Power storage device and manufacturing method of power storage device

Abstract

To provide a novel power storage device that has a configuration made simpler, by utilizing graphenes, than conventional power storage devices.SOLUTION: A power storage device (1) according to the present invention includes: hydrogen-retaining graphenes (11) each being a graphene (111) retaining hydrogen atoms (112) inside a carbon ring; a support (12) that supports the hydrogen-retaining graphenes (11); a vacuum container (13) that stores the hydrogen-retaining graphenes (11) under a vacuum atmosphere; and terminals (14) that are electrically connected to the hydrogen-retaining graphenes (11).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device and a method for manufacturing an electricity storage device. [Background technology]

[0002] Graphene is a sheet-like material formed by carbon atoms bonded in a honeycomb pattern on the same plane. Strictly speaking, graphene refers only to a structure in which benzene rings are densely packed and the thickness is the equivalent of one carbon atom. However, in practice, graphene with slightly different structures is also commonly referred to. That is, when simply referring to graphene, it also includes graphene in which some of the lattices are five- or seven-membered rings rather than six-membered rings, graphene in which two to ten layers of sheet structure are stacked in part or in whole (typically, graphene in which multiple sheet structures are stacked is also called graphite), and graphene in which some carbon-carbon bonds are broken and the structure is discontinuous. In this specification, the term graphene is used in the above sense, and graphene in the narrow sense will be referred to as "ideal graphene."

[0003] In graphene, each carbon atom is connected to three neighboring carbon atoms in sp 2 Graphene has excellent physical properties as an industrial material, such as being thin, light, having a large specific surface area, excellent mechanical strength and flexibility, and extremely high electrical and thermal conductivity, due to the σ-bonding between hybrid orbitals and the formation of a two-dimensional π-bonding network between pz orbitals perpendicular to the plane. For this reason, research and development into the use of graphene has been conducted in various technical fields, and it is also attracting attention in the field of energy storage devices.

[0004] One application of graphene in the field of electricity storage devices is its use as an electrode material (active material). For example, Patent Document 1 describes an electricity storage device in which graphene oxide having a predetermined composition is used as the active material for the positive or negative electrode, thereby improving the charge / discharge capacity per unit weight. Furthermore, Patent Document 2 describes a capacitor in which a block of porous carbon material made of graphene is used as the active material for the positive and negative electrodes, thereby improving the electricity storage performance. Another application is its use as a solid electrolyte. For example, Patent Document 3 describes a secondary battery in which graphene oxide is used as the solid electrolyte, thereby improving the ionic conductivity and mechanical strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-163636 [Patent Document 2] International Publication No. 2020 / 080521 [Patent Document 3] Japanese Patent Application Publication No. 2018-098200 Summary of the Invention [Problem to be solved by the invention]

[0006] Some known secondary batteries and capacitors have a structure in which two electrodes face each other with an electrolyte sandwiched between them. In this structure, the active material and the electrolyte are usually different materials. Therefore, in the past, graphene has been used in only one of the active material and the electrolyte in the same energy storage device.

[0007] The present inventors have focused on the fact that graphene can be used as both an active material and an electrolyte, and have pursued the feasibility of realizing a new electricity storage device that uses the same graphene as both an active material and an electrolyte and has a simpler configuration than conventional electricity storage devices that consist of an electrolyte and two electrodes. In short, the problem that the present invention aims to solve is to provide a new electricity storage device that uses graphene and has a simpler configuration than conventional electricity storage devices. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the inventors discovered that when graphene, in which hydrogen atoms are held inside carbon rings, is connected to a circuit, electric current flows. They then applied this finding to an electricity storage device, thereby completing the present invention.

[0009] That is, the electricity storage device according to the present invention is hydrogen-retaining graphene, which is graphene that retains hydrogen atoms inside carbon rings; A support that supports the hydrogen-retaining graphene; a vacuum container that stores the hydrogen-retaining graphene under a vacuum atmosphere; a terminal that is electrically connected to the hydrogen-retention graphene; Equipped with.

