Electrode

Abstract

To provide a novel electrode, a novel power storage device, an electrode with less deterioration, an electrode with a high capacity, a long-life power storage device, a power storage device with less deterioration, a power storage device with high energy density, and a highly reliable power storage device.SOLUTION: An electrode includes a graphene compound including a graphene layer and a substituted or unsubstituted chain group, and an active material. The graphene layer is bonded to the chain group through a substituent containing silicon. The active material is in particle form. The graphene compound includes a region in contact with the active material. The active material includes an element A, which is one or more elements selected from elements belonging to Group 1 and elements belonging to Group 2, and an element M, which is one or more elements selected from manganese and nickel. The chain group includes one or more groups selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. In particular, one aspect of the present invention relates to a power storage device, a storage battery, an electrode, a positive electrode, a semiconductor device, a display device, a light emitting device, a storage device, a driving method thereof, or a manufacturing method thereof. In particular, one aspect of the present invention relates to an electrode and a method for producing the same. Note that in this specification, the power storage device refers to all elements and devices having a power storage function.

[0002]

Background Art

[0003] In recent years, various power storage devices such as storage batteries such as lithium ion batteries, lithium ion capacitors, and air batteries have been actively developed. In particular, lithium ion batteries with high output and high energy density are used in portable information terminals such as mobile phones, smartphones, and notebook personal computers, electronic devices such as portable music players and digital cameras, or medical devices, hybrid electric vehicles (HEVs), electric vehicles (EVs), or plug-in hybrid vehicles (PHEVs). Along with the development of the semiconductor industry, the demand for these devices has rapidly expanded, and they have become indispensable as a source of rechargeable energy in modern information society.

[0004] When a lithium ion battery is charged and discharged, elements contained in the active material may dissolve into the electrolyte. Due to this dissolution, the capacity of the power storage device may decrease. Patent Document 1 describes the dissolution of manganese ions into the electrolyte. ​

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] One aspect of the present invention aims to provide a novel electrode. Or, one aspect of the present invention aims to provide a novel power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device.

[0007] It should be noted that the description of these problems does not prevent the existence of other problems. It should be noted that one aspect of the present invention does not necessarily need to solve all of these problems. It should be noted that other problems will become apparent from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device.

[0008] It should be noted that the description of these problems does not prevent the existence of other problems. It should be noted that one aspect of the present invention does not necessarily need to solve all of these problems. It should be noted that other problems will become apparent from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device. One aspect of the present invention aims to provide an electrode with less deterioration. Or, one aspect of the present invention aims to provide an electrode with a large capacity. Or, one aspect of the present invention aims to provide a power storage device with a long life. Or, one aspect of the present invention aims to provide a power storage device with less deterioration. Or, one aspect of the present invention aims to provide a power storage device with a high energy density. Or, one aspect of the present invention aims to provide a highly reliable power storage device.

Means for Solving the Problems

[0009] One aspect of the present invention has an active material and a graphene compound, where the graphene compound has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode. The graphene layer has a graphene layer and a substituted or unsubstituted chain group, and the graphene layer is bonded to the chain group via a substituent having silicon. The active material is particulate, the graphene compound has a region in contact with the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the chain group has one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, and is an electrode.

[0010] Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode.

[0011]

Chemical formula

[0012] Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. Alternatively, one aspect of the present invention has an active material and a graphene compound, where the active material is particulate, the graphene compound has a region in contact with the surface of the active material, the active material has element A and element M, element A is one or more selected from Group 1 elements and Group 2 elements, element M has one or more selected from manganese and nickel, and the graphene compound has a structure represented by the following formula (G1) and is an electrode. and an element M, wherein the element A is one or more selected from elements of Group 1 and elements of Group 2 and the element M has one or more selected from manganese and nickel, and the graphene compound is an electrode having a structure represented by the following formula (G2).

[0013] [Chemical formula] (In the general formula (G2), G layer represents a graphene layer, and R 1 represents a substituted or un substituted alkylene group, and R 2 represents hydrogen, or a substituted or unsubstituted alkyl group.) )

[0014] Alternatively, one aspect of the present invention has an active material and a graphene compound, the active material is in a particulate form, the graphene compound has a region in contact with the surface of the active material, and the active material has an element A and an element M, wherein the element A is one or more selected from elements of Group 1 and elements of Group 2 and the element M has one or more selected from manganese and nickel, and the graphene compound is an electrode having a structure represented by the following formula (G3).

[0015] [Chemical formula] (In the general formula (G3), G layer represents a graphene layer, and R 3 represents a substituted or unsubstituted chain-like group having at least two or more ether bonds.)

[0016] Further, in the above aspect, it is preferable that the graphene compound has a function of trapping the element M.

[0017] ​Alternatively, one aspect of the present invention has the electrode described in any one of the above, and includes an exterior body and an electrolytic solution and a separator and a negative electrode, and is a power storage device.

Advantages of the Invention

[0018] According to one aspect of the present invention, a novel electrode can be provided. Also, according to one aspect of the present invention a novel power storage device can be provided.

[0019] Also, according to one aspect of the present invention, an electrode with less deterioration can be provided. Also, according to one aspect of the present invention, an electrode with a large capacitance can be provided. Also, according to one aspect of the present invention a power storage device with a long lifespan can be provided. Also, according to one aspect of the present invention, deterioration of a power storage device with less deterioration can be provided. Also, according to one aspect of the present invention, an energy density a high power storage device can be provided. Also, according to one aspect of the present invention, a highly reliable power storage device can be provided.

[0020] Note that the description of these effects does not preclude the existence of other effects. Note that one aspect of the present invention does not necessarily have to have all of these effects. Note that other effects will be apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc.

Brief Description of the Drawings

[0021]

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Mode for Carrying Out the Invention

[0022] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to these descriptions, and those skilled in the art can easily understand that the form and details can be variously changed. Therefore, the present invention is not construed as being limited to the description of the embodiments shown below.

[0023] In each of the drawings described in this specification, the sizes and thicknesses of elements such as films, layers, substrates, regions, etc. may be exaggerated for the sake of clarity of description. Therefore, each component is not necessarily limited to its size, nor is it limited to the relative size between each component.

[0024] In this specification, etc., ordinal numbers such as first, second, etc. are used for convenience and do not indicate the order of steps or the order of lamination, etc. Therefore, for example, "the first" can be appropriately replaced with "the second" or "the third" etc. for explanation. Also, the ordinal numbers described in this specification, etc. may not match the ordinal numbers used to identify an aspect of the present invention.

[0025] In the configuration of the present invention described in this specification, etc., the same reference numerals are commonly used for the same part or parts having the same function among different drawings, and the repeated description thereof is omitted. Also, when referring to parts having the same function, the hatch patterns may be the same and may not be particularly labeled with reference numerals.

[0026] ​​​​​​ In the present specification and the like, both the positive electrode and the negative electrode for the power storage device are collectively referred to as electrodes. However, in this case, the electrode indicates at least one of the positive electrode and the negative electrode.

[0027] Here, the rate in the charging and discharging of the power storage device will be described. For example, when a secondary battery with a capacity of X Ah] is charged at a constant current, the charging rate of 1C means the current value I [A] at which charging is just completed in exactly 1 hour, and the charging rate of 0.2C means I / 5 [A] (that is, the current value at which charging is just completed in exactly 5 hours). Similarly, the discharging rate of 1C means the current value I [A] at which discharging is just completed in exactly 1 hour, and the discharging rate of 0.2C means I / 5 [A] (that is, the current value at which discharging is just completed in exactly 5 hours).

[0028] (Embodiment 1) A power storage device according to an aspect of the present invention includes a layer having a graphene compound, a positive electrode, and a negative electrode. The positive electrode and the negative electrode each have an active material. By providing a layer having a graphene compound in the power storage device, for example, a metal released from the active material can be captured by the layer. Further, the layer is preferably provided near the active material, for example, such that a part of it is in contact with the active material.

[0029] <Structural Example> FIG. 1(A) shows an example of a cross-section of an electrode according to an aspect of the present invention. The electrode 210 has an active material layer 21 2 and a layer 213 on the active material layer 212.

[0030] The active material layer 212 has an active material 221. The active material 221 has an element M. The element M is a ​​​​​Manganese, nickel, cobalt, chromium, aluminum, iron, molybdenum, zinc, indium ium, gallium, copper, titanium, niobium, vanadium, and one or more selected therefrom, particularly preferably manganese or nickel.

[0031] In addition to element M, the active material 221 has an element A that functions as a carrier ion. Element A is preferably one or more selected from elements of Group 1 and elements of Group 2. As the element of Group 1, for example, alkali metals such as lithium, sodium, potassium, etc. can be used. Also, as the element of Group 2, for example, calcium, beryllium, magnesium, etc. can be used.

[0032] The active material 221 can be either a positive electrode active material or a negative electrode active material.

[0033] Layer 213 has a graphene compound. The graphene compound has a graphene layer and a substituted or unsubstituted chain-like group, and the graphene layer is bonded to the chain-like group through a substituent having, for example, silicon.

[0034] Here, when the graphene compound has, for example, a highly polar functional group as the chain-like group, the function of the graphene compound to trap the cation 252 may be improved. As the chain-like group, it is preferably one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, an epoxy group, etc., and more preferably an ester group or a carboxyl group.

[0035] Here, when the graphene compound has low electron conductivity, when it functions as a separator There is. When the graphene compound has a chain-like group, when it comes into contact with the negative electrode, the reduction at the potential of the negative electrode may be suppressed. There are cases where reduction is suppressed.

[0036] Also, layer 213 is, for example, a graphene compound sheet.

[0037] The longitudinal direction of the graphene and multi-graphene constituting the graphene compound, or the length of the major axis on the plane is 50 nm or more and 100 μm or less, or 800 nm or more and 50 μm or less is. Details about the graphene compound, graphene compound sheet, graphene, and multi-graphene will be described later. Also, it is sometimes preferable for the graphene and multi-graphene to be small. There are cases where it is preferable. There are cases where it is preferable.

[0038] Also, the electrode 210 may have a current collector 211, and it is preferable that the active material layer 212 is provided on the current collector 211. There are cases where it is preferable.

[0039] Layer 213 is provided on the active material layer 212. Layer 213 has a region in contact with the active material 221 that the active material layer 212 has. There are cases where it has a region in contact with the active material 221 that the active material layer 212 has.

[0040] Figure 1(B) is an enlarged view of the region 230 shown in Figure 1(A). In the example shown in Figure 1(B), as the active material 221, a plurality of particles are in contact with layer 213. It can also be said that layer 213 has a plurality of regions in contact with the active material 221. There are cases where it has a plurality of regions in contact with the active material 221.

[0041] In Figure 1(B), layer 213 is shown as a continuous layer or sheet, but as shown in Figure 1(C), layer 213 may be composed of a plurality of sheets. Also, layer 21 3 may penetrate into the active material layer 212.

[0042] FIG. 2 shows an example in which a plurality of sheets overlap as layer 213. It is preferable that the overlapping sheets are partially in contact. with each other.

[0043] <Operation of the power storage device> Next, the operation of the power storage device according to one aspect of the present invention will be described with reference to FIGS. 3 and 4. Here, the case where the electrode 210 functions as the positive electrode and the active material 221 is the positive electrode active material will be described. explained.

[0044] The power storage device according to one aspect of the present invention includes an electrode 210 that functions as a positive electrode and an electrode 220 that functions as a negative electrode. Let the ion of element A be cation 251 and the ion of element M be cation 252. polar 220 and. 52 and.

[0045] First, charging will be described with reference to FIG. 3(A). In charging, element A is cationized from the active material 221 included in the active material layer 212, and cation 251 and electron 253 are released. The cation 251 reaches the electrode 220, which is the negative electrode, and is reduced. Note that in FIGS. 3 and 4, the active material 221 is not shown. active material 221, element A is cationized, and cation 251 and electron 253 are released. The cation 251 reaches the electrode 220, which is the negative electrode, and is reduced. In FIGS. 3 and 4, the active material 221 is not shown. not shown.

[0046] In addition, in charging, cation 252 may be released from the active material 221. The release of this cation 252 may be expressed as the elution of element M. Cation 252 reaches the electrode 220 and is reduced. Here, when cation 252 hardly reacts with the negative electrode active material, element M may form precipitate 254 along with the reduction reaction. Alternatively, when the reaction between cation 252 and the negative electrode active material is not reversible, in discharging, element M may be hardly ionized. 252 is released from the active material 221. The release of this cation 252 may be expressed as the elution of element M. Cation 252 reaches the electrode 2 20 and is reduced. Here, when cation 252 hardly reacts with the negative electrode active material, element M may form precipitate 254 along with the reduction reaction. Alternatively, when the reaction between cation 252 and the negative electrode active material is not reversible, in discharging, element M may be hardly ionized. active material, element M may form precipitate 254 along with the reduction reaction. Alternatively, when the reaction between cation 252 and the negative electrode active material is not reversible, in discharging, element M may be hardly ionized. negative electrode active material is not reversible, in discharging, element M may be hardly ionized. is present.

[0047] When the reaction potential of the negative electrode is lower than the potential at which the reduction decomposition of the electrolytic solution occurs, the electrolytic solution is decomposed by This type of film is formed by an irreversible reaction and may result in a decrease in capacity. When a precipitate 254 of element M is formed on the surface of the electrode 220 during charging, the precipitate A film may tend to build up on the deposits 254, causing a more pronounced loss of capacitance.

[0048] In addition, when the cation 252 is released from the active material 221 during charging (i.e., when the element M is If the active material 221 is dissolved, the crystal structure of the active material 221 may change and become unstable.

[0049] Next, the discharge will be described with reference to FIG. Thione 251 is released and reaches electrode 210 where it is reduced.

[0050] On the other hand, the ionic radius of the cation 252 is larger than the ionic radius of the cation 251 . Furthermore, the release of the cations 252 may cause a change in the crystal structure of the active material 221. In addition, the cations 252 that are desorbed from the active material 221 during charging are re-adsorbed into the active material 221 during discharging. It's difficult to get into 221.

[0051] FIG. 4 shows an example of an electrode 210 having a layer 213. The layer 213 may be, for example, a cation 252 It has the function of trapping.

[0052] When element M is cationized during charging, cation 252 and electron 253 are generated. Since the layer 213 has a function of trapping the cations 252, the electrode 2 On the other hand, cations 251 can diffuse through layer 213 to reach the electrode 20. It is preferable to reach 220.

[0053] When cation 252 is present in the electrolyte and its concentration reaches equilibrium, the dissolution of element M occurs. (Cationization) is suppressed. By capturing cations 252 in layer 213, the active material In layer 212, the concentration of cations 252 near the interface with layer 213 increases. Cations Since the concentration of 252 is high, the release of cations 252 on the surface of the active material layer 212 can be suppressed. That is, by providing layer 213, the elution of element M can be suppressed. It can be done.

[0054] Also, the graphene compound of one aspect of the present invention may have a chain-like group, resulting in low electrical conductivity. By providing layer 213, even when element A is deposited on the surface of electrode 220, the short circuit between the active material 221 of electrode 210 or current collector 211 and Element A deposited on the surface of electrode 220 may be suppressed, which is preferable. After charging, for example, layer 213 has element M.

[0055] After charging, for example, layer 213 has element M.

[0056] <Method for manufacturing an electrode> A method for manufacturing an electrode according to one aspect of the present invention will be described.

[0057] Electrode 210 has an active material and a graphene compound. Also, electrode 210 preferably has a positive electrode active material as the active material. It is preferable to have a positive electrode active material as the active material.

[0058] First, the active material layer 212 is manufactured. The active material layer 212 has an active material. Also, the active material layer 2 12 preferably has a binder and a conductive assistant. The binder and the conductive assistant will be described in the following embodiments. It will be described in the following embodiments.

