Active material layer and secondary battery

Abstract

To provide a graphene oxide with high dispersibility and easy reduction, also provide graphene with high electronic conductivity, also provide a storage battery electrode having an active material layer with high electrical conductivity and a method for manufacturing the same, and also provide a storage battery with increased discharge capacity.SOLUTION: A method for manufacturing an electrode for a power storage battery includes the steps of dispersing graphene oxide in a solution containing alcohol or acid, heating graphene oxide dispersed in the solution, and reducing graphene oxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention is a storage battery electrode, a manufacturing method thereof, a storage battery, an electronic device, and a graph Regarding En.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. One aspect relates to a process, a machine, a method of manufacture. It relates to the composition of matter. More specifically, the technical field of one embodiment of the present invention disclosed in this specification is a semiconductor device, a display device, device, light emitting device, power storage device, storage device, driving method thereof, or manufacturing method thereof, for example. It can be mentioned as follows. [Background technology]

[0003] In recent years, portable devices such as mobile phones, smartphones, electronic books (e-books), and portable game consoles have become With the rapid spread of electronic devices, there is a demand for smaller and larger capacity secondary batteries, which are the driving power source for these devices. As a secondary battery used in portable electronic devices, it has high energy density and large capacity. Non-aqueous secondary batteries, such as lithium-ion secondary batteries, are widely used because of their advantages such as low battery capacity. It has been done.

[0004] Among non-aqueous secondary batteries, lithium ion batteries are widely used due to their high energy density. Lithium cobalt oxide (LiCoO2) and lithium iron phosphate (LiFePO 4) A positive electrode containing an active material such as graphite, which can absorb and release lithium ions. The negative electrode is made of Li and an organic solvent such as ethylene carbonate or diethyl carbonate. It is composed of a non-aqueous electrolyte solution in which an electrolyte made of lithium salt such as BF4 or LiPF6 is dissolved. The charging and discharging of a lithium-ion secondary battery is carried out by transferring the lithium ions in the secondary battery to a non-aqueous electrolyte. Lithium ions move between the positive and negative electrodes through the liquid, and are inserted into and removed from the active material of the positive and negative electrodes. This is done by:

[0005] The positive electrode or negative electrode contains a binder (binder) to bind the active material to the active material or the active material to the current collector. The binder is an insulating polyvinylidene fluoride (PVdF). Generally, polymer organic compounds such as these are used, which have extremely low electronic conductivity. When the ratio of the binder mixed in is increased, the amount of active material in the electrode decreases relatively. As a result, the discharge capacity of the secondary battery decreases.

[0006] Therefore, conductive additives such as acetylene black (AB) and graphite particles are mixed in. This improves the electronic conductivity between the active materials or between the active material and the current collector. This makes it possible to provide an active material with high electrical conductivity (see Patent Document 1).

[0007] In addition, graphene oxide (GO (short for Graphene Oxide)) The active material, binder, solvent, etc. are mixed together to prepare a mixture, which is then subjected to a heat treatment. By the heat treatment, the graphite oxide in the active material can be formed. Since graphene is reduced, an active material having graphene as a conductive additive can be obtained. In such an active material layer, an electron conduction network is formed in the active material layer, and excellent It has been found to exhibit electronic conductivity (see Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-110162 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-7141 Summary of the Invention [Problem to be solved by the invention]

[0009] In the development of storage batteries, in order to increase the discharge capacity, it is necessary to have an active material layer with high electronic conductivity. To form an active material layer with high electron conductivity, it is necessary to use an electrode with a high It is necessary to use graphene oxide that has high dispersibility in the nanoparticles. The graphene obtained must have excellent electronic conductivity. To save energy and time, electrodes can be fabricated using graphene oxide, which is easily reduced. It is necessary to create it.

[0010] In view of the above, an object of one embodiment of the present invention is to improve the dispersibility of graphene oxide in a solvent. Another objective is to improve the electronic conductivity of graphene. One object is to provide graphene oxide that can be used.

[0011] In addition, one embodiment of the present invention provides a storage battery electrode having an active material layer with high electronic conductivity. In one embodiment of the present invention, a semiconductor device having an active material layer with high electron conductivity is provided. Another object of the present invention is to provide a method for manufacturing a storage battery electrode. Another object of the present invention is to provide a storage battery with a large discharge capacity. In this invention, one of the objects is to provide a storage battery with improved cycle characteristics. An object of one embodiment of the present invention is to provide a storage battery with a long life. According to one aspect of the present invention, a novel battery, a novel electrode, a novel material, or a novel graphene Another object of the present invention is to provide a novel storage battery. Method, method for producing a novel electrode, method for producing a novel material, or method for producing a novel graphene One of the objects of the present invention is to provide a method.

[0012] The description of these problems does not preclude the existence of other problems. It is not necessary for the present invention to solve all of these problems. The above will be made clear from the description, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0013] One aspect of the present invention is a method for manufacturing a storage battery electrode, comprising forming an active material layer containing graphene on a current collector. The method includes dispersing graphene oxide in a solution containing an alcohol or an acid, and dispersing the solution. a step of heating the graphene oxide dispersed in the solution; and a step of reducing the graphene oxide. The present invention relates to a method for manufacturing a storage battery electrode, the method comprising the steps of:

[0014] Another embodiment of the present invention is a method for dispersing graphene oxide in a solution containing alcohol or acid, The graphene oxide dispersed in the solution is heated to form a mixture of the graphene oxide, the active material, and the binder. a solvent, and a mixture containing the solvent and the solvent is formed, and the mixture is applied onto a current collector. The solvent was removed, and the graphene oxide in the applied mixture was reduced to form graphene. and forming an active material layer containing the active material on a current collector.

[0015] In addition, graphene oxide is dispersed in a solution containing alcohol or acid, and the acid dispersed in the solution is The graphene oxide is heated and mixed with an active material to form a first mixture. The graphene oxide contained in the first mixture is reduced to form a second mixture. A third mixture containing the second mixture, a binder, a conductive additive, and a solvent is applied onto the current collector. The solvent contained in the third mixture is then removed to form an active material layer containing graphene. This is a method for manufacturing a storage battery electrode, characterized in that it is formed on a body.

[0016] In addition, in each of the above structures, one embodiment of the present invention is a method for reducing graphene oxide by heating. The present invention relates to a method for producing an electrode for a storage battery.

[0017] In each of the above structures, one embodiment of the present invention is a method for growing graphene oxide at a temperature higher than or equal to 60° C. and lowering the temperature to 150° C. The method for producing a storage battery electrode is characterized by heating and reducing the material as follows:

[0018] Further, in each of the above structures, one embodiment of the present invention is a method for manufacturing a semiconductor device, comprising: dissolving graphene oxide in a polar solvent containing a reducing agent; This is a method for manufacturing a storage battery electrode, characterized by immersing the electrode in a solvent and reducing it.

[0019] Another aspect of the present invention is a storage battery manufactured by any of the above methods for manufacturing a storage battery electrode. It is an electrode for use.

[0020] Another embodiment of the present invention includes an active material layer and a current collector. The active material layer includes an active material and a graphite. The graphene is bonded to the surface of the substrate by an ether bond or an ester bond. and the active material layer is located on the current collector. It is the extreme.

[0021] Furthermore, one embodiment of the present invention includes a first electrode and a second electrode, and the first electrode is The first electrode is either a positive electrode or a negative electrode. The second electrode can be operated as the other of the positive electrode and the negative electrode. It is a storage battery with the function of

[0022] Another embodiment of the present invention is a display panel, an operation key, a speaker, or a microphone, which includes the above-described storage battery. The electronic device is characterized by being equipped with a microphone.

