/min, and the sanding time is 1-12 h;
the sand milling and crushing are wet milling, and organic solvents adopted in the wet milling process comprise dimethyl sulfoxide, carbon disulfide, carbon tetrachloride, tetrahydrofuran, N-N dimethylformamide or lower alcohol compounds.
Preferably, the washing reagent used for washing comprises one or more of inorganic acid, organic acid, inorganic base, organic solvent and water;
the inorganic acid comprises HCl and H2SO4、H3PO4、HNO3Or HClO4Wherein the inorganic acid is used in the form of an inorganic acid aqueous solution, and the mass percentage of the inorganic acid in the inorganic acid aqueous solution is 1-85%; the organic acid comprises formic acid or acetic acid; the inorganic base comprises NaOH, KOH and K2CO3Or NaHCO3Wherein the inorganic base is used in the form of an inorganic base aqueous solution, and the mass percentage of the inorganic base in the inorganic base aqueous solution is 1-85Percent; the organic solvent comprises ethanol, methanol, acetone or isopropanol.
Preferably, the drying comprises natural drying, vacuum drying, forced air drying or freeze drying; the temperature of the vacuum drying or the forced air drying is independently 80-120 ℃, and the drying time is independently 4-72 h; the temperature of the freeze drying is-45 to-55 ℃, and the drying time is 24 to 120 hours.
Preferably, the colloidal petroleum asphalt is heat treated prior to use; the temperature of the heating treatment is 70-130 ℃, and the time of the heating treatment is 1-3 h.
Preferably, the graphene in step (a) comprises pure graphene or heteroatom-doped graphene.
Preferably, the heteroatom-doped graphene includes nitrogen-doped graphene, phosphorus-doped graphene, sulfur-doped graphene, or nitrogen-phosphorus-doped graphene.
Preferably, the graphene is used in a solid form or in a graphene slurry form; the graphene slurry is a mixture of graphene and water, and the concentration of graphene in the graphene slurry is 7-12 mg/mL.
Preferably, the activator comprises KOH, NaOH, ZnCl2、K2CO3Or Na2CO3(ii) a The activator is used in solid form or in the form of an aqueous activator solution; the mass percentage of the activating agent in the activating agent water solution is 10-80%.
Preferably, the step (a) is specifically:
and carrying out first mixing on the asphalt and the graphene, and then carrying out second mixing on the obtained first mixed material and an activating agent to obtain a mixed material.
Preferably, the mixing method used for the first mixing and the second mixing independently comprises ball milling mixing, shear stirring mixing, magnetic stirring mixing, pneumatic stirring mixing, vacuum stirring mixing or ultrasonic mixing.
Preferably, when the ball milling and mixing are adopted, the ball milling rotating speed is 200-500 r/min, and the ball milling time is 2-48 h; when the ultrasonic mixing is adopted, the ultrasonic frequency is 20-40 kHz, and the ultrasonic time is 0.5-48 h; when the shearing, stirring and mixing are adopted, the shearing and stirring speed is 500-3000 r/min, and the shearing and stirring time is 1-36 h; when magnetic stirring, pneumatic stirring and vacuum stirring are adopted for mixing, the stirring speed is independently 200-1200 r/min, and the stirring time is independently 3-48 h.
Preferably, the first mixing is performed in the presence of an organic solvent, or in the presence of an organic solvent and a co-solvent.
Preferably, the organic solvent comprises dimethyl sulfoxide, carbon disulfide, benzene, toluene, tetrahydrofuran or N-N dimethylformamide; the cosolvent is low-carbon alcohol; the lower alcohol comprises methanol, ethanol, benzyl alcohol or ethylene glycol.
Preferably, when the mixture obtained after the second mixing includes an organic solvent and/or a cosolvent, the organic solvent and/or the cosolvent is recycled and reused.
Preferably, the method of recovering comprises: heating to 100-180 ℃ by adopting a rotary reduced pressure evaporator, heating to 100-220 ℃ by adopting a blast oven, or adopting a polypropylene bag with the aperture of 2-50 mu m.
The invention provides graphene-asphalt-based activated carbon prepared by the preparation method in the technical scheme, which comprises graphene and activated carbon converted from asphalt on the surface of the graphene in situ, wherein the carbon conversion rate is 70-80%.
Preferably, the content of graphene in the graphene-asphalt-based activated carbon is 5-50 wt%.
Preferably, the morphology of the graphene-asphalt-based activated carbon is a petal-shaped graphene sheet structure, the graphene-asphalt-based activated carbon has a micropore-mesopore-macropore combined pore distribution structure, and the specific surface area is 750-2600 m2/g。
The invention provides application of the graphene-asphalt-based activated carbon in the technical scheme in a double electric layer super capacitor.
Preferably, the application comprises the following steps:
mixing graphene-asphalt-based activated carbon and a binder to obtain mixed slurry;
and coating the mixed slurry on a conductive film, drying and cutting to assemble the double electric layer super capacitor.
Preferably, the mass ratio of the graphene-asphalt-based activated carbon to the binder is 95: (4-6); the binder comprises polyvinylidene fluoride, vinylidene fluoride, hexafluoropropylene, polytetrafluoroethylene, LA132, LA133, LA135, or CMC.
Preferably, the conductive film comprises a copper foil or a nickel foam; the electrolyte used for assembling the electric double layer super capacitor comprises an aqueous electrolyte, an organic electrolyte or an ionic liquid electrolyte; the aqueous electrolyte comprises 6mol/L KOH aqueous solution or 1mol/L H2SO4(ii) a The organic electrolyte comprises a mixed solution of tetraethylammonium tetrafluoroborate and acetonitrile, or a mixed solution of tetraethylammonium tetrafluoroborate and propylene carbonate; the ionic liquid electrolyte comprises 1-ethyl-3-methyloxazole tetrafluoroborate or 1-butyl-3-methyloxazole tetrafluoroborate; the separator used for assembling the electric double layer supercapacitor comprises celgard3501 or celgard 2400.
