WO2023095724A1 - Method for producing thin plate-shaped structure of graphite, method for producing exfoliated graphite, and exfoliated graphite - Google Patents

Method for producing thin plate-shaped structure of graphite, method for producing exfoliated graphite, and exfoliated graphite Download PDF

Info

Publication number
WO2023095724A1
WO2023095724A1 PCT/JP2022/042850 JP2022042850W WO2023095724A1 WO 2023095724 A1 WO2023095724 A1 WO 2023095724A1 JP 2022042850 W JP2022042850 W JP 2022042850W WO 2023095724 A1 WO2023095724 A1 WO 2023095724A1
Authority
WO
WIPO (PCT)
Prior art keywords
graphite
less
exfoliated graphite
mass
electrolyte
Prior art date
Application number
PCT/JP2022/042850
Other languages
French (fr)
Japanese (ja)
Inventor
泰司 西川
Original Assignee
株式会社カネカ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社カネカ filed Critical 株式会社カネカ
Publication of WO2023095724A1 publication Critical patent/WO2023095724A1/en

Links

Images

Classifications

    • 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
    • C01B32/19—Preparation by exfoliation
    • 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
    • C01B32/194—After-treatment
    • 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
    • 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
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • C01B32/22—Intercalation
    • C01B32/225—Expansion; Exfoliation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/042—Electrodes formed of a single material
    • C25B11/043—Carbon, e.g. diamond or graphene
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C25B15/023—Measuring, analysing or testing during electrolytic production
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • C25B15/023—Measuring, analysing or testing during electrolytic production
    • C25B15/025—Measuring, analysing or testing during electrolytic production of electrolyte parameters
    • C25B15/029—Concentration