[0023] In addition, one aspect of the present invention is a compound having an alkyl group linked by an ether bond or an ester bond. The graphene is characterized by being produced by reducing graphene oxide having do.

[0024] In addition, one aspect of the present invention is a compound having an alkyl group linked by an ether bond or an ester bond. The graphene is characterized by having:

[0025] In addition, in each of the above structures, one embodiment of the present invention is a compound in which the alkyl group has 1 to 4 carbon atoms. The graphene is characterized by the following:

[0026] Furthermore, one embodiment of the present invention is a method for reducing alcohol-intercalated graphene oxide. The graphene is characterized by being produced by

[0027] In addition, one embodiment of the present invention is such that, in the above structure, the alcohol has 1 to 4 carbon atoms. The graphene is characterized by the following. [Effects of the Invention]

[0028] According to one embodiment of the present invention, the dispersibility of graphene oxide in a solvent can be improved. In addition, the electron conductivity of graphene can be improved. It is possible to provide graphene oxide that can be

[0029] According to another embodiment of the present invention, a storage battery electrode having an active material layer with high electronic conductivity is provided. In one embodiment of the present invention, a storage battery including an active material layer with high electronic conductivity can be provided. Furthermore, according to one aspect of the present invention, it is possible to provide a method for manufacturing a battery electrode. Furthermore, according to one embodiment of the present invention, it is possible to provide a storage battery with improved cycle characteristics. According to one embodiment of the present invention, a storage battery having a long life can be provided. Alternatively, according to one aspect of the present invention, a novel storage battery, a novel electrode, a novel A new material or a novel graphene can be provided. This allows for the production of a new storage battery, a new electrode, a new material, and can provide a novel method for producing graphene.

[0030] The description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. , the specification, drawings, claims, etc., and It is possible to extract other effects from the claims and other descriptions. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a flowchart illustrating a method for manufacturing an electrode according to an embodiment. [Figure 2] 1A to 1C are diagrams illustrating a structure of an electrode according to an embodiment. [Figure 3] 1A to 1C illustrate reactions and structures of graphene oxide according to an embodiment; [Figure 4] 1 is a flowchart illustrating a method for manufacturing an electrode according to an embodiment. [Figure 5] 1 is a flowchart illustrating a method for manufacturing an electrode according to an embodiment. [Figure 6] Solid-state 13C NMR spectra of each graphene oxide sample. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 1 is a diagram illustrating a coin-type storage battery. [Figure 12] FIG. 1 is a diagram illustrating a laminated storage battery. [Figure 13] FIG. 1 is a diagram illustrating a laminated storage battery. [Figure 14] FIG. 1 is a diagram illustrating a cylindrical storage battery. [Figure 15] 1A to 1C illustrate examples of electronic devices. [Figure 16] 1A to 1C illustrate examples of electronic devices. [Figure 17] 1A to 1C illustrate examples of electronic devices. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments will be described with reference to the drawings. It is possible to implement the present invention in various ways without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the details of the present invention. However, the present invention should not be construed as being limited to the description of the following embodiments.

[0033] In the configuration of the invention described below, the same parts or parts having similar functions are designated by the same reference numerals. The same reference numerals are used in common among different drawings, and the repeated explanations thereof will be omitted. When referring to a function, the hatch pattern may be the same and no particular symbol may be added.

[0034] In each drawing described in this specification, the size of each component, the thickness of the film, or the area is shown for clarity. The figures may be exaggerated for illustrative purposes only and are not necessarily limited to that scale. There is no.

[0035] (Embodiment 1) In this embodiment, a storage battery electrode according to one embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. The following description will be given with reference to FIG. 1. Figure 1 shows the graph of the electrode structure, and Figure 2 shows the graphene oxide reaction and structure. A diagram showing the structure is shown below.

[0036] FIG. 2(A) is a perspective view of the storage battery electrode 100, and FIG. 2(B) is a perspective view of the storage battery electrode 100. 2A shows the storage battery electrode 100 in the form of a rectangular sheet. The shape of the storage battery electrode 100 is not limited to this, and any shape can be selected as appropriate. 2(A) and 2(B), the active material layer 102 is formed on only one surface of the current collector 101. However, the active material layer 102 may be formed on both sides of the current collector 101. The material layer 102 does not need to be formed on the entire surface of the current collector 101, but only on the surface of the current collector 101 to connect to the electrode tab. Non-coated areas, such as areas for coating, should be provided as appropriate.

[0037] 2C shows a cross-sectional view of the active material layer 102. The active material layer 102 is made of granular active material 103. graphene 104 as a conductive additive; a binder (not shown); The graphene 104 is an alkyl group linked by an ether bond or an ester bond. The graphene 104 may have an alcohol intercalated group. It may be possible.

[0038] As shown in FIG. 2(C), the inside of the active material layer 102 is covered with a sheet-like graphite layer. In FIG. 2(C), the graphene 104 is schematically represented by a thick line. Although it is called graphene, it is actually a thin film with a thickness of a single layer or multiple layers of carbon molecules. The active material 104 is disposed so as to surround or cover the active material particles 103, or Since they are formed so as to stick to the surface of the active material 103, they are in surface contact with each other. In addition, the graphenes 104 are in surface contact with each other, so that the plurality of graphenes 104 It forms a three-dimensional electron conduction network.

[0039] This is because graphene oxide, which has extremely high dispersibility in solvents, is used to form graphene 104. The solvent is removed from the dispersion containing uniformly dispersed graphene oxide, and the oxide is then removed. In order to reduce the graphene to form graphene, the graphene 10 remaining in the active material layer 102 is 4 are partially overlapping and dispersed to the extent that they are in surface contact with each other, forming a path for electron conduction. It is being formed.

[0040] Graphene is a carbon material with a crystalline structure in which hexagonal carbon skeletons are arranged in a plane. Graphene has amazing electrical, mechanical and chemical properties. High-mobility field-effect transistors, highly sensitive sensors, highly efficient solar cells, and next-generation It is attracting attention as it is expected to be applied in various fields, such as transparent conductive films for automobiles.

[0041] In this specification, graphene refers to single-layer graphene or multi-layer graphene with 2 to 100 layers. Single-layer graphene is a single-atom layer of carbon molecules with π bonds. Graphene oxide refers to a compound obtained by oxidizing the graphene. The distance between the plurality of monolayer graphenes is greater than 0.34 nm and less than 1.5 nm. In multi-layer graphene, the number of graphene layers is less than or equal to m. While graphene oxide has strong interactions with epoxy groups, carbonyl groups, and carboxyl groups, Because it has polar functional groups such as alkyl groups and hydroxyl groups, interactions between single-layer graphene Therefore, the distance between the monolayer graphenes in the graphene oxide is This is larger than the distance between multiple single-layer graphenes in multi-layer graphene.

[0042] In addition, graphene oxide (RGO) was obtained by reducing graphene. When forming graphene oxide, oxygen contained in the graphene oxide is Not all of the oxygen atoms are released, and some of the oxygen atoms may remain in the graphene via ether bonds or It may have an alkyl group linked by an ester bond. The tercalated alcohol may not be completely removed and may remain in the graphene. .

[0043] In addition, in this specification and the like, a compound having graphene as a basic skeleton is referred to as a “graphene-containing compound.” Compound (also called "Graphene Compound") Graphene, graphene oxide, and RGO are each graphene compounds. It is a seed.

[0044] An active material layer containing graphene as a conductive additive can be produced by the following method. First, graphene is dispersed in a solvent, and then the active material and binder are added and kneaded to form a mixture. Finally, the mixture is applied to a current collector, the solvent is removed, and the graphene is left as a conductive additive. An active material layer is prepared by adding the agent.