The invention provides a preparation method of graphene-asphalt-based activated carbon, which comprises the steps of mixing asphalt, graphene and an activating agent to obtain a mixed material; and (3) under a protective atmosphere, carrying out activation treatment on the mixed material at 400-650 ℃ for 3-10 h to obtain the graphene-asphalt-based activated carbon. According to the invention, the graphene added when the asphalt is used as the raw material for preparing the activated carbon is a cyclic organic component, and a plurality of six-membered ring structured organic matters are arranged in the asphalt and can be well combined with the graphene with a smooth surface and rich chemical bonds, so that the organic rings in the asphalt are opened and uniformly arranged on the surface of the graphene to form a net structure with the graphene, and the graphene are bonded through covalent bonds (including C-C covalent bond sigma bond bonding and changed into pi bond in the activation treatment process, and also including partial C-N and C-S covalent bond bonding), so that the graphene and the graphene are combined more stably, and the chemical bond combination between carbon atoms is formed by carbon-carbon sp single bond in the activation process3Hybridization to sp2Hybridization to finally obtain more stable graphene-asphalt-based activated carbon with a graphene-like structure(ii) a The addition of the graphene also realizes the in-situ conversion of the asphalt into the activated carbon on the surface of the graphene, and the combination of the two is more stable, so that the carbon conversion rate is obviously improved in the activation process and reaches 70-80 percent, and the industrial production requirements are basically met; according to the invention, graphene is combined with asphalt, so that the good thermal conductivity and strong interface effect of graphene are fully utilized, the heat transfer effect of the material is greatly improved in the activation process, the activation temperature of asphalt is greatly reduced (the activation temperature is reduced by more than 200 ℃) and the usage amount of an activating agent (the usage amount of the activating agent is reduced by 2-3 times), a template agent is not required to be added, and the energy consumption and the corrosion to equipment in the activation process are greatly reduced; the graphene has a large specific surface area, so that the pore distribution and the specific surface area (the specific surface area is 750-2600 m) of the graphene-asphalt-based activated carbon can be improved2Between/g).
The graphene-asphalt-based activated carbon provided by the invention has excellent conductivity, and when the graphene-asphalt-based activated carbon is used as an active material of a double electric layer super capacitor, the graphene-asphalt-based activated carbon can meet the conductivity of the material without adding other conductive substances, and the integral energy density and power density are improved.
In addition, the preparation method provided by the invention is simple, low in production cost and suitable for large-scale production.
Drawings
Figure 1 is an SEM image of graphene-pitch based activated carbon prepared in example 1;
FIG. 2 is a charge and discharge diagram of the assembled electric double layer supercapacitor of example 1 at a constant current of 1A/g;
fig. 3 is a pore distribution diagram of graphene-pitch-based activated carbon prepared in example 1;
figure 4 is an SEM image of graphene-pitch based activated carbon prepared in example 2;
FIG. 5 is a test chart of conductivity of the electrode material prepared in example 2;
FIG. 6 is a graph of the charge and discharge of the assembled electric double layer supercapacitor of example 2 at a constant current of 1A/g;
FIG. 7 is a cyclic voltammogram at a scan rate of 5mv/s for an assembled electric double layer supercapacitor of example 3;
FIG. 8 is a cyclic voltammogram at a scan rate of 5mv/s for an assembled electric double layer supercapacitor of example 4;
fig. 9 is an impedance diagram of an electric double layer supercapacitor assembled with graphene-asphalt-based activated carbon and asphalt-based activated carbon prepared in example 5.
Detailed Description
The invention provides a preparation method of graphene-asphalt-based activated carbon, which comprises the following steps:
(A) mixing asphalt, graphene and an activating agent to obtain a mixed material;
(B) and (B) under a protective atmosphere, activating the mixed material in the step (A) at 400-650 ℃ for 3-10 h to obtain the graphene-asphalt-based activated carbon.
The asphalt, the graphene and the activating agent are mixed to obtain a mixed material. In the present invention, the mass ratio of the asphalt, the graphene and the activating agent is preferably 100: (5.26-52.6): (100 to 200), more preferably 100: (10-40): (120-180), most preferably 100: (20-30): (140-160).
In the present invention, the asphalt preferably comprises coal tar pitch or petroleum asphalt, and the petroleum asphalt comprises solid petroleum asphalt or colloidal petroleum asphalt. The coal tar pitch is not particularly limited, and can be prepared by coal tar pitch known to those skilled in the art, such as low-temperature pitch (ring-and-ball softening point of 35-75 ℃), medium-temperature pitch (ring-and-ball softening point of 75-95 ℃) or high-temperature pitch (ring-and-ball softening point of 95-120 ℃). The petroleum asphalt of the present invention is not particularly limited, and may be any petroleum asphalt known to those skilled in the art, specifically, straight asphalt, solvent deoiled asphalt, oxidized asphalt, blended asphalt, emulsified asphalt or modified asphalt. The source of the asphalt in the present invention is not particularly limited, and industrial asphalt known to those skilled in the art may be used.
In the present invention, when colloidal petroleum asphalt is selected as a raw material, it is preferable to use the colloidal petroleum asphalt after heat treatment for easy handling. In the invention, the heating temperature is preferably 70-130 ℃; the heating time is preferably 1-3 h.
In the present invention, when coal tar pitch or solid petroleum pitch is selected as a raw material, the coal tar pitch or solid petroleum pitch is preferably used after being pretreated; the pretreatment preferably comprises crushing, screening, washing and drying in sequence.
The asphalt particles with the particle size of 20-200 meshes are obtained through crushing. The present invention is not particularly limited to the above-mentioned crushing, and the technical solution of crushing that can satisfy the above-mentioned particle size requirement, which is well known to those skilled in the art, may be adopted. In the present invention, the crushing preferably includes ball milling, ultrasonic crushing, high shear dispersion crushing or sand milling. In the embodiment of the invention, specifically, when ball milling crushing is adopted, the ball milling rotation speed is preferably 100-600 r/min, more preferably 200-500 r/min, and the ball milling time is preferably 6-72 h, more preferably 15-50 h; when ultrasonic crushing is adopted, the ultrasonic frequency is preferably 20-40 kHz, more preferably 25-35 kHz, and the ultrasonic time is preferably 0.5-24 h, more preferably 5-15 h; when high-shear dispersion crushing is adopted, the shearing rotating speed is preferably 100-3000 r/min, more preferably 500-2000 r/min, and the shearing time is preferably 2-100 h, more preferably 20-60 h; when sanding crushing is adopted, the sanding rotating speed is preferably 1000-3000 r/min, more preferably 1500-2500 r/min, and the sanding time is preferably 1-12 h, more preferably 4-8 h. In the invention, the sand grinding and crushing are preferably wet grinding, and specifically, the asphalt raw material is mixed with an organic solvent and then sand grinding and crushing are carried out; the kind of the organic solvent is not particularly limited in the present invention, and any organic solvent suitable for wet milling of a pitch raw material, which is well known to those skilled in the art, may be used, specifically, dimethyl sulfoxide, carbon disulfide, carbon tetrachloride, tetrahydrofuran, N-N dimethylformamide, or lower alcohol compounds; the lower alcohol compound preferably includes methanol and ethanol.