[0010] Further, a method for manufacturing an electricity storage device according to the present invention includes the steps of: a step of evaporating hydrocarbons in a vacuum atmosphere, depositing carbon atoms on a support to form graphene, and retaining hydrogen atoms inside the carbon rings of the graphene to form hydrogen-retaining graphene; storing the hydrogen-retaining graphene in a vacuum container; providing a terminal that is electrically connected to the hydrogen-retention graphene; Includes.

[0011] Note that the term "graphene" used here refers to graphene in the broad sense defined above, and does not refer only to graphene in the narrow sense (ideal graphene). [Effects of the Invention]

[0012] When the power storage device according to the present invention is connected to a circuit, the hydrogen atoms held inside the carbon rings of graphene are converted into protons (H + ) and electrons (e - ), and the electrons flow through the circuit as a current. When the circuit is disconnected, the electrons flowing through the circuit react with protons and return to hydrogen atoms, which are more stable than protons. Some conventional secondary batteries and capacitors have a configuration in which two electrodes face each other with an electrolyte sandwiched between them, but the electricity storage device of the present invention essentially charges and discharges using only hydrogen-retaining graphene, which is graphene that retains hydrogen atoms inside carbon rings. Therefore, the electricity storage device of the present invention is a novel electricity storage device with a simpler configuration than conventional electricity storage devices. Furthermore, the method for manufacturing an electricity storage device of the present invention can manufacture such an electricity storage device. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view of a first example of an electricity storage device according to the present invention. [Figure 2] FIG. 1 is a schematic diagram illustrating how a hydrogen atom is held inside a carbon ring. [Figure 3] 1 is a cross-sectional view of a first example of an electricity storage device according to the present invention. [Figure 4] FIG. 2 is a diagram illustrating a terminal used in a first example of an electricity storage device according to the present invention. [Figure 5] FIG. 3 is a cross-sectional view of a second example of an electricity storage device according to the present invention. [Figure 6] FIG. 4 is a cross-sectional view illustrating a terminal used in a second example of an electricity accumulation device according to the present invention. [Figure 7] 5A to 5C are diagrams illustrating the operation of the electricity storage device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] <First Example of the Configuration of the Electricity Storage Device According to the Present Invention> A first example of the configuration of an electricity storage device according to the present invention will be described with reference to the drawings. As shown in Fig. 1, an electricity storage device 1 includes hydrogen-retaining graphene 11, a support 12, a vacuum container 13, and a terminal 14.

[0015] As shown in FIG. 2, hydrogen-retaining graphene 11 is formed on a support 12 and retains hydrogen atoms 112 inside the carbon rings of graphene 111. The graphene 111 is preferably ideal graphene, which has particularly fast electrical conduction, but graphene in the broad sense may also suffice. The interior of the carbon ring refers to the region inside the dashed line in FIG. 2(a). As shown in FIG. 2(b), hydrogen atoms 112 may be retained inside the carbon rings of graphene 111 by attaching to carbon atoms constituting graphene 111, or by attaching to a portion of support 12 that covers the carbon ring from below. Typically, approximately 10 hydrogen atoms are stored per carbon ring. Although the figure shows 1 to 12 hydrogen atoms per carbon ring, the number of hydrogen atoms retained per carbon ring may be more than 12. The larger the area of ​​the hydrogen-holding graphene 11, the greater the amount of hydrogen atoms 112 that can be held, and the greater the capacity of the electricity storage device 1. Therefore, the hydrogen-holding graphene 11 is formed to have any area depending on the capacity required for the electricity storage device 1. A method for forming the hydrogen-holding graphene 11 will be described later.

[0016] The support 12 supports the hydrogen-retaining graphene 11, maintaining the shape of the graphene 111, while also serving as a "bottom" to keep the hydrogen atoms 112 inside the carbon rings. Alumina ceramic (Al2O3) is preferably used as the material for the support 12. Alumina ceramic does not change strength or shape with temperature changes, improving the durability of the electricity storage device 1. Furthermore, alumina ceramic is easy to procure as raw materials and process, which helps reduce the cost required to manufacture the electricity storage device 1.