[0059] The active material, other components, here for example a binder and a conductive assistant, and a solvent are mixed. Knead to prepare a slurry. The solvent used for preparing the slurry is preferably a polar solvent. For example, any one or a mixture of two or more of water, methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO) can be used.

[0060] Next, apply the slurry onto the current collector. The current collector will be described in the embodiments below. .

[0061] Next, perform heat treatment to volatilize the solvent from the slurry applied onto the current collector. Thereafter, pressing may be performed.

[0062] Through the above steps, the active material layer 212 is formed on the current collector.

[0063] Next, form layer 213. First, disperse the graphene compound in a solvent. Here, as the solvent, for example, any one or a mixture of two or more of water, methanol, ethanol, acetone, tetrahydrofuran (THF), di methylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethylene glycol, diethylene glycol, glycerin can be used.

[0064] Next, drop the prepared dispersion onto the active material layer 212. Alternatively, the active material layer 212 may be impregnated with the dispersion.

[0065] Next, perform heat treatment to volatilize the solvent from the dispersion. Performing the treatment in a reduced-pressure atmosphere makes it easier for the solvent to volatilize.

[0066] Through the above process, layer 213 is formed on the active material layer 212. The supported amount of the graphene compound in layer 213 is, for example, 0.2 mg / cm or more and 10 mg / cm 2 or less, or 2 for example, 0.5 mg / cm or more and 3 mg / cm 2 or less. 2

[0067] <Positive Electrode Active Material> As an example of the positive electrode active material 221, a positive electrode active material containing element M will be described.

[0068] As the positive electrode active material, a material having a spinel-type crystal structure represented by the general formula LiM2O4 can be used. Here, element M is preferably a metal, and for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals. For example, it may be manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li Here, element M is preferably a metal, for example, manganese can be used. Also, element M may be two or more selected from a plurality of metals, for example, manganese and one or more selected from metals other than manganese. Examples of metals other than manganese include nickel, cobalt, aluminum, iron, vanadium, etc. For example, when element M has nickel as a metal other than manganese, the discharge voltage may be improved, which is preferable because the energy density is improved. Further, a small amount of lithium nickelate (LiNiO2 or Li x Ni (1-x) XO2) may be mixed. Here, as element X, for example, cobalt, aluminum, etc. can be used. Here, as element X, for example, cobalt, aluminum, etc. can be used.

[0069] As the positive electrode active material, for example, a composite oxide having a layered rock salt-type crystal structure or a spinel-type crystal structure can be used. Also, as the positive electrode active material, for example, a polyanion-based As the positive electrode active material, for example, a composite oxide having a layered rock salt-type crystal structure or a spinel-type crystal structure can be used. Also, as the positive electrode active material, for example, a polyanion-based ​The positive electrode material can be used. Examples of polyanion-based positive electrode materials include olivine-type materials having a crystal structure, NASICON-type materials, and the like.

[0070] As the positive electrode active material, various composite oxides can be used. For example, LiFeO2, compounds such as LiCoO2, LiNiO2, LiMn2O4, V2O5, Cr2O5, and MnO2 can be used.

[0071] As a material having a layered rock salt-type crystal structure, for example, a composite oxide represented by LiMO2 can be used. The element M is preferably one or more selected from cobalt or nickel. LiCoO2 is preferable because it has advantages such as a large capacity, stability in the air, and thermal stability. In addition to one or more selected from cobalt and nickel, the element M may have one or more selected from aluminum and manganese. For example, LiCo Mn x Mn y Ni z O w (x, y, z, and w are, for example, x = y = z = 1 / 3 or in the vicinity thereof, and w = 2 or in the vicinity thereof) can be used.

[0072] The vicinity means, for example, a value greater than 0.9 times and less than 1.1 times that value.

[0073] Further, as the positive electrode active material, for example, a solid solution obtained by combining a plurality of composite oxides can be used. For example, a solid solution of LiCo 1 / 3 Mn 1 / 3 Ni 1 / 3 O2 and Li2MnO3 can be used as the positive electrode active material.

[0074] ​​As a material having a spinel crystal structure, for example, a composite oxide represented by LiM2O4 can be used. It is preferable that the element M has manganese. For example, LiM n2O4 can be used. Also, as the element M, having nickel in addition to manganese may improve the discharge voltage and energy density of the secondary battery, and is preferable . Further, a lithium-containing material having a spinel crystal structure containing manganese such as LiMn2O4 is mixed with a small amount of lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (M = Co, Al, etc.)), whereby the characteristics of the secondary battery can be improved and it is preferable .

[0075] The positive electrode active material preferably has an average particle diameter of primary particles of 5 nm or more and 100 μm or less , more preferably 50 nm or more and 50 μm or less, and even more preferably 100 nm or more and 50 0 nm or less. Also, the specific surface area is preferably 5 m 2 / g or more and 15 m 2 / g or less . Also, the average particle diameter of the secondary particles is preferably 5 μm or more and 50 μm or less . The average particle diameter can be measured by observation with SEM (scanning electron microscope) or TEM , or a particle size distribution meter using the laser diffraction / scattering method, etc. Also , the specific surface area can be measured by the gas adsorption method.

[0076] A conductive material such as a carbon layer may be provided on the surface of the positive electrode active material. By providing a conductive material such as a carbon layer , the conductivity of the electrode can be improved. For example, the coating of the carbon layer on the positive electrode active material is formed by mixing a carbohydrate such as glucose during the firing of the positive electrode active material . It is possible.

[0077] As a polyanion-based positive electrode material, for example, oxygen, element X, metal A, and metal M can be used. A polyanion-based positive electrode material containing oxygen, element X, metal A, and metal M can be used. Metal M is one or more of iron, manganese, cobalt, nickel, titanium, vanadium, and niobium, and metal A is one or more of lithium, sodium, and magnesium. Element X is one or more of sulfur, phosphorus, molybdenum, tungsten, arsenic, and silicon. Moreover, a composite material (general formula LiMPO4, where M is one or more of Fe(II), Mn(II), Co(II), and Ni(II)) can be used. Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFeNiPO4, LiFeCoPO4, LiFeMnPO4, LiNiCoPO4, LiNiMnPO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiFeNiCoPO4, LiFeNiMnPO4, LiNiCoMnPO4, LiFeNiCoMnPO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), and LiFeNiCoC oMnPO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1). Also, a composite material (general formula LiMPO4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II))) can be used. Representative examples of the general formula LiMPO4 are LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFeNiPO4, LiFeCoPO4, LiFeMnPO4, LiNiCoPO4, LiNiMnPO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiFeNiCoPO4, LiFeNiMnPO4, LiNiCoMnPO4, LiFeNiCoMnPO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), and LiFeNiCoCoMnPO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1). are provided.

[0078] Also, a composite material (general formula LiMPO4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II))) can be used. As representative examples of the general formula LiMPO4, LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiF e c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO 4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g C o h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1). Lithium compounds such as <i<1) can be used.

[0079] In particular, LiFePO4 satisfies well 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), and is thus preferable.

[0080] Also, composite materials such as the general formula Li (2-j) MSiO4 (M is one or more of Fe(II), Mn(II), Co( II), Ni(II); 0 ≦ j ≦ 2) can be used. As representative examples of the general formula Li (2-j) MSiO4, there are 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 Mn l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m N i n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Con Mn q SiO4 (where 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 (where r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. Lithium compounds can be used as materials in this way.

[0081] Also, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, N b, X = S, P, Mo, W, As, Si) represented by the general formula of NASICON-type compounds can be used for this purpose. Examples of NASICON-type compounds include Fe2(MnO4)3, Fe2(SO4)3 , Li3Fe2(PO4)3, etc. Also, as the positive electrode active material, compounds represented by the general formula of Li2MPO4F, L i2MP2O7, Li5MO4 (M = Fe, Mn) can be used in this way.

[0082] Also, polyanion-based positive electrode materials containing V can be used. Representative examples include α- LiVOPO4, β-LiVOPO4, α1-LiVOPO4, LiVPO4F, LiV PO4O, LiVP2O7, LiVOSO4, Li2VOSiO4, LiVMoO6, etc. can be mentioned.

[0083] Also, as the positive electrode active material, perovskite-type fluorides such as NaFeF3, FeF3, etc., T iS2, MoS2, etc. metal chalcogenides (sulfides, selenides, tellurides), oxides having an inverse spinel-type crystal structure such as LiM VO4, vanadium oxide-based (V2O5, V 6O 13, materials such as LiV3O8, manganese oxides, and organic sulfur compounds can be used. It is possible.

[0084] Also, as the positive electrode active material, a borate-based positive electrode material represented by the general formula LiMBO3 (M is Fe(II), Mn(II), Co(II)) can be used.

[0085] Also, as the positive electrode active material, a lithium a Mn b M c O d manganese composite oxide represented by can be used. Here, the element M is preferably a metal element selected from those other than lithium and manganese, or silicon or phosphorus, and more preferably nickel. Also, when measuring the entire particle of the lithium manganese composite oxide, it is preferable to satisfy 0 < a / (b + c) < 2, c > 0, and 0.26 ≤ (b + c) / d < 0.5 during discharge. In addition, in order to exhibit high capacity, it is preferable to use a lithium manganese composite oxide having regions with different crystal structures, crystal orientations, or oxygen contents in the surface layer portion and the central portion. To obtain such a lithium manganese composite oxide, for example, it is preferable to set 1.6 ≤ a ≤ 1.848, 0.19 ≤ c / b ≤ 0.935, and 2.5 ≤ d ≤ 3 Furthermore, it is particularly preferable to use a lithium manganese composite oxide represented by the composition formula of Li Mn Ni O3. In this specification, etc., the lithium manganese composite oxide represented by the composition formula of Li Mn Ni 1.68 Mn 0.8062 Ni 0.318 O3 means that the ratio (molar ratio) of the amounts of the raw material materials is Li2CO3:MnCO3:NiO = 0 lithium, and 1. 68 Mn 0.8062 Ni 0.318 O3, the lithium manganese composite A lithium manganese composite oxide formed by setting it to 1.84:0.8062:0.318. Therefore, the lithium manganese composite oxide has a composition formula Li 1.68 Mn 0.80 62 Ni 0.318 O3, but may deviate from this composition.

[0086] In addition, the composition of metals, silicon, phosphorus, etc. in the entire particles of the lithium manganese composite oxide can be measured, for example, using ICP-MS (inductively coupled plasma mass spectrometer). Also, the oxygen composition of the entire particles of the lithium manganese composite oxide can be measured, for example, using EDX (energy dispersive type X-ray analysis method). Also, it can be obtained by using valence evaluation of melting gas analysis and XAFS (X-ray absorption fine structure) analysis in combination with ICP-MS analysis. Here, the lithium manganese composite oxide refers to an oxide containing at least lithium and manganese, and may contain at least one element selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, silicon, and phosphorus. Note that the lithium manganese composite oxide may have regions with different crystal structures, crystal orientations, or oxygen contents. An example of a cross-sectional view of particles of a lithium manganese composite oxide is shown in Fig. 5. As shown in Fig. 5(A), it is preferable for the lithium manganese composite oxide having regions with different crystal structures, crystal orientations, or oxygen contents to have region 331, region 332, and region 333. Region 332 is in contact with at least a part of the outside of region 331. Here, the outside means...

[0087] A cross-sectional view of particles of a lithium manganese composite oxide having regions with different crystal structures, crystal orientations, or oxygen contents is shown in Fig. 5. An example of a cross-sectional view of particles of a lithium manganese composite oxide having regions with different crystal structures, crystal orientations, or oxygen contents is shown in Fig. 5.

[0088] As shown in Fig. 5(A), the lithium manganese composite oxide having regions with different crystal structures, crystal orientations, or oxygen contents preferably has region 331, region 332, and region 333. Region 332 is in contact with at least a part of the outside of region 331. Here, the outside means... means... It indicates being closer to the surface of the particle. Also, region 333 preferably has a region that coincides with the surface of the particle having a lithium manganese composite oxide. It is preferable that the particle having a lithium manganese composite oxide has a region that coincides with the surface.

[0089] Also, as shown in FIG. 5(B), region 331 may have a region not covered by region 332. Also, region 332 may have a region not covered by region 333. Further, for example, region 331 may have a region where region 333 is in contact with it. Also, region 331 may have a region not covered by either region 332 or region 333. For example, region 331 may have a region not covered by either region 332 or region 333. It is preferable that region 332 has a composition different from that of region 331.

[0090] For example, the compositions of region 331 and region 332 are measured separately. Suppose region 331 has lithium, manganese, element M, and oxygen, and region 332 has lithium, manganese, element M, and oxygen, and the atomic ratio of lithium, manganese, element M, and oxygen in region 331 is represented by a1:b1:c1:d1, and the atomic ratio of lithium, manganese, element M, and oxygen in region 332 is represented by a2:b2:c2:d2. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1.

[0091] For example, the compositions of region 331 and region 332 are measured separately. Suppose region 331 has lithium, manganese, element M, and oxygen, and region 332 has lithium, manganese, element M, and oxygen, and the atomic ratio of lithium, manganese, element M, and oxygen in region 331 is represented by a1:b1:c1:d1, and the atomic ratio of lithium, manganese, element M, and oxygen in region 332 is represented by a2:b2:c2:d2. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. For example, the compositions of region 331 and region 332 are measured separately. Suppose region 331 has lithium, manganese, element M, and oxygen, and region 332 has lithium, manganese, element M, and oxygen, and the atomic ratio of lithium, manganese, element M, and oxygen in region 331 is represented by a1:b1:c1:d1, and the atomic ratio of lithium, manganese, element M, and oxygen in region 332 is represented by a2:b2:c2:d2. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. For example, the compositions of region 331 and region 332 are measured separately. Suppose region 331 has lithium, manganese, element M, and oxygen, and region 332 has lithium, manganese, element M, and oxygen, and the atomic ratio of lithium, manganese, element M, and oxygen in region 331 is represented by a1:b1:c1:d1, and the atomic ratio of lithium, manganese, element M, and oxygen in region 332 is represented by a2:b2:c2:d2. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. Each composition of region 331 and region 332 can be measured, for example, by EDX (energy dispersive X-ray analysis method) using TEM (transmission electron microscope). In the measurement using EDX, it may be difficult to measure the composition of lithium. Therefore, hereinafter, the difference in the compositions of region 331 and region 332, or the elements other than lithium will be described. Here, d1 / (b1 + c1) is preferably 2.2 or more, more preferably 2.3 or more, and still more preferably 2.35 or more and 3 or less. Also, d2 / (b2 + c2) is preferably less than 2.2, preferably 2.1. More preferably, it is less than, and even more preferably, it is from 1.1 to 1.9. Also even in this case, the composition of the entire lithium manganese composite oxide particles including region 331 and region 332 preferably satisfies 0.26 ≦ (b + c) / d < 0.5 described above.

[0092] Also, the manganese in region 332 may have a valence different from that of the manganese in region 331. Also, the element M in region 332 may have a valence different from that of the element M in region 331.

[0093] More specifically, region 331 is preferably a lithium manganese composite oxide having a layered rock salt-type crystal structure. Also, region 332 is preferably a lithium manganese composite oxide having a spinel-type crystal structure.

[0094] Here, when there is a spatial distribution in the composition or valence of each region, for example, the composition and valence are evaluated at a plurality of locations, and the average value is calculated, which may also be used as the composition and valence of the region.

[0095] Also, a transition layer may be provided between region 332 and region 331. Here, the transition layer is, for example, a region where the composition changes continuously or stepwise. Or, the transition layer is a region where the crystal structure changes continuously or stepwise. Or, the transition layer is a region where the lattice constant of the crystal changes continuously or stepwise. Or, a mixed layer may be provided between region 332 and region 331. Here, the mixed layer refers to, for example, a case where two or more crystals having different crystal orientations are mixed. Or, the mixed layer refers to, for example, a case where crystals having different crystal structures are present. ​​​​​​​​​​​It refers to the case where two or more crystals are mixed. Alternatively, the mixed layer, for example, has different compositions It refers to the case where two or more crystals are mixed.

