Method for producing thin plate-like graphite structure and method for producing exfoliated graphite

Abstract

To provide a production method capable of obtaining a thinned graphite with low contents of elemental fluorine and elemental boron and low mass ratio of elemental carbon to elemental oxygen (C / O ratio).SOLUTION: A method for producing a graphite sheet structure includes a step of applying a voltage between an anode and a cathode in an electrochemical reaction system that includes an anode containing graphite, a cathode, and an electrolyte solution containing perchlorate and / or perchlorate as the electrolyte. The graphite has a thermal diffusivity of 3.5 cm2 / s or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a graphite lamellar structure, a method for producing exfoliated graphite, and exfoliated graphite. [Background technology]

[0002] Graphene has high carrier mobility, thermal conductivity, and transparency. Graphene is a single-atom-thick sp 2 Because graphene is a sheet of bonded carbon atoms, it is easy to scale up devices with large areas, and it also has high thermal and chemical stability. These excellent properties make it promising for applications in advanced industrial materials, including electronics.

[0003] On the other hand, graphite is a laminate composed of many stacked graphene molecules and is easily available. For this reason, methods have been proposed for producing exfoliated graphite, which has a much smaller number of graphene layers than graphite, by exfoliating the layers of graphite.

[0004] A known method for producing exfoliated graphite is, for example, to apply a voltage between an anode containing graphite, a cathode, and an electrolyte solution in an electrochemical reaction system, thereby intercalating ions derived from the electrolyte between the graphite layers to obtain a thin-plate structure of graphite, and then exfoliating the layers of the thin-plate structure. The exfoliated graphite obtained in this manner is composed of oxygen-containing graphene (graphene oxide) and has functional groups such as hydroxyl groups and carboxyl groups introduced into it. Such exfoliated graphite can be modified with functional groups to enhance its functionality, and is therefore expected to be applied to polymer composite materials, paints, inks, drug conjugates, lubricants, catalysts, and the like.

[0005] Patent Document 1 describes a method of electrolysis using tetrafluoroboric acid or hexafluorophosphoric acid as an electrolyte. Patent Document 1 also describes a method of electrolysis using an anode containing specific graphite as a working electrode and sulfuric acid or nitric acid as an electrolyte. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 129427 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Document 1, when tetrafluoroboric acid or hexafluorophosphoric acid is used as the electrolyte, the obtained exfoliated graphite has a high content of fluorine and boron elements, which may limit its application to advanced industrial materials. Also, 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 obtained exfoliated graphite has a high mass ratio of carbon element to oxygen element (C / O ratio), and the introduction rate of functional groups is insufficient.

[0008] An object of the present invention is to provide a production method capable of obtaining exfoliated graphite having low contents of elemental fluorine and elemental boron and a small mass ratio of elemental carbon to elemental oxygen (C / O ratio). [Means for solving the problem]

[0009] One aspect of the present invention is a method for producing a thin plate-like graphite structure, which comprises applying a voltage between an anode containing graphite, a cathode, and an electrolyte solution containing perchloric acid and / or a perchlorate as an electrolyte in an electrochemical reaction system, and the graphite has a thermal diffusivity of 3.5 cm 2 / s or more.

[0010] The graphite may be a heat-treated product of a polycondensation polymer compound.

[0011] The condensation polymerization polymer compound may be an aromatic polyimide.

[0012] The anode may be a heat-treated expanded graphite sheet.

[0013] The expanded graphite sheet may be a pressed product of expanded graphite obtained by immersing natural graphite in a strong acid and then heat-treating it.

[0014] The electrolyte solution may have an electrolyte concentration of 0.005M or more and 5M or less.

[0015] The voltage may be between 3V and 20V.

[0016] Another aspect of the present invention is a method for producing exfoliated graphite, comprising the steps of obtaining a thin graphite structure by the method for producing a thin graphite structure described above, and exfoliating the layers of the thin graphite structure to obtain exfoliated graphite.

