Secondary battery

Abstract

To provide a layer which prevents short-circuiting between a positive electrode and a negative electrode in a solid-state battery using a layer containing a solid electrolyte.SOLUTION: A layer containing a graphene compound is used as a solid electrolyte disposed between a positive electrode and a negative electrode. The layer containing the graphene compound allows lithium ions to pass therethrough. The lithium ions are preliminarily contained in the layer containing the graphene compound. Specifically, there is used a graphene compound having a functional group, such as ether or ester capable of increasing an interlayer distance, which has been chemically modified with the use of a modifier.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, Pertaining to a machine, manufacture, or composition of matter. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, or an electronic In particular, the present invention relates to electronic devices and their operating systems.

[0002] In this specification, the term "electronic device" refers to any device having a power storage device. An electro-optical device having a power storage device, an information terminal device having a power storage device, and the like are all electronic devices. [Background technology]

[0003] Electronic devices that are carried by users or worn by users have been actively developed.

[0004] Electronic devices carried by users or worn by users are examples of primary energy storage devices. It operates using batteries or secondary batteries as its power source. Electronic devices carried by users are designed to be used for long periods of time. It is desirable to use a large-capacity secondary battery for this purpose. If a battery is built in, the problem is that a large-capacity secondary battery is large and heavy. Progress is being made in developing small or thin, large-capacity secondary batteries that can be built into electronic devices.

[0005] Lithium ion batteries that use liquids such as organic solvents as a medium for transporting lithium ions Liquid secondary batteries are widely used. However, in secondary batteries that use liquid, This causes problems with the temperature range of use and leakage to the outside of the secondary battery. It is difficult to make secondary batteries using liquid thinner because of the need to prevent leakage of the liquid.

[0006] Fuel cells are a type of secondary battery that does not use liquids. They use precious metals for the electrodes and solid electrolyte materials. It is also an expensive device.

[0007] In addition, there is a type of secondary battery that does not use liquid, called a solid-state battery, which uses a solid electrolyte. For example, Patent Document 1 and Patent Document 2 are disclosed. 3. The electrolyte of the lithium-ion secondary battery is either a solvent, a gel, or a solid electrolyte. It is stated that it can be used.

[0008] In addition, an example in which graphene oxide is used in a positive electrode active material layer of a solid-state battery is described in Patent Document 4. There are. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2012-230889 A [Patent Document 2] JP 2012-023032 A [Patent Document 3] JP 2013-229308 A [Patent Document 4] JP 2013-229315 A Summary of the Invention [Problem to be solved by the invention]

[0010] The storage device includes a separator that insulates and separates the positive and negative electrodes to prevent a short circuit between the positive and negative electrodes. There is a material called a short circuit prevention film. When the battery is repeatedly charged, lithium is deposited on the negative electrode. However, the separator prevents the lithium from depositing and causing a short circuit between the positive and negative electrodes. It is said to have the function of preventing

[0011] In order to realize compact and high-output power storage devices, a layer containing a solid electrolyte instead of an organic electrolyte is used. Compared to secondary batteries that use organic electrolytes, solid-state batteries are less likely to catch fire. Solid-state batteries contain a solid electrolyte between the positive and negative electrodes. The layer prevents short circuits between the positive and negative electrodes, and the solid electrolyte also functions as a separator. may not be used.

[0012] The basic function required for a solid electrolyte is high ionic conductivity, which is responsible for the transfer of electric charges. On the other hand, to prevent short circuits between the positive and negative electrodes, In a solid-state battery using a layer containing a solid electrolyte, the short circuit between the positive electrode and the negative electrode is prevented. One of the objectives is to provide a layer that prevents

[0013] Another object of one embodiment of the present invention is to provide a highly reliable power storage device. Another object of one embodiment of the present invention is to provide a power storage device with a long lifetime.

[0014] Another object of one embodiment of the present invention is to provide a highly safe power storage device. Another object of one embodiment of the present invention is to provide a novel power storage device, a novel electrode, or the like. do.

[0015] One embodiment of the present invention provides a power storage device that achieves at least one of the above objects. The description of these problems does not preclude the existence of other problems. The embodiment does not necessarily have to solve all of these problems. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0016] In a solid-state battery, a layer containing a graphene compound is used as a layer to prevent short circuits between the positive and negative electrodes. By using a layer containing a graphene compound as a new material for solid-state batteries, This will broaden the range of materials that can be used in solid-state batteries. This makes it possible to provide a novel solid-state battery.

[0017] The configuration disclosed herein includes a first electrode having a positive electrode active material and a second electrode having a negative electrode active material. and a layer having a graphene compound, The second electrode has a function of preventing a short circuit between the first electrode and the second electrode. Next battery.

[0018] To form a layer that prevents short circuits between the positive and negative electrodes, suitable molecules are attached to the graphene compound. By adsorbing the graphene compound, at least a part of the surface of the graphene compound is chemically modified. The graphene compound is provided with a compound having at least a part of its surface chemically modified. It is also called modified graphene.

[0019] In this specification, modification refers to a process for chemically changing a graphene compound to modify the graphene compound. It can also mean to change a function or property. It can also refer to the addition of a functional group that

[0020] The layer containing the graphene compound can pass lithium ions. The layer containing the substance is impregnated with lithium ions in advance.

[0021] A solid electrolyte is a material that has insulating properties when a voltage is applied between the positive and negative electrodes, while retaining lithium. It can be said that the layer has the property of passing ions such as ammonium ions. In order to achieve this, it is preferable to shorten the distance that ions travel. By reducing the thickness of the layer, the internal resistance is reduced and the output characteristics of the battery are improved. To prevent short circuits between the positive and negative electrodes, the thickness of the layer containing the graphene compound must be kept to a minimum. is preferred.

[0022] Specifically, functional groups such as ether and ester, which increase the interlayer distance, are chemically modified using a modifying agent. A decorated graphene compound is used.

[0023] Since power storage devices are required to have excellent characteristics in both energy density and output density, Therefore, in addition to simply being efficient, a good battery also needs to have low internal resistance. To improve the energy density of a battery, it is necessary to increase the amount of lithium contained in the battery to increase its power. - To increase the power density, the distance between the electrodes is narrowed.

[0024] To increase capacity, multiple units each consisting of a positive and negative electrode may be stacked. For example, a positive electrode, a first solid electrolyte, a chemically modified graphene compound, and a second solid electrolyte The positive and negative electrodes are stacked alternately. A cell with this configuration is also called a bipolar cell. do.

[0025] In addition, if external pressure is applied to the power storage device for some reason, the solid electrolyte contained in the secondary battery changes. The shape, specifically, the positive and negative electrodes are partially crushed and the gap between them is small, which may cause a short circuit. Graphene compounds are resistant to deformation, so by using graphene compounds as solid electrolytes, This makes it possible to suppress deformation of the solid electrolyte due to external pressure.

[0026] In addition, polyethylene oxyethylene is a polymer that can be used in lithium ion secondary batteries. However, the melting point of PEO is around 60°C, and when melted, The temperature range in which it can be used is narrow because it can cause a short circuit. When a layer containing ethylenediaminetetraacetate is used as a solid electrolyte, the electrical conductivity is higher than that of a polymer-based solid electrolyte such as PEO. It is possible to provide an electricity storage device that can withstand high temperatures and can be used in a wide temperature range. If the heat resistance temperature of the graphene compound-containing layer is increased and the layer becomes non-flammable, the risk of breakdown and fire will be reduced. Therefore, high reliability can be expected.

[0027] On the other hand, the separator made of conventional polyolefin-based materials used in the storage battery device using the electrolyte The separator has minute holes, and when the temperature exceeds a certain level due to an abnormality in the battery, it softens and breaks into pieces. When the battery is in a molten state, the microscopic pores that serve as paths for lithium ions are closed. When closed, the movement of lithium ions is interrupted, and electrical current stops flowing in and out of the battery. .

[0028] The separator for the electricity storage device using an electrolytic solution and the separator for the electricity storage device using a solid electrolyte are Even if they are called by the same name, the required performance is different. As a separator for an electricity storage device that uses an electrolyte Since the battery uses an electrolyte, it is made of woven fabrics such as polyethylene and polypropylene with fine holes. Materials that are permeable to the electrolyte, such as nonwoven fabric and glass fiber, are used. The separator of the power storage device using a solid electrolyte is a separator containing a solid electrolyte layer or graphene oxide. In this specification, the term refers to a layer that does not require a separate separator and is a solid electrolyte layer or an oxide layer. The graphene-containing layer also functions as a separator.

[0029] The solid electrolyte may be any electrolyte that can conduct lithium ions and contains a solid component. There is no particular limitation. For example, ceramics, polymer electrolytes, etc. can be mentioned. The electrolytes are broadly divided into polymer gel electrolytes, which contain an electrolyte solution, and polymer solid electrolytes, which do not contain an electrolyte solution. It can be done.

[0030] In addition, a new graphene compound is used as the solid electrolyte, making it possible to withstand shape changes. One embodiment of the present invention is a shape-changing electrolyte. It is also possible to provide a device, i.e. a flexible power storage device.

[0031] As used herein, flexibility refers to the property of an object being soft and able to bend. The property of an object being able to deform in response to an external force applied to it, and is called elasticity or the shape before deformation. The question is not whether an object can restore its shape to its original shape. Flexible objects can be used in a fixed, deformed state, and can be used repeatedly. It may be used in a deformed state or in an undeformed state.

[0032] The solid electrolyte layer may also have a two-layer structure, and other configurations disclosed in this specification include a positive electrode active material. a first electrode having a graphene compound, a solid electrolyte layer, a layer having a graphene compound, and a negative electrode active material and a second electrode having a graphene compound between the solid electrolyte layer and the second electrode. The layer having the graphene compound has ion conductivity and is connected to the first electrode and the second electrode. The secondary battery is characterized by having a function to prevent short-circuiting of the two electrodes.

[0033] The solid electrolyte layer may also have a three-layer structure, and other configurations disclosed herein include a positive electrode active material. a first electrode having a negative electrode active material, a first solid electrolyte layer, a second electrode having a negative electrode active material, and The first solid electrolyte layer and the second solid electrolyte layer and a layer having a graphene compound are disposed in a first solid electrolyte layer and a second solid electrolyte layer. and a layer having a graphene compound between the solid electrolyte layer and the graphene compound. The layer has ion conductivity and a function of preventing a short circuit between the first electrode and the second electrode. It is a secondary battery that has the following characteristics.