Definitions

  • the present invention relates to a method for producing a graphite sheet-like structure, a method for producing exfoliated graphite, and exfoliated graphite.
  • Graphene has high carrier mobility, thermal conductivity, and transparency.
  • graphene is a sheet of sp2 - bonded carbon atoms with a thickness of one atom, it is easy to increase the area of devices and has high thermal and chemical stability. Due to such excellent properties, graphene is expected to be applied to advanced industrial materials including the electronics field.
  • graphite is a laminate composed of many graphenes stacked on top of each other, and is easy to obtain. For this reason, a method has been proposed for producing exfoliated graphite in which the number of laminated layers of graphene is much smaller than that of graphite by exfoliating the layers of graphite.
  • exfoliated graphite for example, in an electrochemical reaction system containing a graphite-containing anode, a cathode, and an electrolyte solution, a voltage is applied between the anode and the cathode to obtain a film between the graphite layers.
  • a method is known in which, after intercalating ions derived from an electrolyte to obtain a graphite sheet-like structure, the layers of the sheet-like structure are separated.
  • the exfoliated graphite thus obtained is composed of oxygen-containing graphene (graphene oxide), into which functional groups such as hydroxy groups and carboxy groups are introduced.
  • Such exfoliated graphite can be modified with functional groups to make it highly functional, so it is expected to be applied to polymer composite materials, paints, inks, drug conjugates, lubricants, catalysts, etc. there is
  • Patent Document 1 describes a method of electrolysis using tetrafluoroboric acid or hexafluorophosphoric acid as an electrolyte. Further, Patent Document 1 describes a method of electrolysis using an anode containing specific graphite as a working electrode and sulfuric acid or nitric acid as an electrolyte.
  • Patent Document 1 when tetrafluoroboric acid or hexafluorophosphoric acid is used as the electrolyte, the exfoliated graphite obtained has a high content of fluorine element and boron element, and is not applicable to advanced industrial materials. There was a risk of being restricted. Further, in Patent Document 1, when an anode containing specific graphite is used as the working electrode and sulfuric acid or nitric acid is used as the electrolyte, the resulting exfoliated graphite has a mass ratio of carbon element to oxygen element (C/O ratio) was large, and the introduction rate of functional groups was not sufficient. Furthermore, in Patent Document 1, since the concentration of the electrolyte is high when sulfuric acid or nitric acid is used as the electrolyte, it is also desired to lower the concentration of the electrolyte from the viewpoint of safety.
  • C/O ratio carbon element to oxygen element
  • an electrolyte solution having a low electrolyte concentration is used to obtain exfoliated graphite having a low content of fluorine element and boron element and a low mass ratio of carbon element to oxygen element (C/O ratio).
  • the aim is to provide a possible manufacturing method.
  • One aspect of the present invention is a method for producing a graphite thin plate structure, in which an electrochemical reaction system including an anode containing graphite, a cathode, and an electrolytic solution containing sulfuric acid and/or sulfate as an electrolyte, and applying a voltage between the anode and the cathode, wherein the graphite has a thermal diffusivity of 3.5 cm 2 /s or more, and the electrolyte solution has a concentration of the electrolyte of 0.005 M or more and 5 M or less. and the voltage is between 3V and 20V.
  • the graphite may be a heat-treated polycondensation polymer compound.
  • the polycondensation polymer compound may be an aromatic polyimide.
  • the anode may be a heat-treated expanded graphite sheet.
  • the expanded graphite sheet may be a pressed product of expanded graphite obtained by soaking natural graphite in a strong acid and then heat-treating it.
  • the electrolyte solution may have an electrolyte concentration of 0.005M or more and 0.05M or less, and the voltage may be 3V or more and 19V or less.
  • the electrolyte solution may have an electrolyte concentration of 0.05M or more and 0.5M or less, and the voltage may be 3V or more and 18V or less.
  • the electrolyte solution may have a concentration of 0.5M or more and 5M or less, and the voltage may be 3V or more and 17V or less.
  • Another aspect of the present invention is a method for producing exfoliated graphite, comprising: obtaining a graphite thin plate-like structure by the method for producing a graphite thin plate-like structure; and exfoliating to obtain exfoliated graphite.
  • the exfoliated graphite has a sulfur element content of 0.01% by mass or more and 2.5% by mass or less and a fluorine element content of less than 0.1% by mass,
  • the content of boron element is less than 0.1% by mass, and the mass ratio of carbon element to oxygen element is 0.7 or more and 3.0 or less.
  • the exfoliated graphite may have a mass ratio of carbon element to oxygen element of 1.5 or more and 2.6 or less.
  • the maximum intensity of the peak contained in the region where 2 ⁇ is 7° or more and 12° or less in the XRD spectrum is X
  • the maximum intensity of the peak contained in the region where 2 ⁇ is 23° or more and 30° or less is X
  • X and Y may satisfy the following formula: 0.8 ⁇ X/Y.
  • X and Y may satisfy the following formula: 2 ⁇ X/Y.
  • an electrolyte solution having a low electrolyte concentration is used to obtain exfoliated graphite having a low content of fluorine element and boron element and a low mass ratio of carbon element to oxygen element (C/O ratio). It is possible to provide a manufacturing method capable of
  • FIG. 1 is a diagram showing an XRD spectrum of exfoliated graphite of Example 1.
  • FIG. FIG. 10 shows an XRD spectrum of exfoliated graphite of Example 3;
  • FIG. 10 shows an XRD spectrum of exfoliated graphite of Example 4;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 7;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 8;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 9;
  • FIG. 11 shows the XRD spectrum of exfoliated graphite of Example 14;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 15;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 18;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 19; 1 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 1.
  • FIG. 3 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 2.
  • FIG. 3 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 3.
  • FIG. 4 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 4.
  • FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 5;
  • FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 6;
  • FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 7;
  • FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 8;
  • FIG. 11 shows an XRD spectrum of exfoliated graphite of Comparative Example 10;
  • FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 11;
  • FIG. 2 shows the electrical conductivity of 0.1 M and 1 M aqueous solutions of electrolytes.
  • FIG. 4 is a diagram showing the relationship between the type of electrolyte and the appearance of a graphite thin plate-like structure when the concentration of the electrolyte is 1M.
  • FIG. 4 is a diagram showing the relationship between the type of electrolyte and the appearance of a graphite thin plate-like structure when the concentration of the electrolyte is 1M.
  • FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reactivity of electrochemical oxidation;
  • FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reactivity of electrochemical oxidation;
  • FIG. 4 is a diagram showing the relationship between electrolyte concentration and electrochemical oxidation reactivity.
  • FIG. 4 is a diagram showing the relationship between electrolyte concentration and electrochemical oxidation reactivity.
  • FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reaction time when the immersion size of the graphite sheet is 5 cm ⁇ 5 cm.
  • the method for producing a graphite thin plate structure comprises an electrochemical reaction system including an anode containing graphite, a cathode, and an electrolytic solution containing sulfuric acid and/or sulfate as an electrolyte, wherein the anode and the cathode and applying a voltage between.
  • Exfoliated graphite can be obtained by exfoliating the layers of the graphite sheet-like structure obtained by this production method.
  • graphite thin plate structure means that an interlayer material is inserted between layers of graphite (graphene laminate) to increase the distance between layers (distance between adjacent graphenes). It refers to a thin plate-like structure that is
  • exfoliated graphite refers to a graphene laminate in which the number of graphene laminates is smaller than that of graphite.
  • the thermal diffusivity of graphite contained in the anode is 3.5 cm 2 /s or more, preferably 5.0 cm 2 /s or more, more preferably 7.0 cm 2 /s or more. More preferably, it is 5 cm 2 /s or more.
  • the upper limit of the thermal diffusivity is not particularly limited, it is preferably 12 cm 2 /s or less, for example.
  • the thermal diffusivity of graphite is 3.5 cm 2 /s or more, the mass ratio (C/O ratio) of carbon element to oxygen element in exfoliated graphite tends to be small.
  • graphite-containing anode having a thermal diffusivity of 3.5 cm 2 /s or more is a graphite-containing anode obtained by heat-treating a polycondensation polymer compound.
  • polycondensation polymer compounds include aromatic polyimides, aromatic polyamides, polyoxadiazoles, and polyparaphenylene vinylenes. Among these, aromatic polyimides are preferred.
  • the heat treatment temperature of the polycondensation polymer compound is preferably, for example, 2400°C or higher and 3200°C or lower.
  • the heat treatment time of the polycondensation polymer compound is preferably, for example, 3 hours or more and 72 hours or less.
  • Graphite obtained by heat-treating a polycondensation polymer compound has a structure in which planar graphite crystals are laminated in layers, and intercalation of sulfate ions between graphite layers is particularly easy to proceed.
  • intercalated flakes and the like are particularly unlikely to occur from the graphite, and the overall form of the anode can be easily maintained. Therefore, it is possible to more efficiently produce a graphite sheet-like structure or exfoliated graphite of higher quality.
  • anode containing graphite having a thermal diffusivity of 3.5 cm 2 /s or more is an anode obtained by heat-treating an expanded graphite sheet.
  • the expanded graphite sheet can be obtained, for example, by soaking natural graphite in a strong acid, heat-treating it in an expansion furnace to obtain expanded graphite, and then pressing this expanded graphite at high pressure.
  • strong acids include concentrated sulfuric acid and nitric acid.
  • the heat treatment temperature of the expanded graphite sheet is preferably, for example, 900°C or higher and 3200°C or lower.
  • the heat treatment time of the expanded graphite sheet is preferably, for example, 1 hour or more and 72 hours or less.
  • the shape of the anode is not particularly limited, and examples thereof include rod-like, plate-like, block-like, sheet-like, foil-like, and roll-like shapes.
  • the material that constitutes the cathode is not particularly limited as long as it has the function of donating electrons to the cations generated in the anode reaction and is capable of constructing an electrochemically stable system.
  • Materials constituting the cathode include, for example, metals such as platinum, stainless steel, copper, zinc and lead; carbonaceous materials such as vitreous carbon and graphite; and the like.
  • the shape of the cathode is not particularly limited, and examples thereof include wire-like, plate-like, and mesh-like shapes.
  • the area of the cathode may be increased as much as possible in order not to impair the efficiency of the cathode reaction or to prevent the electrical resistance of the electrochemical reaction system from increasing unnecessarily. good.
  • an ion-exchange membrane, a spacer, or the like may be placed between both electrodes in order to prevent undesirable reactions from occurring at the anode and/or cathode, or to prevent short-circuiting between the anode and cathode.
  • the electrochemical reaction system may further include a reference electrode when performing precise potential control.
  • a reference electrode when performing precise potential control.
  • the reference electrode include, but are not limited to, Ag/AgCl electrodes.
  • the electrolyte solution is a solution in which sulfuric acid and/or sulfate are dissolved in a solvent.
  • sulfates include ammonium sulfate, sodium sulfate, magnesium sulfate, potassium sulfate, calcium sulfate, and the like.
  • Sulfuric acid, sodium sulfate, and ammonium sulfate are preferred as electrolytes.
  • the solvent is not particularly limited as long as it can be mixed with the electrolyte or electrolyte aqueous solution and is electrochemically stable when manufacturing the graphite thin plate structure.
  • solvents include protic polar solvents such as water and lower alcohols (methanol, ethanol, propanol, etc.); aprotic polar solvents such as acetonitrile, dimethylformamide, dimethoxyethane, dimethyl carbonate, propylene carbonate, and dimethylsulfoxide; and may be used in combination of two or more.
  • the solvent preferably contains water.
  • water may be used alone, water and a protic polar solvent other than water may be used in combination, or water and an aprotic polar solvent may be used in combination.
  • Exfoliated graphite obtained using a solvent containing water tends to have good affinity for water and excellent dispersibility in water.
  • the resulting graphite sheet-like structures and exfoliated graphite have alkoxy groups and/or alkyl groups derived from the alcohol solvent.
  • Exfoliated graphite obtained using an alcohol solvent tends to have good affinity for the alcohol solvent and excellent dispersibility in the alcohol solvent.
  • the concentration of the electrolyte in the electrolyte solution is 0.005M or more and 5M or less, preferably 0.01M or more and 3M or less, and more preferably 0.05M or more and 2M or less.
  • concentration of the electrolyte in the electrolyte solution is 0.005M or more, sulfate ions are likely to intercalate between the layers of graphite, so that the layers of the thin plate-like structure of graphite tend to be easily separated.
  • the concentration of the electrolyte in the electrolyte solution is 5M or less, the mass ratio (C/O ratio) of the carbon element to the oxygen element of the exfoliated graphite tends to be small.
  • the conductivity of the electrolyte solution is, for example, preferably 1 mS/cm or more and 2000 mS/cm or less, more preferably 5 mS/cm or more and 1000 mS/cm or less.
  • the electric conductivity of the electrolyte solution is 1 mS/cm or more, sulfate ions are likely to intercalate between the graphite layers, so that the layers of the graphite sheet-like structure tend to be easily separated.
  • the electric conductivity of the electrolyte solution is 2000 mS/cm or less, the mass ratio (C/O ratio) of the carbon element to the oxygen element of the exfoliated graphite tends to be small.
  • the temperature of the electrolyte solution can vary depending on the type of solvent that dissolves the electrolyte and the concentration of the electrolyte in the electrolyte solution, but effectively, the lower limit is the temperature at which the electrolyte solution does not freeze, and the upper limit is the boiling point of the electrolyte solution.
  • the temperature of the electrolyte solution is, for example, preferably 0° C. or higher and 100° C. or lower, and more preferably 0° C. or higher and 80° C. or lower.
  • the voltage applied between the anode and the cathode is 3 V or more and 20 V or less.
  • the voltage applied between the anode and the cathode is 3 V or more, sulfate ions are likely to intercalate between the graphite layers, so that the layers of the graphite sheet-like structure tend to be easily separated.
  • the voltage applied between the anode and the cathode is 20 V or less, the mass ratio (C/O ratio) of carbon element to oxygen element in exfoliated graphite tends to decrease.
  • the voltage applied between the anode and the cathode is preferably 3V or more and 20V or less, more preferably 3V or more and 19V or less. It is more preferable to have Further, when the concentration of the electrolyte in the electrolyte solution is 0.05 M or more and 0.5 M or less, the voltage applied between the anode and the cathode is preferably 3 V or more and 20 V or less, and is 3 V or more and 18 V or less. is more preferable.
  • the voltage applied between the anode and the cathode is preferably 3V or more and 20V or less, and more preferably 3V or more and 17V or less. more preferred.
  • the voltage applied between the anode and the cathode may fluctuate in the range of 3 V or more and 20 V or less, or may be constant, but it is preferable to apply a constant voltage in the range of 3 V or more and 20 V or less. .
  • the electrolyte, sulfuric acid and/or sulfate is theoretically not consumed before and after the electrolytic reaction. Therefore, the electrolyte solution can be reused after it has been used in the manufacture of graphite lamellar structures. However, the electrolyte that has been removed from the electrolyte solution and adhered to the thin plate-like structure of graphite may be replenished to the electrochemical reaction system, if necessary.
  • the method for recovering the electrolyte solution from the graphite thin plate-like structure is not particularly limited. Examples thereof include a method of continuously separating an electrolyte solution from a thin plate-like structure of graphite on a press.
  • the electrolyte solution can be removed from the graphite sheet-like structure by washing it with excess deionized water until the washing liquid becomes nearly neutral.
  • the thin plate-like structure of graphite can be dried as necessary and then applied to the method for producing exfoliated graphite described later.
  • drying the graphite sheet-like structure for example, it can be dried at a temperature of 80° C. or less using a constant temperature dryer or a vacuum dryer.
  • the method for producing exfoliated graphite according to the present embodiment comprises a step of obtaining a graphite thin plate-like structure and exfoliating the layers of the graphite thin plate-like structure by the method for producing a graphite thin plate-like structure according to the present embodiment. and obtaining exfoliated graphite.
  • the method for separating the layers of the graphite thin plate-like structure is not particularly limited. method, a method of heating a thin plate-like structure of graphite, and the like. Specifically, after dispersing a thin plate-like structure of graphite in an appropriate amount of deionized water, it can be irradiated with ultrasonic waves or treated with a mixer or an apparatus capable of applying a shearing force.
  • the exfoliated graphite may be freeze-dried, or may be filtered or centrifuged and then dried.
  • the method for drying the exfoliated graphite is the same as the method for drying the thin plate-like structure of graphite.
  • exfoliated graphite The exfoliated graphite according to this embodiment can be obtained by the method for producing exfoliated graphite according to this embodiment.
  • the exfoliated graphite according to the present embodiment has a sulfur element content of 0.01% by mass or more and 2.5% by mass or less, a fluorine element content of less than 0.1% by mass, and a boron element content % is less than 0.1% by mass.
  • the exfoliated graphite according to the present embodiment can have a low content of heavy metal elements as impurities.
  • the exfoliated graphite according to the present embodiment can have a manganese element content of less than 0.1% by mass.
  • the mass ratio of carbon element to oxygen element is 0.7 or more and 3.0 or less, preferably 1.5 or more and 3.0 or less, It is more preferably 1.5 or more and 2.6 or less.
  • X is the maximum intensity of the peak included in the region where 2 ⁇ is 7° or more and 12° or less in the XRD spectrum, and the maximum intensity of the peak included in the region where 2 ⁇ is 23° or more and 30° or less.
  • X and Y preferably satisfy the following expression: 0.8 ⁇ X/Y, and more preferably satisfy the following expression: 2 ⁇ X/Y.
  • the thickness of the exfoliated graphite according to the present embodiment is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 10 nm or less, and particularly preferably 1 nm or less.
  • the average particle size of the exfoliated graphite according to the present embodiment is preferably 30 nm or more and 1 mm or less, more preferably 100 nm or more and 200 ⁇ m or less, and even more preferably 200 nm or more and 100 ⁇ m or less.
  • ⁇ Thermal diffusivity of graphite> A sample of graphite cut into a shape of 40 mm ⁇ 40 mm was prepared, and a thermal diffusivity measuring device (Thermo Wave Analyzer TA3, Bethel Co., Ltd.) was used to measure the thermal diffusivity [ cm /s] was measured.
  • Elemental analysis of exfoliated graphite was performed using a scanning fluorescent X-ray spectrometer (ZSX PrimusIII+, manufactured by Rigaku Co., Ltd.), and the content of elemental sulfur (S) [% by mass] and the content of elemental fluorine (F) were determined.
  • the content [% by mass], the content [% by mass] of the boron element (B), and the mass ratio of the carbon element to the oxygen element (C/O ratio) were measured.
  • X-ray diffractometer X'Pert Pro, manufactured by Malvern Panalytical
  • graphite sheet A As the graphite sheet A, a graphite sheet (manufactured by Kaneka Corporation) having a thickness of 32 ⁇ m and a thermal diffusivity of 9 cm 2 /s obtained by heat-treating an aromatic polyimide film having a thickness of 62 ⁇ m at a temperature of 2900° C. or higher was used.
  • Graphite sheet B As the graphite sheet B, a graphite sheet having a thickness of 200 ⁇ m and a thermal diffusivity of 4 cm 2 /s obtained by heat-treating an expanded graphite sheet PF-HP (manufactured by Toyo Tanso Co., Ltd.) at 2400° C. was used.
  • Example 1 After adding 3 L of a 1 M sulfuric acid aqueous solution as an electrolyte solution to a PVC reactor, a graphite sheet A as an anode was fixed so that 6 cm ⁇ 25 cm of the surface area was immersed in the electrolyte solution, and a carbon plate was used as a cathode. was set. Next, the anode and the cathode were connected to a DC power supply, a voltage of 7 V was applied, and electrolysis was performed at room temperature until the current decreased and became constant, thereby obtaining a thin plate-like structure of graphite.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 0.9. Also, the exfoliated graphite had an X/Y ratio of 3.3 (see FIG. 1A).
  • Example 2 Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 0.9.
  • the exfoliated graphite had an X/Y ratio of 3.3.
  • Example 3 Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.0. Also, the exfoliated graphite had an X/Y ratio of 3.4 (see FIG. 1B).
  • Example 4 Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 4 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 3.6 (see FIG. 1C).
  • Example 5 Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 3 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.3.
  • the exfoliated graphite had an X/Y ratio of 2.5.
  • Example 6 Exfoliated graphite was obtained in the same manner as in Example 1, except that a 0.1 M sulfuric acid aqueous solution was used as the electrolyte solution.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.1.
  • the exfoliated graphite had an X/Y ratio of 2.1.
  • Example 7 Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 2.1 (see FIG. 2A).
  • Example 8 Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 4 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.1. Also, the exfoliated graphite had an X/Y ratio of 2.1 (see FIG. 2B).
  • Example 9 Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 3.5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.1. Also, the exfoliated graphite had an X/Y ratio of 3.5 (see FIG. 2C).
  • Example 10 Exfoliated graphite was obtained in the same manner as in Example 1, except that a 0.01 M sulfuric acid aqueous solution was used as the electrolyte solution.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.5.
  • the exfoliated graphite had an X/Y ratio of 1.5.
  • Example 11 Exfoliated graphite was obtained in the same manner as in Example 10, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.5.
  • the exfoliated graphite had an X/Y ratio of 2.5.
  • Example 12 Exfoliated graphite was obtained in the same manner as in Example 7, except that graphite sheet B was used as the anode.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 3.0.
  • the exfoliated graphite had an X/Y ratio of 1.2.
  • Example 13 Exfoliated graphite was obtained in the same manner as in Example 8, except that graphite sheet B was used as the anode.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.7.
  • the exfoliated graphite had an X/Y ratio of 0.8.
  • Example 14 Exfoliated graphite was obtained in the same manner as in Example 1, except that ammonium sulfate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 2.6 (see FIG. 3A).
  • Example 15 Exfoliated graphite was obtained in the same manner as in Example 14, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.5. Also, the exfoliated graphite had an X/Y ratio of 3.0 (see FIG. 3B).
  • Example 16 Exfoliated graphite was obtained in the same manner as in Example 6, except that ammonium sulfate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.0.
  • the exfoliated graphite had an X/Y ratio of 2.5.
  • Example 17 Exfoliated graphite was obtained in the same manner as in Example 16, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.2.
  • the exfoliated graphite had an X/Y ratio of 2.1.
  • Example 18 Exfoliated graphite was obtained in the same manner as in Example 1, except that sodium sulfate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.4. Also, the exfoliated graphite had an X/Y ratio of 2.8 (see FIG. 4A).
  • Example 19 Exfoliated graphite was obtained in the same manner as in Example 18, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.6. Also, the exfoliated graphite had an X/Y ratio of 2.3 (see FIG. 4B).
  • Example 20 Exfoliated graphite was obtained in the same manner as in Example 6, except that sodium sulfate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.2.
  • the exfoliated graphite had an X/Y ratio of 2.5.
  • Example 21 Exfoliated graphite was obtained in the same manner as in Example 20, except that the anode and cathode were connected to a DC power supply and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.4.
  • the exfoliated graphite had an X/Y ratio of 2.1.
  • Exfoliated graphite was obtained in the same manner as in Example 1, except that hydroboric acid was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0.
  • the exfoliated graphite had an X/Y ratio greater than 10 (see FIG. 5A).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0.
  • the exfoliated graphite had an X/Y ratio greater than 10 (see FIG. 5B).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power supply and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1.
  • the exfoliated graphite had an X/Y ratio of 9.0 (see FIG. 5C).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power supply and a voltage of 4 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.4.
  • the exfoliated graphite had an X/Y ratio of 3.0 (see FIG. 5D).
  • Exfoliated graphite was obtained in the same manner as in Example 6, except that hydroboric acid was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1.
  • the exfoliated graphite had an X/Y ratio of 7.8 (see FIG. 6A).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 5, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.3.
  • the exfoliated graphite had an X/Y ratio of 4.2 (see FIG. 6B).
  • Exfoliated graphite was obtained in the same manner as in Example 1, except that ammonium hydroborofluorate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0.
  • the exfoliated graphite had an X/Y ratio of 8.5 (see FIG. 7A).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 7, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.3.
  • the exfoliated graphite had an X/Y ratio of 5.0 (see FIG. 7B).
  • Exfoliated graphite was obtained in the same manner as in Example 7, except that ammonium hydroborofluorate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.5.
  • the exfoliated graphite had an X/Y ratio of 2.8.
  • Exfoliated graphite was obtained in the same manner as in Example 1, except that sodium hydroborofluorate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1.
  • the exfoliated graphite had an X/Y ratio of 9.9 (see FIG. 8A).
  • Exfoliated graphite was obtained in the same manner as in Comparative Example 10, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.4.
  • the exfoliated graphite had an X/Y ratio of 4.7 (see FIG. 8B).
  • Exfoliated graphite was obtained in the same manner as in Example 7, except that sodium hydroborofluorate was used as the electrolyte.
  • the exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.6. Also, the exfoliated graphite had an X/Y ratio of 2.6.
  • Exfoliated graphite was obtained in the same manner as in Example 3, except that a 9.2 M sulfuric acid aqueous solution was used as the electrolyte solution.
  • the exfoliated graphite has a sulfur element (S) content of 0.1 to 2% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was greater than 10. Also, the exfoliated graphite had an X/Y ratio of less than 0.7.
  • Exfoliated graphite has a sulfur element (S) content of less than 2% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and a C/O The ratio was greater than 4.1. Also, the exfoliated graphite had an X/Y ratio of less than 0.7.
  • Deionized water was added to the graphite thin plate structure to adjust the solid content concentration to about 1% by mass. After pulverizing the obtained solution for 5 minutes with a high-speed stirrer, the solution was placed in a petri dish so that the thickness after drying was about 25 ⁇ m, and dried at room temperature to obtain a film of exfoliated graphite.
  • the exfoliated graphite has a sulfur element (S) content of 2.6 to 4% by mass, and a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, The C/O ratio was less than 1.5. Also, the exfoliated graphite had an X/Y ratio greater than 2.
  • Tables 1 to 9 show the production conditions and characteristics of exfoliated graphite.
  • the exfoliated graphite of Examples 1 to 21 has a low content of fluorine element (F) and boron element (B) and a small C/O ratio.
  • fluorine element (F) and boron element (B) have a low content of fluorine element (F) and boron element (B) and a small C/O ratio.
  • elemental fluorine (F) and elemental boron (B) High content.
  • the exfoliated graphite of Comparative Example 13 has a large C/O ratio because a 9.2 M sulfuric acid aqueous solution is used as an electrolyte solution during production.
  • the exfoliated graphite of Comparative Example 14 has a low content of fluorine element (F) and boron element (B), but has a large C/O ratio.
  • the exfoliated graphite of Comparative Example 15 has a low content of fluorine element (F) and boron element (B) and a small C/O ratio, 18.3 M sulfuric acid aqueous solution (concentrated sulfuric acid) was used as an electrolyte solution during production. is used, and safety during manufacturing is lacking.
  • FIG. 9 shows the conductivity of 0.1M and 1M aqueous solutions of the electrolyte.
  • the electrolytes are HBF 4 , NH 4 BF 4 , NaBF 4 , H 2 SO 4 , (NH 4 ) 2 SO 4 and Na 2 SO 4 used in Examples and Comparative Examples.
  • FIG. 10 shows the relationship between the type of electrolyte and the appearance of the graphite thin plate-like structure when the concentration of the electrolyte is 1M.
  • the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.
  • FIG. 13 shows the relationship between the type of electrolyte and the reaction time when the graphite sheet is immersed in a size of 5 cm ⁇ 5 cm.
  • the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.