[0017] In another embodiment of the present invention, in exfoliated graphite, the sulfur content is less than 0.1 mass%, the fluorine content is less than 0.1 mass%, the boron content is less than 0.1 mass%, and the mass ratio of carbon to oxygen is 1.0 or more and 3.0 or less.

[0018] The exfoliated graphite may have a mass ratio of carbon element to oxygen element of 1.5 or more and 2.5 or less.

[0019] In the exfoliated graphite, when the maximum intensity of a peak included in a region where 2θ is equal to or greater than 7° and equal to or less than 12° in an XRD spectrum is defined as X and the maximum intensity of a peak included in a region where 2θ is equal to or greater than 23° and equal to or less than 30° is defined as Y, X and Y may satisfy the following formula: 1≦X / Y.

[0020] In the exfoliated graphite, X and Y may satisfy the following formula: 2≦X / Y. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a production method capable of obtaining exfoliated graphite having low contents of elemental fluorine and elemental boron and a small mass ratio of elemental carbon to elemental oxygen (C / O ratio). [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing an XRD spectrum of exfoliated graphite of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described.

[0024] [Method for manufacturing thin graphite structures] The method for producing a graphite thin plate structure according to this embodiment includes a step of applying a voltage between an anode containing graphite, a cathode, and an electrolyte solution containing perchloric acid and / or a perchlorate as an electrolyte in an electrochemical reaction system. Exfoliated graphite can be obtained by peeling off the layers of the graphite thin plate structure obtained by this production method.

[0025] In this specification and claims, the term "graphite thin plate structure" refers to a thin plate structure in which an interlayer material is inserted between layers of graphite (graphene laminate) to increase the interlayer distance (the distance between adjacent graphene layers). Also, the term "exfoliated graphite" refers to a graphene laminate in which the number of graphene laminates is smaller than that of graphite.

[0026] The thermal diffusivity of the graphite in the anode is 3.5 cm 2 / s or more, and 5.0 cm 2 / s or more is preferable, and 7.0 cm 2 / s or more is preferable, and 8.5 cm 2 The upper limit of the thermal diffusivity is not particularly limited, but for example, it is 12 cm / s or more. 2 / s or less. The thermal diffusivity of graphite is 3.5 cm 2 If the mass ratio is 1 / s or more, the mass ratio of carbon element to oxygen element (C / O ratio) of the exfoliated graphite tends to be small.

[0027] Thermal diffusivity is 3.5cm 2 An example of a graphite-containing anode having a conductivity of 1 / s or more is a graphite-containing anode obtained by heat-treating a condensation polymerization polymer compound. Examples of the condensation polymerization polymer compound include aromatic polyimide, aromatic polyamide, polyoxadiazole, and polyparaphenylene vinylene. Among these, aromatic polyimide is preferred.

[0028] The heat treatment temperature of the condensation polymerization polymer compound is preferably, for example, 2400° C. to 3200° C. The heat treatment time of the condensation polymerization polymer compound is preferably, for example, 3 hours to 72 hours.

[0029] Graphite obtained by heat-treating a condensation polymerization polymer compound has a structure in which planar graphite crystals are stacked in layers, which makes it particularly easy for perchlorate ions to intercalate between the graphite layers, and when intercalated, the graphite is particularly resistant to exfoliation of small pieces, making it easy to maintain the overall shape as an anode. This makes it possible to more efficiently produce higher quality graphite lamellar structures or exfoliated graphite.

[0030] In addition, the thermal diffusivity is 3.5 cm 2Other examples of graphite-containing anodes with a solubility of 0.1 / s or more include anodes obtained by heat-treating an expanded graphite sheet. The expanded graphite sheet can be obtained, for example, by immersing natural graphite in a strong acid, heat-treating it in an expansion furnace to obtain expanded graphite, and then high-pressure pressing the expanded graphite. Examples of strong acids include concentrated sulfuric acid and nitric acid.

[0031] The heat treatment temperature of the expanded graphite sheet is preferably, for example, 900° C. to 3200° C. The heat treatment time of the expanded graphite sheet is preferably, for example, 1 hour to 72 hours.