[0045] However, by using graphene as a conductive additive, an electron-conducting network is formed in the active material layer. To achieve this, graphene must first be uniformly dispersed in the solvent. This is because the dispersibility of graphene depends on the dispersibility of graphene in the active material layer. When the conductivity is low, graphene aggregates and localizes in the active material layer, resulting in the network Therefore, the dispersibility of the graphene used as the conductive additive in the solvent is This is an extremely important factor for increasing the electronic conductivity of the layer.

[0046] On the other hand, graphene oxide is mixed as a conductive additive with the active material, binder, and solvent. When the graphene oxide is reduced, it is easily dispersed. In the graphene active material layer, an electron conduction network is formed in the active material layer. , and exhibits excellent electronic conductivity.

[0047] Graphene and graphene formed by forming a mixture containing graphene oxide and then reducing it. The difference in dispersibility in the active material layer can be explained as follows, as a difference in dispersibility in a polar solvent. This can be done.

[0048] As mentioned above, graphene is a crystalline structure of carbon in which hexagonal skeletons are arranged in a plane. The structure does not contain any functional groups. Therefore, the surface of graphene is not polar. Therefore, the interaction between polar solvents and graphene is extremely small. Graphene is prone to aggregation due to its strong interactions with other graphene molecules.

[0049] On the other hand, graphene oxide contains epoxy groups, carbonyl groups, carboxyl groups, and hydroxyl groups. Therefore, the interaction between graphene oxide and polar solvents is large. Therefore, graphene oxide is less likely to aggregate in polar solvents. It can be uniformly dispersed in a polar solvent.

[0050] From the above, we have developed a conductive electrode with high electronic conductivity in the active material layer by using graphene as a conductive additive. In order to construct a network, the active material and graphene oxide are mixed together. In this case, it is very effective to use graphene oxide, which has high dispersibility in polar solvents. do.

[0051] Graphene oxide has a side length of 50 nm or more and 100 μm or less, and a side length of 800 nm or more and 2 It is preferable that the thickness is 0 μm or less.

[0052] Therefore, the electrode in this embodiment is formed by adding the above-mentioned epoxy group, carbonyl group, carboxyl group, etc. In addition to functional groups such as alkyl groups and hydroxyl groups, aryl groups are linked by ether or ester bonds. Graphene oxide with substituents such as alkyl groups or alcohol intercalated The graphene oxide is used as a raw material for the conductive additive. Substituents such as alkyl groups linked by ester bonds are more easily reacted with epoxy groups and hydroxyl groups. The graphene oxide intercalation also effectively inhibits the aggregation of the graphene oxide. The substituted alcohol prevents the graphene oxide from agglomerating and also promotes the Prevents hydroxyl groups from dehydrating to epoxy groups. is graphene oxide having alkyl groups linked by ester bonds, or alcohol Intercalated graphene oxide can be more highly dispersed in polar solvents. This becomes:

[0053] A method for producing and reducing graphene oxide according to this embodiment will be described with reference to FIG. do.

[0054] The raw material, graphene oxide, is prepared using an oxidation method called the Hummers method. (Step S11) The Hummers method involves adding permanganate to graphite powder. A potassium sulfate solution or the like is added to cause an oxidation reaction, and a first dispersion containing graphite oxide is prepared. Graphite oxide is produced by oxidizing the carbon in graphite, forming epoxy groups, carbonyl groups, and Functional groups such as alkyl, carboxyl, and hydroxyl groups are bonded to the The distance between the layers of the graphene is longer than that of graphite, making it easier to separate the layers and create thin flakes. Therefore, next, ultrasonic vibration is applied to the first dispersion liquid to dissolve the graphite oxide. Cleaving and separating the graphene oxide yields a dispersion containing the graphene oxide. Then, by removing the solvent from the dispersion containing graphene oxide, powder can be obtained. It is possible to obtain graphene oxide in the form of powder.

[0055] Graphene oxide was prepared using a Hummers method using a sulfuric acid solution of potassium permanganate. The method is not limited to the Hu method, but may be, for example, a method using nitric acid, potassium chlorate, or sodium nitrate. A method for producing graphene oxide other than the Hummers method or the Hummers method may be used as appropriate. stomach.

[0056] In addition, graphite oxide can be thinned by adding ultrasonic vibrations, microwaves, radio waves, or The heating may be performed by irradiating thermal plasma or applying physical stress.

[0057] A dispersion liquid containing graphene oxide or powdered graphene oxide is mixed with an alcohol or an acid. A solution is added to disperse graphene oxide, thereby preparing a second dispersion (step S12). .

[0058] In step S12, a solvent containing alcohol or acid is used to disperse graphene oxide. A solution can be used. Examples of alcohol include methanol, ethanol, and 1-propanol. alcohol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, or It is preferable to use an alcohol such as tert-butyl alcohol. The longer the chain, the better the dispersibility of graphene oxide, which is preferable. When alcohol is used, the solvent can be evaporated by heating the second dispersion liquid (step S13). Therefore, ethanol, 1-propanol, 2-propanol, etc. It is more preferable to use alcohol or 2-butanol.

[0059] The acid-containing solution may be a solution containing a carboxylic acid. The more the amount of carbon, the more likely it is that bonding to graphene oxide will improve the dispersibility of graphene oxide. Furthermore, when a carboxylic acid having a low boiling point is used, the second dispersion liquid can be heated. Therefore, it is preferable to use formic acid or acetic acid, since this facilitates evaporation of the solvent. preferable.

[0060] Other acids include organic acids such as sulfonic acid, vinyl carboxylic acid, and nucleic acid, as well as phosphoric acid and halo acid. Inorganic acids such as hydrogen chloride, boric acid, and sulfuric acid can be used. ethanol, 1-propanol, 2-propanol, dichloromethane, Chloroform, tetrahydrofuran (THF), etc. can be used.

[0061] Next, the second dispersion liquid having graphene oxide is heated to remove the solvent contained in the second dispersion liquid. The second dispersion is evaporated (step S13). Preferably, the second dispersion is evaporated under reduced pressure at a temperature of room temperature or higher and 50°C or higher. The solvent is evaporated by heating to a temperature below 1000°C. This step can be performed at low temperatures to prevent the solvent from bumping. In addition, heating accelerates the reaction of graphene oxide, shortening the time required for the reaction. Therefore, it is preferable to heat the mixture to a temperature of, for example, about 30°C or higher and 40°C or lower. The heating temperature is set to the boiling point of the alcohol or acid added to the graphene oxide in step S12. This procedure can be used to modify graphene oxide. In addition, alcohols can be intercalated into graphene oxide.

[0062] The structure and reaction of graphene oxide will be explained using Figure 3. An example of the reaction is shown in Figure 3. For comparison, in Reaction Scheme 1, the acid is produced without performing step S12. Reaction Scheme 2 shows the reaction that occurs when oxidized graphene is heated. After using alcohol as a solvent to disperse graphene, graphene oxide was heated. That is, graphene oxide 106, 107, 108 Graphene oxide before heating, and the acid generated when heating without performing step S12. The graphene oxide produced when heated after step S12 is shown. In FIG. 3, R represents an alkyl group.

[0063] As shown in reaction formula 1, when graphene oxide is heated without going through step S12, the acid Oxidized graphene106 undergoes an intramolecular dehydration reaction between hydroxyl groups attached to two adjacent carbon atoms. On the other hand, after step S12, When heated, the reaction shown in Equation 1 is inhibited, and graphene oxide 1 is formed as shown in Equation 2. An intermolecular dehydration reaction occurs preferentially between the hydroxyl group of 06 and the hydroxyl group of the alcohol. As a result, graphene oxide with alkyl groups linked by ether bonds was obtained. (Also called graphene oxide 108 having alkoxy groups) is produced. The graphene 106 or graphene oxide 108 itself also acts as an acid catalyst.

