WO2023013298A1 - Matériau de graphène, son procédé de production et son application d'utilisation - Google Patents

Matériau de graphène, son procédé de production et son application d'utilisation Download PDF

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WO2023013298A1
WO2023013298A1 PCT/JP2022/025643 JP2022025643W WO2023013298A1 WO 2023013298 A1 WO2023013298 A1 WO 2023013298A1 JP 2022025643 W JP2022025643 W JP 2022025643W WO 2023013298 A1 WO2023013298 A1 WO 2023013298A1
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graphene
graphene oxide
graphene material
present
dispersion
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Japanese (ja)
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捷 唐
師齊 林
坤 張
之規 羽藤
頼重 松葉
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株式会社マテリアルイノベーションつくば
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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
    • 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
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/42—Powders or particles, e.g. composition thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Definitions

  • the present invention relates to a graphene material, its manufacturing method and its use.
  • Graphene is a material in which carbon atoms are arranged in a hexagonal planar structure.
  • the carbon atoms of graphene are sp2 - bonded and form a planar sheet with a thickness of a single atom.
  • Graphene is excellent in electrical conductivity, thermal conductivity, and mechanical strength, and is being researched into various fields such as battery materials, energy storage materials, and electronic devices, as well as automobiles, aerospace, and medicine. is in progress.
  • Graphene production methods include mechanical exfoliation, chemical vapor deposition (CVD), lamination on a silicon carbide (SiC) substrate, and chemical oxidation-reduction.
  • CVD chemical vapor deposition
  • SiC silicon carbide
  • the chemical oxidation-reduction method is a method of producing graphene by a reduction reaction after obtaining graphene oxide by oxidation treatment of natural graphite (for example, Patent Document 1).
  • the chemical oxidation-reduction method is promising as an industrial production method because it enables mass production of graphene.
  • this method requires the use of a reducing agent such as hydrazine for the deoxygenation reaction of graphene oxide.
  • reducing agents have hazards such as high corrosiveness, explosiveness, toxicity to humans, and hazards to the environment, and tend to limit their industrial use.
  • the generated graphene may contain impurities and the like, and there is a concern that the conductivity may be lowered.
  • an object of the present invention is to provide a method for producing graphene having excellent physical properties such as electrical properties without using a reducing agent in the production process.
  • Another object of the present invention is to provide a graphene material produced by such a production method and uses of the graphene material.
  • a method for producing a graphene material according to the present invention comprises the steps of: preparing graphene oxide; heat-treating the graphene oxide at 300° C. to 700° C.; The method includes preparing a reduced graphene oxide dispersion and hydrothermally treating the thermally reduced graphene oxide dispersion at 150° C. to 250° C., thereby solving the above problem.
  • the time of the heat treatment step may be within 1 minute, and the time of the hydrothermal treatment step may range from 10 hours to 36 hours.
  • the dispersion medium may be water or ethanol.
  • the graphene oxide is heat-treated in a muffle furnace at 350° C. to 500° C.
  • the heat treatment step may include hydrothermally treating the thermally reduced graphene oxide dispersion in an autoclave at 160° C. to 220° C. for 12 hours to 24 hours.
  • the graphene material according to the present invention has substantially no aggregation of graphene sheets and has an oxygen content of 7.0% or less by XPS analysis, thereby solving the above problems.
  • the number of layers of the graphene sheets measured from a high-resolution transmission electron microscope (HRTEM) image may be 7 or less.
  • a graphene electrode according to the present invention contains the graphene material described above and thereby solves the above problems.
  • the graphene electrode of the present invention may further contain a conductive material and a binder.
  • the graphene electrode of the present invention may be for electric double layer capacitors.
  • a method for producing a graphene material of the present invention includes the steps of heat-treating graphene oxide under predetermined conditions, and dispersing a thermally reduced graphene oxide dispersion in which the heat-treated graphene oxide is dispersed in a predetermined dispersion medium under predetermined conditions. and hydrothermally treating.
  • the method for producing a graphene material of the present invention it is possible to produce a graphene material having excellent physical properties such as electrical properties through a production process that does not use a reducing agent.
  • the method for producing the graphene material of the present invention not only undergoes a low-risk process, does not require skilled techniques or expensive equipment, is economical and efficient, and has a low environmental load. Suitable for mass production.