[0034] In each of the above structures, the layer containing a graphene compound contains oxygen and a functional group.

[0035] In each of the above structures, the layer having the graphene compound contains oxygen, silicon, and a functional group. Yes.

[0036] In each of the above structures, the layer containing a graphene compound contains graphene oxide, Silicon is bonded to the oxygen of the graphene oxide, and a functional group is bonded to the silicon.

[0037] In each of the above structures, the end of the graphene compound is terminated with an ester, and the alkyl group is is fixed by chemical modification. Effect of the Invention

[0038] According to one aspect of the present invention, a lithium-ion secondary battery using a carbon-based material as a solid electrolyte is provided. In addition, in the power storage device, graphene oxide is used as the solid electrolyte. This prevents direct contact between the two electrodes while providing the desired ionic conductivity and mechanical strength. It is possible to provide a power storage device. Or, it is possible to ensure the long-term reliability of a lithium-ion secondary battery. One of our goals is to achieve this.

[0039] According to one embodiment of the present invention, a lithium ion secondary battery using a novel graphene oxide film can be provided. According to one embodiment of the present invention, a novel power storage device or the like can be provided. It is possible.

[0040] According to one aspect of the present invention, a lithium ion secondary battery in which the battery is fully solidified, i.e., a fully solid-state Lithium-ion secondary batteries can be realized. If the battery is made completely solid-state, it will be possible to eliminate the use of organic electrolyte. This solves problems such as leakage and battery expansion caused by evaporation of the organic electrolyte. do.

[0041] According to one embodiment of the present invention, a power storage device having a shape-changeable function, that is, It is possible to provide a flexible storage battery. This makes it possible to provide a novel graphene oxide film that can withstand shape changes.

[0042] In addition, one or more protection circuits are provided for one or more storage devices, and The battery pack or battery module is a battery that is stored in a battery compartment. Battery modules are not limited to electronic devices carried by users, but are also used in medical equipment, hybrid vehicles (HVs), etc. EV), electric vehicles (EV), plug-in hybrid vehicles (PHEV), and other next-generation It is also used in lean energy vehicles.

[0043] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. Effects other than these may also be included. The above is self-evident from the description, drawings, claims, etc. Other effects can be extracted from the claims and other descriptions. [Brief description of the drawings]

[0044] [Figure 1] FIG. 1 is an example of a cross-sectional view of a power storage device illustrating one embodiment of the present invention. [Diagram 2] FIG. 1 is an example of a cross-sectional view of a power storage device illustrating one embodiment of the present invention. [Diagram 3] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 4] 1 is an example of an electronic device illustrating one embodiment of the present invention. [Diagram 5] 1 is an example of a vehicle illustrating one aspect of the present invention. [Figure 6] FIG. 2 is a cross-sectional view of a single cell for measuring charge / discharge characteristics. [Figure 7] 1 is a graph showing experimental results showing charge / discharge characteristics. [Figure 8] FIG. 2 is a cross-sectional view of a single cell for measuring ion conductivity. [Figure 9] 1 is a graph showing experimental results showing ionic conductivity. [Figure 10] 1A and 1B are diagrams showing an equivalent circuit of a secondary battery during CC charging, the relationship between the secondary battery voltage and time, and the relationship between the charging current of the secondary battery and time. [Figure 11] 4A and 4B are diagrams showing an equivalent circuit of a secondary battery during CCCV charging, a relationship between the secondary battery voltage and time, and a relationship between the charging current of the secondary battery and time. [Figure 12] 11 is a diagram showing the relationship between the secondary battery voltage and time of the secondary battery during CC discharge, and the relationship between the discharge current of the secondary battery and time. FIG. [Figure 13]1 is a TEM observation photograph of the vicinity of an electrode in Example 2 showing one embodiment of the present invention. [Figure 14] 1 is a TEM observation photograph of the vicinity of an electrode in Example 3 showing one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. The present invention is not limited to the description of the following embodiments. It is not something that can be done.

[0046] In addition, in the configuration of the present invention described in this specification, etc., the same parts or parts having similar functions The same reference numerals are used in common between different drawings, and the repeated explanations are omitted. When referring to parts having similar functions, the same hatch pattern is used and no special reference numerals are attached. There may not be.

[0047] In this specification, flexibility refers to the property that an object is flexible and can be bent. It refers to the property of an object being able to deform in response to an external force applied to it, and is called elasticity or pre-deformation property. The question is whether the device can restore its original shape. A flexible power storage device can be fixed in a deformed state for use. It can be repeatedly deformed and used, or it can be used in an undeformed state. In this specification, the inside of the exterior body refers to the exterior of the lithium ion secondary battery. This refers to the area surrounded by the battery enclosure, which contains the positive electrode, negative electrode, separator, and electrolyte. This is an area where

[0048] In this specification, modification refers to chemically changing the graphene oxide film to modify the graphene oxide. It also refers to changing the function or properties of a membrane. It may also refer to the addition of a functional group.

[0049] In addition, the contents described in the description of the embodiment of the present invention can be used in appropriate combination. Cut.

[0050] (Embodiment 1) In this embodiment, a lithium-ion secondary battery 100 according to one embodiment of the present invention and a manufacturing method thereof will be described. Explain the law.

[0051] FIG. 1A is a conceptual diagram of a solid-state battery according to one embodiment of the present invention, in which a positive electrode 101 and a negative electrode 102 are This is an example in which a layer 103 containing a graphene compound is used as a solid electrolyte between the carrier 102. Ions include lithium ions, sodium ions, magnesium ions, etc. Here, a secondary battery using lithium ions will be described as an example. For example, in FIG. The layer 103 containing a graphene compound is an organic solvent in which a graphene compound and a lithium salt are mixed. The medium can be dried and used in the form of a sheet.

[0052] FIG. 1B shows an example of a bulk-type all-solid-state battery, in which particulate positive electrode active material is placed near the positive electrode 101. The negative electrode 102 has a particle-shaped negative electrode active material 108 in the vicinity of the negative electrode 102, and the gap between them is filled. A layer 103 containing a graphene compound as a solid electrolyte is disposed in such a manner that the positive electrode 101 and the negative electrode A plurality of types of particles are filled between the electrode 102 and the electrode 103 by applying pressure to eliminate any gaps. There are.

[0053] The positive electrode active material 107 has a layered rock salt type crystal structure or a spinel type crystal structure. In addition, a composite oxide having a high conductivity can be used as the positive electrode active material. The following positive electrode materials can be used. As a polyanion-based positive electrode material, for example, olivine type The positive electrode active material may be a material having a crystal structure of ZnO, a Nasicon type material, or the like. For example, a cathode material having sulfur can be used.

[0054] Various composite oxides can be used as the positive electrode active material. For example, LiFeO2, L iCoO2, LiNiO2, LiMn2O4, Li2MnO3, Cr2O5, MnO2 etc. Compounds of the formula:

[0055] As an example of a material with a layered rock salt type crystal structure, a composite oxide represented by LiMO2 is used. The element M is preferably at least one selected from Co and Ni. LiCoO2 has a large capacity, is stable in air, and is relatively thermally stable. In addition, the element M is preferably selected from Co and Ni. In addition to one or more of these, it may also contain one or more selected from Al and Mn.

[0056] For example, LiNi x Mn y Co z O w (x, y, z and w are, for example, x=y=z = 1 / 3 or nearby, w = 2 or nearby) can be used. , LiNi x Mn y Co z O w (x, y, z and w are, for example, x=0.8 or its vicinity, y=0.1 or its vicinity, z=0.1 or its vicinity, w=2 or its vicinity For example, LiNi x Mn y Co z O w (x, y, z and w are, for example, x=0.5 or its vicinity, y=0.3 or its vicinity, z=0 .2 or nearby, w=2 or nearby) can be used. iNi x Mn y Co z O w (x, y, z and w are, for example, x=0.6 or (y=0.2 or its vicinity, z=0.2 or its vicinity, w=2 or its vicinity) For example, LiNi x Mn y Co z O w (x, y, z and For example, w is x=0.4 or its vicinity, y=0.4 or its vicinity, z=0.2 or nearby, w=2 or nearby) can be used.

[0057] The neighborhood is, for example, a value greater than 0.9 times and less than 1.1 times the value.

[0058] Some of the transition metals and lithium in the positive electrode active material are replaced with Fe, Co, Ni, Cr, Al, Mg, etc. Materials in which one or more elements selected from the above have been substituted, and materials in which the positive electrode active material is Fe, Co, Ni, Cr, A material doped with one or more elements selected from Al, Mg, etc. is used as the positive electrode active material. Good too.

[0059] In addition, as the positive electrode active material, for example, a solid solution of a combination of multiple composite oxides is used as the positive electrode active material. For example, LiNi x Mny Co z O2(x, y, z>0, x+y +z=1) and Li2MnO3 solid solution can be used as the positive electrode active material.

[0060] As an example of a material with a spinel-type crystal structure, the composite oxide represented by LiM2O4 is It is preferable to have Mn as the element M. For example, LiMnO In addition, by having Ni in addition to Mn as the element M, This is preferable because it may improve the discharge voltage of the secondary battery and improve the energy density. Lithium-containing materials with a spinel-type crystal structure containing manganese, such as iMn2O4, Amount of lithium nickel oxide (LiNiO2 or LiNi 1-x M x O2 (M=Co, Al, etc.) ) is preferably mixed, since it is possible to improve the characteristics of the secondary battery.

[0061] For example, the average particle size of the primary particles of the positive electrode active material is 1 nm or more and 100 μm or less. It is preferable that the thickness is 50 nm or more and 50 μm or less, and more preferable that the thickness is 1 μm or more and 30 μm or less. It is more preferable that the specific surface area is less than 1 m 2 / g or more 20m 2 / g or less The average particle size of the secondary particles is preferably 5 μm or more and 50 μm or less. The average particle size is preferably measured by observation using a SEM (scanning electron microscope) or a TEM. The specific surface area can be measured by a particle size distribution analyzer using the laser diffraction / scattering method. The product can be measured by gas adsorption methods.

[0062] A conductive material such as a carbon layer may be provided on the surface of the positive electrode active material. By providing a carbon layer on the positive electrode active material, the conductivity of the electrode can be improved. The coating is formed by mixing carbohydrates such as glucose during the firing of the positive electrode active material. In addition, graphene, multi-graphene, graphene oxide ( GO: Graphene Oxide) or RGO (Reduced Graphene Here, RGO can be, for example, graphene oxide (GO). ) is reduced.

