WO2017219704A1 - 一种石墨烯、其制备方法及含有该石墨烯的超级电容器电极和超级电容器 - Google Patents

一种石墨烯、其制备方法及含有该石墨烯的超级电容器电极和超级电容器 Download PDF

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WO2017219704A1
WO2017219704A1 PCT/CN2017/076257 CN2017076257W WO2017219704A1 WO 2017219704 A1 WO2017219704 A1 WO 2017219704A1 CN 2017076257 W CN2017076257 W CN 2017076257W WO 2017219704 A1 WO2017219704 A1 WO 2017219704A1
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graphene
powder
magnesium
peak
carbon dioxide
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PCT/CN2017/076257
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English (en)
French (fr)
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马衍伟
李晨
张熊
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中国科学院电工研究所
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Priority to US16/312,851 priority Critical patent/US11111148B2/en
Publication of WO2017219704A1 publication Critical patent/WO2017219704A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00—Structure or properties of graphene
    • C01B2204/20—Graphene characterized by its properties
    • C01B2204/22—Electronic properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • 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
    • 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
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM

Definitions

  • the invention belongs to the field of carbon materials, and particularly relates to a graphene and a preparation method thereof.
  • Graphene is a two-dimensional material in the form of a hexagonal honeycomb lattice composed of carbon atoms connected by sp 2 hybrid orbitals. Its excellent mechanical, electrical, chemical and thermal properties have attracted worldwide attention from material researchers and are considered to be one of the most promising new materials of the next generation. Graphene has been put into practical use in the fields of energy storage, photoelectric conversion and catalysis.
  • the existing methods for preparing graphene are mainly divided into two types, one is a top-down method, that is, graphite is used as a source, and graphene is prepared by stripping a graphite block, which includes liquid phase stripping, mechanical stripping and oxidation. The reduction is stripping or the like; the other is the bottom-up method, which converts various carbon-containing small molecules into graphene, and the method includes chemical vapor deposition and crystal epitaxial growth.
  • the preparation of graphene from carbon dioxide is a new method for preparing graphene in recent years. This method has the advantages of wide source of raw materials, low price, and easy post-treatment of products. Therefore, it is considered to be a way to solve the problem of large-scale preparation of high-quality graphene.
  • Chakrabarti et al. burned magnesium metal in dry ice to prepare a carbon nanocapsule (J. Mater. Chem. 2011, 21, 9491).
  • a method of preparing mesoporous graphene comprising the steps of:
  • Step 1 the metal magnesium powder and the magnesium oxide powder are uniformly mixed to obtain a mixed powder, the mixed powder is placed in a sealed pressure-resistant container, and a tungsten wire coil is embedded in the mixed powder;
  • Step 2 using a molecular pump to reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 ⁇ 4 Pa, and introducing a carbon dioxide gas having a purity of 90-99.99% into the sealed pressure resistant container to the sealed pressure resistant container
  • the internal pressure is 0.125-10 MPa, wherein the rate of introduction of carbon dioxide gas is 100-10000 sccm;
  • Step 3 applying 0.5-30 A DC power to the tungsten wire coil by using a DC power source, and the power-on time is 5-30 seconds.
  • the tungsten wire coil generates a high temperature to initiate the reaction of the magnesium metal powder with carbon dioxide, and a black powder is obtained after 1-2 minutes of reaction;
  • Step 4 the black powder is placed in a dilute acid solution for 6-48 h, and then the black powder is washed by deionized water to neutral to obtain a filter cake, and the filter cake is freeze-dried to obtain a mesoporous layer.
  • Graphene powder is placed in a dilute acid solution for 6-48 h, and then the black powder is washed by deionized water to neutral to obtain a filter cake, and the filter cake is freeze-dried to obtain a mesoporous layer.
  • the metal magnesium powder has a purity of 90-99.99%, an average particle diameter of 1-1000 ⁇ m
  • the magnesium oxide powder has a purity of 90-99.99%, and an average particle diameter of 0.1-1000 ⁇ m.
  • the mass ratio of the metal magnesium powder to the magnesium oxide powder in the mixed powder is 1:0-1:10.
  • the dilute acid solution is dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid having a concentration of 0.2-2M.
  • the sealed pressure-resistant container is a steel sealed pressure-resistant container having a volume of 10-200L.
  • freeze drying in step 4 comprises the following steps:
  • Step 4.1 the filter cake is placed in a plastic beaker, and deionized water is added to the plastic beaker, ultrasonicated and stirred to obtain a paste;
  • Step 4.2 the paste is frozen in a cryogenic liquid for 2-30 minutes to obtain a black solid
  • step 4.3 the black solid is dried in a freeze dryer to obtain the mesoporous graphene powder.
  • step 4.1 the mass ratio of the deionized water to the filter cake is 1:1-8:1.
  • the cryogenic liquid is liquid nitrogen, liquid helium or liquid argon.
  • the mesoporous graphene powder has a carbon oxide atomic ratio of higher than 80, and the pore size distribution has a uniform single peak distribution.
  • the mesoporous graphene powder has a pore diameter of 4 nm.
  • One aspect of the invention provides a method of preparing graphene, comprising the steps of:
  • the chemical equation for the reaction of the magnesium metal powder with carbon dioxide is: 2Mg+CO 2 ⁇ 2MgO+C.
  • the reaction of the magnesium metal powder with carbon dioxide is a self-propagating reaction.
  • the method of preparing graphene of any of the following further comprises the steps of:
  • any of the methods of preparing graphene, step iii) comprises: pickling the product of step ii).
  • the method of preparing graphene of any of the following further comprises the steps of:
  • any one of the methods of preparing graphene, in step i), the mixture consists of metallic magnesium powder and solid oxide powder.
  • step i) comprises mixing the magnesium metal powder and the solid oxide powder in a closed vessel filled with carbon dioxide.
  • the mass ratio of the metal magnesium powder to the solid oxide powder is 1:0.1-10.
  • the mass ratio of the solid oxide powder to the metal magnesium powder is from 1 to 9:1.
  • the method for preparing graphene according to any one of the steps wherein the mass ratio of the solid oxide powder to the metal magnesium powder is from 2 to 9:1.
  • the method for preparing graphene according to any one of the steps wherein the mass ratio of the solid oxide powder to the metal magnesium powder is from 4 to 9:1.
  • the method for preparing graphene according to any one of the steps wherein the mass ratio of the solid oxide powder to the metal magnesium powder is from 6 to 9:1.
  • the method for preparing graphene according to any one of the steps wherein the mass ratio of the solid oxide powder to the metal magnesium powder is from 7 to 9:1.
  • the mass ratio of the solid oxide powder to the metal magnesium powder is from 6 to 8:1.
  • any one of the methods for preparing graphene, in step i), the average particle size of the magnesium metal powder is 9 to 9000 ⁇ m.
  • any one of the methods of producing graphene, the solid oxide being an alkaline earth metal oxide is any one of the methods of producing graphene, the solid oxide being an alkaline earth metal oxide.
  • any one of the methods of producing graphene, the solid oxide being magnesium oxide is any one of the methods of producing graphene, the solid oxide being magnesium oxide.
  • any of the methods of preparing graphene, the environment of step i) is free of oxygen.
  • any one of the methods for producing graphene, in step i), the content of carbon dioxide in the environment is 90% by volume or more.
  • the method of preparing graphene of any one, in step i), the carbon dioxide content in the environment is from 90 to 99.99% by volume.
  • any one of the methods of preparing graphene, in step ii), the metal conductor is a tungsten wire.
  • the method of preparing graphene, in step ii), wherein the energized metal conductor is passed through a direct current of 0.5-30 A eg, 1A, 5A, 10A, 15A, 20A, or 25A.
  • any one of the methods of preparing graphene, in step i), the volume of the closed container is 10-200 L (eg, 15 L, 25 L, 50 L, 100 L, 150 L).
  • the content of the metallic magnesium powder in the closed vessel is from 1 to 100 g/24 L, for example from 8 to 40 g/24 L.
  • the solid oxide powder in step i), is contained in the closed container in an amount of from 1 to 500 g/24 L, for example from 8 to 320 g/24 L.
  • any of the methods of preparing graphene includes the next step or multiple steps:
  • the gas pressure in the sealed pressure vessel is reduced to 2 ⁇ 10 -4 Pa, carbon dioxide gas is introduced into the sealed pressure vessel, the pressure in the sealed pressure vessel is 0.125 ⁇ 10MPa;
  • step d) The powder product of step c) is placed in a dilute acid solution for 6-8 hours, and the powder is washed by suction filtration using deionized water, and the filtrate is collected, and the filtrate is freeze-dried to obtain graphite. Alkene.
  • a graphene having a specific surface area of from 350 to 750 m 2 g -1 and a pore volume of from 1 to 2 cm 3 /g.
  • the graphene of any one has a specific surface area of from 400 to 750 m 2 g -1 .
  • the graphene of any one has a specific surface area of from 500 to 750 m 2 g -1 .
  • the graphene of any one has a specific surface area of from 600 to 750 m 2 g -1 .
  • the graphene of any one has a specific surface area of from 650 to 750 m 2 g -1 .
  • the graphene of any one has a specific surface area of from 680 to 710 m 2 g -1 .
  • the graphene of any one has a pore volume of from 0.8 to 1.8 cm 3 g -1 .
  • the graphene of any one has a pore volume of from 1 to 1.8 cm 3 g -1 .
  • the graphene of any one has a pore volume of from 1.2 to 1.8 cm 3 g -1 .
  • the graphene of any one has a pore volume of from 1.4 to 1.8 cm 3 g -1 .
  • the graphene of any one has a pore volume of from 1.5 to 1.6 cm 3 g -1 .
  • the graphene of any one has a nitrogen isothermal adsorption-desorption curve having a hysteresis loop.
  • the graphene of any one has a pore size distribution curve having a peak in the range of 3 to 5 nm.
  • the graphene of any one has a pore size distribution curve having a peak in the range of 3.5 to 4.5 nm.
  • the graphene of any one has only one peak in the pore size distribution curve.
  • the graphene of any one has a peak having a peak width of 0.5 to 3 nm on a pore size distribution curve.
  • the graphene of any one has a peak having a peak width of 0.5 to 2 nm on a pore size distribution curve.
  • the graphene of any one has a peak having a peak width of 0.5 to 1 nm on a pore size distribution curve.
  • the graphene of any one has a peak having a half width of 0.5 to 3 nm on a pore size distribution curve.
  • the graphene of any one has a peak having a half width of 0.5 to 2 nm on a pore size distribution curve.
  • the graphene of any one has a peak having a half width of 0.5 to 1 nm on a pore size distribution curve.
  • the graphene of any one of the graphene has a side layer number of 10 or less.
  • the graphene of any one of the graphene has a side layer number of 5 or less.
  • the graphene of any one of the graphene has a side layer number of 5 to 15 layers.
  • the graphene of any one of the graphene has an atomic ratio of carbon oxide elements of 70 or more.
  • the graphene of any one of the graphene has an atomic ratio of carbon oxide elements of 80 or more.
  • the graphene of any one of the graphene has an atomic ratio of carbon oxide elements of from 80 to 90, such as 82.
  • the graphene of any one has a carbon content greater than 90 at%.
  • the graphene of any of the graphenes has a carbon content of greater than 92 at%.
  • the graphene of any of the graphenes has a carbon content of greater than 94 at%.