Abstract

Provided is a method for producing a thin plate-shaped structure of graphite that includes a step of applying a voltage between an anode and a cathode in an electrochemical reaction system including the anode that includes graphite, the cathode, and an electrolyte solution that includes sulfuric acid and/or a sulfate as an electrolyte, the graphite having a thermal diffusivity of 3.5 cm2/s or more, the electrolyte solution having a concentration of the electrolyte of 0.005-5 M inclusive, and the voltage being 3-20 V inclusive.

Description

グラファイトの薄板状構造物の製造方法、薄片化グラファイトの製造方法、及び薄片化グラファイトMethod for producing thin plate-like structure of graphite, method for producing exfoliated graphite, and exfoliated graphite
　本発明は、グラファイトの薄板状構造物の製造方法、薄片化グラファイトの製造方法、及び薄片化グラファイトに関する。 The present invention relates to a method for producing a graphite sheet-like structure, a method for producing exfoliated graphite, and exfoliated graphite.
　グラフェンは、キャリア移動度、熱伝導度、及び透明性が高い。また、グラフェンは、１原子分の厚さを有するｓｐ２結合炭素原子のシートであるため、デバイスの大面積化が容易である上に、熱的安定性及び化学的安定性が高い。このような優れた特性から、グラフェンは、エレクトロニクス分野を始めとする先端工業材料への応用が期待されている。 Graphene has high carrier mobility, thermal conductivity, and transparency. In addition, since graphene is a sheet of sp2 - bonded carbon atoms with a thickness of one atom, it is easy to increase the area of devices and has high thermal and chemical stability. Due to such excellent properties, graphene is expected to be applied to advanced industrial materials including the electronics field.
　一方、グラファイトは、多数のグラフェンが積み重なって構成される積層体であり、入手が容易である。このため、グラファイトの層間を剥離することで、グラファイトよりもグラフェンの積層数が遥かに少ない薄片化グラファイトを製造する方法が提案されてきた。 On the other hand, graphite is a laminate composed of many graphenes stacked on top of each other, and is easy to obtain. For this reason, a method has been proposed for producing exfoliated graphite in which the number of laminated layers of graphene is much smaller than that of graphite by exfoliating the layers of graphite.
　薄片化グラファイトの製造方法としては、例えば、グラファイトを含む陽極と、陰極と、電解質溶液と、を含む電気化学反応系において、陽極と陰極との間に電圧を印加することで、グラファイトの層間に電解質由来のイオンをインターカレートさせてグラファイトの薄板状構造物を得た後、この薄板状構造物の層間を剥離する方法が知られている。このようにして得られる薄片化グラファイトは、酸素を含むグラフェン（酸化グラフェン）により構成され、ヒドロキシ基、カルボキシ基等の官能基が導入されている。このような薄片化グラファイトは、官能基を修飾して高機能化することが可能であるため、高分子複合材料、塗料、インク、薬剤共役体、潤滑剤、触媒等への応用が期待されている。 As a method for producing exfoliated graphite, for example, in an electrochemical reaction system containing a graphite-containing anode, a cathode, and an electrolyte solution, a voltage is applied between the anode and the cathode to obtain a film between the graphite layers. A method is known in which, after intercalating ions derived from an electrolyte to obtain a graphite sheet-like structure, the layers of the sheet-like structure are separated. The exfoliated graphite thus obtained is composed of oxygen-containing graphene (graphene oxide), into which functional groups such as hydroxy groups and carboxy groups are introduced. Such exfoliated graphite can be modified with functional groups to make it highly functional, so it is expected to be applied to polymer composite materials, paints, inks, drug conjugates, lubricants, catalysts, etc. there is
　特許文献１には、電解質としてテトラフルオロホウ酸又はヘキサフルオロリン酸を用いて、電解する方法が記載されている。また、特許文献１には、作用極として特定のグラファイトを含む陽極を用い、電解質として硫酸又は硝酸を用いて、電解する方法が記載されている。 Patent Document 1 describes a method of electrolysis using tetrafluoroboric acid or hexafluorophosphoric acid as an electrolyte. Further, Patent Document 1 describes a method of electrolysis using an anode containing specific graphite as a working electrode and sulfuric acid or nitric acid as an electrolyte.
国際公開第２０２０／１２９４２７号WO2020/129427
　しかし、特許文献１において、電解質としてテトラフルオロホウ酸又はヘキサフルオロリン酸を用いた場合、得られる薄片化グラファイトは、フッ素元素及びホウ素元素の含有率が高いものとなり、先端工業材料への応用が制約される虞があった。また、特許文献１において、作用極として特定のグラファイトを含む陽極を用い、電解質として硫酸又は硝酸を用いた場合、得られる薄片化グラファイトは、酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が大きいものとなり、官能基の導入率が十分ではなかった。さらに、特許文献１では、電解質として硫酸又は硝酸を用いた場合の電解質の濃度が高いため、安全性の観点から、電解質の濃度を低めることもまた望まれる。 However, in Patent Document 1, when tetrafluoroboric acid or hexafluorophosphoric acid is used as the electrolyte, the exfoliated graphite obtained has a high content of fluorine element and boron element, and is not applicable to advanced industrial materials. There was a risk of being restricted. Further, in Patent Document 1, when an anode containing specific graphite is used as the working electrode and sulfuric acid or nitric acid is used as the electrolyte, the resulting exfoliated graphite has a mass ratio of carbon element to oxygen element (C/O ratio) was large, and the introduction rate of functional groups was not sufficient. Furthermore, in Patent Document 1, since the concentration of the electrolyte is high when sulfuric acid or nitric acid is used as the electrolyte, it is also desired to lower the concentration of the electrolyte from the viewpoint of safety.
　本発明は、電解質の濃度が低い電解質溶液を使用して、フッ素元素及びホウ素元素の含有率が低く、酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さい薄片化グラファイトを得ることが可能な製造方法を提供することを目的とする。 According to the present invention, an electrolyte solution having a low electrolyte concentration is used to obtain exfoliated graphite having a low content of fluorine element and boron element and a low mass ratio of carbon element to oxygen element (C/O ratio). The aim is to provide a possible manufacturing method.
　本発明の一態様は、グラファイトの薄板状構造物の製造方法において、グラファイトを含む陽極と、陰極と、電解質として硫酸及び／又は硫酸塩を含む電解質溶液と、を含む電気化学反応系において、前記陽極と前記陰極との間に電圧を印加する工程を含み、前記グラファイトは、熱拡散率が３．５ｃｍ２／ｓ以上であり、前記電解質溶液は、前記電解質の濃度が０．００５Ｍ以上５Ｍ以下であり、前記電圧は、３Ｖ以上２０Ｖ以下である。 One aspect of the present invention is a method for producing a graphite thin plate structure, in which an electrochemical reaction system including an anode containing graphite, a cathode, and an electrolytic solution containing sulfuric acid and/or sulfate as an electrolyte, and applying a voltage between the anode and the cathode, wherein the graphite has a thermal diffusivity of 3.5 cm 2 /s or more, and the electrolyte solution has a concentration of the electrolyte of 0.005 M or more and 5 M or less. and the voltage is between 3V and 20V.
　前記グラファイトは、縮重合系高分子化合物の熱処理物であってもよい。 The graphite may be a heat-treated polycondensation polymer compound.
　前記縮重合系高分子化合物は、芳香族ポリイミドであってもよい。 The polycondensation polymer compound may be an aromatic polyimide.
　前記陽極は、膨張黒鉛シートの熱処理物であってもよい。 The anode may be a heat-treated expanded graphite sheet.
　前記膨張黒鉛シートは、天然グラファイトを強酸に浸した後、加熱処理して得られる膨張黒鉛のプレス物であってもよい。 The expanded graphite sheet may be a pressed product of expanded graphite obtained by soaking natural graphite in a strong acid and then heat-treating it.
　前記電解質溶液は、前記電解質の濃度が０．００５Ｍ以上０．０５Ｍ以下であり、前記電圧は、３Ｖ以上１９Ｖ以下であってもよい。 The electrolyte solution may have an electrolyte concentration of 0.005M or more and 0.05M or less, and the voltage may be 3V or more and 19V or less.
　前記電解質溶液は、前記電解質の濃度が０．０５Ｍ以上０．５Ｍ以下であり、前記電圧は、３Ｖ以上１８Ｖ以下であってもよい。 The electrolyte solution may have an electrolyte concentration of 0.05M or more and 0.5M or less, and the voltage may be 3V or more and 18V or less.
　前記電解質溶液は、前記電解質の濃度が０．５Ｍ以上５Ｍ以下であり、前記電圧は、３Ｖ以上１７Ｖ以下であってもよい。 The electrolyte solution may have a concentration of 0.5M or more and 5M or less, and the voltage may be 3V or more and 17V or less.
　本発明の他の一態様は、薄片化グラファイトの製造方法において、前記グラファイトの薄板状構造物の製造方法により、グラファイトの薄板状構造物を得る工程と、該グラファイトの薄板状構造物の層間を剥離して薄片化グラファイトを得る工程と、を含む。 Another aspect of the present invention is a method for producing exfoliated graphite, comprising: obtaining a graphite thin plate-like structure by the method for producing a graphite thin plate-like structure; and exfoliating to obtain exfoliated graphite.
　本発明の他の一態様は、薄片化グラファイトにおいて、硫黄元素の含有率が０．０１質量％以上２．５質量％以下であり、フッ素元素の含有率が０．１質量％未満であり、ホウ素元素の含有率が０．１質量％未満であり、酸素元素に対する炭素元素の質量比が０．７以上３．０以下である。 In another aspect of the present invention, the exfoliated graphite has a sulfur element content of 0.01% by mass or more and 2.5% by mass or less and a fluorine element content of less than 0.1% by mass, The content of boron element is less than 0.1% by mass, and the mass ratio of carbon element to oxygen element is 0.7 or more and 3.0 or less.
　前記薄片化グラファイトは、酸素元素に対する炭素元素の質量比が１．５以上２．６以下であってもよい。 The exfoliated graphite may have a mass ratio of carbon element to oxygen element of 1.5 or more and 2.6 or less.
　前記薄片化グラファイトは、ＸＲＤスペクトルにおける２θが７°以上１２°以下である領域に含まれるピークの最大強度をＸとし、２θが２３°以上３０°以下である領域に含まれるピークの最大強度をＹとしたとき、Ｘ及びＹが次式：０．８≦Ｘ／Ｙを満たしてもよい。 In the exfoliated graphite, the maximum intensity of the peak contained in the region where 2θ is 7° or more and 12° or less in the XRD spectrum is X, and the maximum intensity of the peak contained in the region where 2θ is 23° or more and 30° or less. When Y, X and Y may satisfy the following formula: 0.8≦X/Y.
　前記薄片化グラファイトは、Ｘ及びＹが次式：２≦Ｘ／Ｙを満たしてもよい。 In the exfoliated graphite, X and Y may satisfy the following formula: 2≦X/Y.
　本発明によれば、電解質の濃度が低い電解質溶液を使用して、フッ素元素及びホウ素元素の含有率が低く、酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さい薄片化グラファイトを得ることが可能な製造方法を提供することができる。 According to the present invention, an electrolyte solution having a low electrolyte concentration is used to obtain exfoliated graphite having a low content of fluorine element and boron element and a low mass ratio of carbon element to oxygen element (C/O ratio). It is possible to provide a manufacturing method capable of
実施例１の薄片化グラファイトのＸＲＤスペクトルを示す図である。1 is a diagram showing an XRD spectrum of exfoliated graphite of Example 1. FIG. 実施例３の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 shows an XRD spectrum of exfoliated graphite of Example 3; 実施例４の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 shows an XRD spectrum of exfoliated graphite of Example 4; 実施例７の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 7; 実施例８の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 8; 実施例９の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 9; 実施例１４の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows the XRD spectrum of exfoliated graphite of Example 14; 実施例１５の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 15; 実施例１８の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 18; 実施例１９の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Example 19; 比較例１の薄片化グラファイトのＸＲＤスペクトルを示す図である。1 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 1. FIG. 比較例２の薄片化グラファイトのＸＲＤスペクトルを示す図である。3 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 2. FIG. 比較例３の薄片化グラファイトのＸＲＤスペクトルを示す図である。3 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 3. FIG. 比較例４の薄片化グラファイトのＸＲＤスペクトルを示す図である。4 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 4. FIG. 比較例５の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 5; 比較例６の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 6; 比較例７の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 7; 比較例８の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 8; 比較例１０の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 11 shows an XRD spectrum of exfoliated graphite of Comparative Example 10; 比較例１１の薄片化グラファイトのＸＲＤスペクトルを示す図である。FIG. 10 is a diagram showing an XRD spectrum of exfoliated graphite of Comparative Example 11; 電解質の０．１Ｍ水溶液及び１Ｍ水溶液の電導度を示す図である。FIG. 2 shows the electrical conductivity of 0.1 M and 1 M aqueous solutions of electrolytes. 電解質の濃度が１Ｍである場合の、電解質の種類とグラファイトの薄板状構造物の外観との関係を示す図である。FIG. 4 is a diagram showing the relationship between the type of electrolyte and the appearance of a graphite thin plate-like structure when the concentration of the electrolyte is 1M. 電解質の種類と電気化学酸化の反応性との関係を示す図である。FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reactivity of electrochemical oxidation; 電解質の種類と電気化学酸化の反応性との関係を示す図である。FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reactivity of electrochemical oxidation; 電解質の濃度と電気化学酸化の反応性との関係を示す図である。FIG. 4 is a diagram showing the relationship between electrolyte concentration and electrochemical oxidation reactivity. 電解質の濃度と電気化学酸化の反応性との関係を示す図である。FIG. 4 is a diagram showing the relationship between electrolyte concentration and electrochemical oxidation reactivity. グラファイトシートの浸漬サイズが５ｃｍ×５ｃｍである場合の、電解質の種類と反応時間との関係を示す図である。FIG. 4 is a diagram showing the relationship between the type of electrolyte and the reaction time when the immersion size of the graphite sheet is 5 cm×5 cm.
　以下、本発明の実施形態について説明する。 Embodiments of the present invention will be described below.
　［グラファイトの薄板状構造物の製造方法］
　本実施形態に係るグラファイトの薄板状構造物の製造方法は、グラファイトを含む陽極と、陰極と、電解質として硫酸及び／又は硫酸塩を含む電解質溶液と、を含む電気化学反応系において、陽極と陰極との間に電圧を印加する工程を含む。この製造方法により得られたグラファイトの薄板状構造物の層間を剥離することで、薄片化グラファイトを得ることができる。 [Method for producing thin plate-like structure of graphite]
The method for producing a graphite thin plate structure according to the present embodiment comprises an electrochemical reaction system including an anode containing graphite, a cathode, and an electrolytic solution containing sulfuric acid and/or sulfate as an electrolyte, wherein the anode and the cathode and applying a voltage between. Exfoliated graphite can be obtained by exfoliating the layers of the graphite sheet-like structure obtained by this production method.
　本明細書及び請求の範囲において、「グラファイトの薄板状構造物」とは、グラファイト（グラフェンの積層体）の層間に層間物質が挿入されて、層間の距離（隣り合うグラフェン間の距離）が拡大している薄板状構造物をいう。また、「薄片化グラファイト」とは、グラファイトよりもグラフェンの積層数が少ないグラフェンの積層体をいう。 In the present specification and claims, the term “graphite thin plate structure” means that an interlayer material is inserted between layers of graphite (graphene laminate) to increase the distance between layers (distance between adjacent graphenes). It refers to a thin plate-like structure that is In addition, “exfoliated graphite” refers to a graphene laminate in which the number of graphene laminates is smaller than that of graphite.
　陽極に含まれるグラファイトの熱拡散率は、３．５ｃｍ２／ｓ以上であり、５．０ｃｍ２／ｓ以上であることが好ましく、７．０ｃｍ２／ｓ以上であることがより好ましく、８．５ｃｍ２／ｓ以上であることがさらに好ましい。熱拡散率の上限は特に限定されないが、例えば、１２ｃｍ２／ｓ以下であることが好ましい。グラファイトの熱拡散率が３．５ｃｍ２／ｓ以上であると、薄片化グラファイトの酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さくなる傾向にある。 8. The thermal diffusivity of graphite contained in the anode is 3.5 cm 2 /s or more, preferably 5.0 cm 2 /s or more, more preferably 7.0 cm 2 /s or more. More preferably, it is 5 cm 2 /s or more. Although the upper limit of the thermal diffusivity is not particularly limited, it is preferably 12 cm 2 /s or less, for example. When the thermal diffusivity of graphite is 3.5 cm 2 /s or more, the mass ratio (C/O ratio) of carbon element to oxygen element in exfoliated graphite tends to be small.
　熱拡散率が３．５ｃｍ２／ｓ以上であるグラファイトを含む陽極の一例としては、縮重合系高分子化合物を熱処理して得られるグラファイトを含む陽極が挙げられる。縮重合系高分子化合物としては、例えば、芳香族ポリイミド、芳香族ポリアミド、ポリオキサジアゾール、ポリパラフェニレンビニレン等が挙げられる。これらの中でも、芳香族ポリイミドが好ましい。 An example of a graphite-containing anode having a thermal diffusivity of 3.5 cm 2 /s or more is a graphite-containing anode obtained by heat-treating a polycondensation polymer compound. Examples of polycondensation polymer compounds include aromatic polyimides, aromatic polyamides, polyoxadiazoles, and polyparaphenylene vinylenes. Among these, aromatic polyimides are preferred.
　縮重合系高分子化合物の熱処理温度は、例えば、２４００℃以上３２００℃以下であることが好ましい。また、縮重合系高分子化合物の熱処理時間は、例えば、３時間以上７２時間以下であることが好ましい。 The heat treatment temperature of the polycondensation polymer compound is preferably, for example, 2400°C or higher and 3200°C or lower. Moreover, the heat treatment time of the polycondensation polymer compound is preferably, for example, 3 hours or more and 72 hours or less.