  • the graphene material of the present invention is a graphene material that is produced by the above-described production method, has a small number of layers, suppresses agglomeration due to interactions between graphenes, and has a low oxygen content. Therefore, the graphene material of the present invention is a graphene material that does not use a reducing agent in its manufacturing process and has excellent physical properties such as electrical properties.
  • graphene electrodes for electric storage devices such as electric double layer capacitors and lithium ion batteries can be provided.
  • the graphene material of the present invention has properties comparable to or superior to those of graphene produced by conventional chemical redox methods, it can be applied to various fields other than electrode materials.
  • FIG. 1 shows the XPS spectrum of the graphene material of Example 1.
  • FIG. 2 shows the XPS spectrum of the graphene material of Example 2.
  • FIG. 3 shows the XPS spectrum of the graphene material of Example 3.
  • FIG. 4 shows the XPS spectrum of the graphene material of Example 4.
  • FIG. 4 shows the XPS spectrum of the graphene material of Example 5.
  • Embodiment 1 describes a method for producing a graphene material of the present invention.
  • FIG. 1 is a flow chart showing the manufacturing process of the graphene material of the present invention.
  • Step S110 Prepare graphene oxide.
  • step S110 may further include a step of preparing graphene oxide.
  • GO graphene oxide
  • the graphene oxide may be produced by a known production method. For example, one prepared from natural graphite using the modified Hummers method can be used.
  • Step S120 The graphene oxide is heat-treated at 300°C to 700°C.
  • the graphene oxide is heat-treated under predetermined conditions to thermally reduce the graphene oxide.
  • the conditions for heat-treating the graphene oxide are not particularly limited as long as the above temperature conditions are satisfied, but a shorter time is preferable from the viewpoint of production efficiency and reduction of environmental load.
  • a graphene oxide aqueous dispersion obtained by dispersing a predetermined amount of graphene oxide in water is freeze-dried for several days (about two days) in a freeze dryer, and then the obtained graphene oxide is
  • the target thermally-reduced graphene oxide (TRGO) can be obtained by heat-treating the solid in a muffle furnace at 300° C. to 700° C. within 1 minute and quickly taking it out.
  • the graphene oxide solid described above is heat-treated in a muffle furnace at 350°C to 500°C for less than 1 minute. Thereby, the desired thermally reduced graphene oxide can be obtained more efficiently.
  • Step S130 Disperse the heat-treated graphene oxide in a dispersion medium to prepare a thermally reduced graphene oxide dispersion.
  • the dispersion medium for preparing the thermally reduced graphene oxide dispersion is not particularly limited, and examples thereof include water and ethanol.
  • the concentration of the thermally-reduced graphene oxide dispersion is not particularly limited, and may be appropriately selected so that the thermally-reduced graphene oxide can be well dispersed in the dispersion medium.
  • the concentration of the thermally reduced graphene oxide dispersion may range from 0.1 mg/mL to 1.0 mg/mL.
  • a mixing/dispersing device such as an ultrasonic homogenizer may be used.
  • Step S140 The thermally reduced graphene oxide dispersion is hydrothermally treated at 150°C to 250°C.
  • step S140 the thermally reduced graphene oxide is hydrothermally treated under predetermined conditions to remove functional groups (in particular, oxygen-containing functional groups) remaining on the graphene sheet after thermal reduction in step S120, thereby highly reducing the graphene oxide. and a graphene material in which aggregation of graphene sheets is suppressed.
  • the conditions for hydrothermally treating the thermally reduced graphene oxide are not particularly limited as long as the above-mentioned temperature conditions are satisfied, but a shorter time is preferable from the viewpoint of production efficiency and reduction of environmental load.
  • the desired graphene material can be obtained by subjecting the thermally reduced graphene oxide dispersion obtained in step S130 to hydrothermal treatment in an autoclave at 150° C. to 250° C. for 10 hours to 36 hours.
  • the above thermally reduced graphene oxide dispersion is hydrothermally treated in an autoclave at 160°C to 220°C for 12 hours to 24 hours. Thereby, the desired graphene material can be obtained more efficiently.
  • graphene oxide is produced by a two-step reduction treatment that combines step S120 of heat treatment and step S140 of hydrothermal treatment. It is characterized by removing the oxygen-containing functional groups on the constituent graphene sheets to produce graphene having excellent physical properties such as electrical properties while suppressing structural destruction and defects.