[0096] In region 333, carbon or a metal compound can be used. Here, as the metal for example, cobalt, aluminum, nickel, iron, manganese, titanium, zinc, lithium, etc. are mentioned. As an example of the metal compound, oxides of these metals, fluorides, etc. can be mentioned among others.

[0097] Among the above, region 333 particularly preferably has carbon. Since carbon has high conductivity by using particles coated with carbon for the electrode of the power storage device, for example, the resistance of the electrode can be lowered. Also, region 333 preferably has a graphene compound. By using a graphene compound in region 333, the particles of the lithium manganese composite oxide can be efficiently coated. The graphene compound will be described later. Also, region 3 33 more specifically may, for example, have graphene or may have graphene oxide among others. Also, as the graphene, it is preferable to use graphene obtained by reducing graphene oxide for this purpose. Graphene has excellent electrical properties such as high conductivity, and high flexibility and excellent physical properties such as high mechanical strength. When using graphene oxide in region 333 and performing reduction, there is a case where the region 332 in contact with region 333 is oxidized in some cases.

[0098] Since region 333 has a graphene compound, the cycle characteristics of a secondary battery using the lithium manganese composite oxide as a positive electrode material can be improved.

[0099] The film thickness of the carbon-containing layer is preferably 0.4 nm or more and 40 nm or less.

[0100] In addition, when the carrier ion is an alkali metal ion other than lithium ion or an alkaline earth metal ion, as the positive electrode active material, instead of lithium, an alkali metal (for example, sodium, potassium, etc.), an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium, etc.) may be used. For example, a sodium-containing layered oxide can be used.

[0101] Examples of materials having sodium include, for example, NaFeO2 and Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 O2, Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 O2, Na2Fe2(SO4)3, Na3V2(PO4)3, Na2FePO4F, NaVPO4F, NaMPO4 (M is Fe(II), Mn(II), Co(II), Ni(II)), Na2FePO4F, N a4Co3(PO4)2P2O7, etc. can be used as the positive electrode active material.

[0102] Also, a lithium-containing metal sulfide can be used as the positive electrode active material. For example, L i2TiS3, Li3NbS4, etc. can be mentioned.

[0103] This embodiment can be implemented in appropriate combination with other embodiments.

[0104] (Embodiment 2) In this embodiment, a graphene compound of one aspect of the present invention will be described.

[0105] <Graphene compound> First, graphene and graphene compounds will be described.

[0106] Graphene is a single-atom-layer sheet in which carbon atoms are bonded by sp 2 hybrid orbitals, and the carbon atoms are arranged in a hexagonal lattice structure on a plane. It is a material with stronger carbon-carbon bonds than diamond and very high resistance to deformation and stretching. On the other hand, it has extremely high electrical conductivity, and lithium ions do not permeate sufficiently.

[0107] Graphene with a single-atom-layer arrangement of carbon atoms may be referred to as monolayer graphene. Graphene with 2 or more and 100 or fewer layers stacked may be referred to as multi-layer graphene. Monolayer graphene and multi-layer graphene have, for example, a length in the longitudinal direction or the major axis length in the plane of 50 nm or more and 100 μm or less, or 800 nm or more and 50 μm or less. In this specification, graphene includes monolayer graphene and multi-layer graphene.

[0108] However, generally, graphene may have various types of defects. For example, carbon atoms forming the lattice may be missing, and pentagonal or heptagonal rings may exist in the lattice in addition to six-membered rings. Further, it may have a functional group containing carbon or an element other than carbon. By using such defect sites, atoms or atomic groups can be bonded to graphene to exhibit desired properties.

[0109] In this specification and the like, a compound having graphene as a basic skeleton is called a graphene compound ( GC: Graphene Compound). In this specification, monolayer g Laphenes and multigraphenes are both included in graphene compounds.

[0110] The graphene compound will be described in detail below.

[0111] Graphene compounds include, for example, graphene having atoms other than carbon or having atoms other than carbon. In addition, graphene is a compound chemically modified with an alkyl group, an alkylene group, etc. The compound may be chemically modified with an atomic group mainly composed of carbon, such as a graphene group. The atomic group that chemically modifies a compound may be called a chemical modifying group, a modifying group, a substituent, a functional group, or a characteristic group. In this specification and the like, chemical modification refers to a substitution reaction, an addition reaction, or other By the reaction of This refers to the introduction of an atomic group into (described below).

[0112] Chemical modification does not only involve the introduction of one type of atom or atomic group, but also involves the introduction of multiple types of chemical modifications. Chemical modification also refers to the introduction of multiple types of atoms or atomic groups. This also includes reactions that add halogen atoms, hydrocarbon groups, aromatic hydrocarbon groups, and heterocyclic groups. In addition, reactions for introducing atomic groups into graphene include addition reactions and substitution reactions. In addition, the Friedel-Crafts reaction, Bingel reaction, A radical addition reaction may be carried out on graphene. Alternatively, a ring may be formed between the graphene and the atomic group by a cycloaddition reaction.

[0113] The front and back surfaces of graphene are chemically modified with different atoms or atomic groups. In multi-graphene, each layer may be composed of different atoms or atomic groups. It may be chemically modified.

[0114] As an example of a graphene compound chemically modified by the above atoms or atomic groups, graphene chemically modified with oxygen or a functional group containing oxygen can be mentioned. Graphene compounds chemically modified with oxygen or a functional group having oxygen may be referred to as graphene oxide (GO: Graphene Oxide). In the present specification, graphene oxide shall include multi-layer graphene oxide.

[0115] An example of graphene oxide is shown in structural formula (300). Although structural formula (300) shows an example in which a graphene layer ( G layer) has epoxy groups, hydroxy groups, and carboxy groups, the types and numbers of functional groups possessed by graphene oxide are not limited thereto.

[0116]

Chemical formula

[0117] A simplified structure of graphene oxide is shown in general formula (G3). In general formula (G3), G layer represents a graphene layer. The graphene layer indicates a sheet-like layer formed by bonding of carbon atoms, and the number of layers may be single or plural, and the graphene layer may have defects or functional groups. Hereinafter, graphene oxide will be described using general formula (G3). Note that general formula (G3) shows two hydroxy groups, but in the present invention, the types and numbers of functional groups possessed by the graphene layer are not limited thereto.

[0118]

Chemical formula

[0119] Next, an example of a method for producing graphene oxide will be described. Graphene oxide can be obtained by oxidizing the above-mentioned graphene or multi-layer graphene. Alternatively, graphene oxide can be obtained by separating oxidized graphite. Oxidized graphite can be obtained by oxidizing graphite . Here, the above-mentioned atoms or atomic groups may be further chemically modified on the graphene oxide .

[0120] A compound obtained by reducing graphene oxide may be referred to as RGO (Reduced Graphene Oxide). Note that in RGO, not all of the oxygen contained in graphene oxide is desorbed, and some oxygen or an atomic group containing oxygen may remain bonded to carbon .

[0121] Graphene compounds may be in the form of a single sheet with a plurality of graphene compounds partially overlapping . Such a graphene compound may be referred to as a graphene compound sheet . The graphene compound sheet has, for example, a region with a thickness of 0.33 nm or more and 10 mm or less, more preferably greater than 0.34 nm and 10 μm or less . The graphene compound sheet may be chemically modified by an atom other than carbon, an atomic group having an atom other than carbon, or an atomic group mainly composed of carbon such as an alkyl group . Also, in each of the plurality of layers of the graphene compound sheet, it may be chemically modified by different atoms or atomic groups .

[0122] In addition to the six-membered rings composed of carbon, the graphene compound may have five-membered rings composed of carbon or polycyclic rings of seven or more members composed of carbon . Here, in the vicinity of the polycyclic rings of seven or more members In some cases, a region through which lithium ions can pass may occur.

[0123] Also, for example, a graphene compound may be in a sheet-like form when a plurality of graphene compounds aggregate. It may be in a sheet-like shape.

[0124] Since the graphene compound has a planar shape, it enables surface contact.

[0125] <Chemically modified graphene compound> Next, the chemically modified graphene compound will be described.

[0126] The graphene compound according to one aspect of the present invention preferably has, for example, one or more functional groups selected from a carbonyl group, an ester group, a carboxyl group, an ether group, an epoxy group, etc. by chemical modification, and more preferably a graphene compound having an ester group or a carboxyl group. Here, as the ester group or the carboxyl group in the modifier increases, the molecular weight of the modifier increases, and when chemically modifying graphene or graphene oxide in the process of synthesizing the graphene compound, the modifier may be difficult to dissolve in the solvent. Therefore, the reactivity when chemically modifying graphene or graphene oxide may deteriorate. Also, when the ester group increases, hydrolysis may easily occur. Therefore, it is preferable that the ester group or the carboxyl group in the modifier is 1 or more and 10 or less. Including one or more selected from such as an ester group or a carboxyl group is more preferably a graphene compound having a group. Here, as the ester group or the carboxyl group in the modifier increases, the molecular weight of the modifier increases, and when chemically modifying graphene or graphene oxide in the process of synthesizing the graphene compound, the modifier may become difficult to dissolve in the solvent. Therefore, the reactivity when chemically modifying graphene or graphene oxide may deteriorate. Also, when the ester group increases, hydrolysis may easily occur. Therefore, it is preferable that the ester group or the carboxyl group in the modifier is 1 or more and 10 or less. tend to occur. Therefore, the ester group or the carboxyl group in the modifier is preferably 1 or more and 10 or less.

[0127] Also, the graphene compound according to one aspect of the present invention has high heat resistance compared to, for example, a polymer material such as polyethylene oxide (PEO). Especially, lithium ion batteries have an internal ​If an unexpected reaction occurs due to damage to the structure, it may develop into a major accident such as ignition or explosion, so it is important to have high heat resistance. Therefore, it is important to have high heat resistance.

[0128] The graphene compound of one embodiment of the present invention has, for example, a graphene layer and a substituted or unsubstituted chain -shaped group, and the graphene layer is bonded to the chain-shaped group via a substituent having Si. Here, as shown in the general formula (G1), the substituent having Si has, for example, Si and O. The graphene compound of one embodiment of the present invention has, for example, as shown in the general formula (G1), silicon and oxygen bonded to the silicon, and the silicon is bonded to a chain-shaped group having an ester group.

[0129] One embodiment of the present invention is a graphene compound represented by the following general formula (G1) or general formula (G2).

[0130]

Chemical formula

[0131]

Chemical formula

[0132] In the general formula (G1) and the general formula (G2), G layer represents a graphene layer.

[0133] When the graphene compound of one embodiment of the present invention has the structures of the general formula (G1) and the general formula (G2), the reduction resistance may be improved compared to GO.

[0134] In the general formula (G1) and the general formula (G2), R 1 represents a substituted or unsubstituted alkylene group and R 1 ​​​​It may be branched. Also, R 2 represents hydrogen, or a substituted or unsubstituted al kyl group, and R 2 may be branched. Note that since the general formula (G1) has an ester group, it is classified as an ester. In the general formula (G2), when R is an alkyl group 2 , since the general formula (G2) has an ester group, it is classified as an ester. In the general formula (G2 ), when R is hydrogen, since the general formula (G2) has a carboxyl group, it is classified as a car 2 boxylic acid.

[0135] The substitution in the above general formula (G1) or the above general formula (G2) preferably represents substitution by a substituent such as an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a sec-butyl group, a tert-but yl group, an n-pentyl group, an n-hexyl group, or an aryl group having 6 to 10 carbon atoms such as a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naph thyl group. It also represents substitution by a substituent such as fluorine or trifluoromethane.

[0136] Also preferably, R 1 is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms . Also preferably, R 2 is hydrogen, or a substituted or unsubstituted alkyl group having 1 to 2 0 carbon atoms. Compared with graphene or graphene oxide, the chemically modified graph ene compound may have a larger interlayer distance. The larger the interlayer distance, the lower the electron conductivity . By appropriately selecting R 1 and R 2 , the desired electron conductivity can be achieved. Yes.

[0137] By reducing the electron conductivity of the graphene compound, for example, when the electrode 210 has the layer 213 the electric field on the surface of the electrode 210 may be relaxed.

[0138] Also, preferably, R 1 is a substituted or unsubstituted alkylene group having 1 to 11 carbon atoms and. Also, preferably, R 2 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms For example, from the viewpoint of dispersibility in a solvent, the number of carbon atoms is preferable.

[0139] The graphene of the graphene compound according to one embodiment of the present invention is not limited to only one molecular weight or structure, and graphene of any size can be applied. Therefore, it is impossible to specify in detail and fully represent the molecular structure of the graphene compound according to one embodiment of the present invention. Therefore, it is impossible to specify the chemically modified graphene compound according to one embodiment of the present invention by a production method expression such as a graphene compound chemically modified with a substituted or unsubstituted group containing at least one or more ester groups or a substituted or unsubstituted group containing a carboxyl group, and in some cases it may be impractical or impossible not to express it in that way. Also, the graphene layer and silicon may be fixed to the graphene layer by two Si - O bonds as shown in the above formula, but in some cases the Si - O bond may be fixed by one or three. Also, the bond is not limited to the Si - O bond, and it may be fixed by other bonds. Also, the silicon not bonded to the graphene layer has a hydroxy group or an alkoxy group bonded thereto bonded thereto. In some cases, it is fixed to the graphene layer by two Si - O bonds as shown in the above formula, but in some cases the Si - O bond may be fixed by one or three. Also, the bond is not limited to the Si - O bond, and it may be fixed by other bonds. Also, the silicon not bonded to the graphene layer has a hydroxy group or an alkoxy group bonded thereto bonded thereto. There are also cases.

[0140] Alternatively, the chemically modified graphene compound according to one aspect of the present invention is a graphene compound represented by the following general formula (G3 ).

[0141]

Chemical formula

[0142] In the general formula (G3), G layer represents a graphene layer. Also, in the general formula (G3 ), R 3 represents a substituted or unsubstituted chain-like group having at least two or more ether bonds, and R 3 may be branched. Also, G layer and Si may be fixed to the G layer by two Si-O bonds as shown in the above formula, but may also be fixed by one or three Si-O bonds. Also, the bond is not limited to the Si-O bond, and may be fixed by other bonds.

[0143] Due to the graphene compound of one aspect of the present invention having the structure of the general formula (G3), the reduction resistance may be improved compared to GO.

[0144] <Chemical modification> Next, a method for producing a chemically modified graphene compound by chemically modifying graphene or graphene oxide will be described using the following synthesis scheme (A-1) and synthesis scheme (A-2).

[0145]

[0146]

Chemical formula

[0146]

Chem.

[0147] In synthetic schemes (A-1) and (A-2), the G layer represents a graphene layer.

[0148] As shown in synthetic schemes (A-1) and (A-2), in the presence of a Lewis base, one or more silicon compounds containing ester groups or carboxyl groups can be reacted with graphene or oxidized graphene to obtain a chemically modified target compound. Such a reaction may be called silylation.

[0149] Silylation refers to the substitution of a hydrogen atom such as a hydroxy group, amino group, carboxyl group, amide group or mercapto group with a silicon atom. The silicon compound used in the silylation reaction may be called a silylating agent.

[0150] As the Lewis base, an alkylamine or a heterocyclic aromatic compound may be used. Specifically, one or more selected from butylamine, pentylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, tripropylamine, and pyridine may be used.

[0151] Also, this reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen or argon, a rare gas. In a nitrogen or argon atmosphere, hydrolysis of the silicon compound or oxidation of the Lewis base can be avoided, which is preferable. The atmosphere of the reaction is not limited to nitrogen or argon, and may be, for example, air.

[0152] ​​​​​​​​​​​In synthesis schemes (A-1) and (A-2), R 1 represents a substituted or unsubstituted alkylene group, and R 1 may be branched. R 2 represents hydrogen, or a substituted or unsubstituted alkyl group, and R 2 may be branched.