According to the invention, large asphalt blocks or other large impurities in the crushed asphalt particles are preferably removed by screening to obtain 20-200-mesh asphalt particles with uniform particle size distribution. The screening method is not particularly limited, and the screening method can adopt a screening technical scheme which can meet the requirement of the granularity and is well known to a person skilled in the art. In the present invention, the sieving is preferably performed using a sieve. In the present invention, the mesh number of the screen is preferably 20 to 200 mesh.
In the invention, the washing reagent used for washing preferably comprises one or more of inorganic acid, organic acid, inorganic base, organic solvent and water. In the embodiment of the present invention, specifically, the inorganic acid preferably includes HCl, H2SO4、H3PO4、HNO3Or HClO4The inorganic acid is preferably used in the form of an aqueous solution, and the mass percentage of the inorganic acid in the aqueous solution is preferably 1-85%, and more preferably 15-60%; the organic acid preferably comprises formic acid or acetic acid; the inorganic base preferably comprises NaOH, KOH, K2CO3Or NaHCO3The inorganic base is preferably used in the form of an aqueous solution, and the mass percentage of the inorganic base in the aqueous solution is preferably 1-85%, and more preferably 15-60%; the organic solvent preferably comprises ethanol, methanol, acetone or isopropanol; the water is preferably deionized water. The invention preferably removes impurities soluble in the washing agent from the bitumen particles obtained after sieving by washing. In the present invention, after the washing is completed, it is preferable to perform solid-liquid separation on the obtained material, and to perform subsequent drying on the obtained solid material. The solid-liquid separation is not particularly limited in the present invention, and a technical scheme capable of achieving solid-liquid separation, which is well known to those skilled in the art, may be adopted. In the embodiment of the invention, a polypropylene bag or a polyethylene film is adopted for carrying out solid-liquid separation; the aperture of the polypropylene bag is preferably 2-50 μm; the pore diameter of the polyethylene film is preferably 0.2-0.45 μm.
The drying method of the present invention is not particularly limited, and a drying method known to those skilled in the art may be used. In the present invention, the drying preferably includes natural drying, vacuum drying, forced air drying or freeze drying. In the invention, the drying temperature of the vacuum drying or the forced air drying is preferably 80-120 ℃ independently, and more preferably 90-110 ℃; the drying time is independently preferably from 4h to 72h, more preferably from 20h to 50 h. In the present invention, the freeze-drying temperature is preferably-45 to-55 ℃, more preferably-48 to-51 ℃; the drying time is preferably 24 to 120 hours, more preferably 50 to 90 hours.
In the present invention, the graphene preferably includes pure graphene or heteroatom-doped graphene. In the present invention, the heteroatom-doped graphene preferably includes nitrogen-doped graphene, phosphorus-doped graphene, sulfur-doped graphene, or nitrogen-phosphorus-doped graphene. In the present invention, the graphene is preferably used in a solid form or in a graphene slurry form; the graphene slurry is a mixture of graphene and water, and the concentration of the graphene in the graphene slurry is preferably 7-12 mg/mL. The source of the graphene is not particularly limited in the present invention, and the graphene product may be prepared by commercially available graphene products known to those skilled in the art or by known methods (such as electrochemical exfoliation, mechanical exfoliation, chemical vapor deposition, or redox). In the embodiment of the invention, the graphene is specifically prepared by adopting a method disclosed in a Chinese patent with a publication number of CN 103693638A.
In the present invention, the activator preferably comprises KOH, NaOH, ZnCl2、K2CO3Or Na2CO3. In the present invention, the activator is preferably used in the form of a solid or in the form of an aqueous solution thereof; when the activator is used in the form of an aqueous solution, the mass percentage of the activator in the aqueous solution is preferably 10-80%, more preferably 20-60%, and most preferably 30-40%.
In the invention, the mixing of the asphalt, the graphene and the activating agent is preferably performed by firstly mixing the asphalt and the graphene, and then secondly mixing the obtained first mixed material and the activating agent to obtain a mixed material. In the present invention, the first mixing is preferably performed in the presence of an organic solvent, and more preferably in the presence of an organic solvent and a co-solvent. In the present invention, the organic solvent preferably includes dimethyl sulfoxide, carbon disulfide, benzene, toluene, tetrahydrofuran or N-N dimethylformamide; the cosolvent is preferably a lower alcohol, more preferably comprises methanol, ethanol, benzyl alcohol or ethylene glycol.
The specific mixing method adopted by the first mixing and the second mixing is not particularly limited, and the technical scheme of material mixing, which is well known to those skilled in the art, can be adopted; in the present invention, the specific mixing method adopted for the first mixing and the second mixing preferably independently comprises ball milling, shear stirring, magnetic stirring, pneumatic stirring, vacuum stirring or ultrasound. In the invention, when ball milling and mixing are adopted, the ball milling rotating speed is preferably 200-500 r/min, more preferably 300-400 r/min, and the ball milling time is preferably 2-48 h, more preferably 15-30 h; when ultrasonic mixing is adopted, the ultrasonic frequency is preferably 20-40 kHz, more preferably 25-35 kHz, and the ultrasonic time is preferably 0.5-48 h, more preferably 10-30 h; when the shear stirring and mixing are adopted, the shear stirring speed is preferably 500-3000 r/min, more preferably 1000-2000 r/min, and the shear stirring time is preferably 1-36 h, more preferably 10-20 h; when magnetic force, pneumatic stirring and vacuum stirring are adopted for mixing, the stirring speed is preferably 200-1200 r/min independently, more preferably 400-800 r/min independently, and the stirring time is preferably 3-48 h independently, more preferably 15-30 h independently.
When the material obtained after the second mixing contains a liquid component (the liquid component includes one or more of water in the graphene slurry, water in the aqueous solution of the activating agent, an organic solvent and a cosolvent), the invention preferably removes the liquid component in the material obtained after the second mixing is completed to obtain the mixed material of the asphalt, the graphene and the activating agent. When the liquid component contains the organic solvent and the cosolvent, the organic solvent and the cosolvent are preferably recycled, so that the energy is saved and the environment is protected. The present invention preferably employs a rotary reduced pressure evaporator, forced air oven or polypropylene bag to remove the liquid component. In the embodiment of the invention, when a rotary reduced-pressure evaporator is adopted, specifically, the material obtained after the second mixing is placed in a round-bottom flask, the temperature is heated to 100-180 ℃, the organic solvent and the cosolvent are collected through condensation reflux, and the organic solvent and the cosolvent are recycled; when a blast oven is adopted, specifically, a liquid recovery device is connected to an air outlet of the blast oven, the temperature of the blast oven is adjusted to be 100-220 ℃, and the discharged organic solvent and cosolvent are collected to realize recovery and reuse; when the polypropylene bag is adopted, the aperture of the polypropylene bag is preferably 2-50 μm.