[0017] The vacuum vessel 13 stores the hydrogen-retaining graphene 11 in a vacuum atmosphere. As shown in FIG. 3(a), the vacuum vessel 13 may store the hydrogen-retaining graphene 11 and the support 12 in a vacuum atmosphere so as to have a vacuum portion 15, or as shown in FIG. 3(b), the vacuum vessel 13 may store the hydrogen-retaining graphene 11 and the support 12 such that the hydrogen-retaining graphene 11 is in close contact with the vacuum vessel 13 so as not to include the vacuum portion 15. Alternatively, as shown in FIGS. 3(c) to 3(f), the support 12 may form part of the vacuum vessel 13 so that only the hydrogen-retaining graphene 11 is stored in a vacuum atmosphere.

[0018] The terminals 14 are configured to be electrically connected to the hydrogen-retaining graphene 11 and connectable to a circuit. The terminals 14 may be, for example, chip-shaped terminals 14a as shown in FIG. 4(a), stick-shaped terminals 14b as shown in FIG. 4(b), or terminals 14c forming part of the side surface of the vacuum vessel 13 as shown in FIG. 4(c), or may have a shape other than these. The terminals 14 may be provided at any position on the electricity storage device 1 as long as they are configured to be electrically connected to the hydrogen-retaining graphene 11. The terminals 14 may be provided in two or more pairs. When two or more pairs of terminals 14 are provided, by connecting each pair of terminals 14 to a circuit, the electricity storage device 1 can supply current to each of multiple independent circuits.

[0019] <Second Example of the Configuration of the Electricity Storage Device According to the Present Invention> A second example of the configuration of an electricity storage device according to the present invention will be described with reference to the drawings. The same components as those in the first example described above will be designated by the same reference numerals, and a description thereof will be omitted. As shown in FIGS. 5 and 6 , an electricity storage device 10 includes a laminate 100 formed by stacking a plurality of units, each unit being formed by stacking hydrogen-retaining graphene 11 and a support 12, a vacuum container 13 for storing the laminate 100 under a vacuum atmosphere, and terminals. Examples of the terminals that can be used include terminals 14, such as the terminals 14a, 14b, and 14c described above, as well as a series terminal 14x and a parallel terminal 14y, which will be described later.

[0020] The laminate 100 is formed by stacking a plurality of units, each of which is formed by stacking hydrogen-retention graphene 11 and a support 12. Examples of the units include a unit A in which hydrogen-retention graphene 11 is formed on one side of a support 12, as shown in Fig. 5(a), a unit B in which hydrogen-retention graphene 11 is formed on both sides of a support 12, as shown in Fig. 5(b), and a unit C in which hydrogen-retention graphene 11 is sandwiched between supports 12, but the configuration of the units is not limited to these and can be any desired configuration.

[0021] As an example, FIG. 6 shows a cross-sectional view of an electricity storage device 10 including a laminate 100 formed by stacking three units A. The electricity storage device 10 includes three layers of hydrogen-retention graphene 11. In this configuration, the electricity storage device 10 may include terminals 14a, 14b, and 14c for each of the three hydrogen-retention graphene 11 layers, as shown in FIG. 6(a), for example. This configuration allows the three hydrogen-retention graphene 11 to be connected to different circuits, enabling a single electricity storage device 10 to independently supply current to each of multiple circuits. Alternatively, as shown in FIG. 6(b), a pair of terminals 14 may be provided on two different hydrogen-retention graphene 11, and serial terminals 14x may be provided between the different hydrogen-retention graphene 11 layers so that the three hydrogen-retention graphene 11 layers are electrically connected in series between the pair of terminals 14. This configuration can further increase the capacity of the electricity storage device. 6(c), a parallel terminal 14y may be provided so that three hydrogen-holding graphenes 11 are electrically connected in parallel. With this configuration, the capacity of the electricity storage device can be further increased.

[0022] The configuration shown in Fig. 6 can be realized in a similar manner in cases other than when the laminate 100 is composed of the unit A. The configuration shown in Fig. 6 can also be realized when the laminate 100 includes at least two units or at least two layers of hydrogen-retaining graphene 11. Needless to say, the more units the laminate 100 includes, the more circuits that can independently supply current in one electricity storage device can be increased, and the capacity of the electricity storage device can be increased.