[0064] Graphene oxide 108 has bulky alkoxy groups compared to hydroxyl and epoxy groups. Therefore, it has higher dispersibility than graphene oxide 106 and is easily exfoliated in solvents.

[0065] To reduce graphene oxide 107 with epoxy groups, high temperatures are required. However, in graphene oxide 108, the generation of epoxy groups is inhibited. Therefore, the graphene oxide 108 is reduced (step) at a lower temperature than the graphene oxide 107. It has the property of being easily broken down (S17).

[0066] When graphene oxide is dispersed in a solution containing carboxylic acid, the carboxylic acid An epoxide ring-opening reaction occurs between the carboxyl group and the epoxy group of graphene oxide. Therefore, an alkyl group is linked to graphene oxide via an ester bond. , and can also inhibit the aggregation of graphene oxide.

[0067] An example of the structure of graphene oxide intercalated with alcohol is shown in Figure 3(B). Alcohol 110 interacts with the hydroxyl groups and other substituents of graphene oxide. This allows the carbon nanotube to penetrate (intercalate) between the layers of the graphene oxide 108. This prevents the graphene oxide from aggregating through hydrogen bonds. This can prevent the hydroxyl groups of the phenylene from becoming epoxy groups due to dehydration.

[0068] In addition, graphene oxide that can intercalate alcohol has an alkoxy group. The graphene oxide having an alkoxy group (for example, graphene oxide 108) is not limited to the graphene oxide having an alkoxy group. graphene oxide (e.g., graphene oxide 106 or graphene oxide 107) However, it is possible to intercalate alcohols.

[0069] Next, a method for reducing graphene oxide to produce graphene will be described.

[0070] First, the graphene oxide treated in step S13 is added to a solvent and dispersed therein. A dispersion liquid of the above is prepared (step S14).

[0071] As the solvent used for the third dispersion, a polar solvent other than water can be used. Alcohol, ethanol, acetone, THF, dimethylformamide (DMF), N-methyl either methyl-pyrrolidone (NMP) or dimethyl sulfoxide (DMSO), or A mixture of two or more of these polar solvents can be used.

[0072] Next, an active material is added to the third dispersion liquid and kneaded to prepare a mixture (step S15). At this time, a binder may be mixed into the mixture, and a solvent may be added as necessary.

[0073] Next, the mixture prepared in step S15 is heated (step S16). Heat the mixture at 60°C to 170°C for 1 minute to 10 hours to evaporate the solvent. The atmosphere is not particularly limited.

[0074] Next, the heated mixture is subjected to a reduction treatment (step S17). As described above, the graphene oxide according to the present embodiment is It has the property of being easily reduced at low temperatures. Therefore, under milder reduction conditions than conventional methods, Graphene can be formed.

[0075] In step S17, when thermal reduction is performed, the mixture heated in step S16 is further The heating is then carried out in a reducing atmosphere or under reduced pressure. Preferably, the mixture is heated at a temperature of 60°C to 150°C for 1 hour to 30 hours. The solvent and water remaining in the mixture are evaporated, and the oxygen contained in the epoxy groups in the graphene oxide is released. As a result, graphene oxide can be converted into graphene. Not all of the oxygen contained in the oxidized graphene is released, and some of the oxygen remains in the graphene. The thermal reduction may be carried out simultaneously with the heat treatment in step S16.

[0076] On the other hand, graphene oxide has alkyl groups linked by ether bonds or ester bonds. The substituents such as alcohol, alkoxide ion, carboxylic acid, or carboxylate ion may be The substituents contained in graphene oxide are not all eliminated, but some are eliminated. The substituent may remain on the graphene.

[0077] The above alcohols, alkoxide ions, carboxylic acids, carboxylate ions, etc. Therefore, in the manufacturing method of the electrode according to the present embodiment, In the thermal reduction, the reduction can be carried out at a lower temperature than before. In a reducing atmosphere or under reduced pressure, the temperature is set to 60°C or higher and 100°C or lower for 1 hour or higher and 30 hours. The heating temperature is set to the temperature at which the oxidation is carried out in step S12. This may be adjusted depending on the boiling point of the alcohol or carboxylic acid added to the graphene.

[0078] In step S17, when chemical reduction is performed, the mixture heated in step S16 is treated with a reducing agent. The graphene oxide is reduced by immersing it in a solvent containing oxygen and In addition, all of the substituents such as alkyl groups are not eliminated, and some of the oxygen and substituents remain in the graphene. This reduction treatment is preferably carried out at a temperature of room temperature or higher and 150°C or lower.

[0079] Reducing agents include ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, and water. Sodium borohydride (NaBH4), tetrabutylammonium bromide (TBAB) , LiAlH4, ethylene glycol, polyethylene glycol, N,N-diethyl hydride The alkylamines or derivatives thereof can be used.

[0080] The solvent may be a polar solvent, provided that it can dissolve the reducing agent. The material is not limited to water, methanol, ethanol, acetone, THF, DM F, NMP, or DMSO, or a mixture of two or more of these polar solvents can be used.

[0081] The reducing solution containing a reducing agent and a solvent may be a mixture of ethanol and ascorbic acid, or A mixture of water, ascorbic acid and lithium hydroxide can be used.

[0082] Thereafter, the active material layer is washed to remove the solvent contained in the reducing solution. It is advisable to use the solution listed as a suitable solvent. This step may be carried out under reduced pressure or a reducing atmosphere. For example, it is recommended to heat the material at a temperature of 50°C to 100°C under reduced pressure for 1 hour to 48 hours. This will allow the polar solvent and water to evaporate. The reduction of graphene can be promoted.

[0083] Through the above process, graphene oxide is reduced and graphene is generated on the surface of the active material. This can be done.

[0084] Next, other elements that make up the battery electrode 100 will be described.

[0085] The current collector 101 may be made of stainless steel, gold, platinum, zinc, iron, copper, aluminum, titanium, or other metals. Metals and their alloys have high conductivity and do not alloy with carrier ions such as lithium. Materials that can be used include silicon, titanium, neodymium, scandium, and molybdenum. Aluminum alloys containing elements that improve heat resistance, such as arsenic, can be used. Alternatively, it may be formed of a metal element that reacts with silicon to form a silicide. Metal elements that react with and form silicides include zirconium, titanium, and hafnium. , vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel The current collector 101 may be in the form of a foil, a plate (sheet), a mesh, a punched metal, The current collector 101 may have a shape such as an expanded metal. It is recommended to use one with a thickness of 30 μm or more.

[0086] The active material 103 is made by mixing raw material compounds in a predetermined ratio, baking the mixture, and then baking the mixture by an appropriate means. Granular active material consisting of secondary particles that have been crushed, granulated, and classified and have an average particle size and particle size distribution. Therefore, in FIG. 2(C), the active material 103 is shown as a sphere. The shape is not limited to the above.

[0087] When the produced storage battery electrode is used as a positive electrode of a storage battery, lithium is used as the active material 103. Materials that allow the insertion and extraction of um ions can be used, for example, olivine-type crystals Structures, layered rock salt-type crystal structures, or lithium-containing composite phosphates, lithium-containing composite silicates, lithium manganese-containing composite oxides, etc. having a spinel-type crystal structure can be mentioned. Examples include lithium-containing composite phosphates having an olivine-type structure, such as those represented by the general formula LiMPO4 (M

[0088] is one or more of Fe(II), Mn(II), Co(II), Ni(II)). Examples of the representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, LiCoP O4, LiMnPO4, LiFe O4, LiFe b , b , g Ni​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ It satisfies the requirements for an active material in a balanced manner, such as the presence of lithium ions that can pass through. Therefore, it is preferable.