After the mixed material is obtained, the mixed material is activated for 3-10 hours at 400-650 ℃ under a protective atmosphere, and graphene-asphalt-based activated carbon is obtained. The type of the protective gas for providing the protective atmosphere is not particularly limited in the present invention, and protective gases known to those skilled in the art may be used, such as nitrogen, argon, helium or a mixture of hydrogen and argon. In the invention, the temperature of the activation treatment is 400-650 ℃, preferably 450-600 ℃, and more preferably 550-650 ℃; the activation treatment time is 3-10 h, preferably 5-9 h, and more preferably 6-8 h. In the present invention, the rate of temperature rise to the temperature of the activation treatment is preferably 1 to 10 ℃/min, more preferably 3 to 8 ℃/min, and most preferably 5 to 6 ℃/min.
After the activation treatment is completed, the activated material is preferably subjected to impurity removal, cleaning and drying in sequence to obtain the graphene-asphalt-based activated carbon.
The invention preferably performs said removing impurities by washing; the washing preferably comprises acid or alkali washing. In the present invention, the acid-washing reagent used for the acid-washing is preferably a water-soluble inorganic acid, more preferably comprising H2SO4、HCl、HNO3Or HClO4. In the invention, the water-soluble inorganic acid is preferably used in the form of an aqueous solution, and the mass percentage of the water-soluble inorganic acid in the aqueous solution is preferably 1-98%, more preferably 10-60%, and most preferably 15-40%. In the present invention, the alkali washing agent used for alkali washing is preferably a water-soluble inorganic base or an aqueous organic base, and more preferably comprises NaOH, KOH, NH3·H2O or sodium methoxide. In the present invention, the water-soluble inorganic base or the aqueous organic base is preferably used in the form of an aqueous solution thereof, and the mass percentage of the water-soluble inorganic base or the aqueous organic base in the aqueous solution is preferably 0.5 to 50%, and more preferably 5 to E40%, most preferably 15 to 30%. In the invention, after the impurity removal is finished, preferably, the obtained material is subjected to solid-liquid separation, and the obtained solid material is subjected to subsequent cleaning. The solid-liquid separation is not particularly limited in the present invention, and a technical scheme capable of achieving solid-liquid separation, which is well known to those skilled in the art, may be adopted. In the embodiment of the invention, a polypropylene bag or a polyethylene film is adopted for carrying out solid-liquid separation; the aperture of the polypropylene bag is preferably 2-50 μm; the pore diameter of the polyethylene film is preferably 0.2-0.45 μm.
The cleaning method is not specially limited, and the material obtained after impurity removal can be cleaned to be neutral. In the present invention, the washing reagent used for the washing preferably includes water or an organic solvent; the water is preferably deionized water, and the organic solvent preferably comprises methanol or ethanol. In the present invention, after the washing is completed, preferably, the obtained material is subjected to solid-liquid separation, and the obtained solid material is subjected to subsequent drying. The solid-liquid separation is not particularly limited in the present invention, and a technical scheme capable of achieving solid-liquid separation, which is well known to those skilled in the art, may be adopted. In the embodiment of the invention, a polypropylene bag or a polyethylene film is adopted for carrying out solid-liquid separation; the aperture of the polypropylene bag is preferably 2-50 μm; the pore diameter of the polyethylene film is preferably 0.2-0.45 μm.
The drying method of the present invention is not particularly limited, and a drying method known to those skilled in the art may be used. In the present invention, the drying preferably includes natural drying, vacuum drying, forced air drying or freeze drying. In the invention, the drying temperature of the vacuum drying or the forced air drying is preferably 80-120 ℃ independently, and more preferably 90-110 ℃; the drying time is preferably 4 to 72 hours, and more preferably 20 to 50 hours. In the present invention, the freeze-drying temperature is preferably-45 to-55 ℃, more preferably-48 to-51 ℃; the drying time is preferably 24-120 h, and more preferably 50-90 h.
The invention provides graphene-asphalt-based activated carbon prepared by the preparation method in the technical scheme, which comprises graphene and graphene on the surface of the grapheneThe carbon conversion rate of the activated carbon converted in situ by the asphalt is 70 to 80 percent. In the invention, the content of graphene in the graphene-asphalt-based activated carbon is preferably 5 to 50 wt%, more preferably 10 to 40 wt%, and most preferably 15 to 30 wt%. In the invention, the overall morphology of the graphene-asphalt-based activated carbon is in a petal-shaped lamellar structure, the graphene-asphalt-based activated carbon has a micropore-mesopore-macropore hierarchical pore structure, and the specific surface area is 750-2600 m2/g。
The invention provides application of the graphene-asphalt-based activated carbon in a super capacitor. In the present invention, the supercapacitor is preferably an electric double layer supercapacitor. In the present invention, the application preferably comprises the steps of:
mixing graphene-asphalt-based activated carbon and a binder to obtain mixed slurry;
and coating the mixed slurry on a conductive film, drying and cutting to assemble the double electric layer super capacitor.
In the invention, the graphene-asphalt-based activated carbon is preferably mixed with the binder to obtain the mixed slurry. In the present invention, the mass ratio of the graphene-pitch-based activated carbon to the binder is preferably 95: (4-6), more preferably 95: (4.5 to 5.5), most preferably 95: 5. in the present invention, the binder preferably includes polyvinylidene fluoride, vinylidene fluoride, hexafluoropropylene, polytetrafluoroethylene, LA132, LA133, LA135 or CMC. The invention has no special limitation on the mixing of the graphene-asphalt-based activated carbon and the binder, and adopts the technical scheme that materials can be uniformly mixed, which is well known by the technical personnel in the field.