[0063] A layer containing one or more of an oxide and a fluoride may be provided on the surface of the positive electrode active material. The oxide may have a different composition from the positive electrode active material. Also, the oxide may have the same composition as the positive electrode active material. This is also fine.

[0064] For example, a polyanion-based positive electrode material containing oxygen, element X, metal A, and metal M may be used. The metal M can be Fe, Mn, Co, Ni, Ti, or Nb. The metal A is one or more of Li, Na, and Mg, and the element X is S, P, Mo, W, It is one or more of As and Si.

[0065] Examples of materials having an olivine-type crystal structure include composite materials (general formula LiMPO4 (M is , Fe(II), Mn(II), Co(II), Ni(II) Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, and Li iCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, L iFe a Mn b PO4, LiNi a Cob PO4, LiNi a Mn b PO4 (where a + b = 1 hereinafter, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d M n e PO4, LiNi c Co d Mn e PO4 (where c + d + e ≤ 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (where f + g + h + i ≤ 1 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc., lithium compounds can be used. It is possible.

[0066] In particular, LiFePO4 preferably satisfies the requirements for a cathode active material, such as safety, stability, high capacity density, and the presence of lithium ions that can be extracted during initial oxidation (charging), in a well - balanced manner. Therefore, it is preferable.

[0067] The cathode active material having an olivine - type crystal structure preferably has an average particle diameter of primary particles of 1 nm or more and 20 μm or less, more preferably 10 nm or more and 5 μm or less, and even more preferably 50 nm or more and 2 μm or less. Also, the specific surface area is preferably 1 m 2 / g or more and 20 m 2 / g or less. Also, the average particle diameter of secondary particles is preferably 5 μm or more and 5 0 μm or less.

[0068] Also, the general formula Li (2-j) MSiO4 (where M is Fe(II), Mn(II), Co(I I), one or more of Ni(II), 0 ≦ j ≦ 2), etc. of composite materials can be used. General formula Li (2-j) Representative examples of Li (2-j) FeSiO4, Li (2- j) NiSiO4, Li (2-j) CoSiO4, Li (2-j) MnSiO4, Li ( 2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k M n l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. of lithium compounds can be used as materials can be.

[0069] Also, Ax M2(XO4)3(A=Li, Na, Mg, M=Fe, Mn, Ti, Nb, X It is possible to use Nasicon-type compounds represented by the general formula: Nasicon type compounds include Fe2(MnO4)3, Fe2(SO4)3, Li 3Fe2(PO4)3, etc. Also, as positive electrode active materials, Li2MPO4F, Li2M Compounds represented by the general formula P2O7 and Li5MO4 (M=Fe, Mn) can be used. Cut.

[0070] In addition, as the positive electrode active material, perovskite-type fluorides such as NaFeF3 and FeF3, Ti Metal chalcogenides (sulfides, selenides, tellurides) such as S2 and MoS2, manganese Materials such as oxides and organic sulfur compounds can be used.

[0071] In addition, the positive electrode active material is a lithium-ion battery with the general formula LiMBO3 (where M is Fe(II), Mn(II), or C A borate-based positive electrode material represented by the formula (II) can be used.

[0072] In addition, the positive electrode active material is Li a Mn b M c O d Lithium manium can be expressed as A manganese-based composite oxide can be used. Here, the element M is selected from elements other than lithium and manganese. The selected metal element, silicon, or phosphorus is preferably used, and nickel is the preferred Further, when measuring the entire particle of the lithium manganese composite oxide, When the value is 0 <a / (b+c)<2、かつc>0 and 0.26≦(b+c) / d<0.5 is satisfied In order to realize high capacity, it is preferable to have a crystal structure of the surface layer and the center portion. ​To obtain a lithium manganese composite oxide having regions with different crystal orientations or oxygen contents In order to obtain such a lithium manganese composite oxide, it is preferable that, for example, 1.6≦a It is preferable that c / b≦1.848, 0.19≦c / b≦0.935, and 2.5≦d≦3. In addition, Li 1.68 Mn 0.8062 Ni 0.318 Lithium with the formula O3 In the present specification, Li is preferably used as a Li-manganese composite oxide. 1.6 8Mn 0.8062 Ni 0.318 Lithium manganese complex oxide represented by the formula O3 The ratio (molar ratio) of the amounts of the raw materials is Li2CO3:MnCO3:NiO=0. Lithium manganese composite oxide formed by mixing 84:0.8062:0.318 Therefore, the lithium manganese composite oxide has the composition formula Li 1.68 Mn 0.806 2Ni 0.318 It is represented by O3, but the composition can deviate from this.

[0073] The composition of metals, silicon, phosphorus, etc. of the entire lithium manganese composite oxide particle is, for example, For example, it can be measured using an ICP-MS (inductively coupled plasma mass spectrometer). The oxygen composition of the entire particle of the lithium manganese oxide composite was measured using, for example, EDX (energy dispersive X-ray diffraction). It is possible to measure it using X-ray analysis. It can also be used in combination with ICP-MS analysis. This can be determined by using valence evaluation from melt gas analysis and XAFS (X-ray absorption fine structure) analysis. The lithium manganese composite oxide is a material that contains at least lithium and manganese. The term refers to oxides containing chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, and other elements. Abdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus It may contain at least one element selected from the group consisting of:

[0074] In addition, the carrier ions are alkali metal ions other than lithium ions, alkaline earth metal ions, etc. In the case of metal ions, instead of lithium, an alkali metal (e.g., sodium) is used as the positive electrode active material. Alkaline earth metals (e.g., calcium, strontium, barium, etc.) For example, a layered oxide containing sodium may be used. can be used.

[0075] Examples of materials containing sodium include NaFeO2 and Na 2 / 3 [Fe 1 / 2 Mn1 / 2 ]O2, Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 ]O2, Na2Fe2(SO4)3, N a2FePO4F, NaMPO4 (M is Fe(II), Mn(II), Co(II), Ni(II)), Na2FePO4F, Na4Co3(PO4)2P2O7, etc. A lithium-containing oxide can be used as the positive electrode active material.

[0076] In addition, lithium-containing metal sulfides can be used as the positive electrode active material. For example, Li 2TiS3, Li3NbS4, etc.

[0077] The negative electrode active material 108 can be, for example, an alloy-based material or a carbon-based material.

[0078] As a negative electrode active material, it is possible to carry out charge / discharge reactions by alloying / de-alloying reactions with lithium. For example, silicon, tin, gallium, aluminum, and Rumanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one of these elements can be used. These elements have a large capacity compared to carbon. Silicon has a high theoretical capacity of 4200mAh / g. It is preferable to use silicon. Compounds containing these elements may also be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V 2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3 Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, I nSb, SbSn, etc. Here, the charge / discharge reaction occurs due to alloying / dealloying reactions with lithium. Elements capable of undergoing a reaction and compounds containing such elements are sometimes called alloy materials. do.

[0079] In this specification, SiO refers to, for example, silicon monoxide. Alternatively, SiO x Here, it is preferable that x has a value close to 1. For example, x is 0 A value between 0.2 and 1.5 is preferred, and a value between 0.3 and 1.2 is preferred.

[0080] Carbon-based materials include graphite, graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). Carbon nanotubes, graphene, carbon black, etc. may be used. .

[0081] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesophase graphite. Carbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. Here, as the artificial graphite, spherical graphite having a spherical shape can be used. For example, the MCMB may have a spherical shape, which is preferred. It is relatively easy to reduce the particle size, which may be preferable. Examples of the graphite include flake graphite and spherical natural graphite.

[0082] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It has a low potential similar to that of lithium metal (0.05V to 0.3V vs. Li / L i + This allows the lithium-ion secondary battery to exhibit a high operating voltage. In addition, graphite has a relatively high capacitance per unit volume, a relatively small volume expansion, and is inexpensive. However, lithium ions are preferred because they have the advantage of being safer than metallic lithium.

[0083] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4T i5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0084] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0085] When a composite nitride of lithium and transition metals is used, the negative electrode active material contains lithium ions, The positive electrode active material is made of V2O5, Cr3O8, etc., which do not contain lithium ions. It is preferable that the positive electrode active material contains lithium ions. The lithium ions contained in the positive electrode active material are first removed to form the negative electrode active material. A complex nitride of lithium and a transition metal can be used.

[0086] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. For example, Lithium oxide (LiO), cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not form an alloy with the negative electrode active material may be used. Further materials that are produced include Fe2O3, CuO, Cu2O, RuO2, Cr2O3, etc. oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, Ge3 Nitrides such as N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. It also occurs with fluoride.

[0087] FIG. 1C shows an example of a thin-film all-solid-state battery, which is a lithium-ion battery according to one embodiment of the present invention. 1C is a cross-sectional view showing the on-cell secondary battery 100. In FIG. In this example, after forming the substrate 104, a lithium ion secondary battery is manufactured. Examples of the substrate include a ceramic substrate, a glass substrate, a plastic substrate, and a metal substrate. Plastic and metal substrates are flexible if they are thin, so flexible substrates or The substrate 104 is called a flexible film. In this case, the lithium ion secondary battery 100 can be bent.

[0088] The lithium ion secondary battery 100 includes a positive electrode 101, a layer 103 containing a graphene compound, a negative electrode In this embodiment, the graphene compound-containing layer is used as a solid electrolyte. It works like this.

[0089] It is known that the movement of carrier ions such as Li ions is fast in layers containing graphene compounds. Preferably, a chemically modified graphene compound is used to increase the interlayer distance, thereby increasing the carrier density. The graphene compound layer increases the mobility of carriers such as lithium. Ions may be included in advance.

[0090] In addition, the chemically modified graphene compounds can be used in two regions even if the modification conditions are different. good.

[0091] In this specification, the modification state refers to the state of modification performed on the graphene compound. In addition, the modification status is different in the two regions when the types of modification in the two regions are different. Not only are they different, but even when the same type of modification is performed, the strength of the modification differs. It also refers to a situation where a modification occurs in one region and not in the other. Even if no modification is made, the modification situation is said to be different. The two regions may differ in the types of atoms or atomic groups introduced into the graphene compound. Even when the type of atom or atomic group to be introduced is the same, the amount introduced will differ.

[0092] The modification of the graphene compound containing graphene oxide will be described in detail later.