[0090] Examples of lithium-containing composite silicates having a layered rock salt crystal structure include LiCoO 2, LiNiO2, LiMnO2, Li2MnO3, LiNi 0.8 Co 0.2 O2 etc. NiCo system (general formula: LiNi x Co 1-x O2(0 <x<1))、LiNi 0.5 M n 0.5 O2 etc. NiMn system (general formula: LiNi x Mn 1-x O2(0 <x<1))、 LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 NiMnCo system (also called NMC) such as O2. LiNi x Mn y Co 1-x-y O2(x>0, y>0, x+y<1) Furthermore, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li2MnO3-Li Also included are MO2 (M=Co, Ni, Mn) and the like.

[0091] In particular, LiCoO2 has a large capacity, is more stable in the atmosphere than LiNiO2, and It is preferable because it has advantages such as being more thermally stable than NiO2.

[0092] Examples of lithium manganese-containing composite oxides having a spinel-type crystal structure include Li Mn2O4, Li 1+x Mn 2-x O4, Li(MnAl)2O4, LiMn 1.5 Ni 0.5 Examples include O4.

[0093] Lithium manganese containing spinel crystal structure such as LiMn2O4 The composite oxide contains a small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x MO2(M= Mixing Co, Al, etc., can suppress the elution of manganese and the decomposition of the electrolyte. This has the advantage of being preferable.

[0094] In addition, the active material is a compound of the general formula Li (2-j) MSiO4 (M is Fe(II), Mn(I) I), Co(II), Ni(II), or a composite oxide represented by j=0, 1, 2). It can be used. (2-j) A typical example of MSiO4 is 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 SiO 4. 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 Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q Si O4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. can be mentioned .

[0095] Also, as the active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) represented by the general formula of NASICON type compounds can be used. Examples of NASICON type compounds include Fe2(MnO4)3, [[ID=3�]] Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the active material, Compounds represented by the general formula of Li2MPO4F, Li2MP2O7, Li5MO4 (M = Fe, Mn), Perovskite type fluorides such as NaF3, FeF3, etc., metal chalcogenides (sulfides, selenides, tellurides) such as TiS2, MoS2, etc Lithium-containing composite vanadates having an inverse spinel type crystal structure such as LiMVO4, vanadium oxide-based (V2O5 , V6O 13 , LiV3O8, etc.), manganese oxides, organic sulfur compounds, etc. can be used .

[0096] In addition, when the carrier ion is an alkali metal ion other than lithium ion or an alkaline earth metal ion, as the active material, in the above lithium compounds and lithium-containing metal compounds instead of lithium, an alkali metal (e.g., sodium, potassium, etc.), an alkaline Earth metals (e.g., calcium, strontium, barium, beryllium, magnesium) etc.) may also be used.

[0097] When the battery electrode to be manufactured is used as a negative electrode of a battery, the active material 103 is For example, carbon-based materials, alloy-based materials, etc. can be used.

[0098] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon. (hard carbon), carbon nanotubes, graphene, carbon black, etc.

[0099] Graphite includes mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch. These include artificial graphite such as spheroidized artificial graphite, and natural graphite such as spheroidized natural graphite.

[0100] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It exhibits a low potential similar to that of lithium metal (0.1 to 0.3 V vs. Li / Li + This allows the lithium-ion secondary battery to exhibit a high operating voltage. Graphite has a relatively high capacity per unit volume, small volume expansion, is inexpensive, and is a lithium It is preferable because it has advantages such as higher safety compared to metals.

[0101] As a negative electrode active material, it is possible to carry out charge-discharge reactions by alloying and dealloying reactions with lithium. Materials that can be used include Ga, Si, Al, Ge, Sn, Pb, Sb, Materials containing at least one of Bi, Ag, Zn, Cd, In, etc. can be used. These elements have a larger capacity than carbon, and silicon in particular has a theoretical capacity of 4200m The alloy materials using such elements are, for example, Mg2Si, M g2Ge, Mg2Sn, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6S n5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co Examples include 2Sn7, CoSb3, InSb, and SbSn.

[0102] In addition, stannous oxide (SnO), tin dioxide (SnO2), and titanium dioxide are used as negative electrode active materials. Titanium (TiO2), lithium titanium oxide (Li4Ti5O 12 ), lithium-graphite interlayer Compound (Li x C6), niobium pentoxide (Nb2O5), tungsten oxide (WO2), acid Oxides such as molybdenum oxide (MoO2) or SnS2 can be used.

[0103] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0104] When a composite nitride of lithium and a transition metal is used, the negative electrode active material contains lithium ions, The positive electrode active material is a combination of materials such as V2O5 and Cr3O8 that do not contain lithium ions. It is preferable that a material containing lithium ions is used as the positive electrode active material. By first removing the lithium ions contained in the positive electrode active material, A complex nitride of lithium and a transition metal can be used.

[0105] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not undergo an alloying reaction with the negative electrode active material may be used. Further materials that undergo a reaction include Fe2O3, CuO, Cu2O, RuO2, and Cr2O Third order oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, G Nitrides such as e3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3 This also occurs with fluorides such as

[0106] The binder contained in the active material layer 102 may be a typical PVdF, or may be polyimide, poly Tetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer, Styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, polyacetic acid Vinyl, polymethyl methacrylate, polyethylene, nitrocellulose, etc. can be used. can.

[0107] As described in this embodiment, graphene oxide is dispersed in a solution containing alcohol or acid. After that, heating under reduced pressure improves the dispersibility of the oxide, which has the property of being easily reduced. Graphene can be produced by reducing the graphene oxide under mild conditions. As a result, graphene with improved electrical conductivity can be formed. By using this as a conductive additive, a storage battery electrode with an active material layer with high electrical conductivity was produced. It is possible.

[0108] Note that one embodiment of the present invention can be applied not only to a storage battery but also to various power storage devices. For example, examples of the power storage device include a battery, a primary battery, a secondary battery, a lithium ion battery, Examples of the battery include secondary batteries, lithium-air batteries, and solid-state batteries. For example, it can be applied to a capacitor such as a lithium ion capacitor. It is also possible to apply this to such capacitors.

[0109] Graphene oxide is also used in supercapacitors, which are capacitors with extremely high capacitance. It can be used as an electrode for oxygen reduction, as an electrode catalyst for oxygen reduction, or as a dispersion water with lower friction than lubricating oil. They are used as materials for display devices, transparent electrodes for solar cells, etc., and as gas It can be used as a barrier material, a lightweight polymer material with high mechanical strength, or as a radiation As a material for highly sensitive nanosensors to detect uranium and plutonium in radioactive contaminated water It can be used as a material for removing radioactive materials.

[0110] Note that one embodiment of the present invention has been described in this embodiment. However, the present invention is not limited to these. For example, in one embodiment of the present invention, an electrode includes graphene or graphene oxide. However, one embodiment of the present invention is not limited to this. Alternatively, optionally, in one aspect of the invention, the electrode may be made of a material other than graphene or graphene oxide. Alternatively, for example, in one embodiment of the present invention, Alternatively, depending on the situation, the electrode may or may not have graphene or graphene oxide. good.

[0111] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0112] (Embodiment 2) In this embodiment, a method for manufacturing a battery electrode according to one embodiment of the present invention will be described with reference to FIGS. Specifically, a mixture of an active material, graphene oxide, a binder, and a solvent is prepared. The mixture is applied onto the current collector 101, and then the graphene oxide is reduced to form a A method for manufacturing a storage battery electrode 100 including the active material layer 102 shown in FIG. 2 will now be described. do.