[0153] Also, preferably, R 1 is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms There is. Also, preferably, R 2 is hydrogen, or a substituted or unsubstituted alkyl group having 1 to 2 0 carbon atoms.

[0154] Also, preferably, R 1 is a substituted or unsubstituted alkylene group having 1 to 11 carbon atoms There is. Also, preferably, R 2 is a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms It is.

[0155] In synthesis schemes (A-1) and (A-2), the Lewis bases that can be used include organic bases such as butylamine, pentylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, tripropylamine, pyridine etc. However, the Lewis bases that can be used are not limited to these It is not.

[0156] In synthesis schemes (A-1) and (A-2), the solvents that can be used include aromatic hydrocarbons such as toluene, xylene, mesitylene, and hydrocarbons such as hexane, hepta ene, and ethers such as ethylene glycol dimethyl ether. However, the solvents that can be used are not limited to these. In particular, a combination of using a primary amine for the Lewis salt group and an aromatic hydrocarbon for the solvent is more preferable.

[0157] In addition to the silicon compounds shown in Synthesis Scheme (A-1) and Synthesis Scheme (A-2), those having a tri alkoxysilyl group may also be used. However, they are not limited to these. No.

[0158] <Specific Example> Next, examples of chain-like silicon compounds having one or more ester groups or carboxyl groups are shown below. By using these silicon compounds, it is possible to produce a graphene compound chemically modified with a chain-like group having one or more ester groups or carboxyl groups. Note that Compounds 100 to 149 and Compounds 156 to 161 have an ester group and are classified as esters. Compounds 150 to 155 have a carboxyl group and are classified as carboxylic acids. No.

[0159]

Chemical Formula

[0160]

Chemical Formula

[0161]

Chemical Formula

[0162]

Chemical Formula

[0163] [Chemical formula]

[0164] By using the silicon compound as described above, a graphene compound having a chain-like group containing at least one or more ester groups or a carboxyl group can be produced. However, the graphene compound according to one aspect of the present invention is not limited to being produced using the silicon compound as described above.

[0165] Next, examples of silylating agents containing a chain-like group having two or more ether bonds will be shown below. By using these silylating agents, a graphene compound decorated with a chain-like group having an ether bond can be produced.

[0166] [Chemical formula]

[0167] [Chemical formula]

[0168] [Chemical formula]

[0169] [Chemical formula]

[0170] [Chemical formula]

[0171] [Chemical formula]

[0172] Note that one embodiment of the present invention has been described in this embodiment. In the following, one embodiment of the present invention will be described. 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 including a xyl group has been described, one embodiment of the present invention is This is not limited to the above.

[0173] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0174] (Embodiment 3) In this embodiment, an active material, a binder, a conductive material, and a conductive material that are preferably contained in the electrode of one embodiment of the present invention will be described. The electric auxiliary and the current collector will now be described.

[0175] The electrode of one embodiment of the present invention includes an active material. The positive electrode of one embodiment of the present invention may include a conductive assistant.

[0176] When the electrode of one embodiment of the present invention is a positive electrode, the electrode contains a positive electrode active material as an active material. As for the active material, it is preferable to use the positive electrode active material described in the above embodiment.

[0177] For example, when the electrode 210 described in the previous embodiment is a positive electrode, the electrode 220 is a negative electrode. It is preferable that

[0178] When the electrode of one embodiment of the present invention is a negative electrode, the electrode contains a negative electrode active material as an active material.

[0179] <Negative electrode active material> As the negative electrode active material of the electrode, for example, a carbon-based material or an alloy-based material can be used. Yes.

[0180] As the carbon-based material, graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotube, graphene, carbon black, etc. may be used. That's fine. Yes.

[0181] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape, which is preferable. Also, it is relatively easy to reduce the surface area of MCMB, which may be preferable. Examples of natural graphite include flake graphite, spheroidized natural graphite, etc. That's all. When lithium ions are inserted into graphite (when forming a lithium-graphite intercalation compound), it shows a potential as low as that of metallic lithium (0.05 V or more and 0.3 V or less vs. Li / Li). Yes. Therefore, a lithium-ion secondary battery can show a high operating voltage. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, a relatively small volume expansion, being inexpensive, and having higher safety than metallic lithium, so it is preferable. That's all.

[0182] i + i + ). Thus, a lithium-ion secondary battery can exhibit a high operating voltage. Additionally, graphite has advantages such as a relatively high capacity per unit volume, a relatively small volume expansion, being inexpensive, and having higher safety than metallic lithium, making it preferable. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, a relatively small volume expansion, being inexpensive, and having higher safety than metallic lithium, so it is preferable. That's all.

[0183] Here, when lithium ions are inserted into graphite, for example, it is known that the interlayer distance of graphite increases from 0.3354 nm to 0.370 nm. That is, the interlayer distance increases by about 11%. That's all. That's all.

[0184] As the negative electrode active material, those capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium can be used. For example, elements such as silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Among them, a material containing at least one can be used. Such elements have a larger capacity compared to carbon, and in particular, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Also, compounds containing these elements may be used. For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag 3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. exist. Here, elements capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium, and compounds containing such elements, etc., are sometimes referred to as alloy-based materials.

[0185] Also, in this specification, etc., SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be expressed as SiOx. Here, x preferably has a value near 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0186] Further, the negative electrode active material of one aspect of the present invention may have silicon, lithium, and oxygen. For example, it may have silicon and lithium silicon oxide located outside the silicon.

[0187] Also, as the negative electrode active material, titanium dioxide (TiO2), lithium titanium oxide (Li4​​​ Ti5O 12 )、 lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5 ), tungsten oxide (WO2), molybdenum oxide (MoO2), etc. can be used. It is possible.

[0188] Also, as the negative electrode active material, Li3N-type structure, which is a complex nitride of lithium and transition metals, is also possessed by Li (3-x) M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 shows a large charge-discharge capacity (900 mAh / g, 1890 mAh / cm 3 ) and is preferable.

[0189] When using a complex nitride of lithium and transition metals, since the negative electrode active material contains lithium ions, it can be preferably combined with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material. In addition, even when using a material containing lithium ions for the positive electrode active material, by previously desorbing the lithium ions contained in the positive electrode active material, a complex nitride of lithium and transition metals can be used as the negative electrode active material.

[0190] Also, a material that undergoes a conversion reaction can be used as the negative electrode active material. For example, transition metal oxides such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO) that do not form an alloy with lithium can be used as the negative electrode active material. As materials that undergo a conversion reaction, furthermore, oxides such as Fe2O3, CuO, Cu2O, RuO2, and Cr2O3 , sulfides such as CoS 0.89 , NiS, and CuS, nitrides such as Zn3N2, Cu3N, and Ge Nitrides such as 3N4, phosphides such as NiP2, FeP2, CoP3, fluorides such as FeF3, BiF3, etc. This also occurs with fluorides.

[0191] The lower the reaction potential of the negative electrode active material, the more preferable it is because it can increase the voltage of the power storage device. On the other hand, when the potential is low, the ability to reduce the electrolyte also increases. For example, organic solvents used in the electrolyte may be reductively decomposed. The potential range within which the electrolyte is not electrolyzed is called the potential window. (potential window). Originally, it is preferable that the electrode potential of the negative electrode is within the potential window of the electrolyte. However, for example, most of the active materials used in the negative electrodes of lithium-ion secondary batteries and lithium-ion capacitors have potentials that exceed the potential windows of almost all electrolytes. In particular, materials with low reaction potentials such as graphite and silicon have the advantage of being able to increase the voltage of the power storage device, but there is a problem that the reductive decomposition of the electrolyte is more likely to occur. For lithium-ion secondary batteries and lithium-ion capacitors, Most of the active materials used in the negative electrodes have potentials that exceed the potential windows of almost all electrolytes. Especially for materials with low reaction potentials such as graphite and silicon, while there is an advantage of being able to increase the voltage of the power storage device, there is a problem that the reductive decomposition of the electrolyte is more likely to occur. There is a problem that the reductive decomposition of the electrolyte is more likely to occur.

[0192] <Binder> As the binder of the electrode, it is preferable to use diene-based rubber materials such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene-diene copolymer. Also, fluororubber can be used as the binder. As the binder, it is preferable to use, for example, water-soluble polymers. As the water-soluble polymers, for example, polysaccharides can be used. As the polysaccharides, carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, cellulose derivatives such as diacetyl cellulose, regenerated cellulose, and starch can be used. As the binder, it is preferable to use, for example, water-soluble polymers. As the water-soluble polymers, for example, polysaccharides can be used. As the binder, fluororubber can be used.

[0193] Also, as the binder, it is preferable to use, for example, water-soluble polymers. As the water-soluble polymers, for example, polysaccharides can be used. As the polysaccharides, carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, cellulose derivatives such as diacetyl cellulose, regenerated cellulose, and starch can be used. As the polysaccharides, carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, cellulose derivatives such as diacetyl cellulose, regenerated cellulose, and starch can be used. As the polysaccharides, carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, cellulose derivatives such as diacetyl cellulose, regenerated cellulose, and starch can be used. It can be used. Also, using these water-soluble polymers in combination with the aforementioned rubber material is even more preferable.

[0194] Alternatively, as the binder, polystyrene, polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate (PMMA)), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene lene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), ethylene propylene diene polymer , polyvinyl acetate, nitrocellulose and other materials are preferably used.

[0195] Two or more of the above binders may be used in combination.

[0196] The content of the binder relative to the total amount of the active material layer 102 is preferably 1 wt% or more and 10 wt% or less, more preferably 2 wt% or more and 8 wt% or less, and even more preferably 3 wt% or more and 5 wt% or less. Also, the content of the conductive assistant relative to the total amount of the active material layer 102 is preferably 1 wt% or more and 10 wt % or less, and more preferably 1 wt% or more and 5 wt% or less.

[0197] <Conductive assistant>

[0198] As the conductive assistant of the electrode, for example, a carbon material, a metal material, or a conductive ceramic material etc. can be used. Also, a fibrous material may be used as the conductive assistant. The content of the conductive assistant relative to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, and preferably 1 wt % or more and 10 wt% or less, and 1 wt More preferably, it is 5 wt% or less and more than 0 wt%.

[0199] The conductive assistant can form an electrical conduction network in the electrode. The conductive assistant can maintain the electrical conduction path between the positive electrode active materials. By adding a conductive assistant to the active material layer, an active material layer having high electrical conductivity can be realized.

[0200] As the conductive assistant, for example, natural graphite, artificial graphite such as mesocarbon microbeads, carbon fibers, etc. can be used. As the carbon fibers, for example, carbon fibers such as mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers can be used. Also, as the carbon fibers, carbon nanofibers, carbon nanotubes, etc. can be used. Carbon nanotubes can be produced by, for example, a vapor phase growth method. Also, as the conductive assistant, for example, carbon materials such as carbon black (such as acetylene black (AB)), graphite (black lead) particles graphene, fullerenes, etc. can be used. Also, for example, metal powders such as copper, nickel, aluminum, silver, gold, etc., metal fibers, conductive ceramic materials, etc. can be used.

[0201] A graphene compound may be used as the conductive assistant.

[0202] The graphene compound may have excellent electrical properties such as high electrical conductivity, and excellent physical properties such as high flexibility and high mechanical strength. Also, the graphene compound has a planar shape. The graphene compound enables surface contact with low contact resistance to occur. Also, it may have very high electrical conductivity even when thin, and can efficiently function within the active material layer in a small amount A conductive path can be formed. Therefore, it is preferable to use a graphene compound as a conductive aid. By doing so, it is preferable because the contact area between the active material and the conductive aid can be increased. Also, it is preferable because the electrical resistance may be reduced. Here, as the graphene compound, for example, it is particularly preferable to use graphene or multi-graphene or RGO.

[0203] When using an active material with a small particle size, for example, an active material of 1 μm or less, the specific surface area of the active material is large, and more conductive paths connecting the active materials are required. In such a case, it is particularly preferable to use a graphene compound that can efficiently form a conductive path even in a small amount.

[0204] Hereinafter, as an example, a cross-sectional configuration example of a case where a graphene compound is used as a conductive aid in the active material layer 102 will be described.

[0205] FIG. 6(A) shows a longitudinal sectional view of the active material layer 102. The active material layer 102 includes granular active material 1 03, a graphene compound 321 as a conductive aid, and a binder 104. Here, as the graphene compound 321, for example, graphene or multi-graphene may be used. Here, the graphene compound 321 preferably has a sheet-like shape. Also, the graphene compound 321 may be a sheet formed by partial overlap of a plurality of multi-graphenes and / or a plurality of graphenes.

[0206] In the longitudinal section of the active material layer 102, as shown in FIG. 6(A), the sheet-like graphene compound 321 is dispersed substantially uniformly inside the active material layer 102. In FIG. 6(A), Graphite compound 321 is schematically represented by a thick line, but in reality, it is a thin film having a single layer or multiple layers of carbon molecules. A plurality of graphite compounds 321 are formed so as to wrap, cover, or adhere onto the surfaces of a plurality of granular active materials 103, and thus are in surface contact with each other.

[0207] Here, when a plurality of graphite compounds are bonded to each other, a network-like graphite compound sheet (hereinafter referred to as a graphite compound net or a graphene net) can be formed. When the active material is covered with the graphene net, the graphene net can also function as a binder that binds the active materials to each other. Therefore, since the amount of the binder can be reduced or the binder can be dispensed with, the ratio of the active material in the electrode volume and the electrode weight can be improved. That is, the capacity of the power storage device can be increased.

[0208] Here, it is preferable to use graphene oxide as the graphite compound 321, mix it with the active material to form a layer that becomes the active material layer 102, and then reduce it. By using graphene oxide having extremely high dispersibility in a polar solvent for the formation of the graphite compound 321, the graphite compound 321 can be dispersed substantially uniformly inside the active material layer 102. After volatilizing and removing the solvent from the dispersion medium containing uniformly dispersed graphene oxide and reducing the graphene oxide, the graphite compounds 321 remaining in the active material layer 102 partially overlap with each other and are dispersed to such an extent that they are in surface contact with each other, thereby forming a three-dimensional conductive path. The reduction of graphene oxide may be performed, for It may be performed.

[0209] Therefore, unlike granular conductive aids such as acetylene black that make point contact with the active material, graphene compound 321 enables surface contact with low contact resistance, so it can improve the electrical conductivity between granular active material 103 and graphene compound 321 with a smaller amount than ordinary conductive aids. Therefore, the ratio of the active material 103 in the active material layer 102 can be increased. As a result, the discharge capacity of the power storage device can be increased.

[0210] FIG. 6(B) shows an enlarged view of the region surrounded by the dashed-dotted line in FIG. 6(A). The binder 104 may be present in a layer on the surface of the active material 103. The graphene compound 321 preferably has a region in contact with the surface of the binder 10 4. The binder 104 is located, for example, between the active material 103 and the graphene compound 321. Preferably, the binder 104 is provided on the active material 103, and further, the graphene compound 321 is provided on the binder 104.

[0211] <Current collector> For the current collector 101, metals such as stainless steel, gold, platinum, aluminum, titanium, and alloys thereof can be used, which have high conductivity. When the current collector 101 is used as the positive electrode, it is preferably insoluble at the potential of the positive electrode. When the current collector 101 is used as the negative electrode, it is preferably not alloyed with carrier ions such as lithium. Also, an aluminum alloy added with elements such as silicon, titanium, neodymium, scandium, and molybdenum to improve heat resistance can be used. Also, it can react with silicon to form silicide. It may be formed of a metal element that forms. A metal element that reacts with silicon to form silicide Examples include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium , molybdenum, tungsten, cobalt, nickel, etc. The current collector 101 can appropriately use shapes such as foil shape, plate shape (sheet shape), net shape, punched metal shape, expanded metal shape, etc. The current collector 101 is preferably one with a thickness of 5 μm or more and 30 μm or less .