[0023] <Example of operation of the electricity storage device according to the present invention> An example of the operation of the electricity storage device according to the present invention will be described using an electricity storage device 1, which is a first example of an electricity storage device according to the present invention, with reference to Fig. 7. For the sake of clarity in the drawing, Fig. 7 shows only one to four hydrogen atoms 112 per carbon ring, and omits the vacuum vessel 13.

[0024] As shown in Fig. 7, the electricity storage device 1 is connected to a circuit via terminals 14, 14. When the circuit switch is switched from an off state (Fig. 7(a)) to an on state, hydrogen atoms 112 held in the graphene 111 on the hydrogen-holding graphene 11 are successively separated into protons 1121 and electrons 1122 (H → H + +e - ), the protons 1121 remain inside the carbon ring, and only the electrons 1122 become a current and flow through the graphene 111 and the circuit (Fig. 7(b), (c)). Since the electrical conductivity of graphene 111 is extremely high, the electrons 1122 can move on the graphene at high speed. Although graphene 111 in the broad sense is sufficient, it is desirable that graphene 111 be ideal graphene in order to achieve faster electrical conduction. Some of the electrons 1122 that have completed one circuit are conducted on the graphene 111 and flow out again into the circuit. The remaining electrons 1122 react with the protons that remain inside the carbon ring and return to hydrogen atoms 112 (H + +e - →H), it splits again into protons 1121 and electrons 1122, and only the electrons 1122 flow through the circuit as electric current.

[0025] When the circuit switch is switched from the on state (FIGS. 7(b) and (c)) to the off state, the electrons 1122 flowing through the graphene 111 and the circuit react with the protons 1121 held inside the carbon rings of the graphene 111 and return to hydrogen atoms (H + +e - →H), and returns to the same state as before the switch was turned on (Figure 7(a)). This reaction occurs when the switch is turned off because hydrogen atoms are more stable than protons. When the switch is turned on again, the energy storage device 1 operates as described above and can supply current to the circuit. In other words, the energy storage device 1 can be discharged multiple times without having to be charged.

[0026] An example of the operation of the electricity storage device according to the present invention has been described with reference to electricity storage device 1, but electricity storage device 10, which is a second example of an electricity storage device according to the present invention, also operates in the same manner. Furthermore, even when two or more pairs of terminals 14 are provided on one layer of hydrogen-retaining graphene 11 and a plurality of independent circuits are connected, electricity storage devices 1 and 10 operate as described above and can supply current to each circuit.

[0027] <Example of a method for manufacturing an electricity storage device according to the present invention> An example of a manufacturing method for an electricity storage device according to the present invention will be described using electricity storage device 1, which is a first example of an electricity storage device according to the present invention. Electricity storage device 1 is manufactured by performing the steps of evaporating hydrocarbons in a vacuum atmosphere, depositing carbon atoms on support 12 to form graphene 111, and retaining hydrogen atoms 112 inside the carbon rings of graphene 111 to form hydrogen-retaining graphene 11, storing hydrogen-retaining graphene 11 in vacuum container 13, and providing terminal 14 so as to be electrically connected to hydrogen-retaining graphene 11. The steps may be performed in any order.

[0028] The process of evaporating hydrocarbons in a vacuum atmosphere, depositing carbon atoms on the support 12 to form graphene 111, and retaining hydrogen atoms 112 inside the carbon rings of the graphene 111 to form hydrogen-retaining graphene 11 can be performed using a known vacuum deposition apparatus, such as a batch-type vacuum deposition apparatus. Because methane (CH4) and ethane (C2H6) contain few impurities, using these as materials for graphene formation can form highly pure graphene with almost no impurities. Therefore, the hydrocarbon used as the material for graphene 111 preferably contains methane or ethane, and more preferably consists of methane. Natural gas is a suitable material because it is 99% methane. When the hydrocarbon is evaporated using a vacuum deposition apparatus, carbon atoms are deposited on the support 12 to form graphene 111. The hydrogen atoms 112 are then attracted to the free electrons of the graphene, enter the interior of one of the carbon rings of the graphene 111, and are deposited on the carbon atoms or the support 12.