After the mixed slurry is obtained, the mixed slurry is preferably coated on a conductive film, and after drying and cutting, the electric double layer super capacitor is assembled. The coating is not particularly limited, and the mixed slurry may be uniformly applied to a conductive film. In the present invention, the conductive film preferably includes a copper foil or a nickel foam. In the present invention, the drying is preferably vacuum drying or forced air drying. In the invention, the drying temperature of the vacuum drying or the forced air drying is preferably 50-80 ℃ independently, and more preferably 60-70 ℃; dry matterThe drying time is preferably 4 to 72 hours, and more preferably 20 to 50 hours. The present invention is not limited to the above-mentioned cutting, and the technical solution of cutting known to those skilled in the art may be adopted. The specific method for assembling the electric double layer supercapacitor is not particularly limited in the present invention, and the technical scheme for assembling the electric double layer supercapacitor well known to those skilled in the art may be adopted. In the present invention, the electrolyte used for assembling the electric double layer supercapacitor is preferably an aqueous electrolyte, an organic electrolyte, or an ionic liquid electrolyte; the aqueous electrolyte preferably comprises 6mol/L KOH aqueous solution or 1mol/L H2SO4(ii) a The organic electrolyte preferably includes tetraethylammonium Tetrafluoroborate (TEABF)4) And Acetonitrile (AN), or a mixed solution of tetraethylammonium tetrafluoroborate and Propylene Carbonate (PC); the ionic liquid electrolyte preferably comprises 1-ethyl-3-methylmilbezole tetrafluoroborate (EMIMBF)4) Or 1-butyl-3-methyloxazole tetrafluoroborate (BMIMBF)4). In the present invention, the separator used to assemble the electric double layer supercapacitor preferably includes celgard3501 or celgard 2400.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
(A) Heating petroleum asphalt at 120 ℃ for 2h, mixing 50g of heated petroleum asphalt with tetrahydrofuran and ethanol, stirring for 6h, mixing the obtained asphalt solution with graphene slurry (the mass of graphene in the graphene slurry is 5g), carrying out ultrasonic treatment at 40kHz frequency for 8h, then adding 50g of KOH, carrying out ultrasonic treatment at 40kHz frequency for 10h, removing liquid components in the obtained material by using a rotary evaporator (collecting organic solvent and cosolvent in the liquid components for recycling), and obtaining the rest material which is the mixed material of the petroleum asphalt, the graphene and the KOH;
(B) activating the mixed material at 500 ℃ for 4H in an argon atmosphere, wherein H with the mass concentration of 25 percent is used2SO4Washing the obtained activated material, then washing the activated material to be neutral by using deionized water, carrying out solid-liquid separation by using a polypropylene bag with the aperture of 20 mu m, and carrying out forced air drying on the obtained solid material at 120 ℃ for 6 hours to obtain graphene-asphalt-based activated carbon;
(3) according to the mass ratio of 95: 5, mixing the graphene-asphalt-based activated carbon with a binder LA133, then coating the obtained mixed slurry on foamed nickel, carrying out forced air drying at 60 ℃ for 6 hours, cutting, and assembling the double electric layer super capacitor; the electrolyte used in the assembly of the electric double layer super capacitor is 6mol/L KOH aqueous solution, and the used diaphragm is celgard 3501.
Fig. 1 is an SEM image of the graphene-pitch-based activated carbon prepared in example 1, and it can be seen from fig. 1 that the graphene-pitch-based activated carbon has a petal-like graphene sheet structure.
Fig. 2 is a charge/discharge diagram of the electric double layer supercapacitor assembled in example 1 at a constant current of 1A/g, and it can be seen from fig. 2 that the specific capacity of the graphene-pitch-based activated carbon prepared in example 1 is 268F/g.
Fig. 3 is a pore distribution diagram of the graphene-asphalt-based activated carbon prepared in example 1, and it can be seen from fig. 3 that the graphene-asphalt-based activated carbon prepared in example 1 has a unique pore distribution structure of a combination of micro-pores-meso-pores-macro-pores.
Example 2
(A) Heating petroleum asphalt at 120 ℃ for 2h, mixing 50g of heated petroleum asphalt with toluene and methanol, stirring for 24h, mixing the obtained asphalt solution with graphene slurry (the mass of graphene in the graphene slurry is 20g), performing ultrasonic treatment at 40kHz for 4h, adding 400mL of 3mol/L KOH aqueous solution, stirring for 12h at 800r/min, heating by using a blast oven at 100 ℃ to remove liquid components in the obtained material (collecting an organic solvent and a cosolvent in the liquid components for recycling), and obtaining a mixed material of petroleum asphalt, graphene and KOH as a residual material;
(B) activating the mixed material at 450 ℃ for 10 hours in an argon atmosphere, washing the obtained activated material by using HCl with the mass concentration of 15%, then washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene film with the pore diameter of 0.25 mu m, and performing forced air drying on the obtained solid material at 110 ℃ for 48 hours to obtain graphene-asphalt-based activated carbon;
(3) according to the mass ratio of 95: 5, mixing the graphene-asphalt-based activated carbon with a binder PVDF, then coating the obtained mixed slurry on foamed nickel, drying the foamed nickel in vacuum at 70 ℃ for 5 hours, cutting and assembling the double electric layer super capacitor; wherein the electrolyte used for assembling the double electric layer super capacitor is 1-butyl-3-methylimibenozole tetrafluoroborate (BMIMBF)4) The separator used was celgard 2400.
Fig. 4 is an SEM image of the graphene-asphalt-based activated carbon prepared in example 2, and it can be seen from fig. 4 that the graphene-asphalt-based activated carbon has a thinner petal-like graphene sheet structure.
Adding a binder PVDF into the graphene-asphalt-based activated carbon, and directly using the graphene-asphalt-based activated carbon as an electrode material of a double electric layer super capacitor without adding a conductive agent, wherein fig. 5 is a conductive performance test chart of the electrode material; as can be seen from fig. 5, as the content of graphene increases, the resistivity decreases, the resistance decreases, and the conductivity increases, indicating that the graphene-pitch-based activated carbon has excellent conductivity.
Fig. 6 is a charge/discharge diagram of the assembled electric double layer supercapacitor of example 2 at a constant current of 1A/g, and it can be seen from fig. 6 that the specific capacity of the graphene-pitch-based activated carbon prepared in example 2 is 105F/g.