  • the graphene of any of the graphenes has a carbon content greater than 96 at%.
  • the graphene of any of the graphenes has a carbon content of greater than 97 at%.
  • the graphene of any one of the graphene has a carbon content of from 90 to 99 at%.
  • the graphene of any one of the graphene has a thermogravimetric curve under a nitrogen atmosphere with a weight loss from 600 to 800 ° C of less than or equal to 5%.
  • the graphene of any one of the graphene has a thermogravimetric curve under a nitrogen atmosphere, and the weight loss from 600 to 800 ° C is less than or equal to 4%.
  • the graphene of any one of the graphene has a thermogravimetric curve under a nitrogen atmosphere, and the weight loss from 600 to 800 ° C is less than or equal to 3%.
  • the graphene of any one of the graphene has a thermogravimetric curve under an air atmosphere, and when the temperature is raised to 800 ° C, the weight loss rate is 98% or more.
  • the graphene of any one of the graphene has a thermogravimetric curve under an air atmosphere, and when the temperature is raised to 800 ° C, the weight loss rate is 99% or more.
  • the graphene of any one of the graphene has a thermogravimetric curve under an air atmosphere, and when the temperature is raised to 800 ° C, the weight loss rate is 100%.
  • the graphene of any one has a relaxation time constant of less than or equal to 0.02 s.
  • the graphene of any one has a relaxation time constant of less than or equal to 0.015 s.
  • the graphene of any one of the graphene has a conductivity of 8000 S m -1 or more.
  • the graphene in the graphene of any one, has a conductivity of 10000 S m -1 or more.
  • the graphene of any one of the graphene has a conductivity of 12,000 Sm -1 or more.
  • the graphene of any one of the graphene has a conductivity of 8000 to 15000 S m -1 .
  • the graphene of any one of the graphene has a conductivity of 11,000 to 13000 S m -1 .
  • the graphene of the graphene has an intensity ratio I D /I G of D peak to G peak on the Raman spectrum of the graphene of 0.3 or more.
  • the graphene of the graphene has an intensity ratio I D /I G of D peak to G peak on the Raman spectrum of the graphene of 0.5 or more.
  • the intensity ratio D D /I G of the D peak to the G peak on the Raman spectrum of the graphene is 0.7 or more.
  • the graphene of the graphene has an intensity ratio I D /I G of D peak to G peak on the Raman spectrum of the graphene of 0.9 or more.
  • the graphene of any one of the graphene has an intensity ratio I D /I G of a D peak to a G peak of 0.3 to 1.2 on a Raman spectrum.
  • the graphene of any one of the graphene is assembled into a supercapacitor and the electrolyte is an ionic liquid (EMIMBF 4 ).
  • EMIMBF 4 ionic liquid
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the energy density of the ultracapacitor is 20 ⁇ 100Wh kg -1, for example 50 ⁇ 100Wh kg -1, e.g. 22.3Wh kg -1, 23.5Wh kg -1, 33.8Wh kg -1 , 49.1Wh kg -1 or 73Wh kg -1 .
  • the energy density of the ultracapacitor is 40 ⁇ 60Wh kg -1, e.g. 53Wh kg -1.
  • the supercapacitor has a charge retention rate of 80 to 95%, for example, 90% after a charge and discharge cycle of 1,000,000 cycles at a current density of 100 A g -1 .
  • the graphene of any one of the graphene is assembled into a supercapacitor and the electrolyte is an ionic liquid (EMIMBF 4 ).
  • EMIMBF 4 ionic liquid
  • a constant current charge and discharge test was performed in a voltage range of 0-4V.
  • the charge-discharge current of 5A g -1 the specific capacitance of supercapacitors 150 ⁇ 200F g -1, e.g. 192F g -1; at a charge-discharge current of 100A g -1, the specific capacitance of supercapacitors 100 ⁇ 150F g -1 , for example 148F g -1 .
  • the energy density of the supercapacitor is 70-120 Wh kg -1 , for example 106 Wh kg -1 .
  • the energy density of the ultracapacitor is 50 ⁇ 100Wh kg -1, e.g. 82Wh kg -1.
  • the supercapacitor has a charge retention rate of 70 to 83%, for example, 81%, after a charge and discharge cycle of 100 A g -1 at a current density of 80,000 cycles.
  • the graphene of any one of the graphene is assembled into a supercapacitor and the electrolyte is an ionic liquid (EMIMTFSI).
  • EMIMTFSI ionic liquid
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the charge-discharge current of 2A g -1 the specific capacitance of supercapacitors 150 ⁇ 200F g -1, e.g. 190F g -1; at a charge-discharge current of 100A g -1, the specific capacitance of supercapacitors 100 ⁇ 150F g -1 , for example 143F g -1 .
  • the energy density of the ultracapacitor is 70 ⁇ 100Wh kg -1, e.g. 81Wh kg -1; at a power density of 175kW kg -1, the energy density of the ultracapacitor is 50 ⁇ 80Wh kg -1 , for example 61Wh kg -1 .
  • the supercapacitor was charged and discharged at a current density of 100 A g -1 for 10,000 cycles, and the capacity retention ratio was 80 to 90%, for example, 89%.
  • the graphene of any one of the graphene is assembled into a supercapacitor and the electrolyte is an ionic liquid (EMIMTFSI).
  • EMIMTFSI ionic liquid
  • a constant current charge and discharge test was performed in a voltage range of 0-4V.
  • the charge-discharge current 5A g -1 the specific capacitance of supercapacitors 200 ⁇ 250F g -1, e.g. 244F g -1; at a charge-discharge current of 100A g -1, the specific capacitance of supercapacitors 150 ⁇ 200F g -1 , for example 173F g -1 .
  • the energy density of the ultracapacitor is 100 ⁇ 150Wh kg -1, e.g. 135Wh kg -1; at a power density of 200kW kg -1, the energy density of the ultracapacitor is 80 ⁇ 120Wh kg - 1 , for example 96Wh kg -1 .
  • the supercapacitor was charged and discharged at a current density of 100 A g -1 for 10,000 cycles, and the capacity retention ratio was 65 to 75%, for example, 70%.
  • the graphene of any one, the graphene is mesoporous graphene.
  • the graphene of any one of the graphenes is produced by any of the methods for preparing graphene.
  • Example 1 is a scanning electron micrograph of graphene of Example 1;
  • Example 5 is a nitrogen isothermal adsorption-desorption curve of graphene of Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6;
  • Example 6 is a pore size distribution curve of the graphene of Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6 by nitrogen isothermal adsorption-desorption test;
  • Figure 7 is a graph showing the thermal weight loss curve of graphene and commercial graphite powder of Example 1 in a nitrogen atmosphere;
  • Figure 8 is a graph showing the thermal weight loss curve of graphene of Example 1 in an air atmosphere
  • Example 10 is a charge and discharge curve of graphene in Example 1 in an ionic liquid, wherein charge and discharge current densities are 100, 200, 300, 400, 500 A g -1 , respectively;
  • Figure 11 is a Bode diagram of graphene of Example 1 in an ionic liquid
  • Figure 12 is a graph showing the rate characteristic of the graphene of Example 1 in an ionic liquid
  • Figure 13 is a Ragone diagram of graphene of Example 1 in an ionic liquid
  • Figure 14 is a graph showing the cycle capacity of the graphene of Example 1 in an ionic liquid.
  • the disclosed embodiment uses a mixed powder of magnesium metal powder and magnesium oxide powder as a raw material, and has a wide range of raw materials.
  • the mass ratio of the magnesium metal powder and the magnesium oxide powder is adjusted to regulate the layer number and pore size distribution of the product graphene, and a large amount of magnesium oxide is Agglomeration and stacking of graphene can be successfully prevented during the reaction, and a small amount of graphene is prepared.
  • the reaction is simple and easy, the cost is low, the yield is high, no pollution, and the product graphene has less impurities, high carbon-oxygen ratio, excellent capacitance performance and electrochemical stability, and the graphene of the disclosed embodiment can be directly used as a super capacitor.
  • the graphene of the disclosed embodiments has a lower oxygen content.
  • the graphene of the disclosed embodiments has a higher electrical conductivity.
  • the graphene of the disclosed embodiments has a relatively high specific surface area.
  • the graphene of the disclosed embodiments has a larger pore volume.
  • the supercapacitor having the graphene of the disclosed embodiment as an electrode and an ionic liquid as an electrolyte exhibits a high specific capacitance.
  • the supercapacitor having the graphene of the disclosed embodiment as an electrode and an ionic liquid as an electrolyte exhibits a high cycle capacity retention ratio.
  • the supercapacitor having the graphene of the disclosed embodiment as an electrode and an ionic liquid as an electrolyte exhibits a higher energy density.
  • One function of the oxide powder is to direct the growth of graphene on the surface of the oxide.
  • One function of the oxide powder is to separate the graphene layers from each other as a spacer.
  • the graphene prepared by the disclosed embodiment has rich mesopores, uniform pore size distribution, controllable number of layers, no impurities, high carbon-oxygen atomic ratio, wide source of raw materials, simple and easy reaction, and easy industrialization.
  • test instruments and methods in the following examples are as follows:
  • Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) tests were performed using a Hitachi S-4800 with an acceleration voltage of 20 kV.
  • the graphene sample was first dispersed in ethanol, and then the graphene ethanol was dispersed on a silicon wafer for SEM analysis.
  • Transmission electron microscopy (TEM) and HR-TEM (high resolution-TEM) tests were performed using JEOL JEM-2010 equipped with selected area electron diffraction. The accelerated voltage tested was 200 kV.
  • HR-TEM testing of spherical aberration correction using the JEOL JEM-2100F In the TEM test, the sample preparation method was as follows: The ethanol dispersion of the sample was dropped on an ultrathin amorphous carbon coated copper mesh, and then dried at room temperature for 1 hour.
  • X-ray diffraction (XRD) testing was performed using a Bruker D8 multifunctional X-ray diffractometer. The instrument uses monochromatic copper K ⁇ radiation The scanning speed is 10 degrees per minute.
  • a micro-Raman test was performed using a confocal Raman system (LabRam HR-800, Horiba Jobin Yvon) using an excitation wavelength of 532 nm. The position and full width at half maximum (FWMH) of the D and G bands on the Raman spectrum were determined by Lorentz fitting.
  • X-ray photoelectron spectroscopy was performed using PHI Quantear SXM to analyze the chemical composition of the sample; the test was carried out at 6.7 x 10 -8 Pa, and Al was used as the anode probe.
  • Electron energy loss spectroscopy was performed using a spherical aberration corrected JEOL JEM-2100F TEM, and commercial graphite powder (325 mesh) was used as a reference.
  • the conductivity test method is as follows: SHSG-8 mesoporous graphene powder is now pressed into a sheet having a thickness of 320 ⁇ m at 6 MPa, and then the conductivity of the sheet is tested by a four-probe conductivity tester.
  • Thermogravimetric analysis was performed using a Netzsch TG 209 F3 Tarsus, tested in N 2 and air atmosphere, respectively, and ramped from 50 ° C to 800 ° C at a rate of 5 Kmin -1 .
  • a nitrogen suction/desorption test was performed at 77 K using a Micromeritics ASAP 2020 HD Analyzer to obtain a specific surface area of the graphene sample. Samples were degassed under vacuum at 150 °C for 12 hours prior to the suction/desorption test.