[0212] This embodiment can be implemented in appropriate combination with other embodiments

[0213] (Embodiment 4) In this embodiment, a power storage device to which an electrode according to an aspect of the present invention can be applied will be described .

[0214] As an example of a power storage device according to an aspect of the present invention, a secondary battery using an electrochemical reaction such as a lithium-ion battery, an electrochemical capacitor such as an electric double layer capacitor or a redox capacitor, an air battery, a fuel cell, etc. may be mentioned .

[0215] <Thin power storage battery> Fig. 7 shows a thin power storage battery as an example of a power storage device. If the thin power storage battery has a flexible configuration, when mounted on an electronic device having at least a part of a flexible part, the power storage battery can also be bent in accordance with the deformation of the electronic device .

[0216] Fig. 7 shows an external view of a power storage battery 500 which is a thin power storage battery. Also, Fig. 8(A) and Fig. 8 (B) show a cross section A1 - A2 and a cross section B1 - B2 indicated by a dashed line in Fig. 7. The power storage battery 5 00 has a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, and a negative electrode current collector​ a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505, a separator 507, an electrolytic solution 5 08, and an exterior body 509. A separator 507 is disposed between the positive electrode 503 and the negative electrode 50 6 provided in the exterior body 509. Further, the interior of the exterior body 509 is filled with the electrolytic solution 508 .

[0217] As the solvent of the electrolytic solution 508, an aprotic organic solvent is preferable. For example, ethylene car bonate (EC), propylene carbonate (PC), butylene carbonate, chloro ethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolact one, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl e ther, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sul folane, sultone, etc. can be used alone or in any combination and ratio of two or more of these.

[0218] In addition, by using a polymer material that is gelled as the solvent of the electrolytic solution, the safety against liquid leakage and the like is enhanced. Further, the secondary battery can be made thinner and lighter. Representative examples of the gelled polymer material include silicone gel, acrylic gel, acrylonitrile gel, poly ethylene oxide-based gel, polypropylene oxide-based gel, gel of fluorine-based polymer and the like.

[0219] In addition, as the solvent of the electrolytic solution, an ionic liquid (room temperature molten salt) that is flame retardant and hardly volatile is ​​​When one or more of them are used, even if the internal temperature rises due to internal short circuit or overcharging of the power storage device, etc., rupture or ignition of the power storage device can be prevented. The ionic liquid consists of a cation and an anion, and includes an organic cation and an anion. Examples of the organic cation used in the electrolytic solution include aliphatic onium cations such as quaternary ammonium cation, tertiary sulfonium cation, and quaternary phosphonium cation, and aromatic cations such as imidazolium cation and pyridinium cation. Also, examples of the anion used in the electrolytic solution include monovalent amide-based anion, monovalent methide-based anion, fluorosulfonic acid anion, perfluoroalkylsulfonic acid anion, tetrafluoroborate anion, perfluoroalkylborate anion, hexafluorophosphate anion, or perfluoroalkylphosphate anion, etc. Moreover, as the electrolyte dissolved in the above solvent, in the case of using lithium ions as carriers, for example, LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B Cl 、Li2B Cl 、LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C 2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO 2), LiN(C2F5SO2)2 and other lithium salts can be used alone or in any combination and ratio of two or more of these.

[0220] In addition, the electrolytic solution used in the power storage device is free of particulate dust and elements other than the constituent elements of the electrolytic solution (hereinafter simply referred to as " 10 10 12 12

[0221] foreign elements") (Also referred to as “impurities”). It is preferable to use a highly purified electrolytic solution with a low content of such impurities.) Specifically, the weight ratio of impurities to the electrolytic solution is preferably 1% or less, more preferably 0.1% or less, and even more preferably 0.01% or less.

[0222] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butyl benzene (TBB), fluoroethylene carbonate (FEC), and LiBOB may be added to the electrolytic solution. The concentration of the additive may be, for example, 0.1 weight% or more and 5 weight% or less based on the entire solvent.

[0223] Alternatively, a polymer gel electrolyte obtained by swelling a polymer with an electrolytic solution may be used.

[0224] Examples of the polymer include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, etc., and copolymers containing them. For example, PVDF-HFP, which is a copolymer of PVDF and hexafluoropropylene ( HFP), can be used. Further, the formed polymer may have a porous shape.

[0225] Alternatively, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as a sulfide-based or oxide-based material, or a solid electrolyte having a polymer material such as a PEO (polyethylene oxide)-based material can be used. When using a solid electrolyte, it is not necessary to install a separator or a spacer. In addition, since the entire battery can be solidified, there is no risk of liquid leakage and the safety is significantly improved.

[0226] ​​​​​​​As the separator 507, for example, paper, non-woven fabric, glass fiber, ceramics, or nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, a synthetic fiber made of acrylic, polyolefin, polyurethane, etc. can be used. It is possible to do so.

[0227] The separator 507 is preferably processed into a bag shape and arranged to wrap either the positive electrode 503 or the negative electrode 506. For example, as shown in FIG. 9(A), the separator 507 is folded in half so as to sandwich the positive electrode 503, and sealed by the sealing portion 51 4 outside the region overlapping the positive electrode 503, so that the positive electrode 503 can be reliably carried in the separator 507. Then, as shown in FIG. 9(B), the positive electrode 503 and the negative electrode 5 06 wrapped by the separator 507 are alternately laminated and placed in the exterior body 509 to form the storage battery 500. It is advisable to do so. Next, the aging after manufacturing the storage battery will be described. After manufacturing the storage battery, it is preferable to perform aging. An example of the aging conditions will be described below. First, charge is performed at a rate of 0.001C or more and 0.2C or less. The temperature may be, for example, room temperature or higher and 50

[0228] °C or lower. Here, when the reaction potential of the positive electrode or the negative electrode exceeds the potential window of the electrolytic solution 508, the electrolytic solution may be decomposed by the charge and discharge of the storage battery. When gas is generated due to the decomposition of the electrolytic solution, if the gas accumulates in the cell, a region where the electrolytic solution cannot contact the electrode surface will occur. That is, it corresponds to a decrease in the effective reaction area of the electrode and an increase in the effective resistance.

[0229] ​​​​​​​Also, when the resistance becomes excessively high, the negative electrode potential drops, causing lithium insertion into graphite while at the same time lithium precipitation on the graphite surface also occurs. This lithium precipitation may lead to a decrease in capacity. For example, after lithium has precipitated and a film or the like grows on the surface, the lithium precipitated on the surface cannot be redissolved, increasing the amount of lithium that does not contribute to the capacity. Also, when the precipitated lithium physically breaks off and loses electrical connection with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to vent gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage.

[0230] Also, after venting the gas, at a temperature higher than room temperature, preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 50°C or lower, for example, for 1 hour or more and 100 hours or less, it may be held in a charged state. During the initial charging, the electrolyte decomposed on the surface forms a film on the graphite surface. Therefore, it is conceivable that the formed film becomes denser, for example, by holding at a temperature higher than room temperature after venting the gas.

[0231] FIG. 10 shows an example of welding a current collector to a lead electrode. As shown in FIG. 10(A), the positive electrode 503 wrapped by the separator 507 and the negative electrode 506 are alternately stacked. Next, the positive electrode current collector 501 is welded to the positive electrode lead electrode 510, and the negative electrode current collector 504 is welded to the negative electrode lead electrode 511, respectively. An example of welding the positive electrode current collector 501 to the positive electrode lead electrode 510 is shown in FIG. 10(B). The positive electrode current collector 501 is welded to the positive electrode lead electrode 510 in the welding region 512 using ultrasonic welding or the like. Also, the positive electrode current collector 501 has a curved portion 513 shown in FIG. 10(B). By doing so, the stress generated by applying an external force after the production of the storage battery 500 can be relieved, and the reliability of the storage battery 500 can be improved.

[0232] In the storage battery 500 shown in FIGS. 7 and 8, the positive electrode lead electrode 510 is connected to the positive electrode current collector 501 of the positive electrode 503, and the negative electrode lead electrode 511 is connected to the negative electrode current collector 504 of the negative electrode 506, and they are respectively joined by ultrasonic bonding. Also, the role of the terminal for obtaining electrical contact with the outside can be shared by the positive electrode current collector 501 and the negative electrode current collector 504. In that case, without using the lead electrodes, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be arranged so as to be exposed outside from the exterior body 509.

[0233] Also, in FIG. 7, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side, but as shown in FIG. 11, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 may be arranged on different sides. Thus, in the storage battery according to one aspect of the present invention, the lead electrodes can be freely arranged, so that the degree of design freedom is high. Therefore, the degree of design freedom of a product using the storage battery according to one aspect of the present invention can be increased. Also, the productivity of a product using the storage battery according to one aspect of the present invention can be increased.

[0234] In the storage battery 500, on the exterior body 509, for example, a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, polyamide, etc., a metal thin film excellent in flexibility such as aluminum, stainless steel, copper, nickel, etc. is provided, and further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided as the outer surface of the exterior body on the metal thin film, and a three-layer structure film can be used.

[0235] ​​​​​​​​ Also, in FIG. 8, as an example, the number of pairs of the facing positive electrode active material layer and negative electrode active material layer is five sets. Of course, the number of sets of electrodes is not limited to five sets, and may be more or less. When the number of electrode layers is large, a storage battery having a larger capacity can be obtained. Also, when the number of electrode layers is small, a thin and highly flexible storage battery can be obtained.

[0236] In the above configuration, the exterior body 509 of the secondary battery can be deformed so that the minimum radius of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less. The film that is the exterior body of the secondary battery is composed of one or two sheets. In the case of a secondary battery having a laminated structure, the cross-sectional structure of the curved battery is a structure sandwiched between two curves of the film that is the exterior body. The radius of curvature of the surface will be described with reference to FIG. 12. In FIG. 12(A), in the plane 1701 obtained by cutting the curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated by an arc of a circle, the radius of the circle is defined as the radius of curvature 1703, and the center of the circle is defined as the center of curvature 1704. FIG. 12(B) shows a top view of the curved surface 1700. FIG. 12(C) shows a cross-sectional view obtained by cutting the curved surface 1700 with the plane 1701. When a curved surface is cut by a plane, the radius of curvature of the curve appearing in the cross-section varies depending on the angle of the plane with respect to the curved surface and the cutting position. However, in this specification and the like, the smallest radius of curvature is defined as the radius of curvature of the surface.

[0237] When a secondary battery in which two films are used as the exterior body and sandwich 1805 such as electrodes and electrolytes is curved, the radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery is as follows. Approximate a part of the curve 1702 included in the curved surface 1700 by an arc of a circle, and set the radius of the circle as the radius of curvature 1703 and the center of the circle as the center of curvature 1704. FIG. 12(B) shows a top view of the curved surface 1700. FIG. 12(C) shows a cross-sectional view of the curved surface 1700 cut by the plane 1701. When cutting the curved surface with a plane, depending on the angle of the plane with respect to the curved surface and the cutting position, the radius of curvature of the curve appearing in the cross-section will be different. However, in this specification, etc., the smallest radius of curvature is taken as the radius of curvature of the surface. When a secondary battery with two films as the exterior body sandwiching 1805 such as electrodes and electrolytes is curved, the radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery

[0238] In the case of curving a secondary battery with two films as the exterior body and sandwiching 1805 such as electrodes and electrolytes, the radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery is as follows. is smaller than the radius of curvature 1804 of the film 1803 on the side far from the center of curvature 1800 ( FIG. 13(A)). When the secondary battery is curved to have an arc-shaped cross section, a compressive stress is applied to the surface of the film close to the center of curvature 1800, and a tensile stress is applied to the surface of the film far from the center of curvature 1800 ( FIG. 13(B)). When a pattern formed by a concave portion or a convex portion is formed on the surface of the exterior body, even if such compressive stress or tensile stress is applied, the influence of strain can be suppressed within an allowable range. Therefore, the secondary battery can be deformed so that the minimum radius of curvature of the exterior body on the side close to the center of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 m m or less. Note that the cross-sectional shape of the secondary battery is not limited to a simple arc shape, and a part thereof can have an arc shape, for example, the shape shown in FIG. 13(C), a wave shape ( FIG. 13(D)), an S-shaped, etc. When the curved surface of the secondary battery has a shape having a plurality of centers of curvature, among the radii of curvature at each of the plurality of centers of curvature, in the curved surface having the smallest radius of curvature, the minimum radius of curvature of the exterior body closer to the center of curvature of the two exterior bodies is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less.

[0239] Note that the cross-sectional shape of the secondary battery is not limited to a simple arc shape, and a part thereof can have an arc shape, for example, the shape shown in FIG. 13(C), a wave shape ( FIG. 13(D)), an S-shaped, etc. When the curved surface of the secondary battery has a shape having a plurality of centers of curvature, among the radii of curvature at each of the plurality of centers of curvature, in the curved surface having the smallest radius of curvature, the minimum radius of curvature of the exterior body closer to the center of curvature of the two exterior bodies is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less. Next, various examples of the lamination of the positive electrode, the negative electrode, and the separator will be shown. FIG. 16(A) shows an example in which the positive electrode 111 and the negative electrode 115 are laminated six layers each. A positive electrode active material layer 122 is provided on one side of the positive electrode current collector 121 included in the positive electrode 111. Also a negative electrode active material layer 126 is provided on one side of the negative electrode current collector 125 included in the negative electrode 115.

[0240] Next, various examples of the lamination of the positive electrode, the negative electrode, and the separator will be shown.

[0241] FIG. 16(A) shows an example in which the positive electrode 111 and the negative electrode 115 are laminated six layers each. A positive electrode active material layer 122 is provided on one side of the positive electrode current collector 121 included in the positive electrode 111. Also a negative electrode active material layer 126 is provided on one side of the negative electrode current collector 125 included in the negative electrode 115. ​​

[0242] In the configuration shown in FIG. 16(A), the positive electrode 111 does not have a positive electrode active material layer 122. The positive electrode 115 is placed on the positive electrode 11 so that the surfaces of the negative electrode 115 that do not have the negative electrode active material layer 126 are in contact with each other. 1 and the negative electrode 115 are laminated in this order. The surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 122 are called the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 126. The contact surface between the metals can be created by the active material and the separator. The coefficient of friction can be reduced compared to the contact surface of the other surface.

[0243] Therefore, when the secondary battery is curved, the surface of the positive electrode 111 not having the positive electrode active material layer 122 is flat. In addition, the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer 126 slide against each other, so that the inner and outer diameters of the curve The stress caused by the difference in the curvature can be released. When bending the battery 500, the battery 500 is located on the inside of the bending portion of the exterior body 509. This refers to the radius of curvature of the surface. Therefore, deterioration of the storage battery 500 can be suppressed. In addition, the storage battery 500 can be made highly reliable.

[0244] FIG. 16(B) shows an example of lamination of a positive electrode 111 and a negative electrode 115 different from that shown in FIG. 16(A). In the configuration shown in FIG. 16(B), a positive electrode active material layer 122 is provided on both sides of a positive electrode current collector 121. As shown in FIG. 16(B), the positive electrode current collector By providing the positive electrode active material layer 122 on both sides of the positive electrode active material layer 121, the capacity per unit volume of the storage battery 500 is The amount can be increased.

[0245] FIG. 16(C) shows an example of lamination of a positive electrode 111 and a negative electrode 115 different from that shown in FIG. 16(B). In the configuration shown in FIG. 16(C), the negative electrode active material layers 126 are provided on both sides of the negative electrode current collector 125. This is different from the configuration shown in FIG. 16(B) in that the negative electrode active material layers 126 are provided on both sides of the negative electrode current collector. By providing the negative electrode active material layers 126 on both sides of the negative electrode current collector 125 as shown in FIG. 16(C), the capacity per unit volume of the storage battery 500 can be further increased.