Example 3
(A) Under the condition that the rotation speed of a sand mill is 2000r/min, performing frosting and crushing on coal tar pitch for 10 hours, then screening, sequentially washing 200-mesh coal tar pitch with HCl with the mass concentration of 10%, deionized water and ammonia water with the mass concentration of 10% for 3 times, performing solid-liquid separation by using a polypropylene bag with the aperture of 10 mu m, performing blast drying on the obtained solid material at 100 ℃ for 40 hours, mixing 100g of dried coal tar pitch with 30g of graphene and 100g of KOH, and performing ball milling on the obtained material for 10 hours under the condition that the rotation speed of a ball mill is 400r/min to obtain a mixed material of the coal tar pitch, the graphene and the KOH;
(B) activating the mixed material at 550 ℃ for 6 hours in a nitrogen atmosphere, washing the obtained activated material by using HCl with the mass concentration of 10%, then washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene film with the pore diameter of 0.45 mu m, and performing forced air drying on the obtained solid material at 120 ℃ for 30 hours to obtain graphene-asphalt-based activated carbon;
(3) according to the mass ratio of 95: 5, mixing the graphene-asphalt-based activated carbon with a binder CMC, coating the obtained mixed slurry on foamed nickel, blowing and drying for 5 hours at 70 ℃, cutting, and assembling an electric double layer super capacitor; the electrolyte used in the assembly of the electric double layer super capacitor is 6mol/L KOH aqueous solution, and the used diaphragm is celgard 2400.
FIG. 7 is a cyclic voltammogram of the supercapacitor prepared in example 3 at a sweeping speed of 5mv/s, and it can be seen from FIG. 7 that the specific capacity of the graphene-asphalt-based activated carbon prepared in example 3 is 192F/g.
Example 4
(A) Heating petroleum asphalt at 110 ℃ for 2h, mixing 60g of heated petroleum asphalt with N-N dimethylformamide and ethylene glycol, stirring for 24h, mixing the obtained asphalt solution with graphene slurry (the mass of graphene in the graphene slurry is 10g), stirring at 1200r/min for 8h, and adding 80% ZnCl2Stirring the aqueous solution for 6 hours at 1200r/min for 400mL, removing liquid components in the obtained material by adopting a polypropylene bag with the aperture of 5 mu m (collecting and recycling the organic solvent and the cosolvent in the liquid components), and obtaining the residual materials of petroleum asphalt, graphene and ZnCl2The mixed materials of (1);
(B) activating the mixed material at 600 ℃ for 5h in a nitrogen atmosphere, washing the obtained activated material by using a sodium methoxide aqueous solution with the mass concentration of 10%, then washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene film with the pore diameter of 0.25 mu m, and performing vacuum drying on the obtained solid material at 100 ℃ for 6h to obtain graphene-asphalt-based activated carbon;
(3) according to the mass ratio of 95: 5, mixing the graphene-asphalt-based activated carbon with a binder PTFE, then coating the obtained mixed slurry on foamed nickel, drying the foamed nickel in vacuum at 70 ℃ for 5 hours, cutting and assembling the double electric layer super capacitor; the electrolyte used in the assembly of the electric double layer super capacitor is 6mol/L KOH aqueous solution, and the used diaphragm is celgard 2400.
FIG. 8 is a cyclic voltammogram of the assembled supercapacitor of example 4 at a sweep rate of 5mv/s, and it can be seen from FIG. 8 that the specific capacity of the graphene-pitch-based activated carbon prepared in example 4 is 203F/g.
Example 5
(A) Under the condition that the rotating speed of a ball mill is 500r/min, carrying out ball milling and crushing on coal tar pitch for 4h, then sieving, sequentially washing 20-mesh coal tar pitch with HCl with the mass concentration of 10%, deionized water and ammonia water with the mass concentration of 10% for 3 times, carrying out solid-liquid separation by adopting a polypropylene bag with the aperture of 50 mu m, carrying out forced air drying on the obtained solid material at 100 ℃ for 24h, mixing 20g of dried coal tar pitch with N-N dimethylformamide, stirring for 10h, mixing the obtained asphalt solution with graphene slurry (the mass of graphene in the graphene slurry is 5g), stirring for 10h at 800r/min, and then adding 40g of Na2CO3Performing ultrasonic treatment at 40kHz frequency for 6h, removing liquid components in the obtained material by using a polypropylene bag with the aperture of 2 mu m (collecting organic solvent and cosolvent in the liquid components for recycling), and obtaining residual materials of coal tar pitch, graphene and Na2CO3The mixed materials of (1);
(B) activating the mixed material at 550 ℃ for 10 hours in a nitrogen atmosphere, washing the obtained activated material by using a sodium methoxide aqueous solution with the mass concentration of 10%, then washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene film with the pore diameter of 0.2 mu m, and performing forced air drying on the obtained solid material at 120 ℃ for 15 hours to obtain graphene-asphalt-based activated carbon;
(3) according to the mass ratio of 95: 5, mixing the graphene-asphalt-based activated carbon with a binder PTFE, then coating the obtained mixed slurry on foamed nickel, carrying out forced air drying at 70 ℃ for 5 hours, cutting, and assembling the double electric layer super capacitor; the electrolyte used in the assembly of the electric double layer super capacitor is 6mol/L KOH aqueous solution, and the used diaphragm is celgard 2400.
And (3) preparing the asphalt-based activated carbon according to the method without adding graphene, and assembling the electric double layer super capacitor according to the method.
Fig. 9 is an impedance graph of an electric double layer supercapacitor assembled of graphene-asphalt-based activated carbon and asphalt-based activated carbon prepared in example 5, in which graph a is all impedance data of the electric double layer supercapacitor from high frequency to low frequency, and graph B is an enlarged view of the electric double layer supercapacitor at high frequency and a small portion of low frequency; as can be seen from fig. 9, the impedance test of the electric double layer supercapacitor assembled with the graphene-pitch-based activated carbon showed a decrease in both the reaction resistance and the contact resistance.
Example 6
(A) Heating petroleum asphalt at 100 ℃ for 3h, mixing 50g of heated petroleum asphalt with toluene and ethanol, stirring for 24h, mixing the obtained asphalt solution with nitrogen-doped graphene slurry (the mass of the nitrogen-doped graphene in the nitrogen-doped graphene slurry is 20g), performing ultrasonic treatment at 40kHz frequency for 4h, and adding 80g K2CO3Performing ultrasonic treatment at 40kHz frequency for 5h, removing liquid components in the obtained material by using a rotary evaporator (collecting organic solvent and cosolvent in the liquid components for recycling), and obtaining residual materials of petroleum asphalt, nitrogen-doped graphene and K2CO3The mixed materials of (1);
(B) and (2) activating the mixed material at 600 ℃ for 5h in an argon atmosphere, washing the obtained activated material by using a NaOH aqueous solution with the concentration of 0.1mol/L, washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene membrane with the pore diameter of 0.45 mu m, and freeze-drying the obtained solid material at-55 ℃ for 48h to obtain the graphene-asphalt-based activated carbon.