  • BET Brunauer-Emmett-Teller
  • the specific surface area value was calculated from the amount of adsorption of the lower N 2 at a relative pressure P/P 0 of 0.3 or less.
  • the pore size distribution is calculated based on the Barrett-Joyner-Halenda (BJH) model.
  • the cumulative pore volume is obtained based on density functional theory.
  • Capacitor performance of graphene as a supercapacitor electrode was tested using a two-electrode system.
  • the working electrode was prepared by a doctor blade casting method. 70 wt% of graphene powder, 20 wt% of carbon black was mixed in an agate mill, and then 10 wt% of polyvinylidene fluoride (PVDF) and several drops of N-methylpyrrolidone (NMP) were added to obtain a slurry.
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the prepared electrode was dried at 120 ° C for 12 hours and then punched into a disk having a diameter of 13 mm. Two identical electrodes and one piece of ion porous membrane were clamped in a 2032 coin cell for further testing. Cyclic voltammetry (CV) testing, electrochemical impedance (EIS) testing and constant current charging and discharging testing (GCD) were performed using a BioLogic VMP3 electrochemical analyzer. The EIS test was tested from 100 mHz to 100 kHz with an amplitude of 10 mV.
  • Step 1 taking 40g of magnesium metal powder and 320g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 1 MPa;
  • step 3 a direct current power source is used to apply a direct current of 3 A to both ends of the tungsten wire coil, and the energization time is 10 s.
  • the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 minute. After obtaining a black powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 10 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-8.
  • Example 1 is a scanning electron micrograph of mesoporous graphene obtained in Example 1, from which it can be observed that there is a significant gap between the graphene layers, so that the graphene sheets are isolated from each other with clear boundaries, which proves that the method of the embodiment can be avoided.
  • severe stacking or agglomeration between graphene sheets is common in the preparation of graphene.
  • the mesoporous graphene of the present embodiment is a small layer of graphene. It can be seen by observing the edge of the graphene sheet in the transmission electron micrograph shown in Fig. 2 that the number of graphene layers prepared in this example is below 5 layers.
  • FIG. 3 is an X-ray diffraction pattern of graphene prepared in the present example, in which the abscissa is 2 ⁇ and the ordinate is diffraction intensity. It can be seen that the (002) and (100) characteristic peaks belonging to the graphite structure appear in the vicinity of 26° and 43°, indicating that the product has a graphene six-element honeycomb structure, and no magnesium oxide or magnesium oxide appears in the spectrum. The peak of magnesium indicates that the graphene prepared in this example has high purity and no impurities such as magnesium oxide.
  • XPS X-ray photoelectron spectroscopy
  • the nitrogen isothermal adsorption-desorption curve of the graphene produced in this example showed a hysteresis loop peculiar to the mesoporous material when the P/P 0 range was 0.4-0.9.
  • the mesoporous graphene of the present embodiment has a specific surface area of up to 709 m 2 g -1 and a pore volume of up to 1.52 cm 3 g -1 , which proves that it has a rich mesoporous structure and a large specific surface area.
  • Fig. 6 is a graph showing the pore size distribution of graphene prepared in Examples 1 to 6, wherein the abscissa is the pore diameter and the ordinate is the pore volume. It can be clearly observed that the material exhibits a single pore size distribution around 4 nm, indicating that the product has a highly uniform mesoporous channel. In the pore size distribution curves of the graphenes of Examples 1 to 6, the peak width of each peak was less than 1 nm, and the half width was less than 1 nm.
  • Figure 7 is a graph showing the thermal weight loss curve of mesoporous graphene and commercial graphite powder prepared in the present example under a nitrogen atmosphere. Ratio, wherein the abscissa is the temperature and the ordinate is the weight loss. It can be observed that in the high temperature range of 600-800 ° C, the weight loss of the graphene prepared in this example is lower than that of the commercial graphite powder, indicating that it has excellent Thermal stability. As shown, the graphene of this example was reduced from 96% to 93% at from 600 to 800 °C.
  • Fig. 8 is a graph showing the thermal weight loss curve of the mesoporous graphene produced in the present embodiment under an air atmosphere, wherein the abscissa is temperature, the left ordinate is loss of weight, and the right ordinate is weight loss. Observing the curve, it was found that when the temperature was raised to 800 ° C, the weight loss rate was 100%, indicating that the purity of the product was extremely high, and the impurities were extremely small, and also showed that the magnesium powder and the magnesium oxide powder used in the preparation method of the present example were in the post-treatment process. Can be completely removed.
  • thermogravimetric test is the remaining product mass fraction.
  • Figures 9-14 illustrate the electrochemical performance of mesoporous graphene prepared in this example as an ultracapacitor electrode in an ionic liquid.
  • the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4 ).
  • FIG. 9 is an embodiment of the graphene in the ionic liquid cyclic voltammograms, wherein the scan rates were 2000mV s -1, 5000mV s -1, 10000mV s -1, 20000mV s -1, wherein the abscissa is the voltage The ordinate is the current, and the direction of the arrow indicates that the sweep speed is increased.
  • the cyclic volt-ampere curve of the material is a nearly standard rectangle with no redox peaks.
  • the cyclic voltammetry curve still maintains a rectangular shape, which proves that the material prepared in this embodiment has excellent electric double layer capacitance properties.
  • FIG 10 shows the graphene (SHSG-8) of Example 1 in an ionic liquid charge-discharge curve (GCD curve) (4 EMIMBF) in which, respectively, charge and discharge current density of 100A g -1, 200A g -1, 300A g -1 , 400A g -1 , 500A g -1 , wherein the abscissa is time, the ordinate is voltage, and the direction of the arrow indicates an increase in current density.
  • the charge-discharge curve is a symmetrical triangle, indicating that the graphene produced by the present embodiment has good capacitance behavior and is suitable for use in a supercapacitor electrode material.
  • the GCD curve at 100Ag -1 current showed a voltage drop of 0.06V at the beginning of the discharge curve, indicating that the supercapacitor has low equivalent resistance (ESR) and excellent power capacity and low resistance.
  • ESR equivalent resistance
  • Figure 11 is a Bode diagram of graphene of Example 1 in ionic liquid EMIMBF 4 , wherein the abscissa is the frequency and the ordinate is the phase angle. It can be found that the material has excellent frequency response characteristics, and the relaxation time constant ( ⁇ 0 ) is as low as 0.012 sec, indicating that the graphene based on the embodiment 1 is used as an electrode, and the electrode surface can form an electric double layer quickly and efficiently, that is, The ability to store energy quickly.
  • Fig. 12 is a graph showing the rate characteristic of the graphene of Example 1 in the ionic liquid EMIMBF 4 , wherein the abscissa is the current density and the ordinate is the specific capacitance.
  • the charge-discharge current density is 2A g -1
  • the material capacity is as high as 180F g -1
  • the material can still maintain a capacity of 100F g -1 .
  • the above results demonstrate that the graphene of Example 1 can be used as an electrode material for a high current supercapacitor. Since the mesoporous graphene material of the present embodiment has excellent capacitance properties and rate characteristics, the electrode prepared using the graphene can exhibit superior energy density and power density.
  • Figure 13 shows a Ragone diagram of graphene of Example 1 in ionic liquid EMIMBF 4 , where the abscissa is the power density and the ordinate is the energy density. It can be seen from the figure that when the power density is 3.5 kW kg -1 , the electrode energy density of the graphene produced based on this embodiment is as high as 73 Wh kg -1 . More importantly, when the electrode is operated at a power density of up to 875 kW kg -1 , the energy density is still 42 Wh kg -1 , indicating that the graphene material produced in this embodiment has both high energy density and high power density.
  • the mesoporous graphene prepared in the present example has excellent cycle stability.
  • FIG. 14 is a graph showing the cycle capacity curve of the graphene of Example 1 in the ionic liquid EMIMBF 4 , wherein the abscissa is the number of cycles, the left ordinate is the capacity retention ratio, and the right ordinate is the Coulomb efficiency, up to 100 A g- 1
  • the charge and discharge current works for 1 million cycles, that is, after 600 hours of continuous operation, the material can still maintain 90% of the initial energy. After 1 million cycles, the coulombic efficiency of the electrode is still greater than 99%.
  • the electrochemical characterization results of FIGS. 9 to 14 above demonstrate that the graphene of Example 1 is a supercapacitor electrode having high capacitance value, good rate characteristic, extremely high energy density, and power density in the ionic liquid EMIMBF 4 .
  • the graphene of the first embodiment can be suitably used as an electrode material for a high-power, high-current supercapacitor.
  • the graphene (SHSG-8) of Example 1 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the super capacitor in the charge-discharge current of 2A g -1, the specific capacitance of supercapacitors 172F g -1.
  • the super capacitor power density at 3.5kW kg -1, the energy density of the ultracapacitor is 73Wh kg -1.
  • the super capacitor power density at 175kW kg -1 the energy density of the ultracapacitor is 53Wh kg -1.
  • the supercapacitor has a capacity retention rate of 90% after a charge and discharge cycle of 1,000,000 cycles at a current density of 100 A g -1 .
  • the graphene (SHSG-8) of Example 1 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-4V.
  • the supercapacitor charging and discharging at a current of 5A g -1, the specific capacitance of supercapacitors 192F g -1.
  • the super capacitor charge-discharge current at 100A g -1, the specific capacitance of supercapacitors 148F g -1.
  • the super capacitor power density at 10kW kg -1, the energy density of the ultracapacitor is 106Wh kg -1.
  • the supercapacitor at a power density of 200kW kg -1, the energy density of the ultracapacitor is 82Wh kg -1.
  • the supercapacitor has a capacity retention rate of 81% after a charge and discharge cycle of 80000 g at a current density of 100 A g -1 .
  • the graphene (SHSG-8) of Example 1 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMTFSI).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the super capacitor in the charge-discharge current of 2A g -1, the specific capacitance of supercapacitors 190F g -1.
  • the super capacitor power density at 3.5kW kg -1, the energy density of the ultracapacitor is 81Wh kg -1.
  • the super capacitor power density at 175kW kg -1 the energy density of the ultracapacitor is 61Wh kg -1.
  • the supercapacitor has a charge retention rate of 89% after a charge and discharge cycle of 10000 cycles at a current density of 100 A g -1 .
  • the graphene (SHSG-8) of Example 1 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMTFSI).
  • a constant current charge and discharge test was performed in a voltage range of 0-4V.
  • the supercapacitor charging and discharging at a current of 5A g -1, the specific capacitance of supercapacitors 244F g -1.
  • the super capacitor charge-discharge current at 100A g -1, the specific capacitance of supercapacitors 173F g -1.
  • the super capacitor power density at 10kW kg -1, the energy density of the ultracapacitor is 135Wh kg -1.
  • the super capacitor power density at 200kW kg -1 the energy density of the ultracapacitor is 96Wh kg -1.
  • the supercapacitor has a capacity retention rate of 70% after a charge and discharge cycle of 10000 cycles at a current density of 100 A g -1 .
  • the graphene of Example 1 had an electric conductivity of 13,000 S m -1 .
  • Step 1 taking 8g of magnesium metal powder and 48g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 1 000 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 1000 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, using a molecular pump to reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 ⁇ 4 Pa, and then introducing a carbon dioxide gas having a purity of 99.9% into the sealed pressure vessel at a flow rate of 10000 sccm until the sealed pressure vessel is closed.