[0032] By using an anode obtained by heat treating such an expanded graphite sheet, it is possible to efficiently produce high-quality graphite thin plate structures or exfoliated graphite.

[0033] The shape of the anode is not particularly limited, and examples thereof include a rod, plate, block, sheet, foil, and roll.

[0034] The material for the cathode is not particularly limited as long as it has the function of donating electrons to cations generated in the anode reaction and is capable of constructing an electrochemically stable system. Examples of the material for the cathode include metals such as platinum, stainless steel, copper, zinc, and lead; carbonaceous materials such as glassy carbon and graphite; and the like.

[0035] The shape of the cathode is not particularly limited, and examples thereof include a wire shape, a plate shape, and a mesh shape.

[0036] When gas is generated in the cathode reaction, the area of ​​the cathode may be made as large as possible so as not to impair the efficiency of the cathode reaction or to avoid an unnecessary increase in the electrical resistance of the electrochemical reaction system.

[0037] In order to prevent undesired reactions from occurring at the anode and / or cathode, or to prevent short-circuiting between the anode and cathode, an ion exchange membrane, a spacer, or the like may be placed between the two electrodes.

[0038] Furthermore, the electrochemical reaction system may further include a reference electrode when precise potential control is required. The reference electrode is not particularly limited, but examples thereof include an Ag / AgCl electrode.

[0039] The electrolyte solution is a solution in which perchloric acid and / or a perchlorate is dissolved in a solvent.

[0040] Examples of perchlorates include ammonium perchlorate, sodium perchlorate, magnesium perchlorate, potassium perchlorate, and calcium perchlorate.

[0041] The electrolyte is preferably perchloric acid, sodium perchlorate, or ammonium perchlorate.

[0042] The solvent is not particularly limited as long as it is miscible with the electrolyte or an aqueous electrolyte solution and is electrochemically stable during the production of the graphite thin plate structure. Examples of the solvent include protic polar solvents such as water and lower alcohols (e.g., methanol, ethanol, and propanol); and aprotic polar solvents such as acetonitrile, dimethylformamide, dimethoxyethane, dimethyl carbonate, propylene carbonate, and dimethyl sulfoxide; and two or more of these may be used in combination.

[0043] The solvent preferably contains water. In this case, water may be used alone, or 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.

[0044] Furthermore, when an alcohol solvent is used as the solvent, the resulting graphite lamellar structures and exfoliated graphite have alkoxy groups and / or alkyl groups derived from the alcohol solvent. The exfoliated graphite obtained using an alcohol solvent tends to have good affinity for the alcohol solvent and excellent dispersibility in the alcohol solvent.

[0045] The concentration of the electrolyte in the electrolyte solution is preferably 0.005 M or more and 5 M or less, more preferably 0.01 M or more and 3 M or less, and even more preferably 0.05 M or more and 2 M or less. If the concentration of the electrolyte in the electrolyte solution is 0.005 M or more, perchlorate ions tend to intercalate easily between the layers of the graphite, which tends to facilitate exfoliation between the layers of the graphite thin plate structure. On the other hand, if the concentration of the electrolyte in the electrolyte solution is 5 M or less, the mass ratio of carbon element to oxygen element (C / O ratio) of the exfoliated graphite tends to be small.

[0046] The conductivity of the electrolyte solution is, for example, preferably 1 mS / cm or more and 2000 mS / cm or less, and more preferably 5 mS / cm or more and 1000 mS / cm or less. If the conductivity of the electrolyte solution is 1 mS / cm or more, perchlorate ions tend to intercalate easily between the layers of the graphite, which tends to facilitate peeling between the layers of the graphite thin plate structure. On the other hand, if the conductivity of the electrolyte solution is 2000 mS / cm or less, the mass ratio of carbon element to oxygen element (C / O ratio) of the exfoliated graphite tends to be small.

[0047] The temperature of the electrolyte solution may vary depending on the type of solvent in which the electrolyte is dissolved and the concentration of the electrolyte in the electrolyte solution, but in practice, 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.