　縮重合系高分子化合物を熱処理して得られるグラファイトは、面状のグラファイト結晶が層状に積層された構造を有しており、グラファイトの層間への硫酸イオンのインターカレートが特に進行しやすく、また、インターカレートしたときに、グラファイトから小片の剥離等が特に生じにくく、陽極としての全体的な形態を維持しやすい。このため、より効率よく、より高品質のグラファイトの薄板状構造物又は薄片化グラファイトを製造することができる。 Graphite obtained by heat-treating a polycondensation polymer compound has a structure in which planar graphite crystals are laminated in layers, and intercalation of sulfate ions between graphite layers is particularly easy to proceed. In addition, when intercalated, flakes and the like are particularly unlikely to occur from the graphite, and the overall form of the anode can be easily maintained. Therefore, it is possible to more efficiently produce a graphite sheet-like structure or exfoliated graphite of higher quality.
　また、熱拡散率が３．５ｃｍ２／ｓ以上であるグラファイトを含む陽極の他の例としては、膨張黒鉛シートを熱処理して得られる陽極が挙げられる。膨張黒鉛シートは、例えば、天然グラファイトを強酸に浸した後、膨張炉で加熱処理して膨張黒鉛を得た後、この膨張黒鉛を高圧プレスすることで得ることができる。強酸としては、例えば、濃硫酸、硝酸等が挙げられる。 Another example of the anode containing graphite having a thermal diffusivity of 3.5 cm 2 /s or more is an anode obtained by heat-treating an expanded graphite sheet. The expanded graphite sheet can be obtained, for example, by soaking natural graphite in a strong acid, heat-treating it in an expansion furnace to obtain expanded graphite, and then pressing this expanded graphite at high pressure. Examples of strong acids include concentrated sulfuric acid and nitric acid.
　膨張黒鉛シートの熱処理温度は、例えば、９００℃以上３２００℃以下であることが好ましい。また、膨張黒鉛シートの熱処理時間は、例えば、１時間以上７２時間以下であることが好ましい。 The heat treatment temperature of the expanded graphite sheet is preferably, for example, 900°C or higher and 3200°C or lower. Moreover, the heat treatment time of the expanded graphite sheet is preferably, for example, 1 hour or more and 72 hours or less.
　このような膨張黒鉛シートを熱処理して得られる陽極を使用することによっても、効率よく、高品質のグラファイトの薄板状構造物又は薄片化グラファイトを製造することができる。 By using an anode obtained by heat-treating such an expanded graphite sheet, it is possible to efficiently produce a high-quality graphite lamellar structure or exfoliated graphite.
　陽極の形状としては、特に限定されず、例えば、棒状、板状、塊状、シート状、箔状、ロール状等が挙げられる。 The shape of the anode is not particularly limited, and examples thereof include rod-like, plate-like, block-like, sheet-like, foil-like, and roll-like shapes.
　陰極を構成する材料としては、陽極反応で生じたカチオンに電子を与える機能を有し、かつ、電気化学的に安定な系を構築することが可能であれば、特に限定されない。陰極を構成する材料としては、例えば、白金、ステンレス鋼、銅、亜鉛、鉛等の金属；ガラス状炭素、グラファイト等の炭素質材料；などが挙げられる。 The material that constitutes the cathode is not particularly limited as long as it has the function of donating electrons to the cations generated in the anode reaction and is capable of constructing an electrochemically stable system. Materials constituting the cathode include, for example, metals such as platinum, stainless steel, copper, zinc and lead; carbonaceous materials such as vitreous carbon and graphite; and the like.
　陰極の形状としては、特に限定されず、例えば、ワイヤー状、板状、メッシュ（網目）状等が挙げられる。 The shape of the cathode is not particularly limited, and examples thereof include wire-like, plate-like, and mesh-like shapes.
　なお、陰極反応でガスが発生する場合には、陰極反応の効率を損ねないため、あるいは電気化学反応系の電気抵抗を無用に増加させないために、陰極の面積を可能な範囲で大きくしてもよい。 When gas is generated by the cathode reaction, the area of the cathode may be increased as much as possible in order not to impair the efficiency of the cathode reaction or to prevent the electrical resistance of the electrochemical reaction system from increasing unnecessarily. good.
　また、陽極及び／又は陰極で望ましくない反応が起こるのを防ぐため、あるいは陽陰両極の短絡を防ぐために、両極の間にイオン交換膜、スペーサー等を設置してもよい。 In addition, an ion-exchange membrane, a spacer, or the like may be placed between both electrodes in order to prevent undesirable reactions from occurring at the anode and/or cathode, or to prevent short-circuiting between the anode and cathode.
　さらに、電気化学反応系は、精密な電位制御を実施する場合に、参照電極をさらに含んでいてもよい。参照電極としては、特に限定されないが、例えば、Ａｇ／ＡｇＣｌ電極等が挙げられる。 Furthermore, the electrochemical reaction system may further include a reference electrode when performing precise potential control. Examples of the reference electrode include, but are not limited to, Ag/AgCl electrodes.
　電解質溶液は、硫酸及び／又は硫酸塩が溶媒に溶解したものである。 The electrolyte solution is a solution in which sulfuric acid and/or sulfate are dissolved in a solvent.
　硫酸塩としては、例えば、硫酸アンモニウム、硫酸ナトリウム、硫酸マグネシウム、硫酸カリウム、硫酸カルシウム等が挙げられる。 Examples of sulfates include ammonium sulfate, sodium sulfate, magnesium sulfate, potassium sulfate, calcium sulfate, and the like.
　電解質としては、硫酸、硫酸ナトリウム、及び硫酸アンモニウムが好ましい。 Sulfuric acid, sodium sulfate, and ammonium sulfate are preferred as electrolytes.
　溶媒としては、電解質又は電解質水溶液と混和することが可能であり、かつ、グラファイトの薄板状構造物を製造する際に電気化学的に安定であれば、特に限定されない。溶媒としては、例えば、水、低級アルコール（メタノール、エタノール、プロパノール等）等のプロトン性極性溶媒；アセトニトリル、ジメチルホルムアミド、ジメトキシエタン、ジメチルカーボネート、プロピレンカーボネート、ジメチルスルホキシド等の非プロトン性極性溶媒；などが挙げられ、２種以上を併用してもよい。 The solvent is not particularly limited as long as it can be mixed with the electrolyte or electrolyte aqueous solution and is electrochemically stable when manufacturing the graphite thin plate structure. Examples of solvents include protic polar solvents such as water and lower alcohols (methanol, ethanol, propanol, etc.); aprotic polar solvents such as acetonitrile, dimethylformamide, dimethoxyethane, dimethyl carbonate, propylene carbonate, and dimethylsulfoxide; and may be used in combination of two or more.
　溶媒は、水を含むことが好ましい。この場合、水を単独で使用してもよいし、水及び水以外のプロトン性極性溶媒を併用してもよいし、水及び非プロトン性極性溶媒を併用してもよい。水を含む溶媒を使用して得た薄片化グラファイトは、水に対する親和性が良好となり、水中の分散性に優れる傾向にある。 The solvent preferably contains water. In this case, water may be used alone, water and a protic polar solvent other than water may be used in combination, or water and an aprotic polar solvent may be used in combination. Exfoliated graphite obtained using a solvent containing water tends to have good affinity for water and excellent dispersibility in water.
　また、溶媒としてアルコール溶媒を使用すると、得られるグラファイトの薄板状構造物及び薄片化グラファイトは、アルコール溶媒に由来するアルコキシ基及び／又はアルキル基を有するものとなる。アルコール溶媒を使用して得た薄片化グラファイトは、当該アルコール溶媒に対する親和性が良好となり、当該アルコール溶媒中の分散性に優れる傾向にある。 Further, when an alcohol solvent is used as the solvent, the resulting graphite sheet-like structures and exfoliated graphite have alkoxy groups and/or alkyl groups derived from the alcohol solvent. Exfoliated graphite obtained using an alcohol solvent tends to have good affinity for the alcohol solvent and excellent dispersibility in the alcohol solvent.
　電解質溶液中の電解質の濃度は、０．００５Ｍ以上５Ｍ以下であり、０．０１Ｍ以上３Ｍ以下であることが好ましく、０．０５Ｍ以上２Ｍ以下であることがより好ましい。電解質溶液中の電解質の濃度が０．００５Ｍ以上であると、グラファイトの層間に硫酸イオンがインターカレートしやすくなるため、グラファイトの薄板状構造物の層間を剥離しやすくなる傾向にある。一方、電解質溶液中の電解質の濃度が５Ｍ以下であると、薄片化グラファイトの酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さくなる傾向にある。 The concentration of the electrolyte in the electrolyte solution is 0.005M or more and 5M or less, preferably 0.01M or more and 3M or less, and more preferably 0.05M or more and 2M or less. When the concentration of the electrolyte in the electrolyte solution is 0.005M or more, sulfate ions are likely to intercalate between the layers of graphite, so that the layers of the thin plate-like structure of graphite tend to be easily separated. On the other hand, when the concentration of the electrolyte in the electrolyte solution is 5M or less, the mass ratio (C/O ratio) of the carbon element to the oxygen element of the exfoliated graphite tends to be small.
　電解質溶液の電導度は、例えば、１ｍＳ／ｃｍ以上２０００ｍＳ／ｃｍ以下であることが好ましく、５ｍＳ／ｃｍ以上１０００ｍＳ／ｃｍ以下であることがより好ましい。電解質溶液の電導度が１ｍＳ／ｃｍ以上であると、グラファイトの層間に硫酸イオンがインターカレートしやすくなるため、グラファイトの薄板状構造物の層間を剥離しやすくなる傾向にある。一方、電解質溶液の電導度が２０００ｍＳ／ｃｍ以下であると、薄片化グラファイトの酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さくなる傾向にある。 The conductivity of the electrolyte solution is, for example, preferably 1 mS/cm or more and 2000 mS/cm or less, more preferably 5 mS/cm or more and 1000 mS/cm or less. When the electric conductivity of the electrolyte solution is 1 mS/cm or more, sulfate ions are likely to intercalate between the graphite layers, so that the layers of the graphite sheet-like structure tend to be easily separated. On the other hand, when the electric conductivity of the electrolyte solution is 2000 mS/cm or less, the mass ratio (C/O ratio) of the carbon element to the oxygen element of the exfoliated graphite tends to be small.
　電解質溶液の温度は、電解質を溶解する溶媒の種類や電解質溶液中の電解質の濃度によって変わり得るが、実効的には、下限は電解質溶液が凍結しない温度、上限は電解質溶液の沸点である。電解質溶液の温度は、例えば、０℃以上１００℃以下であることが好ましく、０℃以上８０℃以下であることがより好ましい。 The temperature of the electrolyte solution can vary depending on the type of solvent that dissolves the electrolyte and the concentration of the electrolyte in the electrolyte solution, but effectively, the lower limit is the temperature at which the electrolyte solution does not freeze, and the upper limit is the boiling point of the electrolyte solution. The temperature of the electrolyte solution is, for example, preferably 0° C. or higher and 100° C. or lower, and more preferably 0° C. or higher and 80° C. or lower.
　本実施形態に係るグラファイトの薄板状構造物の製造方法において、陽極と陰極との間に印加する電圧は、３Ｖ以上２０Ｖ以下である。陽極と陰極との間に印加する電圧が３Ｖ以上であると、グラファイトの層間に硫酸イオンがインターカレートしやすくなるため、グラファイトの薄板状構造物の層間を剥離しやすくなる傾向にある。一方、陽極と陰極との間に印加する電圧が２０Ｖ以下であると、薄片化グラファイトの酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が小さくなる傾向にある。 In the method for manufacturing a graphite thin plate structure according to the present embodiment, the voltage applied between the anode and the cathode is 3 V or more and 20 V or less. When the voltage applied between the anode and the cathode is 3 V or more, sulfate ions are likely to intercalate between the graphite layers, so that the layers of the graphite sheet-like structure tend to be easily separated. On the other hand, when the voltage applied between the anode and the cathode is 20 V or less, the mass ratio (C/O ratio) of carbon element to oxygen element in exfoliated graphite tends to decrease.
　ここで、電解質溶液中の電解質の濃度が０．００５Ｍ以上０．０５Ｍ以下である場合、陽極と陰極との間に印加する電圧は、３Ｖ以上２０Ｖ以下であることが好ましく、３Ｖ以上１９Ｖ以下であることがより好ましい。また、電解質溶液中の電解質の濃度が０．０５Ｍ以上０．５Ｍ以下である場合、陽極と陰極との間に印加する電圧は、３Ｖ以上２０Ｖ以下であることが好ましく、３Ｖ以上１８Ｖ以下であることがより好ましい。また、電解質溶液中の電解質の濃度が０．５Ｍ以上５Ｍ以下である場合、陽極と陰極との間に印加する電圧は、３Ｖ以上２０Ｖ以下であることが好ましく、３Ｖ以上１７Ｖ以下であることがより好ましい。 Here, when the concentration of the electrolyte in the electrolyte solution is 0.005M or more and 0.05M or less, the voltage applied between the anode and the cathode is preferably 3V or more and 20V or less, more preferably 3V or more and 19V or less. It is more preferable to have Further, when the concentration of the electrolyte in the electrolyte solution is 0.05 M or more and 0.5 M or less, the voltage applied between the anode and the cathode is preferably 3 V or more and 20 V or less, and is 3 V or more and 18 V or less. is more preferable. Further, when the concentration of the electrolyte in the electrolyte solution is 0.5M or more and 5M or less, the voltage applied between the anode and the cathode is preferably 3V or more and 20V or less, and more preferably 3V or more and 17V or less. more preferred.
　なお、陽極と陰極との間に印加する電圧は、３Ｖ以上２０Ｖ以下の範囲で変動してもよく、一定であってもよいが、３Ｖ以上２０Ｖ以下の範囲の定電圧を印加することが好ましい。 The voltage applied between the anode and the cathode may fluctuate in the range of 3 V or more and 20 V or less, or may be constant, but it is preferable to apply a constant voltage in the range of 3 V or more and 20 V or less. .
　本実施形態に係るグラファイトの薄板状構造物の製造方法において、電解質である硫酸及び／又は硫酸塩は、理論的には電解反応の前後で消耗しない。したがって、グラファイトの薄板状構造物の製造に使用した後の電解質溶液は、再利用することができる。ただし、電解質溶液から取り出したグラファイトの薄板状構造物に付着して減少した電解質は、必要に応じて、電気化学反応系に補充してもよい。 In the method for manufacturing a graphite thin plate structure according to the present embodiment, the electrolyte, sulfuric acid and/or sulfate, is theoretically not consumed before and after the electrolytic reaction. Therefore, the electrolyte solution can be reused after it has been used in the manufacture of graphite lamellar structures. However, the electrolyte that has been removed from the electrolyte solution and adhered to the thin plate-like structure of graphite may be replenished to the electrochemical reaction system, if necessary.
　また、電解反応の直後のグラファイトの薄板状構造物には、電解質溶液の抱き込み及び付着が生じている。このとき、グラファイトの薄板状構造物から電解質溶液を回収することができる。 In addition, entrapment and adhesion of the electrolyte solution occurs in the graphite sheet-like structure immediately after the electrolytic reaction. At this time, the electrolyte solution can be recovered from the graphite sheet-like structure.
　グラファイトの薄板状構造物から電解質溶液を回収する方法としては、特に限定されず、例えば、グラファイトの薄板状構造物を遠心分離する方法、グラファイトの薄板状構造物を加圧プレス濾過する方法、ベルトプレス上で連続的にグラファイトの薄板状構造物から電解質溶液を分取する方法等が挙げられる。 The method for recovering the electrolyte solution from the graphite thin plate-like structure is not particularly limited. Examples thereof include a method of continuously separating an electrolyte solution from a thin plate-like structure of graphite on a press.
　なお、グラファイトの薄板状構造物は、過剰の脱イオン水で、洗液が中性に近くなるまで洗浄することで、電解質溶液を取り除くことができる。 It should be noted that the electrolyte solution can be removed from the graphite sheet-like structure by washing it with excess deionized water until the washing liquid becomes nearly neutral.
　グラファイトの薄板状構造物は、必要に応じて乾燥させた後に、後述する薄片化グラファイトの製造方法に適用することができる。グラファイトの薄板状構造物を乾燥させる場合は、例えば、恒温乾燥器又は真空乾燥器を用いて、８０℃以下の温度で乾燥させることができる。 The thin plate-like structure of graphite can be dried as necessary and then applied to the method for producing exfoliated graphite described later. When drying the graphite sheet-like structure, for example, it can be dried at a temperature of 80° C. or less using a constant temperature dryer or a vacuum dryer.
　［薄片化グラファイトの製造方法］
　本実施形態に係る薄片化グラファイトの製造方法は、本実施形態に係るグラファイトの薄板状構造物の製造方法により、グラファイトの薄板状構造物を得る工程と、グラファイトの薄板状構造物の層間を剥離して薄片化グラファイトを得る工程と、を含む。 [Method for producing exfoliated graphite]
The method for producing exfoliated graphite according to the present embodiment comprises a step of obtaining a graphite thin plate-like structure and exfoliating the layers of the graphite thin plate-like structure by the method for producing a graphite thin plate-like structure according to the present embodiment. and obtaining exfoliated graphite.
　グラファイトの薄板状構造物の層間を剥離する方法としては、特に限定されず、例えば、グラファイトの薄板状構造物に超音波を照射する方法、グラファイトの薄板状構造物に機械的剥離力を付加する方法、グラファイトの薄板状構造物を加熱する方法等が挙げられる。具体的には、グラファイトの薄板状構造物を適量の脱イオン水に分散させた後に超音波を照射したり、ミキサーやせん断力を印加できる装置で処理したりすることができる。 The method for separating the layers of the graphite thin plate-like structure is not particularly limited. method, a method of heating a thin plate-like structure of graphite, and the like. Specifically, after dispersing a thin plate-like structure of graphite in an appropriate amount of deionized water, it can be irradiated with ultrasonic waves or treated with a mixer or an apparatus capable of applying a shearing force.
　薄片化グラファイトは、凍結乾燥させてもよいし、濾過又は遠心分離した後、乾燥させてもよい。なお、薄片化グラファイトの乾燥方法は、グラファイトの薄板状構造物の乾燥方法と同様である。 The exfoliated graphite may be freeze-dried, or may be filtered or centrifuged and then dried. The method for drying the exfoliated graphite is the same as the method for drying the thin plate-like structure of graphite.
　［薄片化グラファイト］
　本実施形態に係る薄片化グラファイトは、本実施形態に係る薄片化グラファイトの製造方法により得ることができるものである。 [Exfoliated graphite]
The exfoliated graphite according to this embodiment can be obtained by the method for producing exfoliated graphite according to this embodiment.
　本実施形態に係る薄片化グラファイトは、硫黄元素の含有率が０．０１質量％以上２．５質量％以下であり、フッ素元素の含有率が０．１質量％未満であり、ホウ素元素の含有率が０．１質量％未満である。 The exfoliated graphite according to the present embodiment has a sulfur element content of 0.01% by mass or more and 2.5% by mass or less, a fluorine element content of less than 0.1% by mass, and a boron element content % is less than 0.1% by mass.