[0246] Also, in the configuration shown in FIG. 16, the separator 123 wraps the positive electrode 111 in a bag shape. However, the present invention is not limited to this. Here, FIG. 17(A) shows an example of a separator 123 having a configuration different from that of FIG. 16(A). In the configuration shown in FIG. 17(A), one sheet of sheet-like separator 123 is provided between the positive electrode active material layer 122 and the negative electrode active material layer 126, which is different from the configuration shown in FIG. 16(A). In the configuration shown in FIG. 17(A), the positive electrode 111 and the negative electrode 115 are stacked six layers each, and six layers of the separator 123 are provided.

[0247] Also, FIG. 17(B) shows an example in which a separator 123 different from that in FIG. 17(A) is provided. In the configuration shown in FIG. 17(B), one sheet of the separator 123 is folded back a plurality of times so as to be sandwiched between the positive electrode active material layer 122 and the negative electrode active material layer 126, which is different from the configuration shown in FIG. 17(A). Also, the configuration of FIG. 17(B) can be said to be a configuration in which the separators 123 of each layer shown in the configuration of FIG. 17(A) are extended and the layers are connected together. In the configuration shown in FIG. 17(B), the positive electrode 111 and the negative electrode 115 are stacked six layers each, and it is preferable that the separator 123 is folded back at least five times or more. Also, the separator 123 is not only provided so as to be sandwiched between the positive electrode active material layer 12 2 and the negative electrode active material layer 126, but is also extended to connect a plurality of positive electrodes 1 11 and the negative electrode 115 may be bound together.

[0248] Alternatively, the positive electrode, the negative electrode, and the separator may be laminated as shown in FIG. FIG. 18(A) is a cross-sectional view of the first electrode assembly 130, and FIG. 18(B) is a cross-sectional view of the second electrode assembly 131. 18(C) is a cross-sectional view taken along dashed line A1-A2 in FIG. For clarity of illustration, the first electrode assembly 130, the second electrode assembly 131 and the separator An excerpt from data 123 is shown below.

[0249] As shown in FIG. 18(C), the storage battery 500 includes a plurality of first electrode assemblies 130 and a plurality of The second electrode assembly 131 has a number of second electrode assemblies 131.

[0250] As shown in FIG. 18(A), in the first electrode assembly 130, the positive electrode current collector 121 has a A positive electrode 111a having a positive electrode active material layer 122, a separator 123, and both sides of a negative electrode current collector 125 The negative electrode 115a having the negative electrode active material layer 126 on both sides of the separator 123 and the positive electrode current collector 121 The positive electrode 111a having the positive electrode active material layer 122 on the surface is laminated in this order. As shown in FIG. 1B, in the second electrode assembly 131, a negative electrode active material is provided on both sides of the negative electrode current collector 125. A layer 126 is formed on both sides of the negative electrode 115a, the separator 123, and the positive electrode current collector 121. A positive electrode 111a having a porous layer 122, a separator 123, and a negative electrode current collector 125 are provided on both sides thereof. A negative electrode 115a having a material layer 126 is laminated in this order.

[0251] Further, as shown in FIG. 18(C), a plurality of first electrode assemblies 130 and a plurality of second The electrode assembly 131 is covered by a wound separator 123 .

[0252] [Coin-shaped battery] Next, as an example of the power storage device, an example of a coin-shaped battery will be described with reference to FIG. 14 . FIG. 14(A) is an external view of a coin-shaped (single-layer flat type) battery, and FIG. 14(B) is , its cross-sectional view.

[0253] The coin-shaped battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal, which are insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact therewith.

[0254] Also, the negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact therewith.

[0255] For the positive electrode 304, refer to the description of the positive electrode 503. For the positive electrode active material layer 306, refer to the positive electrode active material layer 502. For the negative electrode 307, refer to the description of the negative electrode 506. For the negative electrode active material layer 309, refer to the description of the negative electrode active material layer 505. For the separator 310, refer to the description of the separator 507. For the electrolytic solution, refer to the description of the electrolytic solution 508.

[0256] Note that for the positive electrode 304 and the negative electrode 307 used in the coin-shaped battery 300, the active material layers may be formed only on one side.

[0257] For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, and titanium that are corrosion-resistant to the electrolytic solution, or alloys thereof or alloys of these with other metals (for example, stainless steel, etc.) can be used. Also, in order to prevent corrosion by the electrolytic solution, nickel or aluminum or the like It is preferable to coat with um etc. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 3 07 respectively.

[0258] These negative electrode 307, positive electrode 304 and separator 310 are impregnated with an electrolyte, and as shown in Fig. 14( B), with the positive electrode can 301 facing down, the positive electrode 304, separator 310, negative electrode 307 , negative electrode can 302 are laminated in this order, and the positive electrode can 301 and the negative electrode can 302 are crimped through a gasket 303 to manufacture a coin-shaped storage battery 300.

[0259] [Cylindrical storage battery] Next, as an example of a power storage device, a cylindrical storage battery is shown. The cylindrical storage battery will be described with reference to Fig. 15 . As shown in Fig. 15(A), the cylindrical storage battery 600 has a positive electrode cap (battery lid) 601 on the upper surface and a battery can (outer can) 602 on the side surface and the bottom surface. These positive electrode cap and battery can (outer can) 602 are insulated by a gasket (insulating packing) 6 10.

[0260] Fig. 15(B) is a diagram schematically showing a cross section of the cylindrical storage battery. Inside the hollow cylindrical battery can 602, a battery element is provided in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched therebetween. Although not shown, the battery element is wound around a center pin. One end of the battery can 602 is closed and the other end is open. For the battery can 602 , metals such as nickel, aluminum, and titanium that are corrosion-resistant to the electrolytic solution, or alloys thereof , or alloys of these with other metals (for example, stainless steel, etc.) can be used. . Also, in order to prevent corrosion by the electrolytic solution, it is preferable to coat with nickel or aluminum etc. Yes. Inside the battery can 602, a battery element in which a positive electrode, a negative electrode, and a separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Also, the inside of the battery can 602 where the battery element is provided is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte can be the same as that used in a coin-type storage battery.

[0261] For the positive electrode 604, refer to the positive electrode 503. Also, for the negative electrode 606, refer to the negative electrode 506 if necessary. Also, for the positive electrode 604 and the negative electrode 606, for example, the method of manufacturing the electrodes shown in Embodiment 1 can be referred to. Since the positive and negative electrodes used in a cylindrical storage battery are wound it is preferable to form the active material on both sides of the current collector. A positive electrode terminal (positive current collector lead) 603 is connected to the positive electrode 604 and a negative electrode terminal (negative current collector lead) 607 is connected to the negative electrode 606 . Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum . The positive electrode terminal 603 is resistance-welded to the safety valve mechanism 612, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602 respectively. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611 . The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery exceeds a predetermined threshold . Also, the PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and by increasing the resistance it limits the current amount to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO3)-based semiconductor ceramics or the like can be used .

[0262] ​When winding the electrodes like a cylindrical battery as shown in Fig. 15, a large stress acts on the electrodes during winding. In addition, when the wound electrode body is housed in the casing, a stress always acts on the electrodes toward the outside of the winding axis. Even if such a large stress acts on the electrodes, it is possible to prevent the active material from splitting.

[0263] In this embodiment, coin-type, cylindrical, and thin-type batteries are shown as the battery, but other sealed batteries, square batteries, and batteries of various shapes can be used. In addition, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which a positive electrode, a negative electrode, and a separator are wound may be used. For example, examples of other batteries are shown in Figs. 19 to 23.

[0264] [Configuration Example of Thin-Type Battery] Figs. 19 and 20 show a configuration example of a thin-type battery. The wound body 993 shown in Fig. 19(A) has a negative electrode 994, a positive electrode 995, and a separator 996.

[0265] In the wound body 993, the negative electrode 994 and the positive electrode 995 overlap and are stacked with the separator 996 interposed therebetween, and the stacked sheet is wound. By covering this wound body 993 with a square sealing container or the like, a square secondary battery is manufactured.

[0266] The number of stacked layers of the stack composed of the negative electrode 994, the positive electrode 995, and the separator 996 may be appropriately designed according to the required capacity and the element volume. The negative electrode 994 is connected to a negative electrode current collector (not shown) via one of the lead electrodes 997 and 998, and the positive electrode 995 is connected to a positive electrode current collector (not shown) via the other of the lead electrodes 997 and 998. ​​​​​​​​​​​

[0267] The storage battery 990 shown in FIGS. 19(B) and 19(C) is formed by thermocompression bonding or the like a film 981 serving as an exterior body and a film 982 having a concave portion, and storing the above-described wound body 993 in the space formed thereby. The wound body 993 has lead electrodes 997 and lead electrode 998, and is impregnated with an electrolytic solution inside the film 981 and the film 982 having a concave portion .

[0268] As the film 981 and the film 982 having a concave portion, a metal material such as aluminum or a resin material can be used . If a resin material is used as the material of the film 981 and the film 982 having a concave portion, when a force is applied from the outside, the film 981 and the film 982 having a concave portion can be deformed, and a flexible storage battery can be manufactured .

[0269] Also, FIGS. 19(B) and 19(C) show an example using two films, but a space may be formed by bending one film, and the above-described wound body 9 93 may be stored in the space .

[0270] In addition, a flexible power storage device can be manufactured by using a resin material or the like for the exterior body or the sealing container of the power storage device. However, when the exterior body or the sealing container is made of a resin material , the portion for external connection shall be made of a conductive material .

[0271] For example, FIG. 20 shows an example of another thin flexible storage battery. Since the wound body 9 93 in FIG. 20(A) is the same as that shown in FIG. 19(A), detailed description thereof will be omitted .

[0272] ​​ The storage battery 990 shown in FIG. 20(B) and FIG. 20(C) has the above-described The winding body 993 includes a lead electrode 997 and a lead The electrode 998 is impregnated with an electrolyte inside the exterior bodies 991 and 992. The outer casing 992 can be made of a metal material such as aluminum or a resin material. If resin material is used as the material of 991 and 992, the exterior body 9 91, 992 can be deformed to produce a thin storage battery having flexibility. do.

[0273] By using an electrode including an active material according to one embodiment of the present invention in a flexible thin storage battery, This means that even if stress is applied to the electrodes by repeatedly bending a thin storage battery, the battery will remain active. This can prevent the material from being cleaved.

[0274] As a result, the active material having at least a part of the cleavage plane covered with graphene can be used for an electrode. As a result, it is possible to suppress a decrease in the battery voltage and a decrease in the discharge capacity. The cycle characteristics of the battery during charging and discharging can be improved.

[0275] [Example of energy storage system structure] A structural example of the power storage system will be described with reference to Figs. 21 to 23. The power system refers to, for example, a device equipped with a power storage device.

[0276] 21(A) and 21(B) are diagrams showing the external appearance of the power storage system. The system includes a circuit board 900 and a storage battery 913. The storage battery 913 is provided with a label 91. 21B, the power storage system has a terminal 951 and It has a terminal 952, an antenna 914, and an antenna 915.

[0277] The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 95 1, the terminal 952, the antenna 914, the antenna 915, and the circuit 912. Additionally, a plurality of terminals 911 may be provided, and each of the plurality of terminals 911 may be used as a control signal input terminal, a power supply terminal, etc.

[0278] The circuit 912 may be provided on the back surface of the circuit board 900. Note that the antennas 914 and 915 are not limited to being coil-shaped, and may be, for example, linear or plate-shaped. Also, antennas such as planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas, and induced conductive antennas may be used. Alternatively, the antenna 914 or the antenna 91 5 may be a flat conductor. This flat conductor can function as one of the conductors for electric field coupling. That is, the antenna 914 or the antenna 915 may function as one of the two conductors of the capacitor. Thereby, power exchange can be performed not only by electromagnetic fields and magnetic fields but also by electric fields.

[0279] The line width of the antenna 914 is preferably larger than the line width of the antenna 915. Thereby, the amount of power received by the antenna 914 can be increased.

[0280] The power storage system has a layer 9 16 between the antennas 914 and 915 and the storage battery 913. The layer 916 has a function of being able to shield, for example, the electromagnetic field generated by the storage battery 913. As the layer 916, for example, a magnetic material can be used.

[0281] Note that the structure of the power storage system is not limited to the structure shown in FIG. 21.

[0282] For example, as shown in FIGS. 22(A-1) and 22(A-2), among the storage batteries 913 shown in FIGS. 21(A) and 21(B), antennas may be provided on each of a pair of opposing surfaces. FIG. 22(A-1) is an external view seen from one side direction of the pair of surfaces, and FIG. 2 2(A-2) is an external view seen from the other side direction of the pair of surfaces. Note that for the same parts as the power storage system shown in FIGS. 21(A) and 21(B), the description of the power storage system shown in FIGS. 21(A) and 2 1(B) can be appropriately incorporated.

[0283] As shown in FIG. 22(A-1), an antenna 914 is provided with a layer 916 interposed on one of a pair of surfaces of the storage battery 913, and as shown in FIG. 22(A-2), an antenna 915 is provided with a layer 917 interposed on the other of a pair of surfaces of the storage battery 913. The layer 917 has a function of, for example, shielding the electromagnetic field from the storage battery 913. As the layer 917, for example, a magnetic material can be used. used. used. used.

[0284] By adopting the above structure, the sizes of both the antenna 914 and the antenna 915 can be increased. increased.

[0285] Alternatively, as shown in FIGS. 22(B-1) and 22(B-2), among the storage batteries 913 shown in FIGS. 21(A) and 21(B), different antennas may be provided on each of a pair of opposing surfaces. FIG. 22(B-1) is an external view seen from one side direction of the pair of surfaces, and FIG. 22(B-2) is an external view seen from the other side direction of the pair of surfaces. Note that for FIG. 21( For the same parts as the power storage system shown in Fig. 21(A) and Fig. 21(B), the description of the power storage system shown in Fig. 21(A) and Fig. 21(B) can be appropriately cited.

[0286] As shown in Fig. 22(B-1), antennas 914 and 915 are provided with a layer 916 sandwiched between one of the pair of surfaces of the storage battery 913, and as shown in Fig. 22(B-2), an antenna 918 is provided with a layer 917 sandwiched between the other of the pair of surfaces of the storage battery 913. The antenna 91 8 has a function capable of, for example, performing data communication with an external device. For the antenna 91 8, an antenna having a shape applicable to, for example, the antennas 914 and 915 can be applied. As a communication method between the power storage system and other devices via the antenna 918, a response method that can be used between the power storage system and other devices, such as NFC, can be applied.

[0287] Alternatively, as shown in Fig. 23(A), a display device 920 may be provided on the storage battery 91 3 shown in Fig. 21(A) and Fig. 21(B). The display device 920 is electrically connected to the terminal 911 via the terminal 919. Note that a label 910 may not be provided at the portion where the display device 920 is provided. For the same parts as the power storage system shown in Fig. 21(A) and Fig. 21(B), the description of the power storage system shown in Fig. 21(A) and Fig. 21(B) can be appropriately cited.

[0288] The display device 920 may display, for example, an image indicating whether charging is in progress, an image indicating the power storage amount, etc. As the display device 920, for example, an electronic paper, a liquid crystal display device, an electroluminescence (also referred to as EL) display device, etc. can be used. For example, an electronic paper By using a - par, the power consumption of the display device 920 can be reduced.

[0289] Alternatively, as shown in Fig. 23(B), a sensor 921 may be provided in the storage battery 91 shown in Figs. 21(A) and 21(B). The sensor 921 is electrically connected to the terminal 911 via the terminal 922. For the same parts as the power storage system shown in Figs. 21(A) and 21(B), the description of the power storage system shown in Figs. 21(A) and 21(B) can be appropriately incorporated. For the same parts as the power storage system shown in Figs. 21(A) and 21(B), the description of the power storage system shown in Figs. 21(A) and 21(B) can be appropriately incorporated. be used.