Example 7
(A) Ultrasonically crushing coal tar pitch for 20 hours under the condition of the frequency of 30kHz, then sieving, sequentially washing 200-mesh coal tar pitch with HCl with the mass concentration of 20% and NaOH aqueous solution with the mass concentration of 10% and deionized water for 3 times, performing solid-liquid separation by using a polypropylene bag with the pore diameter of 10 mu m, performing forced air drying on the obtained solid material at 80 ℃ for 40 hours, mixing 50g of dried coal tar pitch with toluene and ethylene glycol, stirring for 10 hours, mixing the obtained asphalt solution with graphene slurry (the mass of graphene in the graphene slurry is 20g), stirring for 12 hours at 800r/min, then adding 400mL of KOH aqueous solution with the concentration of 4mol/L, stirring for 10 hours at 800r/min, removing liquid components in the obtained material by using a rotary evaporator (collecting organic solvent and cosolvent in the liquid components for recycling), the obtained residual material is a mixed material of coal tar pitch, graphene and KOH;
(B) and (2) activating the mixed material at 600 ℃ for 6h in a hydrogen-argon mixed atmosphere, washing the obtained activated material by using HCl with the mass concentration of 10%, washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene membrane with the pore diameter of 0.45 mu m, and performing forced air drying on the obtained solid material at 110 ℃ for 24h to obtain the graphene-asphalt-based activated carbon.
Example 8
(A) Under the condition that the rotating speed of a ball mill is 400r/min, carrying out ball milling and crushing on the coal tar pitch for 9 hours, then sieving, and sequentially using H with the mass concentration of 10% for 20 meshes of coal tar pitch2SO4Respectively washing the mixture with ethanol and deionized water for 3 times, performing solid-liquid separation by using a polypropylene bag with the aperture of 50 mu m, performing forced air drying on the obtained solid material at 100 ℃ for 48 hours, mixing 30g of dried coal tar pitch with N-N dimethylformamide, stirring for 10 hours, mixing the obtained pitch solution with phosphorus-doped graphene slurry (the mass of phosphorus-doped graphene in the phosphorus-doped graphene slurry is 6g), stirring for 10 hours at 800r/min, and then adding 40g of Na2CO3Performing ultrasonic treatment at 40kHz frequency for 6h, heating at 150 ℃ by using a blast oven to remove liquid components in the obtained material (collecting organic solvent and cosolvent in the liquid components for recycling), and obtaining residual materials of coal tar pitch, phosphorus-doped graphene and Na2CO3The mixed materials of (1);
(B) and (2) activating the mixed material at 500 ℃ for 6h in a nitrogen atmosphere, washing the obtained activated material by using a sodium methoxide aqueous solution with the mass concentration of 10%, washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene membrane with the pore diameter of 0.2 mu m, and freeze-drying the obtained solid material at-50 ℃ for 48h to obtain the graphene-asphalt-based activated carbon.
Example 9
(A) Heating petroleum asphalt at 120 ℃ for 1h, mixing 50g of heated petroleum asphalt with carbon disulfide and methanol, stirring for 24h, mixing the obtained asphalt solution with nitrogen-doped graphene slurry (the mass of the nitrogen-doped graphene in the nitrogen-doped graphene slurry is 10g), carrying out ultrasonic treatment at 40kHz for 4h, then adding 50g of KOH, carrying out ultrasonic treatment at 40kHz for 5h, heating at 150 ℃ by adopting an air blast drying box to remove liquid components in the obtained material (collecting an organic solvent and a cosolvent in the liquid components for recycling), and obtaining a mixed material of the petroleum asphalt, the nitrogen-doped graphene and the KOH as a residual material;
(B) and (2) activating the mixed material at 450 ℃ for 6h in a nitrogen atmosphere, washing the obtained activated material by using HCl with the mass concentration of 15%, washing the activated material to be neutral by using deionized water, performing solid-liquid separation by using a polyethylene film with the pore diameter of 0.45 mu m, and performing vacuum drying on the obtained solid material at 110 ℃ for 48h to obtain the graphene-asphalt-based activated carbon.
According to the embodiment, the graphene is added when the asphalt is used as the raw material to prepare the activated carbon, so that the activation temperature can be reduced, and a template agent is not required to be added; and the preparation method is simple, low in production cost and suitable for large-scale production.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (26)
1. A preparation method of graphene-asphalt-based activated carbon comprises the following steps:
(A) carrying out first mixing on asphalt and graphene to obtain a first mixed material; the first mixing is carried out in the presence of an organic solvent and a co-solvent; the organic solvent comprises dimethyl sulfoxide, carbon disulfide, benzene, toluene, tetrahydrofuran or N-N dimethylformamide; the cosolvent is low-carbon alcohol, and the low-carbon alcohol comprises methanol, ethanol, benzyl alcohol or ethylene glycol;
secondly, carrying out second mixing on the first mixed material and an activating agent, and removing liquid components in the obtained material after the second mixing is finished to obtain a mixed material of asphalt, graphene and the activating agent;
(B) and (3) under a protective atmosphere, activating the mixed material in the step (A) at 400-650 ℃ for 3-10 h, and sequentially removing impurities from the activated material, cleaning and drying to obtain the graphene-asphalt-based activated carbon.
2. The preparation method according to claim 1, wherein the mass ratio of the asphalt, the graphene and the activating agent in the step (A) is 100: (5.26-52.6): (100-200).
3. The production method according to claim 1 or 2, wherein the asphalt in the step (a) comprises coal tar pitch or petroleum asphalt, and the petroleum asphalt comprises solid petroleum asphalt or colloidal petroleum asphalt.
4. The method of claim 3, wherein the coal tar pitch comprises a low temperature pitch, a medium temperature pitch, or a high temperature pitch.
5. The method according to claim 3, wherein the petroleum asphalt comprises straight asphalt, solvent-deoiled asphalt, oxidized asphalt, blended asphalt, emulsified asphalt, or modified asphalt.
6. The method according to claim 3, wherein the coal tar pitch or the solid petroleum pitch is pretreated before use; the pretreatment comprises the steps of crushing, screening, washing and drying which are sequentially carried out.
7. The preparation method according to claim 6, wherein the particle size of the asphalt obtained after crushing is 20-200 meshes; the crushing comprises ball milling crushing, ultrasonic crushing, high-shear dispersion crushing or sanding crushing.