　本実施形態に係る薄片化グラファイトは、その製造方法に起因して、不純物である重金属元素の含有率を低くすることができる。例えば、本実施形態に係る薄片化グラファイトは、マンガン元素の含有率を０．１質量％未満とすることができる。 Due to the manufacturing method, the exfoliated graphite according to the present embodiment can have a low content of heavy metal elements as impurities. For example, the exfoliated graphite according to the present embodiment can have a manganese element content of less than 0.1% by mass.
　本実施形態に係る薄片化グラファイトは、酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）が０．７以上３．０以下であり、１．５以上３．０以下であることが好ましく、１．５以上２．６以下であることがより好ましい。 In the exfoliated graphite according to the present embodiment, the mass ratio of carbon element to oxygen element (C/O ratio) is 0.7 or more and 3.0 or less, preferably 1.5 or more and 3.0 or less, It is more preferably 1.5 or more and 2.6 or less.
　本実施形態の薄片化グラファイトは、ＸＲＤスペクトルにおける２θが７°以上１２°以下である領域に含まれるピークの最大強度をＸとし、２θが２３°以上３０°以下である領域に含まれるピークの最大強度をＹとしたとき、Ｘ及びＹが次式：０．８≦Ｘ／Ｙを満たすことが好ましく、次式：２≦Ｘ／Ｙを満たすことがより好ましい。 In the exfoliated graphite of the present embodiment, X is the maximum intensity of the peak included in the region where 2θ is 7° or more and 12° or less in the XRD spectrum, and the maximum intensity of the peak included in the region where 2θ is 23° or more and 30° or less. When the maximum intensity is Y, X and Y preferably satisfy the following expression: 0.8≦X/Y, and more preferably satisfy the following expression: 2≦X/Y.
　本実施形態に係る薄片化グラファイトの厚みは、１００ｎｍ以下であることが好ましく、５０ｎｍ以下であることがより好ましく、１０ｎｍ以下であることがさらに好ましく、１ｎｍ以下であることが特に好ましい。また、本実施形態に係る薄片化グラファイトの平均粒子径は、３０ｎｍ以上１ｍｍ以下であることが好ましく、１００ｎｍ以上２００μｍ以下であることがより好ましく、２００ｎｍ以上１００μｍ以下であることがさらに好ましい。 The thickness of the exfoliated graphite according to the present embodiment is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 10 nm or less, and particularly preferably 1 nm or less. The average particle size of the exfoliated graphite according to the present embodiment is preferably 30 nm or more and 1 mm or less, more preferably 100 nm or more and 200 μm or less, and even more preferably 200 nm or more and 100 μm or less.
　以下、本発明の実施例を説明するが、本発明は、実施例に限定されるものではない。 Examples of the present invention will be described below, but the present invention is not limited to the examples.
　＜グラファイトの熱拡散率＞
　グラファイトを４０ｍｍ×４０ｍｍの形状に切り取ったサンプルを作製し、熱拡散率測定装置（サーモウェーブアナライザＴＡ３、（株）ベテル製）を用いて、２０℃の雰囲気下、グラファイトの熱拡散率［ｃｍ２／ｓ］を測定した。 <Thermal diffusivity of graphite>
A sample of graphite cut into a shape of 40 mm × 40 mm was prepared, and a thermal diffusivity measuring device (Thermo Wave Analyzer TA3, Bethel Co., Ltd.) was used to measure the thermal diffusivity [ cm /s] was measured.
　＜薄片化グラファイトの元素分析＞
　走査型蛍光Ｘ線分析装置（ＺＳＸ　ＰｒｉｍｕｓＩＩＩ＋、（株）リガク製）を用いて、薄片化グラファイトの元素分析を実施し、硫黄元素（Ｓ）の含有率［質量％］、フッ素元素（Ｆ）の含有率［質量％］、ホウ素元素（Ｂ）の含有率［質量％］、及び酸素元素に対する炭素元素の質量比（Ｃ／Ｏ比）を測定した。 <Elemental analysis of exfoliated graphite>
Elemental analysis of exfoliated graphite was performed using a scanning fluorescent X-ray spectrometer (ZSX PrimusIII+, manufactured by Rigaku Co., Ltd.), and the content of elemental sulfur (S) [% by mass] and the content of elemental fluorine (F) were determined. The content [% by mass], the content [% by mass] of the boron element (B), and the mass ratio of the carbon element to the oxygen element (C/O ratio) were measured.
　＜電解質溶液の電導度＞
　ポータブル電磁濃度計（ＭＤＭ－２５Ａ、東亜ディーケーケー（株）製）を用いて、電解質溶液の電導度［ｍＳ／ｃｍ］を測定した。 <Conductivity of electrolyte solution>
The electric conductivity [mS/cm] of the electrolyte solution was measured using a portable electromagnetic densitometer (MDM-25A, manufactured by Toa DKK Co., Ltd.).
　＜Ｘ線回折（ＸＲＤ）＞
　Ｘ線回折装置（Ｘ’Ｐｅｒｔ　Ｐｒｏ、Ｍａｌｖｅｒｎ　Ｐａｎａｌｙｔｉｃａｌ製）を用いて、ＣｕＫα（λ＝１．５４１Å）を放射し、２θレンジを５°から７５°までとして、薄片化グラファイトのＸＲＤスペクトルを測定した。次に、ＸＲＤスペクトルにおける２θが７°以上１２°以下である領域に含まれるピークの最大強度（Ｘ）及び２θが２３°以上３０°以下である領域に含まれるピークの最大強度（Ｙ）を求め、Ｘ／Ｙ比を算出した。 <X-ray diffraction (XRD)>
Using an X-ray diffractometer (X'Pert Pro, manufactured by Malvern Panalytical), CuKα (λ=1.541 Å) was emitted, and the XRD spectrum of exfoliated graphite was measured with a 2θ range of 5° to 75°. . Next, the maximum intensity (X) of the peak contained in the region where 2θ is 7° or more and 12° or less in the XRD spectrum and the maximum intensity (Y) of the peak contained in the region where 2θ is 23° or more and 30° or less and calculated the X/Y ratio.
　（グラファイトシートＡ）
　グラファイトシートＡとして、厚み６２μｍの芳香族ポリイミドフィルムを２９００℃以上の温度で熱処理して得られる、厚み３２μｍ、熱拡散率９ｃｍ２／ｓのグラファイトシート（（株）カネカ製）を用いた。 (Graphite sheet A)
As the graphite sheet A, a graphite sheet (manufactured by Kaneka Corporation) having a thickness of 32 μm and a thermal diffusivity of 9 cm 2 /s obtained by heat-treating an aromatic polyimide film having a thickness of 62 μm at a temperature of 2900° C. or higher was used.
　（グラファイトシートＢ）
　グラファイトシートＢとして、膨張黒鉛シートＰＦ－ＨＰ（東洋炭素（株）製）を２４００℃で熱処理して得られる、厚み２００μｍ、熱拡散率４ｃｍ２／ｓのグラファイトシートを用いた。 (Graphite sheet B)
As the graphite sheet B, a graphite sheet having a thickness of 200 μm and a thermal diffusivity of 4 cm 2 /s obtained by heat-treating an expanded graphite sheet PF-HP (manufactured by Toyo Tanso Co., Ltd.) at 2400° C. was used.
　（実施例１）
　ＰＶＣ製の反応器に、電解質溶液としての１Ｍ硫酸水溶液を３Ｌ加えた後、陽極としてのグラファイトシートＡを、表面積のうち６ｃｍ×２５ｃｍが電解質溶液中に浸漬するよう固定するとともに、陰極としてカーボン板をセットした。次に、陽極及び陰極を直流電源に接続して７Ｖの電圧を印加し、電流が減少して一定になるまで室温下で電解し、グラファイトの薄板状構造物を得た。グラファイトの薄板状構造物を電解質溶液から引き揚げて取り出した後、洗液の電導度が１００μＳ／ｃｍ以下になるまで脱イオン水で洗浄し、未乾燥状態の黒褐色のグラファイトの薄板状構造物を得た。 (Example 1)
After adding 3 L of a 1 M sulfuric acid aqueous solution as an electrolyte solution to a PVC reactor, a graphite sheet A as an anode was fixed so that 6 cm × 25 cm of the surface area was immersed in the electrolyte solution, and a carbon plate was used as a cathode. was set. Next, the anode and the cathode were connected to a DC power supply, a voltage of 7 V was applied, and electrolysis was performed at room temperature until the current decreased and became constant, thereby obtaining a thin plate-like structure of graphite. After the graphite sheet-like structure was pulled up from the electrolyte solution and taken out, it was washed with deionized water until the electric conductivity of the washing liquid became 100 μS/cm or less, to obtain an undried blackish-brown graphite sheet-like structure. rice field.
　グラファイトの薄板状構造物に脱イオン水を加え、固形分濃度が約１質量％になるように調整した。得られた溶液を高速撹拌機にて５分間粉砕した後、溶液を乾燥後の厚みが２５μｍ程度になるようにシャーレに入れ、室温で乾燥して、薄片化グラファイトの膜を得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が０．９であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．３であった（図１Ａ参照）。 Deionized water was added to the graphite thin plate structure to adjust the solid content concentration to about 1% by mass. After pulverizing the obtained solution for 5 minutes with a high-speed stirrer, the solution was placed in a petri dish so that the thickness after drying was about 25 μm, and dried at room temperature to obtain a film of exfoliated graphite. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 0.9. Also, the exfoliated graphite had an X/Y ratio of 3.3 (see FIG. 1A).
　（実施例２）
　陽極及び陰極を直流電源に接続して６Ｖの電圧を印加した以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が０．９であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．３であった。 (Example 2)
Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 0.9. The exfoliated graphite had an X/Y ratio of 3.3.
　（実施例３）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．４であった（図１Ｂ参照）。 (Example 3)
Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.0. Also, the exfoliated graphite had an X/Y ratio of 3.4 (see FIG. 1B).
　（実施例４）
　陽極及び陰極を直流電源に接続して４Ｖの電圧を印加した以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．６であった（図１Ｃ参照）。 (Example 4)
Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 4 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 3.6 (see FIG. 1C).
　（実施例５）
　陽極及び陰極を直流電源に接続して３Ｖの電圧を印加した以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．５であった。 (Example 5)
Exfoliated graphite was obtained in the same manner as in Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 3 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.3. The exfoliated graphite had an X/Y ratio of 2.5.
　（実施例６）
　電解質溶液として０．１Ｍ硫酸水溶液を用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．１であった。 (Example 6)
Exfoliated graphite was obtained in the same manner as in Example 1, except that a 0.1 M sulfuric acid aqueous solution was used as the electrolyte solution. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.1. The exfoliated graphite had an X/Y ratio of 2.1.
　（実施例７）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．１であった（図２Ａ参照）。 (Example 7)
Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 2.1 (see FIG. 2A).
　（実施例８）
　陽極及び陰極を直流電源に接続して４Ｖの電圧を印加した以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．１であった（図２Ｂ参照）。 (Example 8)
Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 4 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.1. Also, the exfoliated graphite had an X/Y ratio of 2.1 (see FIG. 2B).
　（実施例９）
　陽極及び陰極を直流電源に接続して３．５Ｖの電圧を印加した以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．５であった（図２Ｃ参照）。 (Example 9)
Exfoliated graphite was obtained in the same manner as in Example 6, except that the anode and cathode were connected to a DC power source and a voltage of 3.5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.1. Also, the exfoliated graphite had an X/Y ratio of 3.5 (see FIG. 2C).
　（実施例１０）
　電解質溶液として０．０１Ｍ硫酸水溶液を用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．５であった。また、薄片化グラファイトは、Ｘ／Ｙ比が１．５であった。 (Example 10)
Exfoliated graphite was obtained in the same manner as in Example 1, except that a 0.01 M sulfuric acid aqueous solution was used as the electrolyte solution. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.5. The exfoliated graphite had an X/Y ratio of 1.5.
　（実施例１１）
　陽極及び陰極を直流電源に接続して６Ｖの電圧を印加した以外は、実施例１０と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．５であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．５であった。 (Example 11)
Exfoliated graphite was obtained in the same manner as in Example 10, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.5. The exfoliated graphite had an X/Y ratio of 2.5.
　（実施例１２）
　陽極としてグラファイトシートＢを用いた以外は、実施例７と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が３．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が１．２であった。 (Example 12)
Exfoliated graphite was obtained in the same manner as in Example 7, except that graphite sheet B was used as the anode. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 3.0. The exfoliated graphite had an X/Y ratio of 1.2.
　（実施例１３）
　陽極としてグラファイトシートＢを用いた以外は、実施例８と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．７であった。また、薄片化グラファイトは、Ｘ／Ｙ比が０．８であった。 (Example 13)
Exfoliated graphite was obtained in the same manner as in Example 8, except that graphite sheet B was used as the anode. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.7. The exfoliated graphite had an X/Y ratio of 0.8.
　（実施例１４）
　電解質として硫酸アンモニウムを用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．６であった（図３Ａ参照）。 (Example 14)
Exfoliated graphite was obtained in the same manner as in Example 1, except that ammonium sulfate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 2.6 (see FIG. 3A).
　（実施例１５）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例１４と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．５であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．０であった（図３Ｂ参照）。 (Example 15)
Exfoliated graphite was obtained in the same manner as in Example 14, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.5. Also, the exfoliated graphite had an X/Y ratio of 3.0 (see FIG. 3B).
　（実施例１６）
　電解質として硫酸アンモニウムを用いた以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．５であった。 (Example 16)
Exfoliated graphite was obtained in the same manner as in Example 6, except that ammonium sulfate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.0. The exfoliated graphite had an X/Y ratio of 2.5.
　（実施例１７）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例１６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．２であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．１であった。 (Example 17)
Exfoliated graphite was obtained in the same manner as in Example 16, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.2. The exfoliated graphite had an X/Y ratio of 2.1.
　（実施例１８）
　電解質として硫酸ナトリウムを用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．４であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．８であった（図４Ａ参照）。 (Example 18)
Exfoliated graphite was obtained in the same manner as in Example 1, except that sodium sulfate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.4. Also, the exfoliated graphite had an X/Y ratio of 2.8 (see FIG. 4A).
　（実施例１９）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例１８と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．６であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．３であった（図４Ｂ参照）。 (Example 19)
Exfoliated graphite was obtained in the same manner as in Example 18, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 1.6. Also, the exfoliated graphite had an X/Y ratio of 2.3 (see FIG. 4B).
　（実施例２０）
　電解質として硫酸ナトリウムを用いた以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．２であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．５であった。 (Example 20)
Exfoliated graphite was obtained in the same manner as in Example 6, except that sodium sulfate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.2. The exfoliated graphite had an X/Y ratio of 2.5.
　（実施例２１）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、実施例２０と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が１～２．５質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が２．４であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．１であった。 (Example 21)
Exfoliated graphite was obtained in the same manner as in Example 20, except that the anode and cathode were connected to a DC power supply and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of 1 to 2.5% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was 2.4. The exfoliated graphite had an X/Y ratio of 2.1.
　（比較例１）
　電解質としてホウフッ化水素酸を用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が１０よりも大きかった（図５Ａ参照）。 (Comparative example 1)
Exfoliated graphite was obtained in the same manner as in Example 1, except that hydroboric acid was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0. Also, the exfoliated graphite had an X/Y ratio greater than 10 (see FIG. 5A).
　（比較例２）
　陽極及び陰極を直流電源に接続して６Ｖの電圧を印加した以外は、比較例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が１０よりも大きかった（図５Ｂ参照）。 (Comparative example 2)
Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power source and a voltage of 6 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0. Also, the exfoliated graphite had an X/Y ratio greater than 10 (see FIG. 5B).
　（比較例３）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、比較例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が９．０であった（図５Ｃ参照）。 (Comparative Example 3)
Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power supply and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1. Also, the exfoliated graphite had an X/Y ratio of 9.0 (see FIG. 5C).
　（比較例４）
　陽極及び陰極を直流電源に接続して４Ｖの電圧を印加した以外は、比較例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．４であった。また、薄片化グラファイトは、Ｘ／Ｙ比が３．０であった（図５Ｄ参照）。 (Comparative Example 4)
Exfoliated graphite was obtained in the same manner as in Comparative Example 1, except that the anode and cathode were connected to a DC power supply and a voltage of 4 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.4. Also, the exfoliated graphite had an X/Y ratio of 3.0 (see FIG. 5D).
　（比較例５）
　電解質としてホウフッ化水素酸を用いた以外は、実施例６と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が７．８であった（図６Ａ参照）。 (Comparative Example 5)