  • the gas pressure is 1 MPa;
  • Step 3 using a DC power source to apply a direct current of 30 A to both ends of the tungsten wire coil, the energization time is 5 s, the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 2 minutes. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 6 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-6.
  • the graphene (SHSG-6) prepared in Example 2 had a specific surface area of 700 m 2 g -1 , a pore volume of 1.16 to 1.55 cm 3 g -1 , and a pore size distribution concentrated around 4 nm. .
  • the graphene (SHSG-6) of Example 2 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the specific capacitance of the supercapacitor is 115F g -1 .
  • the energy density of the supercapacitor is 49.1 Wh kg -1 .
  • Step 1 taking 8 g of magnesium metal powder and 32 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 1 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 0.1 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 100 sccm until the gas pressure in the sealed pressure vessel was 0.5 MPa;
  • step 3 a direct current power source is used to apply a direct current of 3 A to both ends of the tungsten wire coil, and the energization time is 30 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and the reaction is black after 1.5 minutes. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 2M nitric acid for 48 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-4.
  • the graphene (SHSG-4) prepared in Example 3 had a specific surface area of 516 m 2 g -1 , a pore volume of 1.12 to 1.16 cm 3 g -1 , and a pore size distribution concentrated around 4 nm. .
  • the graphene (SHSG-4) of Example 3 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the specific capacitance of the supercapacitor is 79F g -1 .
  • the energy density of the supercapacitor is 33.8 Wh kg -1 .
  • Step 1 taking 8 g of magnesium metal powder and 16 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 300 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 500 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 200 sccm until the gas pressure in the sealed pressure vessel was 10 MPa;
  • step 3 a direct current power source is used to apply a direct current of 10 A to both ends of the tungsten wire coil, and the energization time is 15 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and the reaction is black after 1.5 minutes. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M sulfuric acid for 24 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-2.
  • the graphene (SHSG-2) obtained in Example 4 had a specific surface area of 469 m 2 g -1 , a pore volume of 1.03 to 1.12 cm 3 g -1 , and a pore size distribution concentrated around 4 nm. .
  • the graphene (SHSG-2) of Example 4 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the specific capacitance of the supercapacitor is 55F g -1 .
  • the energy density of the supercapacitor is 23.5 Wh kg -1 .
  • Step 1 taking 8 g of magnesium metal powder and 8 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle 30 ⁇ m diameter, oxidation The magnesium powder has a purity of 99.9% and an average particle diameter of 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 5 MPa;
  • step 3 a direct current power source is used to apply a direct current of 15 A to both ends of the tungsten wire coil, and the energization time is 20 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and after reacting for 1 minute, a black color is obtained. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 36 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-1.
  • the graphene (SHSG-1) obtained in Example 5 had a specific surface area of 401 m 2 g -1 , a pore volume of 0.83 to 1.03 cm 3 g -1 , and a pore size distribution concentrated around 4 nm.
  • the graphene (SHSG-1) of Example 4 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the specific capacitance of the supercapacitor is 52F g -1 .
  • the energy density of the supercapacitor is 22.3 Wh kg -1 .
  • Step 1 taking 8g of metal magnesium powder in a graphite ark, embedding a tungsten wire coil in the metal magnesium powder; wherein the metal magnesium powder has a purity of 99.9% and an average particle diameter of 30 ⁇ m;
  • step 2 the graphite ark containing the magnesium metal powder and the tungsten wire coil in step 1 is placed in a steel sealed pressure vessel having a volume of 24 L, and the pressure of the sealed pressure vessel is reduced to 2 ⁇ 10 using a molecular pump . 4 Pa, and then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel was 0.125 MPa;
  • Step 3 using a DC power source to apply a direct current of 1 A to both ends of the tungsten wire coil, the energization time is 25 s, the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 min. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 12 hours to remove excess magnesium oxide in the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • the mesoporous graphene powder number is SHSG-0.
  • the graphene (SHSG-0) prepared in Example 6 had a specific surface area of 364 m 2 g -1 , a pore volume of 0.73 to 0.83 cm 3 g -1 , and a pore size distribution concentrated around 4 nm.
  • the graphene (SHSG-0) of Example 4 was assembled into a supercapacitor as described above, and the electrolyte was an ionic liquid (EMIMBF 4 ).
  • a constant current charge and discharge test was performed in a voltage range of 0-3.5V.
  • the specific capacitance of the supercapacitor is 30F g -1 .
  • the energy density of the supercapacitor is 12.7 Wh kg -1 .
  • I D /I G The ratio of the D peak to the G peak on the Raman spectrum of the graphenes of Examples 1 to 6 I D /I G is shown in Table 1 below. I D /I G was increased from 0.158 for SHSG-0 to 1.126 for SHSG-8.
  • Step 1 taking 8 g of magnesium metal powder and 80 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 0.125 MPa;
  • step 3 a direct current power source is applied to the two ends of the tungsten wire coil to apply a direct current of 3 A, and the energization time is 15 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and the reaction is black after 1.5 minutes. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 20 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 0.25 MPa;
  • step 3 a direct current power source is applied to the two ends of the tungsten wire coil to apply a direct current of 3 A, and the energization time is 20 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and after reacting for 1 minute, a black color is obtained. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 18 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 600 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 200 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 0.5 MPa;
  • Step 3 using a DC power source to apply a direct current of 18 A to both ends of the tungsten wire coil, and the power-on time is 10 s.
  • the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is initiated spontaneously, and after reacting for 1 minute, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 10 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 2000 sccm until the gas pressure in the sealed pressure vessel was 2 MPa;
  • Step 3 using a DC power source to apply a direct current of 3 A to both ends of the tungsten wire coil, the energization time is 15 s, the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 min. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 20 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 1000 sccm until the gas pressure in the sealed pressure vessel is 5 MPa;
  • Step 3 using a DC power supply to apply a direct current of 3 A to both ends of the tungsten wire coil, the energization time is 18 s, the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 min. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 24 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 placing the graphite ark containing the mixed powder and the tungsten wire coil in the step 1 in a steel sealed pressure vessel having a volume of 10 L, and reducing the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 3000 sccm until the gas pressure in the sealed pressure vessel is 1 MPa;
  • step 3 a direct current power source is applied to the two ends of the tungsten wire coil to apply a direct current of 3 A, and the energization time is 15 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and the reaction is black after 1.5 minutes. powder;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 26 hours to remove excess magnesium oxide from the product, and then using deionized water to pump
  • the black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 placing the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 50 L, and reducing the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 1 MPa;
  • step 3 a direct current power source is used to apply a direct current of 10 A to both ends of the tungsten wire coil, and the energization time is 15 s.
  • the energized tungsten wire coil generates a high temperature to cause the metal magnesium powder to react with carbon dioxide, and the reaction is black after 1.5 minutes. Powder
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1 M hydrochloric acid for 20 hours to remove excess magnesium oxide in the product, and then using deionized water to pump The black powder was filtered to neutralize the filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 200 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 200 ⁇ m;
  • Step 2 placing the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 200 L, and reducing the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 10000 sccm until the gas pressure in the sealed pressure vessel was 1 MPa;
  • step 3 a direct current power source is used to apply a direct current of 3 A to both ends of the tungsten wire coil, and the energization time is 10 s.
  • the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 minute. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 1.5 M hydrochloric acid for 15 hours to remove excess magnesium oxide in the product, and then using deionized water.
  • the black powder was washed by suction filtration until the filtrate was neutral to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 80 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, and then a carbon dioxide gas having a purity of 99.9% was introduced into the sealed pressure vessel at a flow rate of 3500 sccm until the gas pressure in the sealed pressure vessel was 1 MPa;
  • Step 3 using a DC power source to apply a direct current of 1 A to both ends of the tungsten wire coil, the energization time is 10 s, the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 min. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then the black
  • the color powder was placed in a sufficient amount of 2M hydrochloric acid for 22 hours to remove excess magnesium oxide from the product, and the black powder was washed with deionized water to filter the filtrate to be neutral to obtain a filter cake, and the filter cake was freeze-dried to obtain Mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 50 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 1 MPa;
  • step 3 a direct current power source is used to apply a direct current of 3 A to both ends of the tungsten wire coil, and the energization time is 10 s.
  • the energized tungsten wire coil generates a high temperature, and the reaction of the magnesium metal powder and the carbon dioxide gas is spontaneously performed, and the reaction is performed for 1 minute. After that, a black powder is obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 0.5 M sulfuric acid for 15 hours to remove excess magnesium oxide in the product, and then using deionized water.
  • the black powder was washed by suction filtration until the filtrate was neutral to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.
  • Step 1 taking 8 g of magnesium metal powder and 64 g of magnesium oxide powder, mixing uniformly to obtain a mixed powder and placing it in a graphite ark, embedding a tungsten wire coil in the mixed powder; wherein the metal magnesium powder has a purity of 99.9%, an average particle The diameter is 30 ⁇ m, the purity of the magnesium oxide powder is 99.9%, and the average particle diameter is 100 ⁇ m;
  • Step 2 Place the graphite ark containing the mixed powder and the tungsten wire coil in step 1 in a steel sealed pressure vessel having a volume of 24 L, and reduce the pressure of the sealed pressure vessel to 2 ⁇ 10 -4 using a molecular pump. Pa, then a carbon dioxide gas having a purity of 99.9% is introduced into the sealed pressure vessel at a flow rate of 5000 sccm until the gas pressure in the sealed pressure vessel is 1 MPa;
  • Step 3 using a DC power source to apply a direct current of 0.5 A to both ends of the tungsten wire coil, the energization time is 30 s, and the energized tungsten wire coil generates a high temperature, causing the reaction of the magnesium metal powder and the carbon dioxide gas to spontaneously react. After 1 min, a black powder was obtained;
  • Step 4 releasing excess gas in the sealed pressure vessel until the gas pressure in the vessel is normal pressure, and then placing the black powder in a sufficient amount of 0.2 M nitric acid for 48 hours to remove excess magnesium oxide in the product, and then using deionized water. Filtering washing station The black powder was neutralized to a filtrate to obtain a filter cake, and the filter cake was freeze-dried to obtain a mesoporous graphene powder.