[0290] As the sensor 921, for example, those having a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation line, flow rate, humidity, gradient, vibration, odor or infrared rays can be used. By providing the sensor 921, for example, data (such as temperature) indicating the environment where the power storage system is placed can be detected and stored in the memory in the circuit 912. be used. be used. be detected and stored in the memory in the circuit 912. .

[0291] The storage battery and the power storage system shown in this embodiment use the electrode according to one aspect of the present invention. Therefore, the capacity of the storage battery and the power storage system can be increased. Also, the energy density can be increased. Also, the reliability can be increased. Also, the lifespan can be extended. be extended.

[0292] This embodiment can be implemented in appropriate combination with other embodiments.

[0293] (Embodiment 5) In this embodiment, as a form in which the electrode according to one aspect of the present invention can be applied, flexibility An example of mounting a storage battery having the same will be described with respect to an electronic device.

[0294] An example of mounting the flexible storage battery shown in Embodiment 4 to an electronic device is shown in FIG. 24. Examples of electronic devices to which a power storage device having a flexible shape is applied include, for example, a television set (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a cellular phone or a mobile phone device), a portable game machine, a portable information terminal, an audio reproduction device, a pachinko machine, and other large game machines such as those. In addition, it is also possible to incorporate a power storage device having a flexible shape along the inner wall or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile.

[0295]

[0296] FIG. 24(A) shows an example of a mobile phone. The mobile phone 7400 includes, in addition to a display unit 7402 incorporated in a housing 740 1, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 has a power storage device 7407.

[0297] FIG. 24(B) shows a state in which the mobile phone 7400 is bent. When the mobile phone 74 00 is deformed by an external force to be bent as a whole, the power storage device 7407 provided inside thereof is also bent. Further, at that time, the state of the bent power storage device 7407 is shown in FIG. 24( C). The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a bent state. Note that the power storage device 7407 is electrically connected to a current collector 7409. It has a lead electrode 7408. For example, the current collector 7409 is a copper foil, and a part of it is alloyed with gallium to improve the adhesion between the current collector 7409 and the active material layer in contact therewith, and the power storage device 7407 has a configuration with high reliability in a bent state. and is in a configuration with high reliability in a bent state. Figure 24(D) shows an example of a bangle-type display device. The portable display device 7100 includes a housing 7101, a display unit 7102, an operation button 7103, and a power storage device 7104.

[0298] Figure 24(E) shows the state of the power storage device 7104 that is bent. When the power storage device 7104 is bent and worn on the user's arm, the housing deforms and the curvature of part or all of the power storage device 7104 changes. Note that the degree of bending at any point on the curve is represented by the value of the radius of the corresponding circle, which is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, part or all of the main surface of the housing or the power storage device 7104 changes within the range where the radius of curvature is 40 mm or more and 150 mm or less. If the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 150 mm or less, high reliability can be maintained. Figure 24(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, an operation button 7205, input / output terminals 7206, and the like. Figure 24(E) shows the state of the power storage device 7104 that is bent. When the power storage device 7104 is bent and worn on the user's arm, the housing deforms and the curvature of part or all of the power storage device 7104 changes. Note that the degree of bending at any point on the curve is represented by the value of the radius of the corresponding circle, which is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, part or all of the main surface of the housing or the power storage device 7104 changes within the range where the radius of curvature is 40 mm or more and 150 mm or less. If the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 150 mm or less, high reliability can be maintained. When the power storage device 7104 is bent and worn on the user's arm, the housing deforms and the curvature of part or all of the power storage device 7104 changes. Note that the degree of bending at any point on the curve is represented by the value of the radius of the corresponding circle, which is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, part or all of the main surface of the housing or the power storage device 7104 changes within the range where the radius of curvature is 40 mm or more and 150 mm or less. If the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 150 mm or less, high reliability can be maintained. Figure 24(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, an operation button 7205, input / output terminals 7206, and the like. Figure 24(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, an operation button 7205, input / output terminals 7206, and the like.

[0299] Figure 24(F) shows an example of a wristwatch-type portable information terminal. The portable information terminal 7200 can execute various applications such as mobile phone calls, email, text browsing and creation, music playback, Internet communication, and computer games. The portable information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, an operation button 7205, input / output terminals 7206, and the like. The portable information terminal 7200 can execute various applications such as mobile phone calls, email, text browsing and creation, music playback, Internet communication, and computer games.

[0300] The portable information terminal 7200 can execute various applications such as mobile phone calls, email, text browsing and creation, music playback, Internet communication, and computer games. The portable information terminal 7200 can execute various applications such as mobile phone calls, email, text browsing and creation, music playback, Internet communication, and computer games. The portable information terminal 7200 can execute various applications such as mobile phone calls, email, text browsing and creation, music playback, Internet communication, and computer games.

[0301] The display unit 7202 has a curved display surface, and displays information along the curved display surface. The display unit 7202 is equipped with a touch sensor, and the screen can be operated by touching it with a finger or a stylus. For example, the icon 7 displayed on the display unit 7202 can be operated by touching the By touching 207, the application can be launched.

[0302] The operation button 7205 is used to set the time, turn the power on and off, and turn wireless communication on and off. It supports various functions such as auto-start, silent mode and power saving mode. For example, an operating system built into the portable information terminal 7200 can be Depending on the system, the functions of the operation buttons 7205 can be freely set.

[0303] In addition, the mobile information terminal 7200 is capable of performing short-distance wireless communication according to a communication standard. For example, by communicating with a wireless headset, a hands-free You can also make calls.

[0304] The portable information terminal 7200 also includes an input / output terminal 7206 and is connected to other information terminals via a connector. Data can be exchanged directly through the input / output terminal 7206. The charging operation can be performed by wireless power supply without going through the input / output terminal 7206. You may go.

[0305] The display portion 7202 of the portable information terminal 7200 includes an electrode according to one embodiment of the present invention. For example, the power storage device 7104 shown in FIG. It can be installed in a curved state or in a curved state inside the band 7203. do.

[0306] The portable information terminal 7200 preferably has a sensor. For example, a fingerprint sensor may be used as the sensor. Human body sensors such as sensors for measuring body temperature, touch sensors, pressure sensors, and acceleration sensors. It is preferable that the sensor, etc. be mounted.

[0307] FIG. 24G shows an example of a wristband-type display device. The display device 7300 has a display unit The display device 7300 includes a power storage device of one embodiment of the present invention. The display portion 7304 may be provided with a touch sensor, and may function as a portable information terminal. It is also possible.

[0308] The display surface of the display unit 7304 is curved, and the display is performed along the curved display surface. In addition, the display device 7300 can display the image by short-distance wireless communication according to a communication standard. You can change the situation.

[0309] The display device 7300 also has an input / output terminal, and can directly connect to other information terminals via a connector. It is possible to exchange data. It is also possible to charge the device via the input / output terminal. The charging operation may be performed by wireless power supply without going through the input / output terminals.

[0310] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0311] (Embodiment 6) In this embodiment, an example of an electronic device in which a power storage device can be mounted will be described.

[0312] FIG. 25(A) and FIG. 25(B) show an example of a tablet terminal that can be folded in two. The tablet terminal 9600 shown in FIG. 25(A) and FIG. 25(B) includes a housing 9630a, Housing 9630b, movable part 9640 connecting housing 9630a and housing 9630b, display unit 9 631a and display unit 9631 having display unit 9631b, display mode switching switch 96 26, power switch 9627, power saving mode switching switch 9625, fastener 9629 , operation switch 9628. FIG. 25(A) shows the state where the tablet terminal 9600 is opened , and FIG. 25(B) shows the state where the tablet terminal 9600 is closed.

[0313] Also, the tablet terminal 9600 has a power storage body 9635 inside the housing 9630a and the housing 9630b. The power storage body 9635 is provided through the movable part 9640 and extends across the housing 9630a and the housing 9630b.

[0314] Part of the display unit 9631a can be a touch panel area 9632a, and data can be input by touching the displayed operation keys 9638. Note that in the display unit 96 31a, as an example, a configuration where half of the area has only a display function and the other half of the area has a touch panel function is shown, but it is not limited to this configuration. All areas of the display unit 96 31a may also have a touch panel function. For example, the entire surface of the display unit 9 631a can be used to display keyboard buttons as a touch panel, and the display unit 9631b can be used as a display screen.

[0315] Also, in the display unit 9631b, similar to the display unit 9631a, part of the display unit 9631b can be a touch panel area 9632b. Also, when a finger or a stylus touches the position where the keyboard display switching button 9639 of the touch panel is displayed , The keyboard buttons can be displayed on the display unit 9631b.

[0316] Also, touch inputs can be simultaneously performed on the touch panel area 9632a and the touch panel area 9632b. It is also possible to perform touch input.

[0317] In addition, the display mode switching switch 9626 can select the display orientation such as portrait or landscape, and can also select switching between black and white display and color display. The power saving mode switching switch 9625 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal 9600 during use. The tablet terminal can incorporate other detection devices such as sensors that detect inclination, such as a gyro and an acceleration sensor, in addition to the optical sensor. In addition, in FIG. 25(A), an example is shown in which the display areas of the display unit 9631b and the display unit 9631a are the same, but it is not particularly limited, and the size of one may be different from that of the other, and the display quality may also be different. For example, one may be a display panel that can perform higher definition display than the other. It may be used as the display panel.

[0318] In addition, FIG. 25(B) shows a closed state, and the tablet terminal includes a housing 9630, a solar cell 9 633, and a charge and discharge control circuit 9634 including a DCDC converter 9636. Further, as the power storage body 9635, a power storage body according to an aspect of the present invention is used. It may be used as the display panel.

[0319] FIG. 25(B) shows a closed state, and the tablet terminal includes a housing 9630, a solar cell 9 633, and a charge and discharge control circuit 9634 including a DCDC converter 9636. Further, as the power storage body 9635, a power storage body according to an aspect of the present invention is used.

[0320] Since the tablet terminal 9600 is foldable in two, it can be folded so that the housing 9630a and the housing 9630b are overlapped when not in use. By folding, , since it can protect the display units 9631a and 9631b, the durability of the tablet terminal 9600 can be enhanced. Also, the power storage device 9635 using the power storage device of one aspect of the present invention has flexibility, and the charge and discharge capacity is less likely to decrease even when repeated bending and stretching are performed. Therefore, a tablet terminal with excellent reliability can be provided.

[0321] In addition, the tablet terminals shown in FIGS. 25(A) and 25(B) also have functions such as displaying various types of information (still images, moving images, text images, etc.), a calendar, date or time displaying on the display unit, a touch input function for touch input operation or editing of the information displayed on the display unit, a function for controlling processing by various software (programs), and the like can be achieved.

[0322] Power can be supplied to the touch panel, display unit, video signal processing unit, etc. by the solar cell 9633 mounted on the surface of the tablet terminal. Note that the solar cell 9633 can be provided on one side or both sides of the housing 9630, and can be configured to efficiently charge the power storage device 9635. As the power storage device 9635, using a lithium ion battery has advantages such as being able to achieve miniaturization.

[0323] Also, regarding the configuration and operation of the charge and discharge control circuit 9634 shown in FIG. 25(B), a block diagram is shown and explained in FIG. 25 (C). FIG. 25(C) shows the solar cell 9633, the power storage device 96 35, the DCDC converter 9636, the converter 9637, the switches SW1 to SW3, and the display unit 9631. The power storage device 9635, the DCDC converter 9636, the co nverter 9637, and the switches SW1 to SW3 are the charge and discharge control circuit 9 shown in FIG. 25(B)​​​ This corresponds to the location corresponding to 634.

[0324] First, an example of the operation when power is generated by the solar cell 9633 by external light will be described. . The power generated by the solar cell becomes a voltage for charging the power storage body 9635, and is stepped up or down by the DCDC converter 9636. When the power from the solar cell 9633 is used for the operation of the display unit 9631, the switch SW1 is turned on, and the converter 963 7 steps up or down to the voltage required for the display unit 9631. When the display on the display unit 963 1 is not performed, SW1 may be turned off and SW2 may be turned on to charge the power storage body 9635. It may be configured as follows. Although the solar cell 9633 has been shown as an example of a power generation means, it is not particularly limited,

[0325] and the power storage body 9635 may be charged by other power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). For example, a contactless power transmission module that wirelessly (non-contact) transmits and receives power for charging, or a configuration that combines other charging means may be used. to charge may also be used. FIG. 26 shows an example of another electronic device. In FIG. 26, the display device 8000 is an example of an electronic device using the power storage device 8004 according to one aspect of the present invention. Specifically, the display device 80 is equivalent to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker

[0326] unit 8003, a power storage device 8004, and the like. The power storage device 8004 according to one aspect of the present invention is provided inside the housing 8001. The display device 8000 can receive power supply from a commercial power source, or can use the power stored in the power storage device 8004. Therefore, it can also use the power stored in the power storage device 8004. Therefore, it is provided inside the housing 8001. The display device 8000 can receive power supply from a commercial power source, or can use the power stored in the power storage device 8004. Thus, Even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8004 according to one aspect of the present invention as an uninterruptible power supply, the display device 8000 can be used. Even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8004 according to one aspect of the present invention as an uninterruptible power supply, the display device 8000 can be used. becomes possible.

[0327] The display unit 8002 may include a light-emitting device having a light-emitting element such as a liquid crystal display device or an organic EL element in each pixel, an electrophoretic display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), an FED (Field Emission Display), or the like, and a semiconductor display device can be used. ice), PDP (Plasma Display Panel), FED (Field Emission Display), etc., and a semiconductor display device can be used. Emission Display), etc., and a semiconductor display device can be used.

[0328] In addition to being used for receiving TV broadcasts, the display device includes all display devices for information display, such as those for personal computers and advertising displays. In addition to being used for receiving TV broadcasts, the display device includes all display devices for information display, such as those for personal computers and advertising displays.

[0329] In FIG. 26, the installed lighting device 8100 is an example of an electronic device using the power storage device 8103 according to one aspect of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a power storage device 8103, etc. In FIG. 26, the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8101 and the light source 8102 are installed is shown as an example, but the power storage device 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. In FIG. 26, the installed lighting device 8100 is an example of an electronic device using the power storage device 8103 according to one aspect of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a power storage device 8103, etc. In FIG. 26, the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8101 and the light source 8102 are installed is shown as an example, but the power storage device 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. a light source 8102, a power storage device 8103, etc. In FIG. 26, the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8101 and the light source 8102 are installed is shown as an example, but the power storage device 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. 101 and the light source 8102 are installed is shown as an example, but the power storage device 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. 101 and the light source 8102 are installed is shown as an example, but the power storage device 8103 may be provided inside the housing 8101. The lighting device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. device 8100 can receive power supply from a commercial power source and can also use the power stored in the power storage device 8103. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. is received, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used. is received, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 8100 can be used.

[0330] In FIG. 26, an installed lighting device 8100 provided on the ceiling 8104 is illustrated. However, the power storage device according to one aspect of the present invention can be used not only for the ceiling 8104 but also for installed lighting devices provided on, for example, the side wall 8105, the floor 8106, the window 8107, etc., and can also be used for table top lighting devices and the like.

[0331] In addition, as the light source 8102, an artificial light source that artificially obtains light using electric power can be used. Specifically, incandescent bulbs, discharge lamps such as fluorescent lamps, and light emitting elements such as LEDs and organic EL elements are cited as examples of the above artificial light sources.

[0332] In FIG. 26, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using the power storage device 8203 according to one aspect of the present invention. Specifically, the indoor unit 8200 has a housing 8201, an air outlet 8202, a power storage device 8203, etc. In FIG. 26 an example in which the power storage device 8203 is provided in the indoor unit 8200 is illustrated, but the power storage device 8203 may be provided in the outdoor unit 8204. Alternatively, the power storage device 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power supply from a commercial power source, or can use the power stored in the power storage device 8203. In particular, when the power storage device 8 203 is provided in both the indoor unit 8200 and the outdoor unit 8204, even when power supply from the commercial power source cannot be received due to a power outage or the like at that time, by using the power storage device 8203 according to one aspect of the present invention as an uninterruptible power supply, the air conditioner can be used.