[0029] Furthermore, liquefied natural gas (LNG) contains fewer impurities, such as sulfur, than natural gas, and therefore can form highly pure graphene. Furthermore, hydrogen atoms are more easily attached to graphene formed from liquid hydrocarbons than to graphene formed from gaseous hydrocarbons. From this perspective, liquefied natural gas is a suitable material for forming graphene 111 or hydrogen-retaining graphene 11.

[0030] The step of storing the hydrogen-holding graphene 11 in the vacuum container 13 can be achieved by a known method. For example, the hydrogen-holding graphene 11 may be stored in the container in a vacuum atmosphere, or the hydrogen-holding graphene 11 may be stored in the container and then the inside of the container may be evacuated. Alternatively, the hydrogen-holding graphene 11 and the support 12 may be stored together in the vacuum container 13, or the support 12 may be made to form part of the vacuum container 13 and only the hydrogen-holding graphene 11 may be stored in the vacuum container.

[0031] The step of providing terminals 14 that are electrically connected to hydrogen-retention graphene 11 may be performed after or before forming hydrogen-retention graphene 11. That is, terminals 14 may be provided on support 12 and then hydrogen-retention graphene 11 may be formed. Furthermore, the step of providing terminals 14 that are electrically connected to hydrogen-retention graphene 11 may be performed after or before storing hydrogen-retention graphene 11 in vacuum container 13.

[0032] Although an example of a method for manufacturing an electricity storage device according to the present invention has been described with reference to electricity storage device 1, electricity storage device 10, which is a second example of an electricity storage device according to the present invention, can be manufactured in a similar manner. That is, by carrying out the steps described above, a plurality of units each consisting of hydrogen-retaining graphene 11 and support 12 are manufactured, and then the plurality of units are stacked in a vacuum atmosphere to manufacture stack 100. The step of storing stack 100 in a vacuum container can be carried out in the same manner as the step of storing hydrogen-retaining graphene 11 in vacuum container 13 described above. Terminal 14 may be provided to each unit or support 12 of each unit before or after the units are manufactured, or may be provided to stack 100 after the stack 100 is manufactured.

[0033] [Variations] The electricity storage device according to the present invention is not limited to the configuration described above, and various modifications are possible within the scope of the present invention.

[0034] A configuration in which hydrogen-retention graphene is formed over the entire surface of the support is not essential, and a configuration in which it is formed only on a part of the support is also acceptable. When hydrogen-retention graphene is formed only on a part of the support and the support has a margin, an additional configuration such as an electronic component can be added to the margin. Such a configuration can be realized, for example, by masking a part of the support by a known method and then forming graphene on the support.

[0035] The electricity storage device according to the present invention does not necessarily have to be formed in a sheet shape, and the shape is arbitrary. For example, a support for supporting hydrogen-retaining graphene may be fixed to the side of a columnar or cylindrical vacuum vessel such as a vacuum tube. Terminals 14 are provided at appropriate positions. It is clear that the electricity storage device according to the present invention can be manufactured by the above-described method regardless of the shape of the vacuum vessel.

[0036] [Aspect] It will be apparent to those skilled in the art that the above-described exemplary embodiments are examples of the following aspects.

[0037] (Item 1) An electricity storage device according to one aspect of the present invention includes hydrogen-retention graphene, which is graphene that retains hydrogen atoms inside carbon rings; a support that supports the hydrogen-retention graphene; a vacuum container that stores the hydrogen-retention graphene in a vacuum atmosphere; and a terminal that is electrically connected to the hydrogen-retention graphene.

[0038] (Item 5) A method for manufacturing an electricity storage device according to one aspect of the present invention includes the steps of evaporating hydrocarbons in a vacuum atmosphere, depositing carbon atoms on a support to form graphene, and retaining hydrogen atoms inside the carbon rings of the graphene to form hydrogen-retaining graphene, storing the hydrogen-retaining graphene in a vacuum container, and providing a terminal that is electrically connected to the hydrogen-retaining graphene.