[0093] In one embodiment of the present invention, the graphene compound may be used in a structure other than a separator. For example, a positive electrode current collector, a positive electrode active material layer, a negative electrode current collector, a negative electrode active material layer, a solid electrolyte, an outer casing At least one of the positive electrode current collector and the positive electrode current collector can include a graphene compound. The active material layers are collectively referred to as a positive electrode, and the negative electrode current collector and the negative electrode active material are collectively referred to as a negative electrode.

[0094] As described below, the structure and properties of graphene compounds can be selected widely by modification. Therefore, it is possible to develop desirable properties according to the material to which the graphene compound is to be applied. In addition, graphene compounds have high mechanical strength, making them flexible. The graphene compound can also be applied to each component constituting an energy storage device having the graphene compound. This article explains:

[0095] Graphene is a single atomic layer of carbon atoms with π bonds between the carbon atoms. When graphene layers are stacked in a number of layers, up to 100 layers in number, they are sometimes called multi-graphene. Graphene and multi-graphene can be, for example, The length is 50 nm or more and 100 μm or less, or 800 nm or more and 50 μm or less.

[0096] In this specification and the like, a compound having graphene or multi-graphene as a basic skeleton Graphene Compound Graphene compounds include graphene and multi-graphene. .

[0097] The graphene compound will be described in detail below.

[0098] The graphene compound is, for example, a compound in which graphene or multi-graphene contains atoms other than carbon, or a compound modified with an atomic group having an atom other than carbon. The multi-graphene is modified with carbon-based atomic groups such as ether and ester. The atomic group modifying the graphene or multi-graphene may be a substituted one. In this specification and the like, the term "modification" refers to By substitution reactions, addition reactions or other reactions, graphene, multi-graphene, graphene Graphene compounds or graphene oxide (described later) that contain atoms other than carbon or atoms other than carbon This refers to the introduction of an atomic group containing carbon or an atomic group mainly composed of carbon.

[0099] The front and back surfaces of graphene may be modified with different atoms or atomic groups. In multi-graphene, each layer is modified with a different atom or atomic group. It may be possible.

[0100] An example of graphene modified with the above-mentioned atoms or atomic groups is oxygen or an oxygen-containing Examples of such graphene include graphene or multi-graphene modified with functional groups containing oxygen. Examples of functional groups include carbonyl groups such as epoxy groups and carboxyl groups, and hydroxyl groups. The graphene compound modified with oxygen or a functional group having oxygen is In this specification, graphene oxide refers to a multi-layer It also includes graphene oxide.

[0101] As an example of an ether-modified graphene compound, the structure represented by the following formula (200) is Examples of graphene compounds include those having the above structure. [ka]

[0102] In formula (200), the GO surrounded by a square represents graphene or graphene oxide. R represents a substituted or unsubstituted chain group having at least two ether bonds. represent.

[0103] In addition, an example of an ether-modified graphene compound is represented by the following formula (201): Examples of graphene compounds include those having the structure. [ka]

[0104] In formula (201), the GO surrounded by a square represents graphene or graphene oxide. Represents the

[0105] In addition, we will explain the silylation of graphene oxide as an example of its modification. First, graphene oxide is placed in a container in a nitrogen atmosphere, and n-butyl ether is added to the container. Add diphenylamine (C4H9NH2) and keep at 60℃ and stir for 1 hour. Next, add toluene to the container. Add alkyltrichlorosilane as a silylating agent and then immerse in a nitrogen atmosphere. The mixture was then kept at 60°C and stirred for 5 hours. Next, toluene was added to the container and the mixture was filtered by suction. The solid powder is obtained by filtration, which is dispersed in ethanol. The powder is dispersed in acetone, and then filtered with suction to obtain a solid powder. The body components are vaporized to obtain silylated graphene oxide.

[0106] The obtained graphene compound has a structure represented by the following formula (202).

[0107] [ka]

[0108] In formula (202), the GO surrounded by a square represents graphene or graphene oxide. Represents the

[0109] In the formula (202), R is a substituted or unsubstituted group having at least two ether bonds. It represents an unsubstituted chain group, and R may be branched. Also, GO surrounded by a square represents gram. The graphene compound according to one embodiment of the present invention is represented by the formula (1). The molecular weight or structure of the graphene is not limited to a single one, but rather the graphene of various sizes is available. Therefore, the molecular structure of the graphene compound according to one embodiment of the present invention will be described in detail. It is difficult to specify and fully express the chemical compound according to one embodiment of the present invention. The modified graphene compound is a substituted or unsubstituted graphene having at least two or more ether bonds. Graphene compound chemically modified with a silylating agent having an unsubstituted group, etc., and manufacturing method thereof There are cases where it is practical to specify the In some cases, it may be possible or impractical. Also, GO and Si (silicon) are two compounds as shown in the above formula. In some cases, the GO layers are fixed by one or three Si-O bonds. In some cases, the material is fixed by an O bond. The bond is not limited to an Si-O bond. Alternatively, GO and Si may be fixed by other bonds.

[0110] In addition, an example of an ester-modified graphene compound is represented by the following formula (203): Examples of graphene compounds include those having the structure.

[0111] [ka]

[0112] In addition, as an example of an ether-modified and ester-modified graphene compound, 04) is a graphene compound having a structure represented by the formula:

[0113] [ka]

[0114] In addition, whether or not a compound has been chemically modified can be determined by FT-IR analysis to determine whether or not the compound has an ether bond. For example, the measurement can be performed using Thermo ATR was performed using the Nicolet NEXUS 670 manufactured by SCIENTIFIC. Attenuated Total Reflectance (ATH) method Just perform FT-IR analysis.

[0115] In addition, silylation was shown as an example of modification of graphene oxide. The modification is not limited to graphene oxide, but can also be applied to non-oxidized graphene. In addition, the modification described in this embodiment can also be used for graphene oxide. The present invention is not limited to the modification of graphene, but may be applicable to a wide range of graphene compounds. In addition, the modification is not limited to silylation, and the silylation is not limited to the above-mentioned method.

[0116] Modification is not limited to the introduction of one type of atom or atomic group, but rather involves the application of multiple types of modifications to produce multiple compounds. The modification may introduce several kinds of atoms or atomic groups. Also, the modification may include hydrogen, halogen atoms, carbon atoms, etc. The reaction may be a reaction to add a hydride group, an aromatic hydrocarbon group, or a heterocyclic compound group. Reactions that introduce atomic groups into aryl groups include addition reactions and substitution reactions. Friedel-Crafts reaction, Bingel reaction, etc. A radical addition reaction may be carried out on graphene, and a cycloaddition reaction may be carried out. A ring may be formed between the graphene and the atomic group by

[0117] By introducing specific atomic groups into graphene compounds, the physical properties of the graphene compounds can be changed. Therefore, by modifying the graphene compound according to the intended use, This makes it possible to intentionally impart desired properties to the graphene compound.

[0118] Next, an example of a method for producing graphene oxide will be described. Alternatively, multi-graphene can be obtained by oxidizing the graphene. Alternatively, the graphene oxide can be obtained by oxidizing Graphite oxide can be obtained by oxidizing graphite. Here, the graphene oxide can be further modified with the above-mentioned atoms or atomic groups. You may do so.

[0119] The compound obtained by reducing graphene oxide is called "RGO (Reduced Graphene Oxide)." RGO is sometimes called "graphene oxide." Not all oxygen is eliminated, and some oxygen or atomic groups containing oxygen remain bonded to carbon. For example, RGO may contain carbonyl groups such as epoxy groups and carboxyl groups, Alternatively, it may have a functional group such as a hydroxyl group.

[0120] Graphene compounds are composed of multiple graphene compounds that overlap partially to form a single sheet. Such a graphene compound may be referred to as a graphene compound sheet. For example, the graphene compound sheet has a thickness of 0.33 nm or more and 10 mm or less. Preferably, the region is greater than 0.34 nm and less than 10 μm. The aryl group is an ether, ester, or other group that includes an atom other than carbon or an atomic group that includes an atom other than carbon. The graphene compound sheet may be modified with an atomic group mainly composed of carbon. Each of the layers may be modified with a different atom or atomic group. stomach.

[0121] Graphene compounds are composed of not only six-membered rings made of carbon, but also five-membered rings made of carbon and In this case, in the vicinity of the seven-membered or more ring, In some cases, regions through which lithium ions can pass may be generated.

[0122] Furthermore, for example, a plurality of graphene compounds may be gathered together to form a sheet shape. The graphene compound has a planar shape, which allows for surface contact.

[0123] Graphene compounds can be highly conductive even when they are thin, and the graphene compounds can be bonded together by surface contact. It is possible to increase the contact area between objects or between the graphene compound and the active material. Therefore, even if the amount per volume is small, a conductive path can be formed efficiently.

[0124] On the other hand, graphene compounds can also be used as insulators. The sheet can be used as a sheet-like insulator. For example, graphene oxide is In some cases, the insulating properties are higher than those of non-oxidized graphene compounds. Modified graphene compounds can improve their insulating properties depending on the type of atomic group used to modify them. There may be cases where this is possible.

[0125] Here, in this specification and the like, the graphene compound may have a graphene precursor. A graphene precursor is a material used to produce graphene. The ene precursor may include, for example, the above-mentioned graphene oxide or graphite oxide. .

[0126] In addition, graphene containing an alkali metal or graphene containing an element other than carbon, such as oxygen, In the present specification and the like, the graphene compound includes Laphene analogues are also included.

[0127] In addition, the graphene compound in this specification and the like has atoms, atomic groups, and their interlayers. In addition, the graphene compound may have atoms, atomic groups, and their ions between the layers. By having ions, the physical properties of graphene compounds, such as electrical conductivity and ionic conductivity, Also, the interlayer distance may increase.

[0128] Graphene compounds have excellent electrical properties, such as high electrical conductivity, as well as high flexibility and In addition, graphene may have excellent physical properties such as high mechanical strength. Depending on the type of modification, the compound may be able to have extremely low electrical conductivity and become an insulator. In addition, the graphene compound has a planar shape. This allows for low resistance surface contact.

[0129] The lithium ion secondary battery 100 shown in FIG. 1(A) can be used as is. However, for ease of handling, one or more lithium ion secondary batteries are It is preferable to store the device together with the circuit (such as a charge / discharge control circuit or a protection circuit) inside the container. The battery pack contains insulating materials such as glass wool for heat insulation. A thermal material may also be provided.