  • the order of these steps is that reduction by heat treatment is first performed, and then reduction by hydrothermal treatment is performed, thereby improving the effect of removing the above-mentioned functional groups and producing a graphene material having excellent physical properties. .
  • Embodiment 2 describes a graphene material of the present invention.
  • the graphene material of the present invention is preferably manufactured by the manufacturing method described in the first embodiment.
  • the graphene material of the present invention is substantially free of aggregation of graphene sheets and has an oxygen content of 7.0% or less by XPS analysis.
  • the number of layers of the graphene sheet is preferably 7 or less as measured from a high-resolution transmission electron microscope (HRTEM) image.
  • a graphene material is “substantially free of aggregation of graphene sheets”
  • a structure resulting from aggregation of graphene sheets is substantially confirmed in a transmission electron microscope (TEM) image of the material. not intended to be
  • TEM transmission electron microscope
  • the graphene sheets are aggregated, in the transmission electron microscope (TEM) image, the sheet-like structures gathered together and the wrinkle-like pattern are confirmed as high-contrast portions.
  • the graphene material of the present invention is characterized by substantially not having such an aggregate structure.
  • the oxygen content of the graphene material of the present invention can be measured from the spectrum obtained using an X-ray photoelectron spectrometer (XPS). According to the XPS analysis, the graphene material of the present invention has an oxygen content of 7.0% or less, preferably 6.0% or less, and more preferably 5.5% or less. Accordingly, the graphene material of the present invention is excellent in physical properties such as electrical properties, and is suitable for use as an electrode material for electric storage devices such as electric double layer capacitors and lithium ion batteries. Furthermore, the graphene material of the present invention can be suitably used for various applications other than electrode materials.
  • XPS X-ray photoelectron spectrometer
  • the number of layers of graphene sheets that constitute the graphene material of the present invention can be measured from high-resolution transmission electron microscope (HRTEM) images.
  • the number of layers of graphene sheets is preferably 7 or less, more preferably 5 or less, according to the HRTEM image.
  • the graphene material of the present invention has excellent physical properties such as electrical properties, and is more suitable as an electrode material for the above-described electricity storage device or as a material used for various applications other than electrode materials.
  • the graphene material of the present invention can be suitably used as an electrode material.
  • the graphene material of the present invention is suitable for use as an electrode material for electrical storage devices.
  • An electric double layer capacitor will be described below as an example of an electric storage device using the graphene material of the present invention as an electrode material.
  • FIG. 2 is a schematic diagram showing the electric double layer capacitor of the present invention.
  • the electric double layer capacitor of the present invention comprises at least electrodes and an electrolyte.
  • a positive electrode 210 and a negative electrode 220 are immersed in an electrolyte 230 as electrodes.
  • These positive electrode 210 and negative electrode 220 are electrodes containing the graphene material described in the second embodiment.
  • Electrolyte 230 is, for example, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI), 1-ethyl-3-methylimidazolium borofluoride (EMI-BF 4 ) and 1-methyl- An ionic liquid selected from the group consisting of 1-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPp-TFSI) or M'OH (M' is an alkali metal).
  • MPPp-TFSI 1-propylpiperidinium bis(trifluoromethylsulfonyl)imide
  • M'OH is an alkali metal
  • the positive electrode 210 and the negative electrode 220 may further contain a conductive material and a binder in addition to the graphene material described in Embodiment 2. As a result, a film-like electrode having a smooth surface is obtained.
  • the content ratios of the graphene material, the conductive material, and the binder are not particularly limited. do it. By being mixed in such weight ratios, higher power and energy densities can be achieved when applied to capacitors.
  • 80 to 95 means 80 or more and 95 or less
  • 0 to 10 means more than 0 and 10 or less
  • 1 to 10 means 1 or more and 10 or less. It is prepared so that the total with the binder is 100 parts by weight.
  • the conductive material is not particularly limited as long as it is used as a conductive material in a normal electrode, but considering dispersibility with graphene materials, examples include carbon black, acetylene black, channel black, furnace Carbon materials selected from the group consisting of black and ketjen black are preferred.
  • the binder is not particularly limited as long as it is used as a binder in normal electrodes, but typically there are organic solvent-based binders and water-based binders.
  • Organic solvent-based binders include tetrafluoroethylene resin (PTFE), modified tetrafluoroethylene resin, polyvinylidene fluoride (PVDF), and the like.