[0113] In addition, preparation of graphene oxide (step S11), dispersion in a solution containing alcohol or acid (Step S12), and heating the graphene oxide under reduced pressure (Step S13). For this purpose, the manufacturing method described in the first embodiment can be used.

[0114] After step S13, the graphene oxide described in the first embodiment is dispersed in a solvent, and an acid is added. A graphene oxide dispersion (third dispersion) is prepared (step S14). If the amount exceeds 10 wt%, the viscosity of the mixture will increase, although this will depend on the particle size of the active material. When a mixture containing an active material and graphene oxide is applied onto the current collector 101 and then heated, Convection occurs in the mixture, and the light and thin graphene oxide moves and aggregates, forming an active material layer 10 2 may crack, or the active material layer 102 may peel off from the current collector 101. Therefore, the amount of graphene oxide is 0.2 wt% or more and 10 wt% or less of the total amount of the mixture. It is preferable that the graphene oxide is reduced to graphene by a subsequent heat treatment process. The weight of the active material layer 102 is reduced by half, so the weight ratio of the active material layer 102 is 0.1 wt % or more and 5 wt % or less. % or less.

[0115] Next, the active material is added to the dispersion liquid prepared in step S14, and then kneaded (step S 15) When the average particle size of the primary particles of the active material is 50 nm or more and 500 nm or less, The amount of active material to be added should be 85 wt% or more of the total amount of the mixture. For example, it may be 85 wt% or more and 95 wt% or less.

[0116] When firing the active material, carbohydrates such as glucose are mixed in to add carbon to the particles of the active material. It may be coated, which increases its conductivity.

[0117] Next, these mixtures are kneaded (kneaded in a high viscosity state) to form graphene oxide and In addition, the graphene oxide can dissolve the aggregation of the active material. Therefore, different graphene oxides are less likely to aggregate with each other. This allows the fen to be distributed more evenly.

[0118] Next, a binder is added to the mixture (step S21). The amount of binder is determined by the amount of oxidized grime. The amount of the active material and the amount of the lath may be set by the amount of the lath and the active material, and the amount of the lath and the active material may be set by the amount of the lath and the active material. It is sufficient to add 20 wt% or less. The graphene oxide is in surface contact with multiple active material particles. By adding a binder, the dispersion state can be improved. The active material and the graphene oxide can be bonded together while maintaining the same. Depending on the ratio of graphene, it may not be necessary to add a binder, but if a binder is added, This can improve the strength of the storage battery electrode.

[0119] Next, a solvent is added to these mixtures until the desired viscosity is reached, and the mixtures are kneaded to form a mixture. By preparing the mixture through the above steps, graphene oxide, an active material, and The binder and the binder can be mixed uniformly.

[0120] Here, an undercoat may be formed on the current collector. This refers to a coating layer that reduces contact resistance and improves adhesion between the current collector and the active material layer. Examples of the layer include a carbon layer, a metal layer, a layer containing carbon and a polymer, and a layer containing a metal and a polymer. By forming an undercoat on the current collector, a layer containing the This can reduce the contact resistance between the current collector to be formed later and the active material layer. The undercoat can improve the adhesion between the active material layer and the conductive layer. When graphene is used, it is dissolved by the reducing solution during the graphene oxide reduction process. In one embodiment of the present invention, graphene oxide is preferably reduced at low temperature. Therefore, thermal reduction can be preferably used. This is preferable because the material used for the reducing solution is not affected by the material of the reducing solution, and the range of choices is widened.

[0121] In addition, the undercoat may be a dispersion of graphite or acetylene black (AB). An aqueous solution or a mixture of the aqueous solution and a polymer can be used, for example, graphite and Mixtures with sodium polyacrylate (PAA), and mixtures of AB and PVdF, etc. The compounding ratio of graphite to PAA is graphite:PAA=95:5 or more. The blending ratio of AB to PVdF is 50:50 or less, and AB:PVdF is 70:30 or more and 50: It should be 50 or less.

[0122] If there are no problems with the adhesion between the active material layer and the current collector, the electrode strength, or the contact resistance, The coating does not necessarily have to be formed on the current collector.

[0123] Next, a mixture of an active material, graphene oxide, a binder, and a solvent is applied onto the current collector 101. (Step S22).

[0124] Next, the mixture applied to the current collector is subjected to removal of the solvent (step S16) and reduction ( Steps S16 and S17 are described in the first embodiment. The following manufacturing method can be used.

[0125] Through the above steps, an active material layer 102 in which graphene 104 is uniformly dispersed in the active material 103 is obtained. After the solvent removal step, the storage battery electrode 100 can be manufactured. The battery electrode 100 may be subjected to a pressure step.

[0126] As described in this embodiment, the aryl group bonded by an ether bond or an ester bond By adding an active material to a solvent in which graphene oxide with alkyl groups is dispersed and kneading it, In this way, graphene oxide can be uniformly dispersed in the active material layer. By using such an active material layer, a storage battery electrode with high electronic conductivity can be produced. Furthermore, by using the storage battery electrode to create an electrode, a high-capacity storage battery can be manufactured. can.

[0127] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0128] (Embodiment 3) In this embodiment, a method for manufacturing a battery electrode according to one embodiment of the present invention will be described with reference to FIGS. Specifically, the surface of the active material is coated with graphene oxide, and after reduction, the graphene is Formation of the active material layer 102 using an active material having phene, a conductive additive, a binder, and a solvent. A composition containing the solvent used in the above (also referred to as an electrode mixture composition) is prepared. The agent composition is applied to the current collector 101 to form a storage battery including the active material layer 102 shown in FIG. A method for manufacturing the electrode 100 will now be described.

[0129] In addition, preparation of graphene oxide (step S11), dispersion in a solution containing alcohol or acid The steps of (step S12) and (step S13) are the same as those described in the first embodiment. The manufacturing method described above can be used.

[0130] After step S13, the graphene oxide and the solvent are put into a kneader to disperse the graphene oxide. A liquid (third dispersion liquid) is prepared (step S14). At this time, the graphene oxide is 0.5 It is preferable that the content is between 0.5 wt% and 5 wt%. If the content is less than 0.5 wt%, the surface of the active material may be damaged. Furthermore, if the content exceeds 5 wt%, the electrode volume becomes bulky and the electrode weight becomes It becomes heavy.

[0131] Next, as shown in step S15, an active material is added to the dispersion liquid and kneaded. Kneading refers to kneading with high viscosity. By performing high-temperature kneading, the aggregation of the active material powder is almost prevented. In addition, since the graphene oxide has bulky functional groups, it can be easily oxidized. Graphene is less likely to aggregate with other graphene particles. This allows for a more uniform distribution of graphene oxide and active material. It can be dispersed.

[0132] Next, as shown in step S16, the mixture of graphene oxide and the active material (the first mixture) is After removing the solvent contained in the graphene oxide, the graphene oxide is coated by crushing the graphene oxide. A modified active material is obtained.

[0133] Next, as shown in step S17, a reduction treatment is performed on the graphene oxide. For this, the manufacturing method described in the first embodiment can be used.

[0134] In step S17, the graphene oxide is reduced to form the graphene-coated active material (second It is also called a mixture of the above.) The oxygen contained in graphene oxide is It is not necessary to desorb all of the oxygen, and some of the oxygen may remain in the graphene.

[0135] Next, an electrode mixture composition (also referred to as a third mixture) is prepared (step S31). The mixture composition is prepared by adding the above-mentioned active material, binder, conductive additive, etc., together with a solvent. The electrode mixture composition can be prepared by kneading the mixture. The solvent may be, for example, water or NMP. From the viewpoints of safety and cost, it is preferable to use water.