[0048] In the method for producing a graphite thin plate-like structure according to this embodiment, the voltage applied between the anode and the cathode is preferably 3 V or more and 20 V or less. If the voltage applied between the anode and the cathode is 3 V or more, perchlorate ions tend to intercalate easily between the graphite layers, which tends to facilitate peeling between the layers of the graphite thin plate-like structure. On the other hand, if the voltage applied between the anode and the cathode is 20 V or less, the mass ratio of carbon to oxygen (C / O ratio) of the exfoliated graphite tends to decrease.

[0049] Here, when the concentration of the electrolyte in the electrolyte solution is 0.005 M or more and 0.05 M or less, the voltage applied between the anode and the cathode is preferably 3 V or more and 20 V or less, and more preferably 3 V or more and 11 V or less. Furthermore, 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 19 V or less, and more preferably 3 V or more and 10 V or less. Furthermore, when the concentration of the electrolyte in the electrolyte solution is 0.5 M or more and 5 M or less, the voltage applied between the anode and the cathode is preferably 3 V or more and 18 V or less, and more preferably 3 V or more and 9 V or less.

[0050] In the method for producing a graphite thin plate structure according to this embodiment, the electrolyte, perchloric acid and / or perchlorate, is theoretically not consumed before or after the electrolysis reaction. Therefore, the electrolyte solution after use in producing a graphite thin plate structure can be reused. However, the electrolyte that is lost due to adhesion to the graphite thin plate structure removed from the electrolyte solution may be replenished to the electrochemical reaction system as needed.

[0051] Immediately after the electrolysis reaction, the graphite thin plate structure will have the electrolyte solution entrapped and attached thereto, and the electrolyte solution can be recovered from the graphite thin plate structure.

[0052] The method for recovering the electrolyte solution from the graphite thin plate structure is not particularly limited, and examples thereof include a method of centrifuging the graphite thin plate structure, a method of filtering the graphite thin plate structure using a pressure press, and a method of continuously separating the electrolyte solution from the graphite thin plate structure on a belt press.

[0053] The electrolyte solution can be removed from the graphite lamellar structure by washing it with excess deionized water until the washings become nearly neutral.

[0054] The graphite lamellar structure can be dried as needed and then applied to the method for producing exfoliated graphite, which will be described later. When drying the graphite lamellar structure, it can be dried at a temperature of 80°C or less using, for example, a constant temperature dryer or a vacuum dryer.

[0055] [Method for producing exfoliated graphite] The method for producing exfoliated graphite according to this embodiment includes a step of obtaining a thin graphite structure by the method for producing a thin graphite structure according to this embodiment, and a step of exfoliating the layers of the thin graphite structure to obtain exfoliated graphite.

[0056] The method for exfoliating the layers of the graphite thin plate structure is not particularly limited, and examples thereof include a method of irradiating the graphite thin plate structure with ultrasonic waves, a method of applying a mechanical exfoliation force to the graphite thin plate structure, a method of heating the graphite thin plate structure, etc. Specifically, the graphite thin plate structure can be dispersed in an appropriate amount of deionized water and then irradiated with ultrasonic waves or treated with a mixer or a device capable of applying shear force.

[0057] The exfoliated graphite may be freeze-dried, or may be dried after filtration or centrifugation. The method for drying the exfoliated graphite is the same as the method for drying the thin plate-like structure of graphite.

[0058] [Flaked graphite] The exfoliated graphite according to this embodiment can be obtained by the method for producing exfoliated graphite according to this embodiment.

[0059] The exfoliated graphite according to this embodiment has a sulfur element content of less than 0.1 mass %, a fluorine element content of less than 0.1 mass %, and a boron element content of less than 0.1 mass %.

[0060] The exfoliated graphite according to the present embodiment can have a low content of heavy metal elements as impurities due to its manufacturing method. For example, the exfoliated graphite according to the present embodiment can have a manganese content of less than 0.1 mass%.

[0061] The exfoliated graphite according to this embodiment has a mass ratio of carbon element to oxygen element (C / O ratio) of 1.0 or more and 3.0 or less, and preferably 1.5 or more and 2.5 or less.