Exfoliated graphite was obtained in the same manner as in Example 6, except that hydroboric acid was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1. Also, the exfoliated graphite had an X/Y ratio of 7.8 (see FIG. 6A).
　（比較例６）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、比較例５と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が４．２であった（図６Ｂ参照）。 (Comparative Example 6)
Exfoliated graphite was obtained in the same manner as in Comparative Example 5, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 4.2 (see FIG. 6B).
　（比較例７）
　電解質としてホウフッ化水素酸アンモニウムを用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．０であった。また、薄片化グラファイトは、Ｘ／Ｙ比が８．５であった（図７Ａ参照）。 (Comparative Example 7)
Exfoliated graphite was obtained in the same manner as in Example 1, except that ammonium hydroborofluorate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.0. Also, the exfoliated graphite had an X/Y ratio of 8.5 (see FIG. 7A).
　（比較例８）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、比較例７と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．３であった。また、薄片化グラファイトは、Ｘ／Ｙ比が５．０であった（図７Ｂ参照）。 (Comparative Example 8)
Exfoliated graphite was obtained in the same manner as in Comparative Example 7, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.3. Also, the exfoliated graphite had an X/Y ratio of 5.0 (see FIG. 7B).
　（比較例９）
　電解質としてホウフッ化水素酸アンモニウムを用いた以外は、実施例７と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．５であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．８であった。 (Comparative Example 9)
Exfoliated graphite was obtained in the same manner as in Example 7, except that ammonium hydroborofluorate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.5. The exfoliated graphite had an X/Y ratio of 2.8.
　（比較例１０）
　電解質としてホウフッ化水素酸ナトリウムを用いた以外は、実施例１と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．１であった。また、薄片化グラファイトは、Ｘ／Ｙ比が９．９であった（図８Ａ参照）。 (Comparative Example 10)
Exfoliated graphite was obtained in the same manner as in Example 1, except that sodium hydroborofluorate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.1. Also, the exfoliated graphite had an X/Y ratio of 9.9 (see FIG. 8A).
　（比較例１１）
　陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した以外は、比較例１０と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．４であった。また、薄片化グラファイトは、Ｘ／Ｙ比が４．７であった（図８Ｂ参照）。 (Comparative Example 11)
Exfoliated graphite was obtained in the same manner as in Comparative Example 10, except that the anode and cathode were connected to a DC power source and a voltage of 5 V was applied. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.4. Also, the exfoliated graphite had an X/Y ratio of 4.7 (see FIG. 8B).
　（比較例１２）
　電解質としてホウフッ化水素酸ナトリウムを用いた以外は、実施例７と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１質量％未満、フッ素元素（Ｆ）の含有率が１～３質量％、ホウ素元素（Ｂ）の含有率が０．１～１質量％であり、Ｃ／Ｏ比が１．６であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２．６であった。 (Comparative Example 12)
Exfoliated graphite was obtained in the same manner as in Example 7, except that sodium hydroborofluorate was used as the electrolyte. The exfoliated graphite has a sulfur element (S) content of less than 0.1% by mass, a fluorine element (F) content of 1 to 3% by mass, and a boron element (B) content of 0.1 to 1%. % by mass, and the C/O ratio was 1.6. Also, the exfoliated graphite had an X/Y ratio of 2.6.
　（比較例１３）
　電解質溶液として９．２Ｍ硫酸水溶液を用いた以外は、実施例３と同様にして、薄片化グラファイトを得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が０．１～２質量％、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１０よりも大きかった。また、薄片化グラファイトは、Ｘ／Ｙ比が０．７未満であった。 (Comparative Example 13)
Exfoliated graphite was obtained in the same manner as in Example 3, except that a 9.2 M sulfuric acid aqueous solution was used as the electrolyte solution. The exfoliated graphite has a sulfur element (S) content of 0.1 to 2% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and C/ The O ratio was greater than 10. Also, the exfoliated graphite had an X/Y ratio of less than 0.7.
　（比較例１４）
　ＰＶＣ製の反応器に、電解質溶液としての０．２Ｍ硫酸ナトリウム水溶液を加えた後、陽極としての平均粒径２５μｍの天然黒鉛粒子を、電解質溶液中に浸漬するよう固定するとともに、陰極としてカーボン板をセットした。次に、陽極及び陰極を定電流電源に接続して３００ｍＡの電流を流して、室温下で電解し、グラファイトの薄板状構造物を得た。グラファイトの薄板状構造物を電解質溶液から引き揚げて取り出した後、洗液の電導度が１００μＳ／ｃｍ以下になるまで脱イオン水で洗浄し、未乾燥状態の黒褐色のグラファイトの薄板状構造物を得た。 (Comparative Example 14)
After adding a 0.2 M sodium sulfate aqueous solution as an electrolyte solution to a PVC reactor, natural graphite particles with an average particle size of 25 μm as an anode were fixed so as to be immersed in the electrolyte solution, and a carbon plate was used as a cathode. was set. Next, the anode and the cathode were connected to a constant current power supply, and a current of 300 mA was applied to electrolyze at room temperature to obtain a thin plate-like structure of graphite. After the graphite sheet-like structure was pulled up from the electrolyte solution and taken out, it was washed with deionized water until the electric conductivity of the washing liquid became 100 μS/cm or less, to obtain an undried blackish-brown graphite sheet-like structure. rice field.
　グラファイトの薄板状構造物に脱イオン水を加え、固形分濃度が約１質量％になるように調整した。得られた溶液を高速撹拌機にて５分間粉砕した後、溶液を乾燥後の厚みが２５μｍ程度になるようにシャーレに入れ、室温で乾燥して、薄片化グラファイトの膜を得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が２質量％未満であり、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が４．１よりも大きかった。また、薄片化グラファイトは、Ｘ／Ｙ比が０．７未満であった。 Deionized water was added to the graphite thin plate structure to adjust the solid content concentration to about 1% by mass. After pulverizing the obtained solution for 5 minutes with a high-speed stirrer, the solution was placed in a petri dish so that the thickness after drying was about 25 μm, and dried at room temperature to obtain a film of exfoliated graphite. Exfoliated graphite has a sulfur element (S) content of less than 2% by mass, a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, and a C/O The ratio was greater than 4.1. Also, the exfoliated graphite had an X/Y ratio of less than 0.7.
　（比較例１５）
　ＰＶＣ製の反応器に、電解質溶液としての１８．３Ｍ硫酸水溶液（濃硫酸）を加えた後、陽極としての熱拡散率３ｃｍ２／ｓ未満のフレキシブルグラファイトシートを、電解質溶液中に浸漬するよう固定するとともに、陰極としてカーボン板をセットした。次に、陽極及び陰極を直流電源に接続して６０Ｖの電圧を印加した後、電解質の濃度を１Ｍに変更し、５０Ｖの電圧を印加し、電流が減少して一定になるまで室温下で電解し、グラファイトの薄板状構造物を得た。グラファイトの薄板状構造物を電解質溶液から引き揚げて取り出した後、洗液の電導度が１００μＳ／ｃｍ以下になるまで脱イオン水で洗浄し、未乾燥状態の黒褐色のグラファイトの薄板状構造物を得た。 (Comparative Example 15)
After adding an aqueous 18.3 M sulfuric acid solution (concentrated sulfuric acid) as an electrolyte solution to a PVC reactor, a flexible graphite sheet with a thermal diffusivity of less than 3 cm 2 /s as an anode was fixed so as to be immersed in the electrolyte solution. At the same time, a carbon plate was set as a cathode. Next, after connecting the anode and cathode to a DC power supply and applying a voltage of 60 V, the concentration of the electrolyte was changed to 1 M, a voltage of 50 V was applied, and electrolysis was performed at room temperature until the current decreased and became constant. Then, a thin plate-like structure of graphite was obtained. After the graphite sheet-like structure was pulled up from the electrolyte solution and taken out, it was washed with deionized water until the electric conductivity of the washing liquid became 100 μS/cm or less, to obtain an undried blackish-brown graphite sheet-like structure. rice field.
　グラファイトの薄板状構造物に脱イオン水を加え、固形分濃度が約１質量％になるように調整した。得られた溶液を高速撹拌機にて５分間粉砕した後、溶液を乾燥後の厚みが２５μｍ程度になるようにシャーレに入れ、室温で乾燥して、薄片化グラファイトの膜を得た。薄片化グラファイトは、硫黄元素（Ｓ）の含有率が２．６～４質量％であり、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率がいずれも０．１質量％未満であり、Ｃ／Ｏ比が１．５未満であった。また、薄片化グラファイトは、Ｘ／Ｙ比が２よりも大きかった。 Deionized water was added to the graphite thin plate structure to adjust the solid content concentration to about 1% by mass. After pulverizing the obtained solution for 5 minutes with a high-speed stirrer, the solution was placed in a petri dish so that the thickness after drying was about 25 μm, and dried at room temperature to obtain a film of exfoliated graphite. The exfoliated graphite has a sulfur element (S) content of 2.6 to 4% by mass, and a fluorine element (F) and a boron element (B) content of both less than 0.1% by mass, The C/O ratio was less than 1.5. Also, the exfoliated graphite had an X/Y ratio greater than 2.
　表１～９に、薄片化グラファイトの製造条件及び特性を示す。 Tables 1 to 9 show the production conditions and characteristics of exfoliated graphite.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　表１～９から、実施例１～２１の薄片化グラファイトは、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率が低く、Ｃ／Ｏ比が小さいことがわかる。これに対して、比較例１～１２の薄片化グラファイトは、製造時に、電解質としてホウフッ化水素酸又はホウフッ化水素酸塩が用いられているため、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率が高い。また、比較例１３の薄片化グラファイトは、製造時に、電解質溶液として９．２Ｍ硫酸水溶液が用いられているため、Ｃ／Ｏ比が大きい。なお、比較例１４の薄片化グラファイトは、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率が低いものの、Ｃ／Ｏ比が大きい。また、比較例１５の薄片化グラファイトは、フッ素元素（Ｆ）及びホウ素元素（Ｂ）の含有率が低く、Ｃ／Ｏ比が小さいものの、製造時に電解質溶液として１８．３Ｍ硫酸水溶液（濃硫酸）を使用しており、製造時の安全性に欠ける。 From Tables 1 to 9, it can be seen that the exfoliated graphite of Examples 1 to 21 has a low content of fluorine element (F) and boron element (B) and a small C/O ratio. On the other hand, in the exfoliated graphite of Comparative Examples 1 to 12, since fluoroboric acid or hydrofluoroborate is used as the electrolyte at the time of production, elemental fluorine (F) and elemental boron (B) High content. In addition, the exfoliated graphite of Comparative Example 13 has a large C/O ratio because a 9.2 M sulfuric acid aqueous solution is used as an electrolyte solution during production. The exfoliated graphite of Comparative Example 14 has a low content of fluorine element (F) and boron element (B), but has a large C/O ratio. In addition, although the exfoliated graphite of Comparative Example 15 has a low content of fluorine element (F) and boron element (B) and a small C/O ratio, 18.3 M sulfuric acid aqueous solution (concentrated sulfuric acid) was used as an electrolyte solution during production. is used, and safety during manufacturing is lacking.
　［電解質の種類及び濃度と電解質水溶液の電導度との関係］
　図９に、電解質の０．１Ｍ水溶液及び１Ｍ水溶液の電導度を示す。ここで、電解質は、実施例および比較例で用いたＨＢＦ４、ＮＨ４ＢＦ４、ＮａＢＦ４、Ｈ２ＳＯ４、（ＮＨ４）２ＳＯ４、Ｎａ２ＳＯ４である。 [Relationship between type and concentration of electrolyte and conductivity of aqueous electrolyte solution]
FIG. 9 shows the conductivity of 0.1M and 1M aqueous solutions of the electrolyte. Here, the electrolytes are HBF 4 , NH 4 BF 4 , NaBF 4 , H 2 SO 4 , (NH 4 ) 2 SO 4 and Na 2 SO 4 used in Examples and Comparative Examples.
　図９から、アニオン、カチオン、及び濃度に着目すると、以下のような傾向がわかる。
　ａ）アニオン：ＢＦ４ －＜ＳＯ４ ２－
　ｂ）カチオン：Ｎａ＋＜ＮＨ４ ＋＜Ｈ＋
　ｃ）濃度：０．１Ｍ＜１Ｍ
　また、電解質に着目すると、Ｈ２ＳＯ４の電導度が最も高く、ＮａＢＦ４の電導度が最も低い。 Focusing on anions, cations, and concentrations from FIG. 9, the following tendencies can be seen.
a) Anion: BF 4 − <SO 4 2−
b) cations: Na + <NH 4 + <H +
c) Concentration: 0.1M<1M
Also, focusing on the electrolyte, H 2 SO 4 has the highest conductivity and NaBF 4 has the lowest conductivity.
　［電解質の種類とグラファイトの薄板状構造物の外観との関係］
　図１０に、電解質の濃度が１Ｍである場合の、電解質の種類とグラファイトの薄板状構造物の外観との関係を示す。なお、この実験では、陽極としてグラファイトシートＡ、陰極としてカーボン板を用い、陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した。 [Relationship between type of electrolyte and appearance of graphite thin plate structure]
FIG. 10 shows the relationship between the type of electrolyte and the appearance of the graphite thin plate-like structure when the concentration of the electrolyte is 1M. In this experiment, the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.
　図１０から、電解質のアニオンが同一であると、グラファイトの薄板状構造物の外観が類似していることがわかる。これは、電気化学酸化過程において、電解質のアニオンがグラファイトシートにインターカレートされる、すなわち、電解質のアニオンがグラファイトシートに直接作用しているためであると考えられる。 From FIG. 10, it can be seen that when the anion of the electrolyte is the same, the appearance of the graphite sheet-like structure is similar. This is probably because the anions of the electrolyte are intercalated with the graphite sheets in the electrochemical oxidation process, that is, the anions of the electrolyte act directly on the graphite sheets.
　［電解質の種類と電気化学酸化の反応性との関係］
　図１１Ａ及び図１１Ｂに、電解質の種類と電気化学酸化の反応性との関係を示す。なお、この実験では、陽極としてグラファイトシートＡ、陰極としてカーボン板を用い、陽極及び陰極を直流電源に接続して５Ｖの電圧を印加した。 [Relationship between type of electrolyte and reactivity of electrochemical oxidation]
11A and 11B show the relationship between the type of electrolyte and the reactivity of electrochemical oxidation. In this experiment, the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.
　図１１Ａ及び図１１Ｂから、電解質の電導度が高い（Ｎａ＋＜ＮＨ４ ＋＜Ｈ＋）程、電気化学酸化の開始電流が高くなり、反応時間が短くなっているため、電解質の電導度と電気化学酸化の開始電流及び反応時間とには相関があることがわかる。電気化学酸化される条件（電気化学酸化が生じる電圧以上）においては、インターカレーション及び電気化学酸化は、非常にスピーディに進行する。そのため、反応の律速は、電解質のアニオンの供給になる。電解質の電導度が高い程、電解質のアニオンの供給量が多くなり、その結果、電気化学酸化の開始電流が高くなり、反応時間が短くなると考えられる。 11A and 11B, the higher the conductivity of the electrolyte (Na + <NH 4 + <H + ), the higher the starting current for electrochemical oxidation and the shorter the reaction time. It can be seen that there is a correlation between the starting current of electrochemical oxidation and the reaction time. Intercalation and electrochemical oxidation proceed very quickly under electrochemical oxidation conditions (at or above the voltage at which electrochemical oxidation occurs). Therefore, the rate limiting of the reaction is the supply of electrolyte anions. It is believed that the higher the conductivity of the electrolyte, the greater the supply of anions from the electrolyte, resulting in a higher starting current for electrochemical oxidation and a shorter reaction time.
　［電解質の濃度と電気化学酸化の反応性との関係］
　図１２Ａ及び図１２Ｂに、電解質の濃度と電気化学酸化の反応性との関係を示す。なお、この実験では、陽極としてグラファイトシートＡ、陰極としてカーボン板を用いた。 [Relationship between electrolyte concentration and electrochemical oxidation reactivity]
12A and 12B show the relationship between electrolyte concentration and electrochemical oxidation reactivity. In this experiment, the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.
　図１２Ａ及び図１２Ｂから、電解質の濃度が高く、電気化学酸化の電圧が高い程、電気化学酸化の開始電流が高くなり、反応時間が短くなっていることがわかる。ここで、電解質の濃度が高く、電気化学酸化の電圧が高い程、電解質のアニオンの供給量が多くなり、電気化学酸化の開始電流が高くなり、反応時間が短くなると考えられる。また、１Ｍの５Ｖと０．１Ｍの７Ｖとは、似た電流曲線になっているため、消費電力を下げたい場合は、電解質の濃度を上げて、電圧を下げることが有効である。一方、後処理工程の洗浄作業を簡略化するためには、電解質の濃度を下げて、電圧を上げることが有効である。 From FIGS. 12A and 12B, it can be seen that the higher the electrolyte concentration and the higher the electrochemical oxidation voltage, the higher the electrochemical oxidation start current and the shorter the reaction time. Here, it is thought that the higher the concentration of the electrolyte and the higher the voltage of the electrochemical oxidation, the larger the amount of anions supplied from the electrolyte, the higher the starting current of the electrochemical oxidation, and the shorter the reaction time. Also, since 5V at 1M and 7V at 0.1M have similar current curves, it is effective to increase the concentration of the electrolyte and decrease the voltage in order to reduce the power consumption. On the other hand, in order to simplify the cleaning work in the post-treatment process, it is effective to lower the electrolyte concentration and raise the voltage.
　［電解質の種類と反応時間との関係］
　図１３に、グラファイトシートの浸漬サイズが５ｃｍ×５ｃｍである場合の電解質の種類と反応時間との関係を示す。なお、この実験では、陽極としてグラファイトシートＡ、陰極としてカーボン板を用いた。 [Relationship between type of electrolyte and reaction time]
FIG. 13 shows the relationship between the type of electrolyte and the reaction time when the graphite sheet is immersed in a size of 5 cm×5 cm. In this experiment, the graphite sheet A was used as the anode, and the carbon plate was used as the cathode.