[0039] When the electricity storage device according to paragraph 1 is connected to a circuit, the hydrogen atoms held inside the carbon rings of the graphene split into protons and electrons, and the electrons flow through the circuit as a current. When the circuit is disconnected, the electrons flowing through the circuit react with the protons and return to hydrogen atoms, which are more stable than the protons. Some conventional secondary batteries and capacitors are configured with two electrodes facing each other with an electrolyte sandwiched between them, but the electricity storage device according to paragraph 1 essentially charges and discharges using only hydrogen-retaining graphene, which is graphene that holds hydrogen atoms inside the carbon rings. Therefore, the electricity storage device according to paragraph 1 is a novel electricity storage device with a simpler configuration than conventional electricity storage devices. Furthermore, the method for manufacturing an electricity storage device according to paragraph 5 can manufacture such an electricity storage device.

[0040] (Item 2) The electricity storage device according to item 2 is the electricity storage device according to item 1, further comprising a laminate formed by stacking a plurality of units each formed by stacking the hydrogen-holding graphene and the support.

[0041] The electricity storage device according to paragraph 2 includes a laminate made up of multiple stacked units each made up of a stack of hydrogen-retaining graphene and a support, and therefore has a greater number of circuits that can independently supply current and a larger capacity for the electricity storage device.

[0042] (Item 3) The electricity storage device according to item 3 is the electricity storage device according to item 1 or 2, wherein the graphene is ideal graphene.

[0043] In the electricity storage device according to the third aspect, ideal graphene is used as the graphene, and therefore electrical conduction is faster.

[0044] (Item 4) The electricity storage device according to item 4 is the electricity storage device according to item 1 or 2, wherein the support body is made of alumina ceramic (Al2O3).

[0045] In the electricity storage device according to paragraph 4, alumina ceramic is used as the support, so the support does not change in strength or shape due to temperature changes, and is therefore highly durable.

[0046] (Item 6) The method for manufacturing an electricity storage device according to Item 6 is the method for manufacturing an electricity storage device according to Item 5, wherein methane (CH4) or ethane (C2H6) is used as the hydrocarbon.

[0047] In the method for manufacturing an electricity storage device according to the sixth aspect, methane (CH4) or ethane (C2H6) is used as the hydrocarbon, so that highly pure graphene can be formed.

[0048] (Item 7) The method for producing an electricity storage device according to item 7 is the method for producing an electricity storage device according to item 5 or 6, wherein liquefied natural gas is used as a supply source of the hydrocarbon.

[0049] In the method for producing an electricity storage device according to the seventh aspect, liquefied natural gas is used as a supply source of the hydrocarbon, so that highly pure graphene can be formed, and hydrogen atoms can be easily attached to the graphene. [Explanation of symbols]

[0050] 1,10...Electricity storage device 100...Laminate 11...Hydrogen-retaining graphene 111...Graphene 112...hydrogen atom 1121...Proton 1122...electronic 12...Support 13...Vacuum container 14, 14a, 14b, 14c...Terminals 14x...Series terminals 14y…Parallel terminal 15...Vacuum part

Claims

1. hydrogen-retaining graphene, which is graphene that retains hydrogen atoms inside carbon rings; A support that supports the hydrogen-retaining graphene; a vacuum container that stores the hydrogen-retaining graphene under a vacuum atmosphere; a terminal that is electrically connected to the hydrogen-retention graphene; An electricity storage device comprising:

2. The electricity storage device according to claim 1 , comprising a laminate formed by stacking a plurality of units each formed by stacking the hydrogen-retaining graphene and the support.

3. The electricity storage device according to claim 1 or 2, wherein the graphene is ideal graphene.

4. The support is made of alumina ceramic (Al 2 O 3 The electricity storage device according to claim 1 or 2, comprising:

5. a step of evaporating hydrocarbons in a vacuum atmosphere, depositing carbon atoms on a support to form graphene, and retaining hydrogen atoms inside the carbon rings of the graphene to form hydrogen-retaining graphene; storing the hydrogen-retaining graphene in a vacuum container; providing a terminal that is electrically connected to the hydrogen-retention graphene; A method for manufacturing an electricity storage device, comprising:

6. The hydrocarbon is methane (CH 4 ) or ethane (C 2 H 6 The method for producing an electricity storage device according to claim 5 , wherein

7. The method for producing an electricity storage device according to claim 5 or 6, wherein liquefied natural gas is used as the hydrocarbon supply source.

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