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Abstract

提供一种介孔石墨烯、其制备方法以及含有该石墨烯的超级电容器电极和超级电容器。该方法包括：i)将含金属镁粉和固体氧化物粉的混合物置于含二氧化碳的环境中；ii)加热所述混合物，使金属镁粉与二氧化碳反应，获得石墨烯。该石墨烯的比表面积为350－750 m 2/g，孔容为 1－2 cm 3/g。该方法简单易行，成本低，产率高，且产物石墨烯杂质少，碳氧比高，具有优异的电容性能和电化学稳定性。

Description

[根据细则37.2由ISA制定的发明名称]　一种石墨烯、其制备方法及含有该石墨烯的超级电容器电极和超级电容器 技术领域
本发明属于碳材料领域，具体涉及一种石墨烯及其制备方法。
背景技术
石墨烯是一种由碳原子以sp2杂化轨道相连接构成的呈六角型蜂巢晶格的二维材料。其具有优异的力学，电学、化学和热学性质，受到全球材料研发人员的广泛关注，被认为是最具有潜力的下一代新材料之一。石墨烯已经在能量存储、光电转化和催化等领域得到实际应用。现有的石墨烯的制备方法主要分为两类，一类是自上向下法，即以石墨为来源，通过剥离石墨块体来制备石墨烯，该方法包括液相剥离，机械剥离和氧化还原剥离等；另一类是自下向上法，即将各种含碳小分子转化为石墨烯，该方法包括化学气相沉积和晶体外延生长等。
以二氧化碳为原料制备石墨烯是近年来新兴的石墨烯制备方法，该方法具有原料来源广泛，价格低廉，产物后处理简便等优点，因而被认为是有望解决规模化制备高质量石墨烯的途径之一。Chakrabarti等人在干冰中燃烧金属镁，制备得到碳纳米盒(J.Mater.Chem.2011,21,9491)。
发明内容
本发明一个目的在于提供一种石墨烯的制备方法，本发明的再一个目的在于提供一种石墨烯。
本发明的目的是通过以下技术方案实现的：
一种制备介孔石墨烯的方法，包括以下步骤：
步骤1，将金属镁粉与氧化镁粉混合均匀，得到混合粉末，将所述混合粉末放入密封耐压容器中，并在所述混合粉末中埋入钨丝线圈；
步骤2，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，向所述密封耐压容器中通入纯度为90-99.99％的二氧化碳气体，至所述密封耐压容器内压力为0.125-10MPa，其中通入二氧化碳气体的速率为100-10000sccm；
步骤3，使用直流电源对所述钨丝线圈施加0.5-30A直流电，通电时间为5-30秒，所 述钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1-2min后得到黑色粉末；
步骤4，将所述黑色粉末置于稀酸溶液中静置6-48h，再使用去离子水抽滤洗涤所述黑色粉末至中性得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
进一步的，步骤1中，所述金属镁粉纯度为90-99.99％，平均粒径为1-1000μm，所述氧化镁粉纯度为90-99.99％，平均粒径为0.1-1000μm。
进一步的，步骤1中，所述混合粉末中金属镁粉与氧化镁粉的质量比为1:0-1:10。
进一步的，所述稀酸溶液为浓度为0.2-2M的稀盐酸、稀硫酸或稀硝酸。
进一步的，所述密封耐压容器为体积10-200L的钢制密封耐压容器。
进一步的，步骤4中所述冷冻干燥包括以下步骤：
步骤4.1，将所述滤饼放入塑料烧杯中，再向所述塑料烧杯中加入去离子水，超声并搅拌后得到糊状物；
步骤4.2，将所述糊状物置于低温液体中冷冻2-30分钟，得到黑色固体；
步骤4.3，将所述黑色固体置于冷冻干燥机中干燥得到所述介孔石墨烯粉末。
进一步的，步骤4.1中，所述去离子水与滤饼的质量比为1:1-8:1。
进一步的，步骤4.2中低温液体为液氮、液氦或液氩。
进一步的，所述介孔石墨烯粉末的碳氧元素原子比高于80，孔径分布呈均一单峰分布。
进一步的，所述介孔石墨烯粉末的孔径为4nm。
本发明一方面提供一种制备石墨烯的方法，包括以下步骤：
i)将含金属镁粉和固体氧化物粉的混合物置于含二氧化碳的环境中；
ii)加热所述混合物，使金属镁粉与二氧化碳反应，获得石墨烯。
在一个实施方案，任一项制备石墨烯的方法中，金属镁粉与二氧化碳反应的化学方程式为：2Mg+CO2→2MgO+C。
在一个实施方案，任一项制备石墨烯的方法中，金属镁粉与二氧化碳的反应为自蔓延反应。
在一个实施方案，任一项制备石墨烯的方法还包括以下步骤：
iii)从步骤ii)的产物中去除氧化镁和/或所述固体氧化物。
在一个实施方案，任一项制备石墨烯的方法，步骤iii)包括：酸洗步骤ii)的产物。
在一个实施方案，任一项制备石墨烯的方法还包括以下步骤：
iv)对步骤iii)的产物进行洗涤、过滤或干燥中的一项或多项操作。
在一个实施方案，任一项制备石墨烯的方法，步骤i)中，所述混合物由金属镁粉和固体氧化物粉构成。
在一个实施方案，任一项制备石墨烯的方法中，步骤i)包括，将金属镁粉和固体氧化物粉混合后置于充有二氧化碳的密闭容器中。
在一个实施方案，任一项制备石墨烯的方法中，步骤i)中，金属镁粉与固体氧化物粉的质量比为1:0.1～10。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为1～9:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为2～9:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为4～9:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为6～9:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为7～9:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为6～8:1。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉的平均粒径为0.1～1000μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉的平均粒径为30～600μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉的平均粒径为30～300μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉的平均粒径为30～100μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉的平均粒径为30～50μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉的平均粒径为 9～9000μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉的平均粒径为30～600μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉的平均粒径为30～300μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉的平均粒径为30～900μm。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉的平均粒径为30～50μm。
在一个实施方案中，任一项制备石墨烯的方法，所述固体氧化物为金属氧化物。
在一个实施方案中，任一项制备石墨烯的方法，所述固体氧化物为碱土金属氧化物。
在一个实施方案中，任一项制备石墨烯的方法，所述固体氧化物为氧化镁。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)的环境中不含氧。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，二氧化碳在的气压为0.125MPa以上。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，二氧化碳在的气压为0.5MPa以上。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，二氧化碳在的气压为1MPa以上。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，二氧化碳在的气压为5MPa以上。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，二氧化碳在的气压为0.125～10MPa。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，环境中二氧化碳的含量为90体积％以上。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，环境中二氧化碳的含量为90-99.99体积％。
在一个实施方案中，任一项制备石墨烯的方法，步骤ii)中，使用通电的金属导体加热所述混合物。
在一个实施方案中，任一项制备石墨烯的方法，步骤ii)中，所述金属导体是钨丝。
在一个实施方案中，任一项制备石墨烯的方法，步骤ii)中，所述通电的金属导体中通有0.5-30A的直流电(例如1A、5A、10A、15A、20A或25A)。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，密闭容器的体积为10-200L(例如15L、25L、50L、100L、150L)。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，金属镁粉在密闭容器中的含量为1～100g/24L，例如8～40g/24L。
在一个实施方案中，任一项制备石墨烯的方法，步骤i)中，固体氧化物粉在密闭容器中的含量为1～500g/24L，例如8～320g/24L。
在一个实施方案中，任一项制备石墨烯的方法，包括以下一步或多步：
a)将金属镁粉与氧化镁粉混合均匀，得到混合粉末，将所述混合粉末放入密封耐压容器中，并在所述混合粉末中埋入钨丝线圈；
b)将所述密封耐压容器内气体压力降至2×10-4Pa，向所述密封耐压容器中通入二氧化碳气体，至所述密封耐压容器内压力为0.125～10MPa；
c)使用直流电源对所述钨丝线圈施加0.5～30A直流电，通电时间为5-30s，所述钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应后得到粉末；
d)将步骤c)的粉末产物置于稀酸溶液中静置6～8h，再使用去离子水抽滤洗涤所述粉末，收集滤出物，将所述滤出物经冷冻干燥后得到石墨烯。
本发明又一个方面提供一种石墨烯，其比表面积为350～750m2g-1，孔容为1～2cm3/g。
在一个实施方案中，任一项的石墨烯，其比表面积为400～750m2g-1。
在一个实施方案中，任一项的石墨烯，其比表面积为500～750m2g-1。
在一个实施方案中，任一项的石墨烯，其比表面积为600～750m2g-1。
在一个实施方案中，任一项的石墨烯，其比表面积为650～750m2g-1。
在一个实施方案中，任一项的石墨烯，其比表面积为680～710m2g-1。
在一个实施方案中，任一项的石墨烯，其孔容为0.8～1.8cm3g-1。
在一个实施方案中，任一项的石墨烯，其孔容为1～1.8cm3g-1。
在一个实施方案中，任一项的石墨烯，其孔容为1.2～1.8cm3g-1。
在一个实施方案中，任一项的石墨烯，其孔容为1.4～1.8cm3g-1。
在一个实施方案中，任一项的石墨烯，其孔容为1.5～1.6cm3g-1。
在一个实施方案中，任一项的石墨烯，其氮气等温吸脱附曲线有滞后环。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线在3～5nm范围内有峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线在在3.5～4.5nm范围内有峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上仅有一个峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有峰宽为0.5～3nm的峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有峰宽为0.5～2nm的峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有峰宽为0.5～1nm的峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有半峰宽为0.5～3nm的峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有半峰宽为0.5～2nm的峰。
在一个实施方案中，任一项的石墨烯，其孔径分布曲线上有半峰宽为0.5～1nm的峰。
在一个实施方案中，任一项的石墨烯，所述石墨烯的侧层数为10层以下。
在一个实施方案中，任一项的石墨烯，所述石墨烯的侧层数为5层以下。
在一个实施方案中，任一项的石墨烯，所述石墨烯的侧层数为5～15层。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳氧元素的原子比为70以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳氧元素的原子比为80以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳氧元素的原子比为80～90，例如82。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量高于90at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量高于92at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量高于94at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量高于96at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量高于97at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的碳含量为90～99at％。
在一个实施方案中，任一项的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于5％。
在一个实施方案中，任一项的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于4％。
在一个实施方案中，任一项的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于3％。
在一个实施方案中，任一项的石墨烯，所述石墨烯在空气氛围下的热失重曲线，升温至800℃时，失重率为98％以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯在空气氛围下的热失重曲线，升温至800℃时，失重率为99％以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯在空气氛围下的热失重曲线，升温至800℃时，失重率为100％。
在一个实施方案中，任一项的石墨烯，所述石墨烯的弛豫时间常数小于或等于0.02s。
在一个实施方案中，任一项的石墨烯，所述石墨烯的弛豫时间常数小于或等于0.015s。
在一个实施方案中，任一项的石墨烯，所述石墨烯的导电率为8000S m-1以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的导电率为10000S m-1以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的导电率为12000S m-1以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的导电率为8000～15000S m-1。