Claims (13)

  1. 　グラファイトを含む陽極と、陰極と、電解質として硫酸及び／又は硫酸塩を含む電解質溶液と、を含む電気化学反応系において、前記陽極と前記陰極との間に電圧を印加する工程を含み、
    　前記グラファイトは、熱拡散率が３．５ｃｍ２／ｓ以上であり、
    　前記電解質溶液は、前記電解質の濃度が０．００５Ｍ以上５Ｍ以下であり、
    　前記電圧は、３Ｖ以上２０Ｖ以下である、グラファイトの薄板状構造物の製造方法。     In an electrochemical reaction system comprising an anode containing graphite, a cathode, and an electrolyte solution containing sulfuric acid and/or sulfate as an electrolyte, applying a voltage between the anode and the cathode;
    The graphite has a thermal diffusivity of 3.5 cm 2 /s or more,
    The electrolyte solution has a concentration of the electrolyte of 0.005 M or more and 5 M or less,
    The method for manufacturing a graphite sheet-like structure, wherein the voltage is 3 V or more and 20 V or less.
  2. 　前記グラファイトは、縮重合系高分子化合物の熱処理物である、請求項１に記載のグラファイトの薄板状構造物の製造方法。 The method for producing a thin plate-like structure of graphite according to claim 1, wherein the graphite is a heat-treated polycondensation polymer compound.
  3. 　前記縮重合系高分子化合物は、芳香族ポリイミドである、請求項２に記載のグラファイトの薄板状構造物の製造方法。 The method for manufacturing a graphite thin plate-like structure according to claim 2, wherein the polycondensation polymer compound is an aromatic polyimide.
  4. 　前記陽極は、膨張黒鉛シートの熱処理物である、請求項１に記載のグラファイトの薄板状構造物の製造方法。 The method for manufacturing a graphite sheet-like structure according to claim 1, wherein the anode is a heat-treated expanded graphite sheet.
  5. 　前記膨張黒鉛シートは、天然グラファイトを強酸に浸した後、加熱処理して得られる膨張黒鉛のプレス物である、請求項４に記載のグラファイトの薄板状構造物の製造方法。 The method for producing a thin plate-like structure of graphite according to claim 4, wherein the expanded graphite sheet is a pressed expanded graphite obtained by soaking natural graphite in a strong acid and then heat-treating it.
  6. 　前記電解質溶液は、前記電解質の濃度が０．００５Ｍ以上０．０５Ｍ以下であり、
    　前記電圧は、３Ｖ以上１９Ｖ以下である、請求項１から５のいずれか一項に記載のグラファイトの薄板状構造物の製造方法。     The electrolyte solution has a concentration of the electrolyte of 0.005 M or more and 0.05 M or less,
    6. The method for manufacturing a graphite sheet-like structure according to claim 1, wherein the voltage is 3 V or more and 19 V or less.
  7. 　前記電解質溶液は、前記電解質の濃度が０．０５Ｍ以上０．５Ｍ以下であり、
    　前記電圧は、３Ｖ以上１８Ｖ以下である、請求項１から５のいずれか一項に記載のグラファイトの薄板状構造物の製造方法。     The electrolyte solution has a concentration of the electrolyte of 0.05 M or more and 0.5 M or less,
    6. The method for manufacturing a graphite sheet-like structure according to claim 1, wherein said voltage is 3V or more and 18V or less.
  8. 　前記電解質溶液は、前記電解質の濃度が０．５Ｍ以上５Ｍ以下であり、
    　前記電圧は、３Ｖ以上１７Ｖ以下である、請求項１から５のいずれか一項に記載のグラファイトの薄板状構造物の製造方法。     The electrolyte solution has a concentration of the electrolyte of 0.5 M or more and 5 M or less,
    6. The method for manufacturing a graphite sheet-like structure according to claim 1, wherein said voltage is 3V or more and 17V or less.
  9. 　請求項１から８のいずれか一項に記載のグラファイトの薄板状構造物の製造方法により、グラファイトの薄板状構造物を得る工程と、
    　該グラファイトの薄板状構造物の層間を剥離して薄片化グラファイトを得る工程と、
    を含む、薄片化グラファイトの製造方法。     a step of obtaining a graphite sheet-like structure by the method for producing a graphite sheet-like structure according to any one of claims 1 to 8;
    a step of exfoliating the layers of the graphite sheet-like structure to obtain exfoliated graphite;
    A method for producing exfoliated graphite, comprising:
  10. 　硫黄元素の含有率が０．０１質量％以上２．５質量％以下であり、
    　フッ素元素の含有率が０．１質量％未満であり、
    　ホウ素元素の含有率が０．１質量％未満であり、
    　酸素元素に対する炭素元素の質量比が０．７以上３．０以下である、薄片化グラファイト。     The sulfur element content is 0.01% by mass or more and 2.5% by mass or less,
    The fluorine element content is less than 0.1% by mass,
    The boron element content is less than 0.1% by mass,
    Exfoliated graphite, wherein the mass ratio of the carbon element to the oxygen element is 0.7 or more and 3.0 or less.
  11. 　酸素元素に対する炭素元素の質量比が１．５以上２．６以下である、請求項１０に記載の薄片化グラファイト。 The exfoliated graphite according to claim 10, wherein the mass ratio of the carbon element to the oxygen element is 1.5 or more and 2.6 or less.
  12. 　ＸＲＤスペクトルにおける２θが７°以上１２°以下である領域に含まれるピークの最大強度をＸとし、２θが２３°以上３０°以下である領域に含まれるピークの最大強度をＹとしたとき、Ｘ及びＹが次式：０．８≦Ｘ／Ｙを満たす、請求項１０又は１１に記載の薄片化グラファイト。 When the maximum intensity of the peak contained in the region where 2θ is 7 ° or more and 12 ° or less in the XRD spectrum is X and the maximum intensity of the peak contained in the region where 2θ is 23 ° or more and 30 ° or less is Y, and Y satisfy the following formula: 0.8≦X/Y.
  13. 　Ｘ及びＹが次式：２≦Ｘ／Ｙを満たす、請求項１２に記載の薄片化グラファイト。 The exfoliated graphite according to claim 12, wherein X and Y satisfy the following formula: 2≤X/Y.
PCT/JP2022/042850 2021-11-24 2022-11-18 Method for producing thin plate-shaped structure of graphite, method for producing exfoliated graphite, and exfoliated graphite WO2023095724A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2021-190516 2021-11-24
JP2021190516 2021-11-24