[0136] As an example, a case where the battery electrode 100 is a positive electrode for a battery will be described. an active material including graphene according to one embodiment of the present invention is used as a conductive additive; For example, carbon black is used, PVdF is used as the binder, and NMP is used as the solvent. I will explain.

[0137] First, the active material according to one embodiment of the present invention, acetylene black, and PVdF are mixed. NMP is added to these mixtures until a predetermined viscosity is reached, and the mixture is kneaded to obtain an electrode mixture. In this process, the kneading and addition of the polar solvent are repeated multiple times. You may return it.

[0138] Through the above steps, an electrode mixture composition in which the active material, the conductive additive, and the binder are uniformly mixed is obtained. can be formed.

[0139] Next, the electrode mixture composition is applied to one or both surfaces of the current collector by, for example, a doctor blade method. The distance is set by a method or the like (step S32).

[0140] Next, the solvent contained in the electrode mixture composition applied to the current collector is removed by ventilation drying or reduced pressure drying. This step is performed by hot air blowing at a temperature of 50° C. or higher and 180° C. or lower (step S33). This step allows the polar solvent contained in the active material layer to evaporate. The atmosphere is not particularly limited.

[0141] Here, this active material layer is pressed by a compression method such as a roll press method or a flat plate press method. In addition, when pressing, the temperature is set to 90°C or higher and 180°C or lower, preferably 12 By applying heat below 0°C, the binder (e.g., For example, PVdF) is softened to a degree that does not change the properties of the electrode, allowing the current collector and active material to be The adhesion to the material layer can be further improved.

[0142] Next, the pressed active material layer is heated. Heating is preferably carried out under reduced pressure or in a reducing atmosphere. This process is carried out, for example, at a temperature of 50°C to 300°C for 1 hour to 48 hours. This step thoroughly evaporates the polar solvent and water present in the active material layer.

[0143] Furthermore, the active material layer may be pressed, which improves the adhesion between the active material layer and the current collector. In addition, the active material layer can be compacted. When the mixture is heated, heat is applied to the mixture at 90°C or higher and 180°C or lower, preferably 120°C or lower. The binder (e.g., PVdF) contained in the dark coat or active material layer is used to change the properties of the electrode. By softening the current collector to a degree that does not cause adhesion, it is possible to further improve the adhesion between the current collector and the active material layer. can.

[0144] Through the above steps, an active material layer 102 in which graphene 104 is uniformly dispersed in the active material 103 is obtained. In addition, the current collector and the active material layer can be formed by a predetermined method. Electrodes are made by molding to size.

[0145] Graphene has excellent electrical properties, such as high conductivity, as well as flexibility and mechanical strength. Therefore, active materials with graphene on their surfaces have excellent physical properties. By using electrodes containing the active material in a battery, the active material expands as the battery is repeatedly charged and discharged. Even if the active material shrinks, it can be prevented from cleaving and cracking due to volume change. do.

[0146] In addition, when rolling the electrode in the electrode manufacturing process, the pressure applied to the active material is reduced by the mechanical strength of graphene. This can be alleviated by adjusting the degree. This prevents the active material from cleaving and cracking. It is possible.

[0147] Furthermore, even if a large stress acts on the electrode, the active material is prevented from cleaving and cracking. It can be stopped.

[0148] As described above, by using an active material with graphene formed on the surface as an electrode, the battery This can prevent the decrease in the battery voltage and discharge capacity due to charging and discharging. The cycle characteristics can be improved.

[0149] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0150] (Fourth embodiment) In this embodiment, the storage battery electrode manufactured by the manufacturing method shown in Embodiment 1 is used. The structure of the storage battery will be described with reference to FIGS.

[0151] (Coin-type battery) FIG. 11(A) is an external view of a coin-type (single-layer flat) storage battery, and FIG. 11(B) is a FIG.

[0152] The coin-type storage 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. 02 is insulated and sealed by a gasket 303 made of polypropylene or the like. The electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector. The negative electrode 307 is formed by a negative electrode current collector 308 and a The positive electrode active material layer 306 and the negative electrode active material layer 309 are formed. Between them, there is a separator 310 and an electrolyte (not shown).

[0153] At least one of the positive electrode 304 and the negative electrode 307 may contain the same material as in the embodiment 1 of the present invention. The storage battery electrode manufactured by the method for manufacturing a storage battery electrode according to the present invention can be used.

[0154] The separator 310 is made of a porous material such as cellulose (paper), polypropylene, polyethylene, etc. An insulator with holes may be used.

[0155] As the electrolyte, in addition to solid electrolytes and electrolytes containing supporting electrolytes, some electrolytes are gelled. A gel electrolyte can be used.

[0156] Materials with carrier ions can be used as supporting electrolytes. Typical examples of supporting electrolytes Examples include LiPF6, LiClO4, LiAsF6, LiBF4, LiCF3SO3, Lithium salts include Li(CF3SO2)2N and Li(C2F5SO2)2N. The electrolytes may be used alone or in any combination and ratio of two or more. Good too.

[0157] In addition, the carrier ions are alkali metal ions other than lithium ions, alkaline earth metal ions, etc. In the case of ions, the electrolyte is an alkali metal salt instead of lithium. Metals (e.g., sodium and potassium), alkaline earth metals (e.g., calcium, strontium) Other suitable materials include titanium, barium, beryllium, magnesium, etc.

[0158] In addition, a material in which carrier ions can move can be used as the solvent for the electrolyte. The solvent for the solution is preferably an aprotic organic solvent. Representative examples of aprotic organic solvents are: Examples include ethylene carbonate (EC), propylene carbonate, and dimethyl carbonate. diethyl carbonate (DEC), γ-butyrolactone, acetonitrile, dimethicone Examples of the methyl ether include methyl ethane and tetrahydrofuran, and one or more of these can be used. In addition, by using a polymer material that gels as a solvent for the electrolyte, it is possible to reduce leakage and other issues. This increases safety. It also makes it possible to make storage batteries thinner and lighter. Typical examples of materials are silicone gel, acrylic gel, acrylonitrile gel, and polyethylene gel. Styrene oxide gel, polypropylene oxide gel, fluorine polymer gel, etc. There is.

[0159] In addition, flame-retardant and non-volatile ionic liquids (especially room-temperature molten salts) are used as the solvent for the electrolyte. By using one or more, the internal temperature of the storage battery can be prevented from rising due to an internal short circuit or overcharging. Even if the battery is damaged, it can prevent explosion or fire. Ionic liquids are made up of cations and anions. The organic cations that make up the ionic liquid include quaternary ammonium cations, tertiary sulfur cations, and aliphatic onium cations such as phosphonium cations and quaternary phosphonium cations, and imines Examples of aromatic cations include the benzodiazepine and pyridinium cations. In addition, the anions used in the electrolyte include monovalent amide anions and monovalent methide anions. , fluorosulfonic acid anion, perfluoroalkylsulfonic acid anion, tetrafluoro perfluoroborate, perfluoroalkylborate, hexafluorophosphate, or perfluoroalkyl fluoroalkyl phosphates.

[0160] In addition, instead of the electrolyte solution, solid electrolytes containing inorganic materials such as sulfides and oxides, and P A solid electrolyte containing a polymer material such as EO (polyethylene oxide) can be used. When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire pond can be solidified, there is no risk of leakage, dramatically improving safety.