[0062] In the exfoliated graphite of the present embodiment, when the maximum intensity of a peak included in a region where 2θ is equal to or greater than 7° and equal to or less than 12° in an XRD spectrum is defined as X and the maximum intensity of a peak included in a region where 2θ is equal to or greater than 23° and equal to or less than 30° is defined as Y, X and Y preferably satisfy the following formula: 1≦X / Y, and more preferably satisfy the following formula: 2≦X / Y.

[0063] The thickness of the exfoliated graphite according to this 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 this 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. [Example]

[0064] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments.

[0065] <Thermal diffusivity of graphite> A sample of graphite cut into a shape of 40 mm × 40 mm was prepared, and the thermal diffusivity of graphite [cm 2 / s] was measured using a thermal diffusivity measuring device (Thermo Wave Analyzer TA3, manufactured by BETEL Co., Ltd.) in an atmosphere of 20°C.

[0066] <Elemental analysis of thinned graphite> Elemental analysis of thinned graphite was performed using a scanning fluorescence X-ray analyzer (ZSX PrimusIII +, manufactured by Rigaku Corporation), and the content rate [mass%] of sulfur element (S), the content rate [mass%] of fluorine element (F), the content rate [mass%] of boron element (B), and the mass ratio of carbon element to oxygen element (C / O ratio) were measured.

[0067] <Conductivity of electrolyte solution> The conductivity of the electrolyte solution was measured using a portable electromagnetic densitometer (MDM-25A, manufactured by Toa DKK Corporation).

[0068] <X-ray diffraction (XRD)> Using an X-ray diffractometer (X’Pert Pro, manufactured by Malvern Panalytical), CuKα (λ = 1.541 Å) was irradiated, and the XRD spectrum of thinned graphite was measured with a 2θ range from 5° to 75°. Next, the maximum intensity (X) of the peak included in the region where 2θ in the XRD spectrum is 7° or more and 12° or less and the maximum intensity (Y) of the peak included in the region where 2θ is 23° or more and 30° or less were obtained, and the X / Y ratio was calculated.

[0069] (Graphite sheet A) As the graphite sheet A, a graphite sheet having a thickness of 32 μm and a thermal diffusivity of 9 cm 2 / s obtained by heat-treating an aromatic polyimide film with a thickness of 62 μm at a temperature of 2900°C or higher (manufactured by Kaneka Corporation) was used.

[0070] (Graphite sheet B) Graphite sheet B was obtained by heat treating expanded graphite sheet PF-HP (manufactured by Toyo Tanso Co., Ltd.) at 2400°C, with a thickness of 200 μm and a thermal diffusivity of 4 cm 2 A graphite sheet of / s was used.

[0071] Example 1 After adding 100 mL of 1 M perchloric acid aqueous solution as the electrolyte solution to a PVC reactor, graphite sheet A was fixed as the anode so that a 6 cm x 25 cm surface area was immersed in the electrolyte solution, and a platinum wire electrode was set as the cathode. Next, the anode and cathode were connected to a DC power supply and a voltage of 5 V was applied. Electrolysis was carried out at room temperature until the current decreased and became constant, yielding a graphite thin plate structure. The graphite thin plate structure was then removed from the electrolyte solution and washed with deionized water until the washings became neutral, yielding a wet, dark brown graphite thin plate structure.

[0072] A small amount of deionized water was added to the graphite lamellar structure, and the resulting mixture was subjected to ultrasonic irradiation for 15 minutes and freeze-dried to obtain exfoliated graphite. The exfoliated graphite contained sulfur (S), fluorine (F), and boron (B) elements in an amount of less than 0.1 mass%, and had a C / O ratio of 1.3. The exfoliated graphite also had an X / Y ratio of 3.2 (see Figure 1).

[0073] Example 2 Exfoliated graphite was obtained in the same manner as in Example 1, except that a 0.1 M aqueous solution of perchloric acid was used as the electrolyte solution. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 1.6. The exfoliated graphite also had an X / Y ratio of 1.9.