Publications (1)

Publication Number Publication Date
WO2023095724A1 true WO2023095724A1 (en) 2023-06-01

Family

ID=86539686

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2022/042850 WO2023095724A1 (en) 2021-11-24 2022-11-18 Method for producing thin plate-shaped structure of graphite, method for producing exfoliated graphite, and exfoliated graphite

Country Status (1)

Country Link
WO (1) WO2023095724A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017502168A (en) * 2013-11-20 2017-01-19 ザ・ユニバーシティ・オブ・マンチェスターＴｈｅ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ｍａｎｃｈｅｓｔｅｒ Production of graphene oxide
JP2019510721A (en) * 2016-03-22 2019-04-18 中国科学院金属研究所 Graphene oxide nanoplatelet continuous preparation method
WO2020129427A1 (en) * 2018-12-19 2020-06-25 株式会社カネカ Method for producing thin sheet-shaped structure of graphite, exfoliated graphite and method for producing same
JP2021513750A (en) * 2017-12-29 2021-05-27 シクソニア・テック・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング Methods for Manufacture of Functionalized Semiconductor-or Conductor Materials and Their Use

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017502168A (en) * 2013-11-20 2017-01-19 ザ・ユニバーシティ・オブ・マンチェスターＴｈｅ Ｕｎｉｖｅｒｓｉｔｙ Ｏｆ Ｍａｎｃｈｅｓｔｅｒ Production of graphene oxide
JP2019510721A (en) * 2016-03-22 2019-04-18 中国科学院金属研究所 Graphene oxide nanoplatelet continuous preparation method
JP2021513750A (en) * 2017-12-29 2021-05-27 シクソニア・テック・ゲゼルシャフト・ミト・ベシュレンクテル・ハフツング Methods for Manufacture of Functionalized Semiconductor-or Conductor Materials and Their Use
WO2020129427A1 (en) * 2018-12-19 2020-06-25 株式会社カネカ Method for producing thin sheet-shaped structure of graphite, exfoliated graphite and method for producing same

Similar Documents

Publication Publication Date Title
EP3434645B1 (en) Method for continuously preparing graphene oxide nanoplatelets
Paredes et al. Recent advances and energy-related applications of high quality/chemically doped graphenes obtained by electrochemical exfoliation methods
JP7336987B2 (en) Graphene production
CN107235485B (en) The preparation method of graphene
EP2647600A1 (en) Carbonaceous material, process for producing carbonaceous material, process for producing flaked graphite, and flaked graphite
Hashimoto et al. Bipolar anodic electrochemical exfoliation of graphite powders
US20230075308A1 (en) Black phosphorus nanosheet, preparation method therefor, and application thereof
CN108840327B (en) Electrochemical method for preparing nitrogen-doped graphene material
US11731876B2 (en) Method for producing a functionalized semiconductor or conductor material and use thereof
CN111217361B (en) Method for preparing graphene nanosheet through electrochemical cathode stripping
Li et al. Electrochemical synthesis of 2D antimony, bismuth and their compounds
US20150060297A1 (en) Graphite oxide and graphene preparation method
Quan et al. Highly efficient purification of natural coaly graphite via an electrochemical method
WO2023095724A1 (en) Method for producing thin plate-shaped structure of graphite, method for producing exfoliated graphite, and exfoliated graphite
WO2019224619A1 (en) A method for the manufacture of graphene oxide from electrode graphite scrap
JP2023077270A (en) Method for producing graphite sheet structure, method for producing thinned graphite, and thinned graphite
CN113816368B (en) Method for preparing graphene oxide by electrolyzing muddy graphite interlayer compound
US20210309524A1 (en) Method of producing thin plate-shaped graphite product, flaky graphite, and method of producing flaky graphite
WO2021085551A1 (en) Graphite thin plate-shaped structure production method and exfoliated graphite production method
JP7403036B2 (en) Method for producing exfoliated graphite
CN106629674A (en) Method for preparing graphene by oxidation reduction
CN114408909B (en) Method for preparing graphene by electrochemical stripping of graphite
CN117867529A (en) Method for preparing lactobionic acid by electrocatalytic action of carbon-based nonmetallic catalyst
CN117385376A (en) Method for rapidly preparing graphene oxide based on electrochemical method and application of method
WO2017093731A1 (en) Oxygenated 2-d materials

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22898507

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2023563661

Country of ref document: JP