  • Water-based binders include carboxymethylcellulose sodium (CMC), styrene-butadiene rubber (SBR), and the like. In particular, it is preferable to use a combination of CMC and SBR in a water-based binder.
  • the electric double layer capacitor 200 further has a separator 240 between the positive electrode 210 and the negative electrode 220 to separate the positive electrode 210 and the negative electrode 220 .
  • Materials for the separator 240 include, for example, fluorine-based polymers, polyethers such as polyethylene oxide and polypropylene oxide, polyolefins such as polyethylene and polypropylene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polymethyl acrylate, polyvinyl alcohol, and polymethacrylonitrile.
  • the positive electrode 210, the negative electrode 220, the electrolyte 230 and the separator 240 described above are accommodated in the cell 250. Also, the positive electrode 210 and the negative electrode 220 each have an existing current collector.
  • Such an electric double layer capacitor 200 may be a chip-type, coin-type, mold-type, pouch-type, laminate-type, cylindrical-type, rectangular-type capacitor, etc., and is used in a module in which a plurality of these are connected.
  • the electrolyte ions (anions) of the electrolyte 230 are adsorbed to the positive electrode 210, and the electrolyte ions (cations) of the electrolyte 230 are adsorbed to the negative electrode 220, respectively.
  • an electric double layer is formed on each of the positive electrode 210 and the negative electrode 220 and charged.
  • the positive electrode 210 and the negative electrode 220 are formed of the graphene material described in Embodiment 2, cations and anions are easily adsorbed and diffused by graphene, and high rate characteristics can be achieved.
  • the positive electrode 210 and the negative electrode 220 are formed of the graphene material described in Embodiment 2, many electrolyte ions are adsorbed not only on the surface of the graphene but also inside, forming an electric double layer. . As a result, exchange of electrons between graphene and electrolyte ions increases, and high energy density can be achieved.
  • the anions and cations adsorbed to the positive electrode 210 and the negative electrode 220 are desorbed and discharged.
  • the positive electrode 210 and the negative electrode 220 are made of the graphene material described in Embodiment 2, electrolyte ions can be easily desorbed and diffused, and high rate characteristics and energy density can be achieved.
  • the power density can be improved with the easiness of desorption/diffusion.
  • the electric double layer capacitor 200 of the present invention can fully exhibit the properties of graphene in the electrodes, enabling quick charging and achieving high energy density and high power density.
  • the formation of an electric double layer is used for charging and discharging, it is excellent in repeated use.
  • the electric double layer capacitor 200 of the present invention can be used for wind power generation, electric vehicles, and the like.
  • an electric double layer capacitor is used as an example for explanation, but it goes without saying that the graphene material of the present invention can be applied as an electrode material for electric storage devices such as lithium ion batteries in addition to electric double layer capacitors.
  • Example 1 a graphene oxide aqueous dispersion (0.5 mg/mL) of graphene oxide in water was freeze-dried in a freeze dryer for 2 days, and then the resulting sponge-like The graphene oxide was heated in a muffle furnace at 400° C. within 1 minute and quickly taken out (step S120 in FIG. 1).
  • Example 2 the graphene oxide aqueous dispersion described above was hydrothermally treated in an autoclave at 160°C for 12 hours (hydrothermal reduction).
  • Example 3 after hydrothermal treatment under the same conditions as in Example 2, the hydrothermally treated graphene oxide was heated in a muffle furnace at 400°C within 1 minute and quickly taken out (thermal reduction).
  • Example 4 the graphene oxide obtained in the same manner as in Example 1 was heated in a muffle furnace at 400° C. within 1 minute and quickly taken out (step S120 in FIG. 1). Next, the heat-treated graphene oxide was dispersed in water to prepare a thermally reduced graphene oxide dispersion (0.5 mg/mL) (step S130 in FIG. 1). The thermally reduced graphene oxide dispersion was then hydrothermally treated in an autoclave at 160° C. for 12 hours (step S140 in FIG. 1).
  • Example 5 the graphene oxide obtained in the same manner as in Example 1 was reduced with hydrazine (hydrazine reduction).
  • FIG. 3A shows that the graphene material of Example 1 has a small number of layers and is in the form of a thin sheet. However, as indicated by arrows in the HRTEM image, amorphous portions with low crystallinity were present, and had crystal structural defects.