[0130] (Embodiment 2) In this embodiment, a lithium ion secondary battery is formed by forming a multi-layer structure using a plurality of types of solid electrolyte layers. Here is an example of how it can be used.

[0131] Figure 2(A) shows a solid electrolyte using a polymer such as polyethylene oxide (PEO). The solid electrolyte layer using the graphene compound layer and the graphene compound layer are shown in FIG. is.

[0132] A solid electrolyte layer using a layer 113 containing a graphene compound in contact with a current collector 111 serving as a positive electrode. When the graphene compound-containing layer is provided, the graphene compound and the collector are disposed at the interface between the current collector and the layer containing the graphene compound. There are multiple points of contact with the electrical body.

[0133] In order to reduce the contact resistance, the current collector 112 having the negative electrode active material layer which becomes the negative electrode and the graphite Between the layer 113 containing the phenanthrene compound, a polymer-based solid electrolyte, such as PEO, is provided. A solid electrolyte layer 119 is provided.

[0134] In addition, FIG. 2(A) shows an example in which two different electrolyte layers are laminated, but the present invention is not limited thereto. Three or more layers may be laminated. For example, a graphene compound is sandwiched between two layers of PEO. Alternatively, the solid electrolyte layers may be stacked to form a three-layered structure.

[0135] In order to increase the capacity of the secondary battery, the positive and negative electrodes may be stacked alternately. An example of this case is shown in Figure 2(B).

[0136] The stacked structure shown in FIG. 2B includes three graphene compound layers 113a, 113b, and 113c. The laminated structure shown in FIG. 2B is a laminate having a negative electrode active material layer 13c. A current collector having a current collector 112, a layer 113a containing a graphene compound, and a positive electrode active material layer that serves as a positive electrode. A current collector having a body 111, a layer 113b containing a graphene compound, and a negative electrode active material layer that serves as a negative electrode. 112, a layer 113c containing a graphene compound, and a current collector 1 having a positive electrode active material layer that serves as a positive electrode In this manner, the positive electrode active material layer 111 is laminated in this order. There are only two pairs of current collectors 112 each having a negative electrode active material layer that serves as a negative electrode. This makes it a secondary battery with a large capacity per volume.

[0137] In the laminated structure shown in FIG. 2B, the current collector 11 having the negative electrode active material layer that becomes the negative electrode A solid electrolyte having a polymer-based solid electrolyte between the layer 2 and the layer 113a containing a graphene compound. A layer of polymer may be provided.

[0138] This embodiment mode can be freely combined with the first embodiment mode.

[0139] (Embodiment 3) In this embodiment, a graphene compound used for a solid electrolyte will be described. A method for producing a graphene compound by modification will also be described. The graphene compound produced by the method is lithium, sodium, magnesium, calcium For example, it is used as a solid electrolyte in lithium-ion secondary batteries. However, one embodiment of the present invention is not limited thereto.

[0140] Graphene oxide has relatively low electronic conductivity, but it has poor reduction resistance and is highly electronically conductive. Therefore, graphene oxide or graphene is chemically modified to For example, it is preferable to insulate the acid by using a molecule having an alkyl chain with a relatively large number of carbon atoms. It is possible to chemically modify graphene oxide or graphene. When both sides of the silicon are chemically modified with a compound having a long-chain alkyl group, the alkyl chain becomes electronically conductive. Since the functional group is poorly functionalized, it is possible to increase the distance between multiple graphene oxide sheets and generate electrical conductivity. It can be insulated to block electron conduction.

[0141] However, alkyl groups are non-polar functional groups and are not responsible for the battery reaction in lithium-ion secondary batteries. Therefore, it is difficult to obtain a good affinity with lithium ions, which are compounds with long-chain alkyl groups. When laphene is chemically modified, the movement of lithium ions is inhibited, inhibiting the battery reaction. Therefore, graphene compounds chemically modified with compounds having long-chain alkyl groups can be used as solid-state electrodes. A lithium ion secondary battery using this as an electrolyte has poor output characteristics.

[0142] In view of this, the graphene compound according to one embodiment of the present invention has insulating properties and at the same time has lithium ionization properties. For example, a graphene compound that has an affinity for cations can be chemically modified to have an ester group. Alternatively, it is preferable to use a graphene compound having a functional group including a carboxyl group. The alkyl and carboxyl groups are also classified as hydrophilic groups, and their polarity determines their affinity with lithium ions. It has compatibility with other metals and can contribute to the dissociation of the lithium salt and the migration of lithium ions. Furthermore, when the graphene compound is used as a solid electrolyte in a lithium ion secondary battery, The more ester or carboxyl groups in the functional group of the laphene compound, the more lithium This is preferred since it improves the mobility of ions.

[0143] The more ester or carboxyl groups there are, the larger the molecular weight becomes, and the more difficult it is to dissolve in a solvent. This may result in poor reactivity when chemically modifying graphene or graphene oxide. In addition, if the number of ester groups increases, hydrolysis may occur more easily. The number of ester groups or carboxyl groups is preferably 1 or more and 10 or less.

[0144] In addition, the graphene compound according to one embodiment of the present invention has a property as a solid electrolyte similar to that of a polymer. Compared to electrolytes, one of their features is their high heat resistance. If damage to the internal structure causes unexpected reactions, it can develop into a major accident such as a fire or explosion. It is important that the lithium-ion secondary battery is durable because it may cause damage to the battery. When used in harsh environments such as inside a vehicle, the low heat resistance of the internal structure is a major problem. The graphene compound according to one embodiment of the present invention has high heat resistance, so that it can be used in a high-temperature environment. Therefore, the internal structure of the lithium-ion secondary battery, specifically the solid It is suitable for use as an electrolyte.

[0145] An example of graphene oxide is shown in structural formula (300). In structural formula (300), a graphene layer ( G layer) has epoxy groups, hydroxyl groups, and carboxyl groups. The type and number of functional groups contained in the oxidized graphene are not limited thereto.

[0146] [ka]

[0147] A simplified structure of graphene oxide is shown in general formula (G3). In general formula (G3), "Graphene layer" stands for graphene layer. Graphene layer is formed by bonding carbon atoms. The number of layers may be one or more, and the graphene layer may be free of defects or The graphene oxide may have a functional group. Hereinafter, the graphene oxide will be described using the general formula (G3). Although the general formula (G3) shows two hydroxyl groups, in the present invention, The type and number of functional groups in the phenyl layer are not limited to those mentioned above.

[0148] [ka]

[0149] Next, an example of a method for producing graphene oxide will be described. Alternatively, multi-graphene can be oxidized to obtain graphene oxide. Graphite oxide can be obtained by oxidizing graphite. Here, the graphene oxide can be further chemically modified with the above-mentioned atoms or atomic groups. You may do so.

[0150] <Chemically modified graphene compounds> Next, we will explain chemically modified graphene compounds. The graphene compound produced by the production method according to one aspect of the present invention is, for example, It can be used as a solid electrolyte in a lithium ion secondary battery. In that case, the positive and negative electrodes In order to prevent shorting, the insulating material must have insulating properties. The graphene compound can contain not only lithium but also sodium, magnesium, calcium, etc. Since it also has metal ion conductivity, it can be used for purposes other than lithium-ion secondary batteries. In the present embodiment, lithium ions are used as a representative of such metal ions. This article describes a storage device using metal ions as a carrier, but it is also possible to use other metal ions as a carrier. The description can also be applied to a power storage device.

[0151] Pure graphene is known to have high electronic conductivity, and in its original form, it is difficult to transfer lithium ions. Graphene oxide cannot be used as a solid electrolyte in secondary batteries. Although the thermal conductivity is relatively low, it is easily reduced to RGO, which has poor reduction resistance and high electronic conductivity. In order to make these insulating, graphene oxide or graphene is chemically modified. For example, it is preferable to insulate the acid by using a molecule having an alkyl chain with a relatively large number of carbon atoms. It is possible to chemically modify graphene oxide or graphene. When both sides of the silicon are chemically modified with a compound having a long-chain alkyl group, the alkyl chain becomes electronically conductive. Since the functional group is poor in electron transport, the distance between multiple graphene oxide sheets is increased, It can be insulated to block conduction.

[0152] However, alkyl groups are non-polar functional groups and are not responsible for the battery reaction in lithium-ion secondary batteries. Therefore, it is difficult to obtain a good affinity with lithium ions, which are compounds with long-chain alkyl groups. When laphene is chemically modified, the movement of lithium ions is inhibited, inhibiting the battery reaction. Therefore, graphene compounds chemically modified with compounds having long-chain alkyl groups can be used as solid-state electrodes. A lithium ion secondary battery using this as an electrolyte has poor output characteristics.

[0153] In view of this, the graphene compound according to one embodiment of the present invention has insulating properties and at the same time has lithium ionization properties. For example, a graphene compound that has an affinity for cations can be chemically modified to have an ester group. Alternatively, it is preferable to use a graphene compound having a functional group including a carboxyl group. The alkyl and carboxyl groups are also classified as hydrophilic groups, and their polarity determines their affinity with lithium ions. It has compatibility with other metals and can contribute to the dissociation of the lithium salt and the migration of lithium ions. Furthermore, when the graphene compound is used as a solid electrolyte in a lithium ion secondary battery, The more ester or carboxyl groups in the functional group of the laphene compound, the more lithium This is preferred since it improves the mobility of ions.

[0154] The more ester or carboxyl groups there are, the larger the molecular weight becomes, and the more difficult it is to dissolve in a solvent. This may result in poor reactivity when chemically modifying graphene or graphene oxide. In addition, if the number of ester groups increases, hydrolysis may occur more easily. The number of ester groups or carboxyl groups is preferably 1 or more and 10 or less.

[0155] Another embodiment of the present invention is a graphene represented by the following general formula (G1) or general formula (G2). It is a compound.

[0156] [ka]

[0157] In the general formula (G1) and the general formula (G2), G layer represents a graphene layer.

[0158] In the general formula (G1) and the general formula (G2), R 1 represents a substituted or unsubstituted alkyl group. S, R 1 may be branched. Also, R 2 is hydrogen, or a substituted or unsubstituted alkyl represents a group, R 2 In addition, the general formula (G1) may have an ester group. In the general formula (G2), R 2 When is an alkyl group, Since the general formula (G2) has an ester group, it is classified as an ester. Hey, R 2 When is hydrogen, general formula (G2) has a carboxyl group, so It is classified as an acylphosphoric acid.