[0333] Note that in FIG. 26, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated. However, the power storage device according to one aspect of the present invention can also be used for an integrated type air conditioner having the functions of the indoor unit and the outdoor unit in one housing.

[0334] In FIG. 26, the electric refrigerator 8300 is an example of an electronic device using the power storage device 8304 according to one aspect of the present invention. Specifically, the electric refrigerator 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a power storage device 8304, and the like. In FIG. 26, the power storage device 8304 is provided inside the housing 8301. The electric refrigerator 8300 can receive power supply from a commercial power source, or can use the power stored in the power storage device 8304. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the power storage device 8304 according to one aspect of the present invention as an uninterruptible power supply, the electric refrigerator 8300 can be used.

[0335] Note that among the above-described electronic devices, high-frequency heating devices such as microwave ovens and electronic devices such as electric rice cookers require high power in a short time. Therefore, by using the power storage device according to one aspect of the present invention as an auxiliary power supply to supplement the power that cannot be covered by the commercial power source, it is possible to prevent the breaker of the commercial power source from tripping when the electronic device is in use.

[0336] Also, during the time when the electronic device is not in use, particularly during the time when the ratio of the actually used power amount to the total power amount that can be supplied by the commercial power source supplier (referred to as the power usage rate) is low, by storing power in the power storage device, it is possible to suppress an increase in the power usage rate outside the above time period. It is possible. For example, in the case of an electric refrigerator 8300, at night when the temperature is low and the doors 83 02 and 8303 of the freezer compartment are not opened or closed, power is stored in the power storage device 8304. Then, during the day when the temperature rises and the doors 8302 and 8303 of the refrigerator compartment and the freezer compartment are opened and closed, by using the power storage device 8304 as an auxiliary power source, the power consumption rate during the day can be kept low.

[0337] This embodiment can be implemented in appropriate combination with other embodiments.

[0338] (Embodiment 7) In this embodiment, an example of mounting a power storage device on a vehicle is shown.

[0339] Also, when a power storage device is mounted on a vehicle, next-generation clean energy vehicles such as hybrid electric vehicles (HEV), electric vehicles (EV), or plug-in hybrid electric vehicles (PHEV) can be realized.

[0340] In FIG. 27, a vehicle using one aspect of the present invention is illustrated. The automobile 8400 shown in FIG. 27(A) is an electric vehicle that uses an electric motor as a power source for running. Or it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as power sources for running. By using one aspect of the present invention, a vehicle with a long cruising range can be realized. Also, the automobile 8400 has a power storage device. The power storage device can not only drive the electric motor 8406, but also supply power to lighting devices such as the headlight 8401 and the room light (not shown).

[0341] Also, the power storage device supplies power to meters such as the speedometer and tachometer that the automobile 8400 has.​​​​​​​ Power can be supplied to the display device. Also, the power storage device can supply power to semiconductor devices such as the navigation system of the vehicle 8400.

[0342] The vehicle 8500 shown in FIG. 27(B) can be charged by receiving power supply from external charging facilities by means such as a plug-in method or a non-contact power supply method. FIG. 27(B) shows a state in which charging is being performed from a ground-mounted charging device 8021 to a power storage device 8024 mounted on the vehicle 8500 via a cable 8022. When charging, the charging method, connector specifications, etc. may be appropriately carried out in a predetermined manner such as CHAdeMO (registered trademark) or Combo. The charging device 8021 may be a charging station provided in a commercial facility, or may also be a household power source. For example, by plug-in technology, the power storage device 8024 mounted on the vehicle 8500 can be charged by external power supply. Charging can be performed by converting AC power into DC power through a conversion device such as an AC-DC converter.

[0343] Also, although not shown, a power receiving device can be mounted on the vehicle, and power can be supplied and charged to the vehicle non-contact from a ground power transmission device. In the case of this non-contact power supply method, by incorporating a power transmission device into a road or an outer wall, charging can be performed not only while the vehicle is stopped but also while it is running. Also, using this non-contact power supply method, power can be transmitted and received between vehicles. Furthermore, a solar cell may be provided on the exterior of the vehicle to charge the power storage device when the vehicle is stopped or running. For such non-contact power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0344] According to one aspect of the present invention, the cycle characteristics of the power storage device can be improved, and the reliability can be enhanced. In addition, according to one aspect of the present invention, the characteristics of the power storage device can be improved, and thus the power storage device itself can be made smaller and lighter. If the power storage device itself can be made smaller and lighter, it contributes to the weight reduction of the vehicle, so that the cruising range can be improved. Also, the power storage device mounted on the vehicle can be used as a power supply other than the vehicle. In this case, it is possible to avoid using the commercial power supply at the peak of the power demand.

[0345] This embodiment can be implemented in appropriate combination with other embodiments.

Example

[0346] In this example, the characteristics when charging and discharging are performed using the electrode of one aspect of the present invention in the power storage device will be described.

[0347] Electrodes M, N, and O were prepared as the electrodes.

[0348] <Synthesis of Particles Having Lithium Manganese Nickel Oxide> Lithium manganese nickel oxide was synthesized. As raw materials, Li2CO3, MnCO 3, and NiO were used, and the ratio (molar ratio) was weighed so that Li2CO3:MnCO3:NiO = 0.84 :0.8062:0.318.

[0349] Next, the weighed raw materials were mixed. Then, heat treatment was performed at 1000 °C to synthesize lithium manganese nickel oxide. After that, the obtained lithium manganese nickel oxide was subjected to a crushing treatment using a bead mill.

[0350] Next, the surface of the obtained lithium manganese nickel oxide was coated with a graphene compound. . First, water was added to graphene oxide to prepare a dispersion. Water was added to 5.2 g of graphene oxide. 160 ml of water was added to make the concentration of the graphene oxide dispersion 32.5 g / l.

[0351] Next, lithium manganese nickel oxide was added to the prepared graphene oxide dispersion and mixed. 260 g of lithium manganese nickel oxide was added to the dispersion containing 5.2 g of graphene oxide by weight. That is, 2% by weight of graphene oxide based on the weight of the positive electrode active material was added. . Then, heat treatment was performed at 50 °C under reduced pressure to obtain Sample A, which is lithium manganese nickel oxide coated with graphene oxide.

[0352] Next, for the reduction of graphene oxide, 240 g of Sample A, 40.5 g of ascorbic acid, 9.36 g of lithium hydroxide monohydrate, 1029 ml of ethanol, and 9.3 6 g of water were added and mixed. Spray drying treatment was performed on the obtained mixed solution, and powder was recovered from the mixed solution. Then, heat treatment was performed at 170 °C under reduced pressure.

[0353] Through the above steps, particles B having lithium manganese nickel oxide were prepared.

[0354] <Formation of the active material layer 212> Next, a slurry was prepared. The prepared particles B, acetylene black (AB), and PV dF were mixed at a ratio of particles B:AB:PVdF = 90:5:5 (weight ratio), and NMP was added as a solvent and kneaded. The solid content ratio of the slurry was 47% by weight.

[0355] Next, the slurry was coated on one side of the current collector. On both sides of an aluminum foil with a thickness of 20 μm, An undercoated current collector was used. Then, after the solvent was volatilized at 65 °C, it was volatilized at 75 °C and volatilized at 75 °C.

[0356] Next, heat treatment was performed at 250 °C under reduced pressure. Then, pressing was performed at 120 °C and a pressure of 1000 kN / m. Through the above steps, an electrode having the active material layer 212 was formed on the current collector.

[0357] <Synthesis of Graphene Compound> Next, a graphene compound having the structure of the following structural formula (202) was synthesized.

[0358] [Chemical Formula]

[0359] First, 0.41 g of graphene oxide (manufactured by Nippon Material Co., Ltd., product name: Rap dG O(TQ-11)-1) and 5.6 g (77 mmol) of n-butylamine were added to a flask. This mixture was irradiated with ultrasonic waves for 5 minutes under a nitrogen stream, and further stirred at 60 °C for 1 hour. After stirring, the mixture was cooled to room temperature, 20 mL of toluene was added, and ultrasonic waves were irradiated for 5 minutes . After cooling this mixture to 0 °C, 11 g (3 1 mmol) of 11-acetoxyundecyltrichlorosilane was added dropwise, and the mixture was stirred at 60 °C for 5 hours. After stirring, toluene was added to this mixture for washing, and the solid was recovered by suction filtration. The obtained solid (filtered product) was further washed with ethanol and acetone. The obtained solid was dried to obtain 0. 52 g of the target black powder (Sample 1).

[0360] <Formation of Layer 213> First, the method for manufacturing electrode M will be described. Electrode M has a graphene compound on electrode O The layer 213 is formed. First, a layer 2 13 having a graphene compound is formed on the active material layer 212. First, the graphene compound and ethanol are mixed to prepare a dispersion liquid. Next, the electrode O having the active material layer 212 on the current collector is placed on a hot plate at 70 °C, and the prepared dispersion liquid is dropped onto the active material layer 212. Further, heat treatment is performed at 70 °C under reduced pressure. Through the above steps, an electrode M having the active material layer 212 and the layer 213 on the current collector is fabricated.

[0361] Next, the method for fabricating the electrode N will be described. For the electrode N, a layer 213 having graphene oxide is formed on the electrode O. First, graphene oxide and ethanol are mixed to prepare a dispersion liquid. After that, the prepared dispersion liquid is dropped onto the active material layer 212, and heat treatment is performed to volatilize ethanol. Through the above steps, an electrode N having the active material layer 212 and a layer having graphene oxide on the current collector is fabricated. The total thickness of the active material layer 212 and the layer 213 was about 9 0 μm.

[0362] Next, the fabricated electrodes are punched out to a size of 12 mmφ to serve as positive electrodes. Two positive electrodes (No.1 and No.2) are punched out from each electrode. Using a lithium foil punched out to a size of 15 mmφ as the negative electrode, a separator is sandwiched between the positive electrode and the negative electrode, and a coin-type battery of CR2032 type is fabricated. Polypropylene is used as the separator. As the electrolytic solution, a mixed solution in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1 :1 and lithium hexafluorophosphate (LiPF6) is dissolved at a concentration of 1 mol / L is used.

[0363] ​​​​​​Electrode O, Electrode M and Electrode N (Positive Electrode Active Material) loading of the positive electrode active material, and the loading of graphene oxide or graphene compound (GO or GC) of Electrode M and Electrode N are shown in Table 1. The loading of the positive electrode active material is 18.6 to 19.5 mg / cm , and the loading of graphene oxide or graphene compound is 1.1 to 1.8 mg / cm 2 . 2

[0364]

Table 1

[0365] Charging and discharging of the fabricated storage battery were performed. Charging was carried out at a constant current of 30 mA / g (about 0.08 C) with a maximum of 4.8 V. Discharging was carried out at a constant current of 30 mA / g ( about 0.08 C) with a minimum of 2 V.

[0366] The charge-discharge cycle characteristics of Electrode M in Fig. 28, Electrode N in Fig. 29(A), and Electrode O in Fig. 29(B) are shown respectively. For each electrode condition, since two positive electrodes were punched out, the results of the charge-discharge cycle characteristics are shown in two for each condition. The vertical axis is the capacity ( Capacity), and the horizontal axis is the number of cycles (Cycle). Compared with the condition using Electrode O, in Electrode N where a layer with graphene oxide was formed, the decrease in capacity was alleviated. Also, in Electrode M where a layer with the graphene compound of one aspect of the present invention was formed, the decrease in capacity with the cycle was small, and good results were obtained.

Explanation of symbols

[0367] ​​​​​​​ 101 Current collector 102 Active material layer 103 Active material 111 Positive electrode 111a Positive electrode 115 Negative electrode 115a Negative electrode 121 Positive current collector 122 Positive active material layer 123 Separator 125 Negative current collector 126 Negative active material layer 130 Electrode assembly 131 Electrode assembly 210 Electrode 211 Current collector 212 Active material layer 213 Layer 220 Electrode 221 Active material 230 Region 251 Cation 252 Cation 253 Electron 300 Storage battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive current collector 306 Positive active material layer 307 Negative electrode 308 Negative current collector 309 Negative active material layer 310 Separator 321 Graphene compound 331 Region 332 Region 333 Region 500 Storage battery 501 Positive current collector 502 Positive active material layer 503 Positive electrode 504 Negative current collector 505 Negative active material layer 506 Negative electrode 507 Separator 508 Electrolyte 509 Outer package 510 Positive lead electrode 511 Negative lead electrode 512 Welding area 514 Sealing part 600 Storage battery 601 Positive electrode cap 602 Battery can 603 Positive electrode terminal 604 Positive electrode 605 Separator 606 Negative electrode 607 Negative electrode terminal 608 Insulating plate 609 Insulating plate 611 PTC element 612 Safety valve mechanism 900 Circuit board 910 Label 911 Terminal 912 Circuit 913 Storage battery 914 Antenna 915 Antenna 916 Layer 917 Layer 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 951 Terminal 952 Terminal 981 Film 982 Film 990 Storage battery 991 Outer package 992 Outer package 993 Wound body 994 Negative electrode 995 Positive electrode 996 Separator 997 Lead electrode 998 Lead electrode 1700 Curved surface 1701 Plane 1702 Curve 1703 Radius of curvature 1704 Center of curvature 1800 Center of curvature 1801 Film 1802 Radius of curvature 1803 Film 1804 Radius of curvature 7100 Portable display device 7101 Housing 7102 Display unit 7103 Operation button 7104 Power storage device 7200 Portable information terminal 7201 Housing 7202 Display unit 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 Display device 7304 Display unit 7400 Mobile phone 7401 Housing 7402 Display unit 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Power storage device 7408 Lead electrode 7409 Current collector 8000 Display device 8001 Housing 8002 Display unit 8003 Speaker unit 8004 Power storage device 8021 Charging device 8022 Cable 8024 Power storage device 8100 Lighting device 8101 Housing 8102 Light source 8103 Power storage device 8104 Ceiling 8105 Side wall 8106 Floor 8107 Window 8200 Indoor Unit 8201 Housing 8202 Air Outlet 8203 Power Storage Device 8204 Outdoor Unit 8300 Electric Refrigerator 8301 Housing 8302 Door for Refrigerator Compartment 8303 Door for Freezer Compartment 8304 Power Storage Device 8400 Automobile 8401 Headlight 8406 Electric Motor 8500 Automobile 9600 Tablet-Type Terminal 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fastener 9630 Housing 9630a Housing 9630b Housing 9631 Display Unit 9631a Display Unit 9631b Display Unit 9632a Area 9632b Area 9633 Solar Cell 9634 Charge and Discharge Control Circuit 9635 Energy Storage Element 9636 DCDC Converter 9637 Converter 9638 Operation Key 9639 Button 9640 Movable Part

Claims

1. having an active material and a graphene compound, the graphene compound having a graphene layer and a substituted or unsubstituted chain-like group, the graphene layer being bonded to the chain-like group via a substituent having silicon, the active material being particulate, the graphene compound having a region in contact with the active material, the active material having element A and element M, element A being one or more selected from elements of Group 1 and elements of Group 2, element M having one or more selected from manganese and nickel, the chain-like group having one or more selected from a carbonyl group, an ester group, a carboxyl group, an ether group, and an epoxy group, an electrode.

2. having an active material and a graphene compound, the active material being particulate, the graphene compound having a region in contact with the surface of the active material, the active material having element A and element M, element A being one or more selected from elements of Group 1 and elements of Group 2, element M having one or more selected from manganese and nickel, the graphene compound having a structure represented by the following formula (G1), an electrode. 【Chemical 1】 (In the general formula (G1), Glayer represents a graphene layer, and R １ represents a substituted or unsubstituted alkylene group, and R ２ represents hydrogen, or a substituted or unsubstituted alkyl group.)

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