在一个实施方案中，任一项的石墨烯，所述石墨烯的导电率为11000～13000S m-1。
在一个实施方案中，任一项的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.3以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.5以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.7以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.9以上。
在一个实施方案中，任一项的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.3～1.2。
在一个实施方案中，任一项的石墨烯，该石墨烯组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为50～200F g-1，例如150～200F g-1，例如52F g-1、55F g-1、79F g-1、115F g-1或172F g-1；在100A g-1的充放电电流下，超级电容器的比电容为100～150F g-1，例如125F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为20～100Wh kg-1，例如50～100Wh kg-1，例如22.3Wh kg-1、23.5Wh kg-1、33.8Wh kg-1、49.1Wh kg-1 或73Wh kg-1。例如在175kW kg-1的功率密度下，超级电容器的能量密度为40～60Wh kg-1，例如53Wh kg-1。优选该超级电容器在100A g-1的电流密度下充放电循环1000000周后，容量保持率为80～95％，例如90％。
在一个实施方案中，任一项的石墨烯，该石墨烯组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-4V的电压范围内进行恒流充放电测试。在5A g-1的充放电电流下，超级电容器的比电容为150～200F g-1，例如192F g-1；在100A g-1的充放电电流下，超级电容器的比电容为100～150F g-1，例如148F g-1。在10kW kg-1的功率密度下，超级电容器的能量密度为70～120Wh kg-1，例如106Wh kg-1。例如在200kW kg-1的功率密度下，超级电容器的能量密度为50～100Wh kg-1，例如82Wh kg-1。优选该超级电容器在100A g-1的电流密度下充放电循环80000周后，容量保持率为70～83％，例如81％。
在一个实施方案中，任一项的石墨烯，该石墨烯组装成超级电容器，电解质采用离子液体(EMIMTFSI)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为150～200F g-1，例如190F g-1；在100A g-1的充放电电流下，超级电容器的比电容为100～150F g-1，例如143F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为70～100Wh kg-1，例如81Wh kg-1；在175kW kg-1的功率密度下，超级电容器的能量密度为50～80Wh kg-1，例如61Wh kg-1。该超级电容器在100A g-1的电流密度下充放电循环10000周后，容量保持率为80～90％，例如89％。
在一个实施方案中，任一项的石墨烯，该石墨烯组装成超级电容器，电解质采用离子液体(EMIMTFSI)。在0-4V的电压范围内进行恒流充放电测试。在5A g-1的充放电电流下，超级电容器的比电容为200～250F g-1，例如244F g-1；在100A g-1的充放电电流下，超级电容器的比电容为150～200F g-1，例如173F g-1。在10kW kg-1的功率密度下，超级电容器的能量密度为100～150Wh kg-1，例如135Wh kg-1；在200kW kg-1的功率密度下，超级电容器的能量密度为80～120Wh kg-1，例如96Wh kg-1。该超级电容器在100A g-1的电流密度下充放电循环10000周后，容量保持率为65～75％，例如70％。
在一个实施方案中，任一项的石墨烯，所述石墨烯是介孔石墨烯。
在一个实施方案中，任一项的石墨烯，所述石墨烯由任一项制备石墨烯的方法制得。
附图说明
图1是实施例1的石墨烯的扫描电子显微镜照片；
图2是实施例1的石墨烯的透射电子显微镜照片；
图3是实施例1的石墨烯的X射线衍射图谱；
图4是实施例1的石墨烯的X射线光电子能谱；
图5是实施例1、实施例2、实施例3、实施例4、实施例5和实施例6的石墨烯的氮气等温吸脱附曲线；
图6是实施例1、实施例2、实施例3、实施例4、实施例5和实施例6的石墨烯经氮气等温吸脱附测试所得孔径分布曲线；
图7是实施例1的石墨烯和商业石墨粉在氮气气氛中的热失重曲线；
图8是实施例1的石墨烯在空气气氛中的热失重曲线；
图9为实施例1的石墨烯在离子液体中的循环伏安曲线，其中，扫描速率分别为2000，5000，10000，20000mV s-1；
图10为实施例1的石墨烯在离子液体中的充放电曲线，其中，充放电电流密度分别为100，200，300，400，500A g-1；
图11为实施例1的石墨烯在离子液体中的Bode图；
图12为实施例1的石墨烯在离子液体中的倍率特性曲线；
图13为实施例1的石墨烯在离子液体中的Ragone图；
图14为实施例1的石墨烯在离子液体中的循环容量曲线。
发明的有益效果
公开实施方案以金属镁粉和氧化镁粉的混合粉末为原料，原料来源广泛，通过调节金属镁粉和氧化镁粉的质量比来调控产物石墨烯的层数和孔径分布，大量的氧化镁在反应过程中能够成功阻止石墨烯的团聚和堆叠，制备得到少层石墨烯。反应简单易行，成本低，产率高，无污染，且产物石墨烯杂质少，碳氧比高，具有优异的电容性能和电化学稳定性，公开实施方案的石墨烯能够直接用作超级电容器等能量存储器件的电极材料，并能够表现出优异的双电层电容性能。
公开实施方案的石墨烯具有以下一项或多项优点：
公开实施方案的石墨烯具有较低的氧含量。
公开实施方案的石墨烯具有较高的电导率。
公开实施方案的石墨烯具有较高的比表面积。
公开实施方案的石墨烯具有较大的孔容。
以公开实施方案的石墨烯为电极、以离子液体作为电解质的超级电容器，表现出较高的比电容。
以公开实施方案的石墨烯为电极、以离子液体作为电解质的超级电容器，表现出较高的循环容量保持率。
以公开实施方案的石墨烯为电极、以离子液体作为电解质的超级电容器，表现出较高的能量密度。
氧化物粉末的一个作用是引导石墨烯在氧化物表面生长。
氧化物粉末的一个作用是作为间隔物使石墨烯层彼此分离。
公开实施方案所制备的石墨烯介孔丰富，孔径分布均一，层数可控，不含杂质，碳氧元素原子比高，且原料来源广泛，反应简便易行，易于工业化推广。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
以下实施例中各测试仪器及方法如下：
使用Hitachi S-4800进行了扫描电子显微镜(SEM)和能量色散X射线光谱(EDS)测试，加速电压为20kV。先将石墨烯样品先分散在乙醇中，再将石墨烯的乙醇分散液滴在硅片上进行SEM分析。使用装备有选区电子衍射的JEOL JEM-2010进行透射电子显微镜(TEM)和HR-TEM(高分辨-TEM)测试。测试的加速电压为200kV。使用JEOL JEM-2100F进行球差校正的HR-TEM测试。在TEM测试中，样品制备方法如下：将样品的乙醇分散液滴在超薄无定型覆碳铜网上，然后在室温下干燥1小时。
使用Bruker D8多功能X射线衍射仪进行X射线衍射(XRD)测试。仪器使用单色铜Kα辐射
Figure PCTCN2017076257-appb-000001
扫描速度10度每分钟。使用共焦拉曼系统(LabRam HR-800,Horiba Jobin Yvon)进行显微拉曼测试，测试使用的激发波长为532nm。通过洛伦兹拟和确定了拉曼光谱上D带和G带的位置和半高全宽(FWMH)。使用PHI Quantear SXM进行了X射线光电子能谱测试，以分析样品的化学成分；测试在6.7×10-8Pa进行，且使用Al作为阳极探针。使用球面像差校正的JEOL JEM-2100F TEM进行电子能量损失谱 分析(EELS)，测试以商用石墨粉(325目)作为参照。电导率的测试方法如下：现将SHSG-8介孔石墨烯粉末在6MPa下压成厚度为320μm的片，然后用四探针电导率测试仪测试片的电导率。
使用Netzsch TG 209 F3 Tarsus进行热重分析(TGA)，分别在N2和空气气氛中测试，以5Kmin-1速率自50℃升温至800℃。使用Micromeritics ASAP 2020 HD Analyzer在77K下进行氮气吸/脱附测试，获得石墨烯样品的比表面积。在吸/脱附测试前，样品在150℃下真空脱气12小时。基于Brunauer-Emmett-Teller(BET)理论，根据相对压力P/P0在0.3以下时的下N2的吸附量计算获得比表面积值。孔径分布是基于Barrett-Joyner-Halenda(BJH)模型计算获得。累计孔体积是基于密度泛函理论获得。
电化学测试：使用两电极体系测试了石墨烯作为超级电容器电极的电容器性能。采用刮刀流延法制备工作电极。将70wt％的石墨烯粉末，20wt％的炭黑在玛瑙研磨中混合，然后再加入10wt％聚偏氟乙烯(PVDF)和若干滴N-甲基吡咯烷酮(NMP)，获得浆料。将浆料用刮刀流延法均匀地涂覆在铝箔集流体上(平均石墨烯负载量为～0.5mg cm-2)。然后对电涂覆后的铝箔施加6MPa压力，得到电极。制备好的电极在120℃干燥12小时，然后被冲压成直径13mm的圆片。将两片相同的电极和一片离子多孔隔膜夹在一个2032币式电池中，以用于进一步测试。使用BioLogic VMP3电化学分析仪进行循环伏安(CV)测试，电化学阻抗(EIS)测试和恒电流充放电测试(GCD)。EIS测试以10mV的振幅从100mHz测试到100kHz。
实施例1
步骤1，取40g金属镁粉和320g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为10s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中10h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-8。
本实施例中金属镁粉与二氧化碳气体的反应按下式进行：
2Mg+CO2→2MgO+C
图1是实施例1所得介孔石墨烯的扫描电子显微镜照片，从中可以观察出石墨烯层之间存在明显的间隙，使得石墨烯片层互相隔离，界限分明，证明本实施例的方法能够避免目前石墨烯制备过程中普遍存在的石墨烯片层间严重的堆叠或团聚现象。
此外，本实施例的介孔石墨烯为少层石墨烯。通过观察图2所示透射电子显微镜照片中石墨烯片层的边缘可以看出，本实施例制备得到的石墨烯层数在5层以下。
图3是本实施例制备的石墨烯的X射线衍射图谱，其中横坐标为2θ，纵坐标是衍射强度。从中可以看出材料在26°和43°附近出现了属于石墨结构的(002)和(100)特征峰，表明产物具有石墨烯六元蜂巢状晶格结构，且图谱中未出现属于氧化镁或镁的杂峰，表明本实施例制备的石墨烯纯度高，无氧化镁等杂质。
图4示出本实施例的介孔石墨烯的X射线光电子能谱(XPS)，其中横坐标是结合能，纵坐标是强度。从中可以看出本实施例制备的石墨烯主要的化学成分是碳元素，氧元素含量极少，碳氧元素的原子比高达82，表明产物石墨烯质量高，不含杂原子。
XPS分析结果显示，SHSG-8包含约98.7at％的碳元素和1.2at％的氧元素。这说明实施例1的石墨烯碳元素含量高。
EDS分析结果也显示，SHSG-8包含约97.5at％的碳元素。
如图5示出实施例1～6的介孔石墨烯的氮气等温吸脱附曲线，其中，横坐标是相对压力，纵坐标是气体吸收量。本实施例所制石墨烯的氮气等温吸脱附曲线在P/P0范围为0.4-0.9时出现了介孔材料所特有的滞后环。本实施例的介孔石墨烯的比表面积高达709m2g-1，而孔容可达1.52cm3g-1，证明其具有丰富的介孔结构和较大的比表面积。
图6为实施例1～6所制石墨烯的孔径分布图，其中，横坐标是孔径，纵坐标是孔容。可以明显观察出材料在4nm附近呈现单一孔径分布，表明产物具有高度均一的介孔通道。实施例1～6的石墨烯的孔径分布曲线上，各峰的峰宽小于1nm，半峰宽小于1nm。
图7为本实施例制备的介孔石墨烯与商业化石墨粉末在氮气氛围下的热失重曲线对 比，其中，横坐标是温度，纵坐标是失重量，可以观察出，在600-800℃的高温范围内，本实施例制备的石墨烯的失重量低于商业化石墨粉，表明其具有优异的热稳定性。如图所示，本实施例的石墨烯在自600至800℃，重量由96％下降至93％。
图8示出本实施例所制介孔石墨烯在空气氛围下的热失重曲线，其中，横坐标是温度，左纵坐标是失重量，右纵坐标是失重率。观察该曲线发现，升温至800℃时，失重率为100％，表明产物的纯度极高，杂质极少，同时也表明本实施例制备方法中所使用的镁粉和氧化镁粉在后处理过程中能完全除去。图中，590℃为热失重起始温度，660℃为热失重峰值温度，710℃为热失重率再次为零时的温度，90％为590℃时，热重测试剩余产物质量分数。
图9-14展示了本实施例所制介孔石墨烯作为超级电容器电极在离子液体中的电化学性能。离子液体为1-乙基-3-甲基咪唑鎓四氟硼酸盐(EMIMBF4)。
图9为实施例1的石墨烯在离子液体中的循环伏安曲线，其中，扫描速率分别为2000mV s-1，5000mV s-1，10000mV s-1，20000mV s-1，其中横坐标是电压，纵坐标为电流，箭头方向表示扫速增加。在高达2000mV s-1的扫描速率下，材料的循环伏安曲线呈近乎标准的矩形，没有出现氧化还原峰。继续增大扫描速率至20000mV s-1，循环伏安曲线仍然维持矩形状，证明本实施例所制备材料具有优异的双电层电容性质。
图10示出实施例1的石墨烯(SHSG-8)在离子液体(EMIMBF4)中的充放电曲线(GCD曲线)，其中，充放电电流密度分别为100A g-1，200A g-1，300A g-1，400A g-1，500A g-1，其中横坐标是时间，纵坐标为电压，箭头方向表示电流密度增加。从中可以观察到，在0-3.5V的电压范围内，充放电曲线成对称的三角形，表明利用本实施例所制石墨烯拥有良好的电容行为，适合用于超级电容器电极材料。在100Ag-1电流下的GCD曲线在放电曲线的起点部分表现出0.06V的电压下降，说明该超级电容具有低的等效电阻(ESR)和出色的功率容量和较小的电阻。
图11是实施例1的石墨烯在离子液体EMIMBF4中的Bode图，其中，横坐标为频率，纵坐标为相角。从中能够发现，材料具有优异的频率响应特性，弛豫时间常数(τ0)低至0.012秒，表明基于实施例1的石墨烯作为电极使用，电极表面能够快速高效地形成双电层，即具有快速存储能量的特性。
图12为实施例1的石墨烯在离子液体EMIMBF4中的倍率特性曲线，其中，横坐标为电流密度，纵坐标为比电容。当充放电电流密度为2A g-1时，材料的容量高达180F g-1，而继续增大电流密度至500A g-1时，材料仍然能维持100F g-1的容量。以上结果证明实施 例1的石墨烯能够作为大电流超级电容器的电极材料。由于本实施例的介孔石墨烯材料具有优异的电容性质和倍率特性，因此，用该石墨烯制备的电极能表现出优越的能量密度和功率密度。
图13示出实施例1的石墨烯在离子液体EMIMBF4中的Ragone图，其中，横坐标为功率密度，纵坐标为能量密度。从图中可以得出，当功率密度为3.5kW kg-1时，基于本实施例所制石墨烯的电极能量密度高达73Wh kg-1。更为重要的是，当电极以高达875kW kg-1的功率密度工作时，能量密度仍然为42Wh kg-1，表明了本实施例所制的石墨烯材料同时具有高能量密度和高功率密度的特点。此外，本实施例所制备的介孔石墨烯具有优异的循环稳定性。
图14示出实施例1的石墨烯在离子液体EMIMBF4中的循环容量曲线，其中，横坐标为循环次数，左纵坐标为容量保持率，右纵坐标为库伦效率，以高达100A g-1的充放电电流工作100万周，即连续工作600小时后，材料仍然能保持90％的初始能量。循环100万周后，电极的库伦效率仍大于99％。