[0159] The substitution in the above general formula (G1) or the above general formula (G2) is preferably a methyl group. , ethyl group, n-propyl group, iso-propyl group, sec-butyl group, tert-butyl group an alkyl group having 1 to 6 carbon atoms, such as an n-pentyl group, an n-hexyl group, Phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group, 2-naphthyl group It represents substitution by a substituent such as an aryl group having 6 to 10 carbon atoms. It also represents substitution by a substituent such as fluorine or trifluoromethane.

[0160] Also preferably, R 1 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms Also preferably, R 2 is hydrogen, or a substituted or unsubstituted C1 to C20 The alkyl group is a carboxyl group. Compared to graphene or graphene oxide, chemically modified graphene Compounds may have a large interlayer distance. The larger the interlayer distance, the lower the electronic conductivity. Therefore, when used as a solid electrolyte, it is possible to prevent short circuits (internal short circuits) between the positive and negative electrodes. Alternatively, R is preferably set to a layer distance that provides the desired electronic conductivity. 1 and R 2 can be appropriately selected.

[0161] Also preferably, R 1 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms Also preferably, R 2 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms. From the viewpoint of dispersibility in a solvent and ionic conductivity, the solid electrolyte of a lithium-ion secondary battery It is a preferred material for quality control.

[0162] The graphene of the graphene compound according to one embodiment of the present invention has only one molecular weight or structure. The present invention is not limited to the above, and graphene of any size can be applied. It is not possible to specify the molecular structure of the graphene compound according to the embodiment in detail and to completely express it. Therefore, the chemically modified graphene compound according to one embodiment of the present invention can be used at least A substituted or unsubstituted group containing one or more ester groups, or a substituted or unsubstituted group containing a carboxyl group Graphene compounds chemically modified with silicon compounds having substituted or unsubstituted groups, In some cases, it may be practical to specify the product by expressing its manufacturing process, etc. In some cases, it may be impossible or impractical to have no such layer. In some cases, the material is fixed to the graphene layer by two Si-O bonds, as shown in Fig. 1. In some cases, the material is fixed by one or three O bonds. The bond is also Si-O bond. The immobilization is not limited to this, and may be achieved by other bonding methods. Silicon atoms that are not bonded to the silicon layer may have hydroxyl or alkoxy groups bonded to them. be.

[0163] <Chemical modification> Next, the graphene or graphene oxide is chemically modified to form a chemically modified graphene compound. The following synthesis schemes (A-1) and (A-2) are shown for the method of producing the product. I will use this to explain.

[0164] [ka]

[0165] [ka]

[0166] In the synthetic scheme (A-1) and the synthetic scheme (A-2), the G layer is a graph Represents the yen layer.

[0167] As shown in the synthesis scheme (A-1) and the synthesis scheme (A-2), graphene or oxide Graphene is treated with a compound containing one or more ester or carboxyl groups in the presence of a Lewis base. By reacting the silicon compound containing the silane with the silicon compound, a chemically modified target compound can be obtained. Such a reaction is sometimes called silylation.

[0168] Silylation refers to the reaction of a hydroxyl group, an amino group, a carboxyl group, an amide group, or a mercapto group with a silyl group. This indicates that hydrogen atoms such as aryl, aryl, and aryl groups are replaced by silicon atoms. The compound may be referred to as a silylating agent.

[0169] The Lewis base may be an alkylamine or a heterocyclic aromatic compound. ethylamine, pentylamine, hexylamine, diethylamine, dipropylamine, di One or more selected from butylamine, triethylamine, tripropylamine, and pyridine Just use it.

[0170] Also, an atmosphere of a gas inert to the reaction, for example a noble gas such as nitrogen or argon, may be used. It is preferable to carry out the reaction under a nitrogen or argon atmosphere. The reaction atmosphere is preferably nitrogen or ammonia. The gas is not limited to argon, but may be, for example, air.

[0171] In the synthetic scheme (A-1) and the synthetic scheme (A-2), R 1 is substituted or unsubstituted represents an alkyl group, R 1 may be branched. R 2 is hydrogen, or a substituted or unsubstituted represents an alkyl group, R 2 may be branched.

[0172] Also preferably, R 1 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms Also preferably, R 2 is hydrogen, or a substituted or unsubstituted C1 to C20 It is an alkyl group.

[0173] Also preferably, R 1 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms Also preferably, R 2 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms. do.

[0174] In the synthetic scheme (A-1) and the synthetic scheme (A-2), usable Lewis Examples of bases include butylamine, pentylamine, hexylamine, diethylamine, diamine, Propylamine, dibutylamine, triethylamine, tripropylamine, pyridine, etc. However, the Lewis bases that can be used are not limited to these. It is not something that can be done.

[0175] Solvents that can be used in the synthetic scheme (A-1) and the synthetic scheme (A-2) Examples include aromatic hydrocarbons such as toluene, xylene, and methanesulfonate, as well as hexane and heptane. and ethers such as ethylene glycol dimethyl ether. However, the solvents that can be used are not limited to these. In particular, Lewis bases A more preferable combination is one in which a primary amine is used as the reactant and an aromatic hydrocarbon is used as the solvent.

[0176] In addition to the silicon compounds shown in the synthetic schemes (A-1) and (A-2), triazines can also be used. However, the present invention is not limited to these. stomach.

[0177] <Specific Example> Here, a chain-like silicon compound having one or more ester groups or carboxyl groups is Examples of the silicon compounds are shown below. By using these silicon compounds, one or more esters can be To prepare a graphene compound chemically modified with a chain-like group having a carboxyl group or a carboxyl group. Compounds 100 to 149 and Compounds 156 to 1 Compound 61 has an ester group and is classified as an ester. Compounds 150 to 155 are It has a carboxyl group and is classified as a carboxylic acid.

[0178] [ka]

[0179] [ka]

[0180] [ka]

[0181] [ka]

[0182] [ka]

[0183] By using the silicon compound as described above, at least one ester group or carboxyl group can be obtained. It is possible to produce a graphene compound having a chain-like group containing a carboxyl group. The graphene compound chemically modified with the silicon compound has low electronic conductivity. On the other hand, because of its high lithium ion conductivity, it is used as a solid electrolyte and separator for lithium ion secondary batteries. However, the graphene compound according to one embodiment of the present invention is It is not limited to being made using the silicon compounds mentioned above.

[0184] Note that one embodiment of the present invention has been described in this embodiment. An embodiment of the present invention will be described below. However, the embodiment of the present invention is not limited to these. For example, in one embodiment of the present invention, at least one ester group or carboxyl group is Although an example of a graphene compound having a chain group containing a sil group has been shown, one embodiment of the present invention is Not limited to:

[0185] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0186] (Embodiment 4) A novel power storage device can be realized by using the solid electrolyte obtained in the above embodiment.

[0187] The new power storage device can be used in, for example, mobile information terminals such as mobile phones, hearing aids, imaging devices, vacuum cleaners, Power tools, electric shavers, lighting equipment, toys, medical equipment, robots, electric vehicles (hybrid It is used as a power source for driving vehicles (electric vehicles) and as a power storage source for buildings including homes. It can be used.

[0188] In addition to supplying power to various components, the new power storage device can also be charged. This allows electricity to be stored from other sources, and is useful for storing electricity in power generation facilities such as solar panels. It can also be used as a device, which leads to energy savings and CO2 reduction.

[0189] 3A and 3B show an example of the configuration of a thin power storage device. A wound body 993 shown in FIG. , a positive electrode 995 , and a separator 996 .

[0190] The wound body 993 is formed by stacking a negative electrode 994 and a positive electrode 995 with a separator 996 in between. The laminated sheet is then wound. This wound body 993 is placed in a square sealed container or the like. A rectangular electricity storage device is manufactured by covering the device with a material such as a polysilicon.

[0191] The number of layers of the negative electrode 994, the positive electrode 995, and the separator 996 is determined as required. The negative electrode 994 is connected to the lead electrode 997 and the lead The positive electrode 995 is connected to a negative electrode collector (not shown) via one of the lead electrodes 998. The other of the electrode 997 and the lead electrode 998 is connected to a positive electrode current collector (not shown).

[0192] The power storage device 990 shown in FIG. 3B and FIG. 3C has the above-described winding inside an exterior body 991. The winding body 993 includes a lead electrode 997 and a lead electrode 998, and the inside of the exterior bodies 991 and 992 is impregnated with an electrolyte. The outer casing 99 can be made of a metal material such as aluminum or a resin material. If a resin material is used as the material for 1, 992, the exterior body 991 will not break when a force is applied from the outside. , 992 can be deformed, and a flexible thin power storage device can be manufactured. .

[0193] FIG. 4A shows an example of a mobile phone. A mobile phone 7400 is provided in a housing 7401. In addition to the built-in display unit 7402, operation buttons 7403, external connection port 7404, The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. The device has a position 7407.

[0194] 4B is a projection view for explaining an example of the external appearance of the information processing device 200. The information processing device 200 described below includes a calculation device 210, an input / output device 220, and a display unit 230. and a power storage device 250.

[0195] The information processing device 200 includes a communication unit, which supplies information to a network and It also has a function to acquire information from the work. It also distributes information to a specific space using the communication unit 290. The image information may be generated based on the received information. For example, It can receive and display educational materials distributed in classrooms at schools or universities, etc., and can be used as textbooks. Or, materials distributed in a conference room of a company or the like can be received and displayed.

[0196] In addition, a graphene according to one embodiment of the present invention may be mounted on a wearable device as shown in FIG. It is possible to mount an electricity storage device using an inorganic compound.

[0197] For example, it can be mounted on a glasses-type device 400 as shown in FIG. The device 400 includes a frame 400a and a display unit 400b. By installing a power storage device in the temple of the 400a, the weight balance is good and the continuous use time is long. The device 400 may be a long pair of glasses.

[0198] The present invention can also be implemented in a headset type device 401. 401 includes at least a microphone part 401a, a flexible pipe 401b, and an earphone. The flexible pipe 401b and the earphone section 401c are provided with a storage battery. A location can be provided.

[0199] It can also be mounted on a device 402 that can be attached directly to the body. A power storage device 402b can be provided in the second thin housing 402a.

[0200] It can also be mounted on a device 403 that can be attached to clothing. A power storage device 403b can be provided in the thin housing 403a.