8. The preparation method according to claim 7, wherein when the ball milling crushing is adopted, the ball milling rotation speed is 100-600 r/min, and the ball milling time is preferably 6-72 h; when the ultrasonic crushing is adopted, the ultrasonic frequency is 20-40 kHz, and the ultrasonic time is 0.5-24 h; when the high-shear dispersing crushing is adopted, the shearing rotating speed is 100-3000 r/min, and the shearing time is 2-100 h; when the sanding is adopted for crushing, the sanding rotating speed is 1000-3000 r/min, and the sanding time is 1-12 h;
the sand milling and crushing are wet milling, and organic solvents adopted in the wet milling process comprise dimethyl sulfoxide, carbon disulfide, carbon tetrachloride, tetrahydrofuran, N-N dimethylformamide or lower alcohol compounds.
9. The preparation method of claim 6, wherein the washing reagent used for washing comprises one or more of inorganic acid, organic acid, inorganic base, organic solvent and water;
the inorganic acid comprises HCl and H2SO4、H3PO4、HNO3Or HClO4Wherein the inorganic acid is used in the form of an inorganic acid aqueous solution, and the mass percentage of the inorganic acid in the inorganic acid aqueous solution is 1-85%; the organic acid comprises formic acid or acetic acid; the inorganic base comprises NaOH, KOH and K2CO3Or NaHCO3The inorganic base is used in the form of an inorganic base aqueous solution, and the mass percentage of the inorganic base in the inorganic base aqueous solution is 1-85%;the organic solvent comprises ethanol, methanol, acetone or isopropanol.
10. The method according to claim 6, wherein the drying comprises natural drying, vacuum drying, forced air drying or freeze drying; the temperature of the vacuum drying or the forced air drying is independently 80-120 ℃, and the drying time is independently 4-72 h; the temperature of the freeze drying is-45 to-55 ℃, and the drying time is 24 to 120 hours.
11. The method of claim 3, wherein the colloidal petroleum asphalt is subjected to a heating treatment before use; the temperature of the heating treatment is 70-130 ℃, and the time of the heating treatment is 1-3 h.
12. The method according to claim 1 or 2, wherein the graphene in the step (a) comprises pure graphene or heteroatom-doped graphene.
13. The method of claim 12, wherein the heteroatom-doped graphene comprises nitrogen-doped graphene, phosphorus-doped graphene, sulfur-doped graphene, or nitrogen-phosphorus-doped graphene.
14. The production method according to claim 1 or 2, characterized in that the graphene is used in a solid form or in a graphene slurry form; the graphene slurry is a mixture of graphene and water, and the concentration of graphene in the graphene slurry is 7-12 mg/mL.
15. Preparation process according to claim 1 or 2, characterized in that the activator comprises KOH, NaOH, ZnCl2、K2CO3Or Na2CO3(ii) a The activator is used in solid form or in the form of an aqueous activator solution; the mass percentage of the activating agent in the activating agent water solution is 10-80%.
16. The method of claim 1, wherein the first mixing and the second mixing are performed by mixing methods independently comprising ball milling, shear stirring, magnetic stirring, pneumatic stirring, vacuum stirring, or ultrasonic mixing.
17. The preparation method of claim 16, wherein when the ball milling mixing is adopted, the ball milling rotation speed is 200-500 r/min, and the ball milling time is 2-48 h; when the ultrasonic mixing is adopted, the ultrasonic frequency is 20-40 kHz, and the ultrasonic time is 0.5-48 h; when the shearing, stirring and mixing are adopted, the shearing and stirring speed is 500-3000 r/min, and the shearing and stirring time is 1-36 h; when magnetic stirring, pneumatic stirring and vacuum stirring are adopted for mixing, the stirring speed is independently 200-1200 r/min, and the stirring time is independently 3-48 h.
18. The preparation method according to claim 1, wherein when the mixed material obtained after the second mixing includes an organic solvent and/or a cosolvent, the organic solvent and/or the cosolvent is recovered and reused.
19. The method of claim 18, wherein the method of recovering comprises: heating to 100-180 ℃ by adopting a rotary reduced pressure evaporator, heating to 100-220 ℃ by adopting a blast oven, or adopting a polypropylene bag with the aperture of 2-50 mu m.
20. The graphene-asphalt-based activated carbon prepared by the preparation method of any one of claims 1 to 19 comprises graphene and activated carbon in-situ converted from asphalt on the surface of the graphene, and the carbon conversion rate is 70% to 80%.
21. The graphene-pitch-based activated carbon as claimed in claim 20, wherein the content of graphene in the graphene-pitch-based activated carbon is 5 to 50 wt%.
22. The graphene-asphalt-based activated carbon as claimed in claim 20 or 21, wherein the morphology of the graphene-asphalt-based activated carbon is a petal-like graphene sheet structure, and the graphene-asphalt-based activated carbon has a micropore-mesopore-macropore combined pore distribution structure and a specific surface area of 750-2600 m2/g。
23. Use of the graphene-pitch-based activated carbon as claimed in any one of claims 20 to 22 in an electric double layer supercapacitor.
24. Use according to claim 23, characterized in that it comprises the following steps:
mixing graphene-asphalt-based activated carbon and a binder to obtain mixed slurry;
and coating the mixed slurry on a conductive film, drying and cutting to assemble the double electric layer super capacitor.
25. The use as claimed in claim 24, wherein the graphene-pitch based activated carbon to binder mass ratio is 95: (4-6); the binder comprises polyvinylidene fluoride, vinylidene fluoride, hexafluoropropylene, polytetrafluoroethylene, LA132, LA133, LA135, or CMC.
26. The use of claim 23, wherein the conductive film comprises copper foil or nickel foam; the electrolyte used for assembling the electric double layer super capacitor comprises an aqueous electrolyte, an organic electrolyte or an ionic liquid electrolyte; the aqueous electrolyte comprises 6mol/L KOH aqueous solution or 1mol/L H2SO4(ii) a The organic electrolyte comprises a mixed solution of tetraethylammonium tetrafluoroborate and acetonitrile, or a mixed solution of tetraethylammonium tetrafluoroborate and propylene carbonate; the ionic liquid electrolyte comprises 1-ethyl-3-methyloxazole tetrafluoroborate or 1-butyl-3-methyloxazole tetrafluoroborate; the separator used for assembling the electric double layer supercapacitor comprises celgard3501 or celgard 2400.
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| CN105923632A (en) * | 2016-04-18 | 2016-09-07 | 方大炭素新材料科技股份有限公司 | Preparation method of active carbon for super capacitor based on graphene composite modification |
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