[0074] Example 3 Except for using ammonium perchlorate as the electrolyte, exfoliated graphite was obtained in the same manner as in Example 1. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 1.4. The exfoliated graphite also had an X / Y ratio of 2.5.

[0075] Example 4 Exfoliated graphite was obtained in the same manner as in Example 2, except that ammonium perchlorate was used as the electrolyte. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 1.7. The exfoliated graphite also had an X / Y ratio of 1.6.

[0076] Example 5 Exfoliated graphite was obtained in the same manner as in Example 1, except that sodium perchlorate was used as the electrolyte. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 1.5. The exfoliated graphite also had an X / Y ratio of 2.2.

[0077] Example 6 Exfoliated graphite was obtained in the same manner as in Example 2, except that sodium perchlorate was used as the electrolyte. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 1.8. The exfoliated graphite also had an X / Y ratio of 1.3.

[0078] Example 7 Exfoliated graphite was obtained in the same manner as in Example 1, except that graphite sheet B was used as the anode. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, a C / O ratio of 2.7, and an X / Y ratio of 3.6.

[0079] Example 8 Exfoliated graphite was obtained in the same manner as in Example 2, except that graphite sheet B was used as the anode. The exfoliated graphite had a sulfur (S), fluorine (F), and boron (B) content of less than 0.1 mass%, and a C / O ratio of 3.0. The exfoliated graphite also had an X / Y ratio of 3.3.

[0080] (Comparative Example 1) Exfoliated graphite was obtained in the same manner as in Example 1, except that a 9.2 M aqueous sulfuric acid solution was used as the electrolyte solution. The exfoliated graphite had a sulfur element (S) content of 0.1 to 2 mass%, a fluorine element (F) content of 0.1 mass% and a boron element (B) content of less than 0.1 mass%, and a C / O ratio of more than 10. The exfoliated graphite also had an X / Y ratio of less than 0.7.

[0081] (Comparative Example 2) Exfoliated graphite was obtained in the same manner as in Example 1, except that fluoroboric acid was used as the electrolyte. The exfoliated graphite had a sulfur (S) content of less than 0.1 mass%, a fluorine (F) content of 1 to 3 mass%, a boron (B) content of 0.1 to 1 mass%, and a C / O ratio of 1.1. The exfoliated graphite also had an X / Y ratio of 3.0.

[0082] Table 1 shows the production conditions and properties of exfoliated graphite.

[0083] [Table 1]

[0084] From Table 1, it can be seen that the exfoliated graphite of Examples 1 to 8 have low contents of elemental sulfur (S), elemental fluorine (F), and elemental boron (B), and have small C / O ratios. In contrast, the exfoliated graphite of Comparative Example 1 has a high content of elemental sulfur (S) and a high C / O ratio because a 9.2 M aqueous sulfuric acid solution was used as the electrolyte solution during production. Furthermore, the exfoliated graphite of Comparative Example 2 has a high content of elemental fluorine (F) and elemental boron (B) because fluoroboric acid was used as the electrolyte during production.

Claims

1. A process of heat-treating an expanded graphite sheet at a temperature of 900°C or higher and 3200°C or lower to obtain graphite having a thermal diffusivity of 3.5 cm2 / s or higher; a cathode; and an electrolyte solution containing perchloric acid and / or a perchlorate salt as an electrolyte.

2. 2. The method for producing a graphite thin plate structure according to claim 1, wherein the expanded graphite sheet is a pressed product of expanded graphite obtained by immersing natural graphite in a strong acid and then heat-treating it.

3. 3. The method for producing a graphite thin plate structure according to claim 1, wherein the electrolyte solution has an electrolyte concentration of 0.005M or more and 5M or less.

4. The method for producing a thin graphite structure according to claim 1 , wherein the voltage is 3 V or more and 20 V or less.

5. a step of obtaining a graphite thin plate structure by the method for producing a graphite thin plate structure according to any one of claims 1 to 4; and a step of exfoliating the layers of the graphite lamellar structure to obtain exfoliated graphite.

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