[0201] In addition, a power storage device can be mounted on the wristwatch type device 405. 05 has a display part 405a and a belt part 405b, and the display part 405a or the belt part 405b When a power storage device is provided in the belt portion 405b, It is preferable that the storage medium has flexibility. In addition, the storage medium has a curved surface so that it can be shaped to fit the arm. An electrical device may also be provided.

[0202] The display unit 405a can display not only the time, but also various other information such as incoming mail and phone calls. This can be done.

[0203] The wristwatch type device 405 is a wearable device that is worn directly on the arm. Therefore, sensors for measuring the user's pulse, blood pressure, etc. may be installed. It can also accumulate data on your health and can be used to help maintain your health.

[0204] It can also be mounted on a belt-type device 406. The belt-type device 406 is The wireless power supply receiving unit 406b is disposed inside the belt portion 406a. A power storage device can be mounted.

[0205] In addition, by using the power storage device of one embodiment of the present invention as a power storage device for daily electronic products, We can provide products with long life spans. For example, electric toothbrushes, electric shavers, and other everyday electronic products. These products include electric beauty devices, etc., and the storage devices for these products are Considering the convenience of using the battery, there is a demand for a small, lightweight, large-capacity storage device that is stick-shaped. FIG. 4(D) is a perspective view of a device also called a tobacco-containing smoking device (electronic cigarette). In FIG. 4(D), an electronic cigarette 7410 includes an atomizer 7411 including a heating element and an atomizer 7412. A power storage device 7414 that supplies power to the myser, and a cart including a liquid supply bottle, a sensor, etc. In order to improve safety, the power storage device 7414 is configured to be overcharged or overcharged. A protective circuit for preventing discharge may be electrically connected to the power storage device 7414. The power storage device 7414 has an external terminal so that it can be connected to a charging device. 14 is the tip when held, so the total length is short and the weight is light. Since the power storage device of one embodiment of the present invention has a high capacity and favorable cycle characteristics, We offer the 7410, a small and lightweight electronic cigarette that can be used for long periods of time. can.

[0206] When a power storage device is installed in a vehicle, it becomes a hybrid vehicle (HEV), an electric vehicle (EV), or a power storage device. This will make it possible to realize next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs). .

[0207] The automobile 8400 shown in FIG. 5A is a hybrid vehicle (HV) having a power storage device 8402. The power storage device 8402 is a power source for driving the vehicle or a headlight. Used as a power source for 8401 etc.

[0208] The automobile 8500 shown in FIG. 5B is an electric vehicle (EV). The power storage device receives power from an external charging facility by plugging in or contactless power supply. FIG. 5(B) shows a charging device 8021 installed on the ground and a charging station 8022 installed on the ground. This shows the state in which the power storage device mounted on the 8500 is being charged via cable 8022. When charging, please refer to CHAdeMO (registered trademark) or the specifications of the connector. The charging device 8021 may be a charging device provided in a commercial facility. It can be a station or a home power source. For example, plug-in technology This allows the power storage device mounted on the automobile 8500 to be charged by an external power supply. Charging is done by converting AC power to DC power through a converter such as an AC / DC converter. This can be done.

[0209] Although not shown, a power receiving device is mounted on the vehicle and receives power from a ground power transmitting device in a non-contact manner. In this non-contact power supply method, a power transmission device is installed on the road or exterior wall. By incorporating this technology, charging can be done not only when the vehicle is stopped but also while it is moving. Using this method, electric power may be transmitted between vehicles. A solar cell may be provided to charge the power storage device while the vehicle is stopped or running. The power can be supplied using an electromagnetic induction method or a magnetic resonance method.

[0210] In addition, the power storage device mounted on the vehicle can be used as a power supply source for something other than the vehicle. In this case, it is possible to avoid using commercial power sources during peak power demand periods.

[0211] In addition, the power storage device can be used not only for large four-wheeled vehicles but also as a power source for small vehicles. For example, a scooter or other motorcycle, or a flat surface between the two wheels on which you can place your feet, The power storage device is installed in a mobile support robot that moves by shifting the center of gravity of the rider, etc. It may be used.

[0212] A scooter 8600 shown in FIG. 5C includes a power storage device 8602, a side mirror 8601, and a steering wheel. The power storage device 8602 supplies electricity to the direction indicator light 8603. This can be done.

[0213] The power storage device 8602 used in this embodiment has high heat resistance and can be used in a harsh environment such as a vehicle. In addition, the battery storage device used in this embodiment can be used for a long period of time. The device 8602 is useful because it can be used in a wide range of temperatures.

[0214] Note that this embodiment mode can be appropriately combined with other embodiment modes. EXAMPLES

[0215] A single cell using a layer including a graphene compound described in the above embodiment as a solid electrolyte of a secondary battery We fabricated a battery and conducted experiments to measure its charge and discharge characteristics.

[0216] FIG. 6 shows a secondary battery electrically connected to a measuring device 600 and a layer including a graphene compound. A schematic cross-sectional view of a sample used in the solid electrolyte layer of a secondary battery. Li4Ti5O 12 Thin Film 602 (manufactured by Toshima Manufacturing Co., Ltd.), a first PEO film 603, a second PEO film 604, A layer 601 containing a graphene compound (graphene compound + LiTFSA) and LiCoO2 A solid-state battery was assembled using a graphene thin film 602 (manufactured by Toshima Manufacturing Co., Ltd.). As a lithium salt to be mixed with the lithium compound, LiTFSA (LiN(CF3SO2)2:Li However, the present invention is not limited to the above. , other lithium salts (LiPF6, LiClO4, LiAsF6, LiBF4, LiAlC l4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, L iC(C2F5SO2)3, LiN(C4F9SO2)(CF3SO2), LiN(C2 F5SO2)2, etc.) may be used. The layer containing the graphene compound contains 3.3 wt% 300 μL of THF (tetrahydrofuran) solution containing the graphene compound and 5. The solution containing 100 μL of 1 wt% LiTFSA in THF was added to Naflon ( The first and second PEO films were dried on a PEO film to obtain a film. The film was made of approximately 1 g of PEO, approximately 0.32484 g of LiTFSA, and 15 ml of acetonite. The film was obtained by drying a solution containing ethylcellulose on a Naflon® film. The drying was carried out by holding the sample at 90° C. under vacuum and then leaving the sample in the air for 24 hours.

[0217] FIG. 7 shows the charge / discharge characteristics of an electricity storage device using the solid electrolyte. The figures show the results of measurements made on a single cell.

[0218] In Figure 7, the material shown as EO4-GO as an ether-modified graphene compound is This corresponds to the above-mentioned chemical formula 2. The thickness of this graphene compound-containing layer was 29 μm. In addition, the material shown as EO7-10-GO, which is an ether-modified graphene compound, This corresponds to the above-mentioned chemical formula 3. The thickness of this layer containing the graphene compound is 88 μm. In addition, the material shown as AUD-GO as an ester-modified graphene compound was This corresponds to chemical formula 4. The layer containing this graphene compound had a thickness of 25 μm.

[0219] In addition, the graphene compound (EO7-10-GO) was prepared at 70°C in a vacuum for 1 hour. The electrical conductivity after drying for 10 min was 1×10 -8 In addition, the tensile strength was 100°C and in a vacuum atmosphere. The conductivity after drying for 1 hour was 3.1 x 10 -9 S / cm. The conductivity after drying for 1 hour in an empty atmosphere was 3.2×10 -1 S / cm.

[0220] As shown in Figure 7, ether-modified graphene compounds and ester-modified graphene compounds The compound was confirmed to function as a solid electrolyte in a secondary battery. In comparison, ether-modified graphene compounds have excellent properties as solid electrolytes for secondary batteries. It can be said that this shows that.

[0221] The charge / discharge characteristics shown in FIG. 7 were measured as follows.

[0222] The theoretical capacity of the positive electrode is 137mAh / g, the rate is calculated, and the charging voltage is 2.6V. CCCV (constant current constant voltage) charging is performed, and CC discharging is performed with the discharge voltage set to 1V.

[0223] Here, CC (constant current) charging, CCCV charging, and CC discharging will be explained.

[0224] CC charging: CC charging is a method of charging a battery with a constant current throughout the entire charging period. This is a charging method in which current flows through a secondary battery and charging stops when the battery voltage reaches a certain level. As shown in FIG. 10(A), an equivalent circuit is assumed with an internal resistance R and a secondary battery capacity C. In this case, the secondary battery voltage V B is the voltage V across the internal resistance R R and the voltage V applied to the secondary battery capacity C C It is the sum of.

[0225] During CC charging, the switch is turned on and a constant current is applied, as shown in Figure 10(A). A current I flows through the secondary battery. During this time, the current I is constant, so according to Ohm's law (V R =R × I), the voltage V across the internal resistance R R On the other hand, depending on the secondary battery capacity C, Voltage V C increases over time. Therefore, the secondary battery voltage V B Over time, It increases with time.

[0226] And the secondary battery voltage V B When the voltage reaches a certain value, for example 4.1V, charging is stopped. When CC charging is stopped, the switch is turned off and the current I = 0. Therefore, the voltage V applied to the internal resistance R R Therefore, the internal resistance The voltage drop at R disappears, and the secondary battery voltage V B decreases.

[0227] The secondary battery voltage V during CC charging and after CC charging is stopped B and the charging current An example is shown in FIG. 10(C). The secondary battery voltage V B but, It shows a slight decrease after CC charging is stopped.

[0228] <CCCV charging> Next, we will explain CCCV charging. CCCV charging is first The battery is charged to a specified voltage, and then the current flowing is reduced by CV (constant voltage) charging. This is a charging method in which charging is performed until the battery reaches a cut-off current value, specifically, until the battery reaches a cut-off current value.

[0229] During CC charging, as shown in Figure 11(A), the constant current power supply switch is on, The constant voltage power supply is switched off and a constant current I flows through the secondary battery. During this time, the current I Since is constant, V R According to Ohm's law, the voltage V across the internal resistance R is R too On the other hand, the voltage V applied to the secondary battery capacity C is constant. C increases over time. Therefore, the secondary battery voltage V B increases over time.