  • 3B and 3C it can be seen that the graphene sheets of both the graphene materials of Examples 2 and 3 have a large number of layers and aggregate graphene sheets in portions with high contrast.
  • the graphene material of Example 5 has a large number of layers, is partially wrinkled as indicated by the arrows in the figure, and has a portion where the graphene sheets aggregate (the contrast is It can be seen that there is a dark portion).
  • the graphene material of Example 4 has a small number of layers, and the surface of the edge region where the graphene sheets are not folded is almost transparent. Also, a single graphene sheet can be clearly identified from the HRTEM image. Here, when the number of layers was evaluated from the HRTEM image, the number of layers of graphene sheets in this frame was about 3-4.
  • the specific surface area and oxygen content of the graphene materials obtained in Examples 1-5 were measured. Table 1 shows the results. The specific surface area was evaluated from the nitrogen adsorption/desorption isotherm by the BET method. The oxygen content was evaluated from the spectrum obtained using an X-ray photoelectron spectrometer (XPS: PHI Quantera SXM manufactured by ULVAC-Phi, Inc., X-ray source: Al K ⁇ , analyzer: hemispherical analyzer).
  • XPS PHI Quantera SXM manufactured by ULVAC-Phi, Inc.
  • analyzer hemispherical analyzer
  • FIGS. 4A to 4E are diagrams showing XPS spectra of the graphene materials of Examples 1 to 5, respectively. Each figure shows raw data (Raw) that has not been analyzed, data that has undergone fitting processing on the raw data (Fitting), and four-component data obtained by performing peak separation (waveform separation). (CC, CO, COOH, ⁇ - ⁇ ).
  • the graphene material of Example 4 has a higher specific surface area and a lower oxygen content than the graphene material of Example 5 (i.e., conventional hydrazine-reduced graphene oxide).
  • graphene sheets constituting graphene oxide are produced by a production process that does not use a reducing agent without using a hazardous chemical substance such as hydrazine. It has been found that oxygen-containing functional groups can be effectively removed to produce graphene materials with physical properties comparable to or superior to chemically reduced graphene oxide.
  • the graphene material of Example 1 has a larger specific surface area than the graphene material of Example 4, it has a large oxygen content and the reduction of graphene oxide is insufficient.
  • the graphene materials of Examples 2 and 3 have a smaller specific surface area and a higher oxygen content than the graphene material of Example 4. From these results, in the method for producing a graphene material of the present invention, the oxygen-containing functional groups on the graphene sheet constituting the graphene oxide are effectively reduced by a two-step reduction treatment that combines a heat treatment step and a hydrothermal treatment step. In addition, the order of these steps is first reduction by heat treatment and then reduction by hydrothermal treatment, thereby improving the effect of removing the above-mentioned functional groups and obtaining a graphene material having excellent physical properties. was shown to be able to produce
  • the graphene materials of Examples 1 to 5 are dispersed in a CMC (carbomexymethyl cellulose) aqueous dispersion, and mixed with conductive carbon black as a conductive material and SBR (styrene butadiene rubber) as a binder to form a slurry. Obtained.
  • This slurry was applied onto an Al (aluminum) current collector and dried in vacuum at 120° C. for 24 hours to obtain an electrode film.
  • a separator glass fiber
  • an ionic liquid EMI-BF 4
  • the coin cell was assembled in a glove box filled with Ar gas.
  • Electrochemical measurements of coin cells were performed using a multi-channel potentiostat galvanostat (Bio-Logic, VMP-300). Specific capacity-voltage measurement (CV measurement) and galvanostat charge-discharge measurement were performed at room temperature in a potential range of 0V to 3.5V. Also, an electrochemical impedance measurement was performed.
  • FIGS. 5(a) to 5(d) are diagrams showing the constant current charge/discharge curve (GCD curve), rate characteristics, electrochemical impedance spectrum (EIS), and cycle characteristics of the prototype coin cell, respectively.
  • GCD curve constant current charge/discharge curve
  • EIS electrochemical impedance spectrum
  • FIGS. 5(b) to (d) plot figures corresponding to Examples 1 to 5 are circles, squares, downward triangles, upward triangles, and rhombuses, respectively.
  • the GCD curve shown in FIG. 5(a) was measured at a current density of 0.2 A/g.
  • the rate characteristics shown in FIG. 5(b) are the results obtained in the current density range of 0.1 A/g to 5.0 A/g.