以上图9～图14的电化学表征结果证明，实施例1的石墨烯作为超级电容器电极，在离子液体EMIMBF4中，具有高的电容值、良好的倍率特性、极高的能量密度和功率密度以及优异的循环稳定性，进而说明，实施例1的石墨烯能够适用作大功率、大电流超级电容器的电极材料。
实施例1的石墨烯(SHSG-8)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。优选地，该超级电容器在2A g-1的充放电电流下，超级电容器的比电容为172F g-1。优选地，该超级电容器在100A g-1的充放电电流下，超级电容器的比电容为125F g-1。优选地，该超级电容器在3.5kW kg-1的功率密度下，超级电容器的能量密度为73Wh kg-1。优选地，该超级电容器在175kW kg-1的功率密度下，超级电容器的能量密度为53Wh kg-1。优选地，该超级电容器在100A g-1的电流密度下充放电循环1000000周后，容量保持率为90％。
实施例1的石墨烯(SHSG-8)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-4V的电压范围内进行恒流充放电测试。优选地，该超级电容器在5A g-1的充放电电流下，超级电容器的比电容为192F g-1。优选地，该超级电容器在100A g-1的充放电电流下，超级电容器的比电容为148F g-1。优选地，该超级电容器在10kW kg-1的功率密度下，超级电容器的能量密度为106Wh kg-1。优选地，该超级电容器在200kW kg-1 的功率密度下，超级电容器的能量密度为82Wh kg-1。优选地，该超级电容器在100A g-1的电流密度下充放电循环80000周后，容量保持率为81％。
实施例1的石墨烯(SHSG-8)按上述方法组装成超级电容器，电解质采用离子液体(EMIMTFSI)。在0-3.5V的电压范围内进行恒流充放电测试。优选地，该超级电容器在2A g-1的充放电电流下，超级电容器的比电容为190F g-1。优选地，该超级电容器在100A g-1的充放电电流下，超级电容器的比电容为143F g-1。优选地，该超级电容器在3.5kW kg-1的功率密度下，超级电容器的能量密度为81Wh kg-1。优选地，该超级电容器在175kW kg-1的功率密度下，超级电容器的能量密度为61Wh kg-1。优选地，该超级电容器在100A g-1的电流密度下充放电循环10000周后，容量保持率为89％。
实施例1的石墨烯(SHSG-8)按上述方法组装成超级电容器，电解质采用离子液体(EMIMTFSI)。在0-4V的电压范围内进行恒流充放电测试。优选地，该超级电容器在5A g-1的充放电电流下，超级电容器的比电容为244F g-1。优选地，该超级电容器在100A g-1的充放电电流下，超级电容器的比电容为173F g-1。优选地，该超级电容器在10kW kg-1的功率密度下，超级电容器的能量密度为135Wh kg-1。优选地，该超级电容器在200kW kg-1的功率密度下，超级电容器的能量密度为96Wh kg-1。优选地，该超级电容器在100A g-1的电流密度下充放电循环10000周后，容量保持率为70％。
实施例1的石墨烯的电导率为13000S m-1。
实施例2
步骤1，取8g金属镁粉和48g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为1 000μm，氧化镁粉纯度为99.9％，平均粒径为1000μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以10000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为30A的直流电，通电时间为5s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应2min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中6h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-6。
如图5和6所示，实施例2所制得的石墨烯(SHSG-6)的比表面积为700m2g-1，孔容为1.16～1.55cm3g-1，孔径分布集中在4nm附近。
实施例2的石墨烯(SHSG-6)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为115F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为49.1Wh kg-1。
实施例3
步骤1，取8g金属镁粉和32g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为1μm，氧化镁粉纯度为99.9％，平均粒径为0.1μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以100sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为0.5MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为30s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1.5min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量2M硝酸中48h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-4。
如图5和6所示，实施例3所制得的石墨烯(SHSG-4)的比表面积为516m2g-1，孔容为1.12～1.16cm3g-1，孔径分布集中在4nm附近。
实施例3的石墨烯(SHSG-4)按上述方法组装成超级电容器，电解质采用离子 液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为79F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为33.8Wh kg-1。
实施例4
步骤1，取8g金属镁粉和16g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为300μm，氧化镁粉纯度为99.9％，平均粒径为500μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以200sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为10MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为10A的直流电，通电时间为15s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1.5min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M硫酸中24h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-2。
如图5和6所示，实施例4所制得的石墨烯(SHSG-2)的比表面积为469m2g-1，孔容为1.03～1.12cm3g-1，孔径分布集中在4nm附近。
实施例4的石墨烯(SHSG-2)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为55F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为23.5Wh kg-1。
实施例5
步骤1，取8g金属镁粉和8g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化 镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为5MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为15A的直流电，通电时间为20s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中36h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-1。
如图5和6所示，实施例5所制得的石墨烯(SHSG-1)比表面积为401m2g-1，孔容为0.83～1.03cm3g-1，孔径分布集中在4nm附近。
实施例4的石墨烯(SHSG-1)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为52F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为22.3Wh kg-1。
实施例6
步骤1，取8g金属镁粉放于石墨方舟中，在金属镁粉中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm；
步骤2，将步骤1中盛有金属镁粉及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为0.125MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为1A的直流电，通电时间为25s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中12h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。该介孔石墨烯粉末编号为SHSG-0。
如图5和6所示，实施例6所制得的石墨烯(SHSG-0)比表面积为364m2g-1，孔容为0.73～0.83cm3g-1，孔径分布集中在4nm附近。
实施例4的石墨烯(SHSG-0)按上述方法组装成超级电容器，电解质采用离子液体(EMIMBF4)。在0-3.5V的电压范围内进行恒流充放电测试。在2A g-1的充放电电流下，超级电容器的比电容为30F g-1。在3.5kW kg-1的功率密度下，超级电容器的能量密度为12.7Wh kg-1。
实施例1～6的石墨烯的拉曼光谱上D峰与G峰的比值ID/IG如下表1所示。ID/IG由SHSG-0的0.158增加至SHSG-8的1.126。
表1
石墨烯 ID/IG
SHSG-8 1.126
SHSG-6 1.110
SHSG-4 1.102
SHSG-2 0.766
SHSG-1 0.306
SHSG-0 0.158
实施例7
步骤1，取8g金属镁粉和80g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为0.125MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为15s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1.5min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中20h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例8
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为0.25MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为20s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中18h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例9
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为600μm，氧化镁粉纯度为99.9％，平均粒径为200μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为0.5MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为18A的直流电，通电时间为10s， 所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中10h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例10
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以2000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为2MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为15s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中20h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例11
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以1000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为5MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为18s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min 后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中24h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例12
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为10L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以3000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为15s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1.5min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中26h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例13
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为50L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为10A的直流电，通电时间为15s，所述通电的钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1.5min后得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1M盐酸中20h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例14
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为200μm，氧化镁粉纯度为99.9％，平均粒径为200μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为200L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以10000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为10s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量1.5M盐酸中15h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例15