[0230] and the secondary battery voltage V B When the voltage reaches a certain value, for example 4.3V, the CC charge is switched to C During CV charging, the constant voltage supply is switched to constant voltage charging, as shown in Figure 11(B). The power supply switch is turned on, the constant current power supply switch is turned off, and the secondary battery voltage V B is constant On the other hand, the voltage V of the secondary battery capacity C C V increases over time. B =V R +V C Therefore, V R According to Ohm's law, the current I flowing through the secondary battery is reduced. This causes the voltage V across the internal resistance R R However, it becomes smaller over time. Voltage V across resistor R R As a result, the secondary battery voltage V B becomes constant.

[0231] When the current I flowing through the secondary battery becomes a certain current, for example, a current equivalent to 0.01C, When CCCV charging is stopped, all switches are turned off as shown in Figure 11(C). The switch is turned off and the current I becomes 0. Therefore, the voltage V across the internal resistance R R is 0V However, the voltage V applied to the internal resistance R due to CV charging R was small enough Therefore, even if the voltage applied to the internal resistance R disappears, the secondary battery voltage V B Almost fell do not have.

[0232] The secondary battery voltage V during CCCV charging and after CCCV charging is stopped B And An example of the charging current is shown in Figure 11(D). Even if the CCCV charging is stopped, the secondary battery voltage V B Gahoto The figure shows that the aircraft barely descends at all.

[0233] CC discharge: Next, we will explain CC discharge. CC discharge is a type of discharge in which the current is constant throughout the entire discharge period. When a current flows from the secondary battery and the secondary battery voltage VB reaches a certain voltage, for example 2.5 V, This is a discharge method in which the discharge is stopped immediately.

[0234] The secondary battery voltage V during CC discharge B An example of the discharge current is shown in Fig. 12. According to the secondary battery voltage V B The figure shows how the light descends.

[0235] Next, the discharge rate and the charge rate will be described. It is the relative ratio of the current during discharge and is expressed in units of C. For a battery with a rated capacity of X (Ah), In this case, the current equivalent to 1C is X(A). When discharging with a current of 2X(A), the current is 2C. If it is discharged at a current of X / 5(A), it is said to be discharged at 0.2C. The charging rate is also the same; if you charge with a current of 2X(A), it will be charged at 2C. When the battery was charged with a current of X / 5(A), it was charged at 0.2C. .

[0236] Next, the ionic conductivity of the layer containing the graphene compound is measured. A first PEO filter is placed between a pair of stainless steel electrodes 802 and 805 electrically connected to 800. A layer 801 containing a graphene compound is sandwiched between a first PEO film 803 and a second PEO film 804. FIG. 8(B) is a schematic cross-sectional view of a sample electrically connected to a measuring device 800. A pair of stainless steel electrodes, a first PEO film 803 between the pair of stainless steel electrodes, 8 is a schematic cross-sectional view of a comparative cell in which only the second PEO film 804 is sandwiched.

[0237] A first PEO film 803 and a second PEO film 804 are placed between a pair of stainless steel electrodes. The comparison cell containing only 04 contains about 1g of PEO, about 0.32584g of LiTFSA, and Two films were obtained by vacuum drying at 65°C using a solution containing 15 ml of acetonitrile. The thickness of the two PEO films was 190 μm. Although an example in which a stainless steel electrode is used as a current collector has been shown, an aluminum electrode may also be used.

[0238] A film was formed by using a THF solution as a solvent and heating at 90°C in vacuum. The thickness of the AUD-GO film was 37 μm. The AUD-GO film weighed approximately 1 g. A solution containing PEO, approximately 0.32584 g of LiTFSA, and 15 ml of acetonitrile Two films were prepared by vacuum drying at 65°C using AU 37μm thick. The AUD-GO film was prepared using a 37 μm thick film of 3.3 wt% A. 300 μL of THF solution containing UD-GO, 3.7988 g of THF, and LiTFSA The solution was mixed with 100 μL of a THF solution prepared with 0.2046 g of Naflon ( The film was obtained by drying on a 37 μm-thick AUD-GO film. The sample was sandwiched between two PEO films (PEO / AUD-GO / PEO film thickness). The total thickness is 144 μm.

[0239] The AUDEO4-GO film was prepared by dissolving 3.3 wt% AUDEO4-GO in THF (tetrahydrofuran). 300 μL of a trihydrofuran solution and 5.1 wt% LiTFSA in THF solution The solution was dried on a Naflon® film to obtain a filter. The thickness of the AUDEO4-GO film was 32 μm. A sample in which an AUDEO4-GO film of 1.0 m was sandwiched between two PEO films (PEO / A The total thickness of the UDEO4-GO / PEO film is 145 μm. The material shown as AUDEO4-GO, which is an ester-modified graphene compound, was This corresponds to chemical formula 5.

[0240] The EO4-GO film was also prepared by dissolving 3.3 wt% EO4-GO in THF (tetrahydrofuran). 300 μL of a THF solution containing 5.1 wt% LiTFSA The solution was dried on a Naflon® film to form a film. The thickness of the EO4-GO film was 52 μm. A sample in which a GO film was sandwiched between two PEO films (PEO / EO4‐GO / PEO The total thickness of the film is 151 μm.

[0241] The EO7-10-GO film was also prepared by dissolving 3.3 wt% EO7-10-GO in THF. (tetrahydrofuran) solution 300 μL and T containing 5.1 wt% LiTFSA The solution to which 100 μL of HF solution had been added was dried on a Naflon® film. The thickness of the EO7-10-GO film was 41 μm. A sample in which a 41 μm EO7-10-GO film was sandwiched between two PEO films (PE The total thickness of the O / EO7-10-GO / PEO is 299 μm.

[0242] The result of calculating the lithium ion conductivity by measuring the AC impedance using the measuring device 800 The results are shown in Figure 9. After the cell was assembled, measurements were taken at 25°C, and the temperature was held at 60°C for 3 hours. Measurements were performed at 0°C and finally at 25°C. From the results in Figure 9, it is clear that these graphene The compound is capable of lithium ion conduction. The measurements are performed by adding lithium salt (LiTFSA) to the graphene compound.

[0243] As shown in FIG. 9, the ether-modified graphene compound (EO7-1 0-GO) exhibits the same or higher lithium ion conductivity at temperatures below 20°C.

[0244] From these findings, ether- or ester-modified graphene compounds are expected to be useful in solid-state batteries. It has sufficient lithium ion conductivity as a solid electrolyte for solid-state batteries. It has become clear that the oxygen contained in ethers and esters is highly polar. Therefore, it is considered that this contributes to the dissociation of the lithium salt and lithium ion conduction. In addition, these graphene compounds are easy to form into films, making them ideal for producing solid electrolyte membranes. I found that it also has the advantage of being easy to use. EXAMPLES

[0245] In this example, ether-modified and ester-modified graphene compounds (AUDEO4-G An example of fabricating a layer containing

[0246] In addition, AUDEO4-GO was used as an ether- and ester-modified graphene compound. The material shown corresponds to formula 5 above.

[0247] LiCoO2:AUDEO4-GO:LiTFSA:AB=50:26.4:13.6: The resulting ether- and ester-modified graphene compounds ( A cross-sectional photograph of a layer containing AUDEO4-GO is shown in Figure 13.

[0248] Then, a film (AUDEO4-GO) consisting of a layer containing a graphene compound was placed on top of it. The sample is prepared by placing a PEO film and a lithium foil. EXAMPLES

[0249] In this example, a layer containing an ether-modified graphene compound (EO7-10-GO) was prepared. An example of how to make it is shown below.

[0250] In addition, the material shown as EO7-10-GO as an ether-modified graphene compound is This corresponds to chemical formula 3 described above.

[0251] LiCoO2:EO7-10-GO:LiTFSA:AB=50:26.4:13.6: The resulting ether-modified graphene compound (EO7-10-G A cross-sectional photograph of a layer containing SiO is shown in FIG.

[0252] Then, a film consisting of a layer containing a graphene compound (EO7-10-GO film) was formed on the graphene compound. The sample is prepared by placing a PEO film and a lithium foil on the substrate. [Explanation of symbols]

[0253] 100 Lithium-ion secondary battery 101 Positive electrode 102 Negative electrode 103 Layer containing graphene compounds 104 Substrate 105 Wiring electrode 106 Wiring electrode 107 Cathode active material 108 Negative electrode active material 111 Current collector 112 Current collector 113 Layer containing graphene compounds 113a Layer containing graphene compound 113b Layer containing graphene compounds 113c Layer containing graphene compound 119 Solid electrolyte layer 200 Information processing device 210 Arithmetic equipment 220 I / O device 230 Display section 250 Energy Storage Device 290 Communications Department 300 THF solution 400 Glasses-type device 400a frame 400b Display section 401 Headset-type device 401a Microphone section 401b Flexible Pipe 401c Earphone section 402 Devices 402a Case 402b Energy storage device 403 Device 403a Case 403b Energy storage device 405 Wristwatch-type device 405a Display section 405b Belt section 406 Belt-type device 406a Belt section 406b Wireless power receiving unit 600 Measuring Equipment 601 Layer containing graphene compounds 602 Thin Film 603 First PEO film 604 Second PEO film 800 Measuring Equipment 801 Graphene compound-containing layer 802 Stainless steel electrode 803 First PEO film 804 2nd PEO film 805 Stainless steel electrode 990 Power storage device 991 Exterior body 992 Exterior body 993 Wound body 994 negative electrode 995 positive electrode 996 Separator 997 Lead Electrode 998 Lead Electrode 7400 Mobile Phone 7401 Case 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Mike 7407 Energy storage devices 7410 Electronic cigarettes 7411 Atomizer 7412 Cartridge 7414 Electricity storage device 8021 Charging device 8022 Cable 8400 Automobiles 8401 Headlight 8402 Energy storage devices 8500 Automobiles 8600 Scooter 8601 Side mirror 8602 Energy storage devices 8603 Turn signal light

Claims

1. a first electrode having a positive electrode active material, a solid electrolyte layer, a layer having a graphene compound, and a second electrode having a negative electrode active material; a layer having the graphene compound between the solid electrolyte layer and the second electrode; The graphene compound-containing layer has ion conductivity and a function of preventing a short circuit between the first electrode and the second electrode.

2. a first electrode having a positive electrode active material, a first solid electrolyte layer, a second electrode having a negative electrode active material, a second solid electrolyte layer, and a layer having a graphene compound; a layer having the graphene compound between the first solid electrolyte layer and the second solid electrolyte layer; The graphene compound-containing layer has ion conductivity and a function of preventing a short circuit between the first electrode and the second electrode.

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