  • the EIS shown in FIG. 5(c) is obtained by fitting using an equivalent circuit model.
  • the cycle characteristics shown in FIG. 5(d) showed capacitance retention up to 10000 cycles.
  • Table 2 summarizes the electrical properties of the graphene materials of Examples 1 to 5 obtained from these measurement results.
  • the graphene material of Example 4 exhibits a specific capacity of 154 F/g at 0.1 A/g and retains a specific capacity of 128 F/g even at a higher 5.0 A/g, yielding over 80% showed the rate characteristics of In addition, it was found that the capacitance retention rate exceeded 90% even after 10000 cycles, indicating excellent long life. In addition, the energy density and power density reached 66 Wh/kg and 172 kW/kg respectively at a current density of 0.1 A/g. In addition, the graphene material of Example 4 exhibited the lowest equivalent resistance (3.3 ⁇ ) (Fig. 5(c)).
  • a laminate type electric double layer capacitor was produced using the graphene material of Example 4 as an electrode, and the electrical characteristics were further evaluated.
  • the structure of this electric double layer capacitor was the same as that shown in FIG. Specifically, two electrodes were cut into pieces each having a size of 3 ⁇ 3 cm 2 to form a positive electrode and a negative electrode. A positive electrode terminal and a negative electrode terminal are ultrasonically fused to the positive electrode and the negative electrode, respectively, facing each other with a cellulose separator having a thickness of 25 ⁇ m in between, and housed in an outer package made of a laminated film in which polypropylene, aluminum, and nylon are laminated.
  • An ionic liquid (EMI-BF 4 ) was injected as an electrolyte into the exterior body, and the exterior body was heat-sealed with the ends of the positive electrode terminal and the negative electrode terminal drawn out of the exterior body to enclose the laminate cell. .
  • CV curve specific capacity-voltage curve
  • GCD curve constant current charge/discharge curve
  • EIS electrochemical impedance spectrum
  • the graphene material of Example 4 showed a rectangular CV curve representing an ideal electric double layer capacitor.
  • 6(b) and (c) show a specific capacity of 150 F/g at 0.1 A/g and retain a specific capacity of 132 F/g even at a higher 5.0 A/g, yielding 80% The above rate characteristics are shown.
  • the graphene material of Example 4 exhibited a low equivalent resistance (0.8 ⁇ ), similar to that of the coin cell described above (Fig. 6(d)).
  • Examples 6-10 the graphene materials were produced by varying the temperature conditions from 120° C. to 220° C. as shown in Table 3 below. Using the obtained graphene material as an electrode, an electric double layer capacitor (CR2032 type coin cell) similar to that described above was produced, and an electrochemical measurement was performed. Specific capacity-voltage measurement (CV measurement) and galvanostat charge-discharge measurement were performed at room temperature in a potential range of 0V to 3.5V. Table 3 shows the specific capacity and rate characteristic results obtained in the current density range of 0.1 A/g to 5.0 A/g.
  • Table 3 shows the specific capacity and rate characteristic results obtained in the current density range of 0.1 A/g to 5.0 A/g.
  • the temperature condition for the hydrothermal treatment is preferably 150° C. or higher, more preferably 160° C. or higher.
  • Examples 11-15 graphene materials were produced by varying the time conditions from 2 hours to 24 hours as shown in Table 4 below. Using the obtained graphene material as an electrode, an electric double layer capacitor (CR2032 type coin cell) similar to that described above was produced, and an electrochemical measurement was performed. Specific capacity-voltage measurement (CV measurement) and galvanostat charge-discharge measurement were performed at room temperature in a potential range of 0V to 3.5V. Table 4 shows the specific capacity and rate characteristic results obtained in the current density range of 0.1 A/g to 5.0 A/g.
  • the graphene material was prepared as a 9:1 (volume ratio) mixed solvent.
  • an electric double layer capacitor (CR2032 type coin cell) similar to that described above was produced, and an electrochemical measurement was performed.
  • Specific capacity-voltage measurement (CV measurement) and galvanostat charge-discharge measurement were performed at room temperature in a potential range of 0V to 3.5V.
  • Table 5 shows the specific capacity and rate characteristic results obtained in the current density range of 0.1 A/g to 1.0 A/g.