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为80μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以3500sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为1A的直流电，通电时间为10s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑 色粉末置于足量2M盐酸中22h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例16
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为50μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为3A的直流电，通电时间为10s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量0.5M硫酸中15h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
实施例17
步骤1，取8g金属镁粉和64g氧化镁粉，混合均匀后得到混合粉末并放于石墨方舟中，在混合粉末中埋入钨丝线圈；其中所述金属镁粉纯度为99.9％，平均粒径为30μm，氧化镁粉纯度为99.9％，平均粒径为100μm；
步骤2，将步骤1中盛有混合粉末及钨丝线圈的石墨方舟置于容积为24L的钢制密闭耐压容器中，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，再以5000sccm的流速向该密闭耐压容器内通入纯度为99.9％的二氧化碳气体，直至密闭耐压容器内气体压力为1MPa；
步骤3，使用直流电源对所述钨丝线圈两端施加电流为0.5A的直流电，通电时间为30s，所述通电的钨丝线圈产生高温，引发金属镁粉与二氧化碳气体的反应自发进行，反应1min后，得到黑色粉末；
步骤4，释放密闭耐压容器内多余气体，直至容器内气体压力为常压，随后将所述黑色粉末置于足量0.2M硝酸中48h，除去产物中多余的氧化镁，再使用去离子水抽滤洗涤所 述黑色粉末至滤液呈中性，得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (95)

  1. 一种制备介孔石墨烯的方法，其特征在于，包括以下步骤：
    步骤1，将金属镁粉与氧化镁粉混合均匀，得到混合粉末，将所述混合粉末放入密封耐压容器中，并在所述混合粉末中埋入钨丝线圈；
    步骤2，使用分子泵将所述密封耐压容器压力降至2×10-4Pa，向所述密封耐压容器中通入二氧化碳气体，至所述密封耐压容器内压力为0.125-10MPa；
    步骤3，使用直流电源对所述钨丝线圈施加0.5-30A直流电，通电时间为5-30s，所述钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应1-2min后得到黑色粉末；
    步骤4，将所述黑色粉末置于稀酸溶液中静置6-48h，再使用去离子水抽滤洗涤所述黑色粉末至中性得到滤饼，将所述滤饼冷冻干燥后得到介孔石墨烯粉末。
  2. 根据权利要求1所述的制备介孔石墨烯的方法，其特征在于，步骤1中，所述金属镁粉的平均粒径为1-1000μm，所述氧化镁粉的平均粒径为0.1-1000μm。
  3. 根据权利要求1所述的制备介孔石墨烯的方法，其特征在于，步骤1中，所述混合粉末中金属镁粉与氧化镁粉的质量比为1:0-1:10。
  4. 根据权利要求1所述的制备介孔石墨烯的方法，其特征在于，所述稀酸溶液为浓度为0.2-2M的稀盐酸、稀硫酸或稀硝酸。
  5. 根据权利要求1所述的制备介孔石墨烯的方法，其特征在于，所述密封耐压容器为体积10-200L的钢制密封耐压容器。
  6. 根据权利要求1所述的制备介孔石墨烯的方法，其特征在于，步骤4中所述冷冻干燥包括以下步骤：
    步骤4.1，将所述滤饼放入塑料烧杯中，再向所述塑料烧杯中加入去离子水，超声并搅拌后得到糊状物；
    步骤4.2，将所述糊状物置于低温液体中冷冻30分钟，得到黑色固体；
    步骤4.3，将所述黑色固体置于冷冻干燥机中干燥得到所述介孔石墨烯粉末。
  7. 根据权利要求6所述的制备介孔石墨烯的方法，其特征在于，步骤4.1中，所述去离子水与滤饼的质量比为1:1-8:1。
  8. 根据权利要求6所述的制备介孔石墨烯的方法，其特征在于，步骤4.2中低温液体为液氮、液氦或液氩。
  9. 一种制备石墨烯的方法，包括以下步骤：
    i)将含金属镁粉和固体氧化物粉的混合物置于含二氧化碳的环境中；
    ii)加热所述混合物，使金属镁粉与二氧化碳反应，获得石墨烯。
  10. 根据权利要求9所述方法，金属镁粉与二氧化碳反应的化学方程式为：2Mg+CO2→2MgO+C。
  11. 根据权利要求9所述的方法，还包括以下步骤：
    iii)从步骤ii)的产物中去除氧化镁和/或所述固体氧化物。
  12. 根据权利要求11所述的方法，步骤iii)包括：酸洗步骤ii)的产物。
  13. 根据权利要求11所述的方法，还包括以下步骤：
    iv)对步骤iii)的产物进行洗涤、过滤或干燥中的一项或多项操作。
  14. 根据权利要求9所述的方法，步骤i)包括，将含金属镁粉和固体氧化物粉的混合物置于充有二氧化碳的密闭容器中。
  15. 根据权利要求9所述的方法，步骤i)中，金属镁粉与固体氧化物粉的质量比为1:0.1～10。
  16. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为1～9:1。
  17. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为2～9:1。
  18. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为4～9:1。
  19. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为6～9:1。
  20. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉和金属镁粉的质量比为6～8:1。
  21. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉的平均粒径为0.1～1000μm。
  22. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉的平均粒径为30～600μm。
  23. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉的平均粒径为30～300μm。
  24. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉的平均粒径为30～100μm。
  25. 根据权利要求14所述的方法，步骤i)中，固体氧化物粉的平均粒径为30～50μm。
  26. 根据权利要求9所述的方法，步骤i)中，金属镁粉的平均粒径为9～9000μm。
  27. 根据权利要求9所述的方法，步骤i)中，金属镁粉的平均粒径为30～600μm。
  28. 根据权利要求9所述的方法，步骤i)中，金属镁粉的平均粒径为30～300μm。
  29. 根据权利要求9所述的方法，步骤i)中，金属镁粉的平均粒径为30～900μm。
  30. 根据权利要求9所述的方法，步骤i)中，金属镁粉的平均粒径为30～50μm。
  31. 根据权利要求9所述的方法，所述固体氧化物为金属氧化物。
  32. 根据权利要求9所述的方法，所述固体氧化物为碱土金属氧化物。
  33. 根据权利要求30所述的方法，所述固体氧化物为氧化镁。
  34. 根据权利要求9所述的方法，步骤i)中，二氧化碳在的气压为0.125MPa以上。
  35. 根据权利要求9所述的方法，步骤i)中，二氧化碳在的气压为0.5MPa以上。
  36. 根据权利要求9所述的方法，步骤i)中，二氧化碳在的气压为1MPa以上。
  37. 根据权利要求9所述的方法，步骤i)中，二氧化碳在的气压为5MPa以上。
  38. 根据权利要求9所述的方法，步骤i)中，二氧化碳在的气压为0.125～10MPa。
  39. 根据权利要求9所述的方法，步骤i)中，环境中二氧化碳的含量为90体积％以上。
  40. 根据权利要求9所述的方法，步骤i)中，环境中二氧化碳的含量为90-99.99体积％。
  41. 根据权利要求9所述的方法，步骤ii)中，使用通电的金属导体加热所述混合物。
  42. 根据权利要求41所述的方法，步骤ii)中，所述金属导体是钨丝。
  43. 根据权利要求41所述的方法，步骤ii)中，所述通电的金属导体中通有0.5-30A的直流电。
  44. 根据权利要求9所述的方法，包括以下一步或多步：
    a)将金属镁粉与氧化镁粉混合均匀，得到混合粉末，将所述混合粉末放入密封耐压容器中，并在所述混合粉末中埋入钨丝线圈；
    b)将所述密封耐压容器内气体压力降至2×10-4Pa，向所述密封耐压容器中通入二氧化碳气体，至所述密封耐压容器内压力为0.125～10MPa；
    c)使用直流电源对所述钨丝线圈施加0.5～30A直流电，通电时间为5-30s，所述钨丝线圈产生高温引发金属镁粉与二氧化碳发生反应，反应后得到粉末；
    d)将步骤c)的粉末产物置于稀酸溶液中静置6～48h，再使用去离子水抽滤洗涤所述粉末，收集滤出物，将所述滤出物经冷冻干燥后得到石墨烯。
  45. 一种石墨烯，所述石墨烯的比表面积为350～750m2g-1，孔容为1～2cm3g-1。
  46. 根据权利要求45所述的石墨烯，所述石墨烯的表面积为400～750m2g-1。
  47. 根据权利要求45所述的石墨烯，所述石墨烯的表面积为500～750m2g-1。
  48. 根据权利要求45所述的石墨烯，所述石墨烯的表面积为600～750m2g-1。
  49. 根据权利要求45所述的石墨烯，所述石墨烯的表面积为650～750m2g-1。
  50. 根据权利要求45所述的石墨烯，所述石墨烯的表面积为680～710m2g-1。
  51. 根据权利要求45所述的石墨烯，所述石墨烯的孔容为0.8～1.8cm3g-1。
  52. 根据权利要求45所述的石墨烯，所述石墨烯的孔容为1.2～1.8cm3g-1。
  53. 根据权利要求45所述的石墨烯，所述石墨烯的孔容为1.4～1.8cm3g-1。
  54. 根据权利要求45所述的石墨烯，所述石墨烯的孔容为1.5～1.6cm3g-1。
  55. 根据权利要求45所述的石墨烯，所述石墨烯的氮气等温吸脱附曲线有滞后环。
  56. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线在3～5nm范围内有峰。
  57. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线在在3.5～4.5nm范围内有峰。
  58. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上仅有一个峰。
  59. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有峰宽为0.5～3nm的峰。
  60. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有峰宽为0.5～2nm的峰。
  61. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有峰宽为0.5～1nm的峰。
  62. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有半峰宽为0.5～3nm的峰。
  63. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有半峰宽为0.5～2nm的峰。
  64. 根据权利要求45所述的石墨烯，所述石墨烯的孔径分布曲线上有半峰宽为 0.5～1nm的峰。
  65. 根据权利要求45所述的石墨烯，所述石墨烯的侧层数为10层以下。
  66. 根据权利要求45所述的石墨烯，所述石墨烯的侧层数为5层以下。
  67. 根据权利要求45所述的石墨烯，所述石墨烯的碳氧元素的原子比为70以上。
  68. 根据权利要求45所述的石墨烯，所述石墨烯的碳氧元素的原子比为80以上。
  69. 根据权利要求45所述的石墨烯，所述石墨烯的碳氧元素的原子比为80～90。
  70. 根据权利要求45所述的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于5％。
  71. 根据权利要求45所述的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于4％。
  72. 根据权利要求45所述的石墨烯，所述石墨烯在氮气氛围下的热失重曲线，自600至800℃的失重小于或等于3％。
  73. 根据权利要求45所述的石墨烯，所述石墨烯在空气氛围下的热失重曲线，升温至800℃时，失重率为100％。
  74. 根据权利要求45所述的石墨烯，所述石墨烯的弛豫时间常数小于或等于0.02s。
  75. 根据权利要求45所述的石墨烯，所述石墨烯的弛豫时间常数小于或等于0.015s。
  76. 根据权利要求45所述的石墨烯，所述石墨烯的碳含量高于90at％。
  77. 根据权利要求45所述的石墨烯，所述石墨烯的碳含量高于92at％。
  78. 根据权利要求45所述的石墨烯，所述石墨烯的碳含量高于94at％。
  79. 根据权利要求45所述的石墨烯，所述石墨烯的碳含量高于96at％。
  80. 根据权利要求45所述的石墨烯，所述石墨烯的碳含量高于97at％。
  81. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为6000S m-1以上。
  82. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为8000S m-1以上。
  83. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为10000S m-1以上。
  84. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为12000S m-1以上。
  85. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为8000～15000S m-1。
  86. 根据权利要求45所述的石墨烯，所述石墨烯的导电率为11000～13000S m-1。
  87. 根据权利要求45所述的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.3以上。
  88. 根据权利要求45所述的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.5以上。
  89. 根据权利要求45所述的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.7以上。
  90. 根据权利要求45所述的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.9以上。
  91. 根据权利要求45所述的石墨烯，所述石墨烯的拉曼光谱上D峰与G峰的强度比值ID/IG为0.3～1.2。
  92. 根据权利要求45所述的石墨烯，所述石墨烯是介孔石墨烯。
  93. 根据权利要求45所述的石墨烯，所述石墨烯由权利要求1～44任一项的方法制得。
  94. 一种超级电容器电极，含有权利要求45～93任一项的石墨烯。
  95. 一种超级电容器，含有权利要求45～93任一项的石墨烯。
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