  • the method for producing a graphene material of the present invention can produce a graphene material with excellent physical properties such as electrical properties through a production process that does not use a reducing agent. That is, it is a method that can economically and efficiently produce graphene materials through a low-risk process, and is easy to scale up for mass production.
  • the graphene material of the present invention produced by such a production method can effectively exhibit the electrical properties inherent in graphene, and can be used as an electrode material for electrical storage devices (especially for electric double layer capacitors). It is expected to be applied to various fields including

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  • Electric Double-Layer Capacitors Or The Like (AREA)

Abstract

La présente invention concerne un procédé de production de graphène présentant d'excellentes propriétés physiques telles que des caractéristiques électriques et qui n'utilise pas d'agent réducteur lors du processus de production. Le procédé de production d'un matériau de graphène selon la présente invention comprend : une étape de préparation d'oxyde de graphène ; une étape consistant à chauffer l'oxyde de graphène entre 300 et 700 °C ; une étape de dispersion de l'oxyde de graphène chauffé dans un milieu de dispersion pour produire un liquide de dispersion d'oxyde de graphène réduit thermiquement ; et une étape consistant à effectuer un traitement hydrothermique sur le liquide de dispersion d'oxyde de graphène réduit thermiquement entre 150 et 250° C.
PCT/JP2022/025643 2021-08-04 2022-06-28 Matériau de graphène, son procédé de production et son application d'utilisation WO2023013298A1 (fr)

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JP2014505002A (ja) * 2010-12-10 2014-02-27 東レ株式会社 グラフェン粉末、グラフェン粉末の製造方法およびグラフェン粉末を含むリチウム二次電池用電気化学素子
WO2014065241A1 (fr) * 2012-10-24 2014-05-01 独立行政法人物質・材料研究機構 Pièce en graphène ultramince, dispositif et procédé de fabrication d'une pièce en graphène ultramince, capacité, et son procédé de fabrication
JP2019501100A (ja) * 2015-12-03 2019-01-17 ナノテック インストゥルメンツ インコーポレイテッドＮａｎｏｔｅｋ Ｉｎｓｔｒｕｍｅｎｔｓ， Ｉｎｃ． グラフェン材料のケミカルフリー製造
JP2019531999A (ja) * 2016-08-18 2019-11-07 ナノテク インストゥルメンツ, インコーポレイテッドNanotek Instruments, Inc. 高配向フミン酸フィルムおよびそれから得られる高導電性黒鉛フィルムならびに同フィルムを含有するデバイス
JP2020507181A (ja) * 2017-01-26 2020-03-05 ナノテク インストゥルメンツ, インコーポレイテッドNanotek Instruments, Inc. リチウム電池におけるグラフェンフォームで保護された金属フッ化物及び金属塩化物カソード活物質

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011162411A1 (fr) * 2010-06-25 2011-12-29 日本電気株式会社 Procédé permettant de déterminer le nombre de couches de la structure atomique d'un film mince bidimensionnel et dispositif afférent
JP2012031024A (ja) * 2010-08-02 2012-02-16 Fuji Electric Co Ltd グラフェン薄膜の製造方法
JP2014505002A (ja) * 2010-12-10 2014-02-27 東レ株式会社 グラフェン粉末、グラフェン粉末の製造方法およびグラフェン粉末を含むリチウム二次電池用電気化学素子
WO2014065241A1 (fr) * 2012-10-24 2014-05-01 独立行政法人物質・材料研究機構 Pièce en graphène ultramince, dispositif et procédé de fabrication d'une pièce en graphène ultramince, capacité, et son procédé de fabrication
JP2019501100A (ja) * 2015-12-03 2019-01-17 ナノテック インストゥルメンツ インコーポレイテッドＮａｎｏｔｅｋ Ｉｎｓｔｒｕｍｅｎｔｓ， Ｉｎｃ． グラフェン材料のケミカルフリー製造
JP2019531999A (ja) * 2016-08-18 2019-11-07 ナノテク インストゥルメンツ, インコーポレイテッドNanotek Instruments, Inc. 高配向フミン酸フィルムおよびそれから得られる高導電性黒鉛フィルムならびに同フィルムを含有するデバイス
JP2020507181A (ja) * 2017-01-26 2020-03-05 ナノテク インストゥルメンツ, インコーポレイテッドNanotek Instruments, Inc. リチウム電池におけるグラフェンフォームで保護された金属フッ化物及び金属塩化物カソード活物質

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