[0161] The positive electrode can 301 and the negative electrode can 302 are made of a material that is resistant to liquids such as electrolytes during charging and discharging of the secondary battery. Metals such as nickel, aluminum, and titanium that are corrosion-resistant, alloys of these metals, and Alloys of metals with other metals (e.g., stainless steel, etc.), laminations of the metals, and the metals and the above-mentioned Lamination with alloys (e.g., stainless steel, aluminum, etc.), lamination of the metal with other metals A layer (e.g., nickel, iron, nickel, etc.) can be used. 304 and the negative electrode can 302 are electrically connected to the negative electrode 307, respectively.

[0162] The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with an electrolyte, and the resultant structure shown in FIG. 11(B) is As shown in FIG. 1, the positive electrode can 301 is placed downward, and the positive electrode 304, separator 310, negative electrode 307, and negative electrode 308 are connected to the positive electrode can 301. The positive electrode can 301 and the negative electrode can 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected with a gasket 303 interposed therebetween. Then, the coin-type storage battery 300 is manufactured by crimping the components.

[0163] (Laminated battery) FIG. 12 shows an external view of a laminated storage battery 500. Also, FIGS. 13(A) and 13 (B) shows the A1-A2 cross section and the B1-B2 cross section shown by the dashed dotted line in FIG. The battery 500 is a battery of the type having a positive electrode 501 and a positive electrode active material layer 502. 3, a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505, and a separator 5 507, an electrolyte 508, and an outer casing 509. A separator 507 is provided. In addition, the area surrounded by the exterior body 509 contains the electrolyte 5 08 is injected.

[0164] The laminated storage battery 500 shown in FIG. 12 includes a positive electrode current collector 501 and a positive electrode active material layer 50 2, and a negative electrode 50 having a negative electrode current collector 504 and a negative electrode active material layer 505. 6, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in the area surrounded by In addition, electrolyte 508 is poured into the area surrounded by exterior body 509.

[0165] In the laminated storage battery 500 shown in FIG. 12, a positive electrode current collector 501 and a negative electrode current collector 504 also serves as a terminal for electrical contact with the outside. The negative electrode current collector 501 and a part of the negative electrode current collector 504 are arranged so as to be exposed to the outside from the outer casing 509. do.

[0166] In the laminated storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, etc. Al is applied to a membrane made of a material such as propylene, polycarbonate, ionomer, or polyamide. A thin metal film with excellent flexibility, such as aluminum, stainless steel, copper, or nickel, is applied, and the metal On the thin film, an insulating synthetic resin such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A laminate film having a three-layer structure with a film can be used. This prevents the permeation of electrolyte and gas, ensures insulation, and is also electrolyte-resistant. It has sexuality.

[0167] (cylindrical storage battery) Next, an example of a cylindrical storage battery will be described with reference to FIG. 14. As shown in FIG. 14(A), the battery lid 601 has a positive electrode cap (battery lid) on the top surface, and The battery can (external can) 602 is provided on the bottom surface. The container 602 is insulated from the container 602 by a gasket (insulating packing) 610.

[0168] Fig. 14(B) is a schematic diagram showing the cross section of a cylindrical storage battery. Inside 602, a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. Although not shown, the battery element is wound around a center pin. The battery can 602 is closed at one end and open at the other. Nickel and aluminum, which are corrosion-resistant to liquids such as electrolytes during charging and discharging of secondary batteries, are used. Metals such as aluminum and titanium, alloys of these metals, alloys of these metals with other metals (e.g., stainless steel, etc.), lamination of the metal, lamination of the metal and the alloy mentioned above (e.g., stainless steel, etc.), Laminated metals with other metals (e.g., nickel, iron, nickel, etc.) Inside the battery can 602, a positive electrode, a negative electrode, and a separator are arranged. The battery element with the coil wound around it is sandwiched between a pair of opposing insulating plates 608 and 609. The battery can 602 in which 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 coin-type or laminated batteries. can.

[0169] The positive electrode 604 and the negative electrode 606 are manufactured in the same manner as the positive electrode and the negative electrode of the coin-type storage battery described above. However, since the positive and negative electrodes used in cylindrical storage batteries are wound, active materials are placed on both sides of the current collector. The positive electrode 604 is connected to a positive electrode terminal (positive electrode current collecting lead) 603. The negative electrode 606 is connected to a negative electrode terminal (negative electrode current collecting lead) 607. The positive electrode terminal 3 and the negative electrode terminal 607 can both be made of a metal material such as aluminum. The positive terminal 603 is connected to the safety valve mechanism 612, and the negative terminal 607 is connected to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. The positive electrode cap 601 is electrically connected to the positive electrode cap 601 via a re coefficient 611. The safety valve mechanism 612 releases the positive electrode cap when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 601 and the positive electrode 604. is a thermal resistance element whose resistance increases when the temperature rises, and the amount of current increases as the resistance increases. The PTC element is made of barium titanate (BaTi O3) based semiconductor ceramics, etc. can be used.

[0170] In this embodiment, the storage battery may be a coin type, a laminate type, or a cylindrical type. However, other types of batteries such as sealed batteries and rectangular batteries can also be used. In addition, there are also structures in which a plurality of positive electrodes, negative electrodes, and separators are stacked, and structures in which a plurality of positive electrodes, negative electrodes, and separators are stacked. The structure may be such that the motor is wound around the core.

[0171] The positive or negative electrodes of the coin-type storage battery 300, the storage battery 500, and the storage battery 600 shown in this embodiment The electrode is manufactured by the method for manufacturing a storage battery electrode according to one aspect of the present invention. Therefore, the discharge capacity of the coin-type storage battery 300, storage battery 500, and storage battery 600 is It can be increased.

[0172] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0173] (Embodiment 5) A storage battery using the storage battery electrode according to one embodiment of the present invention can be used in various electronic devices driven by electric power. It can be used as a power source for devices.

[0174] As a specific example of an electronic device using a storage battery including a storage battery electrode according to one embodiment of the present invention, Display devices such as TVs and monitors, lighting devices, desktop or notebook personal computers, Computer, word processor, DVD (Digital Versatile Disk) c) Image playback devices that play still images or videos stored on recording media such as portable C D player, radio, tape recorder, headphone stereo, stereo, table clock, wall-mounted Clocks, cordless telephone handsets, transceivers, mobile phones, car phones, portable game consoles, Calculators, personal digital assistants, electronic organizers, e-book readers, electronic translators, voice input devices, video cameras lasers, digital still cameras, toys, electric shavers, microwave ovens and other high-frequency heating devices, electric Rice cookers, electric washing machines, electric vacuum cleaners, water heaters, electric fans, hair dryers, air conditioners, Humidifiers, dehumidifiers and other air conditioning equipment, dishwashers, dish dryers, clothes dryers, futon dryers, electric appliances Electric refrigerators, electric freezers, electric refrigerator-freezers, freezers for DNA storage, flashlights, chainsaws These include power tools such as fire extinguishers, smoke detectors, and medical equipment such as dialysis machines. Units, belt conveyors, elevators, escalators, industrial robots, power storage systems , industrial equipment such as power storage devices for power leveling and smart grids. Mobile devices propelled by electric motors using power from storage batteries are also included in the category of electronic devices. The above-mentioned moving body may be, for example, an electric vehicle (EV), a vehicle that combines an internal combustion engine and an electric motor. Hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), Tracked vehicles with tires and wheels replaced with endless tracks, motorized bicycles including electrically assisted bicycles, Motorized two-wheeled vehicles, electric wheelchairs, golf carts, small or large ships, submarines, helicopters, aircraft Examples include aircraft, rockets, satellites, space probes, planetary probes, and spacecraft.

[0175] The electronic device uses a power supply according to one embodiment of the present invention as a main power source for covering almost all of the power consumption. Alternatively, the electronic device may be configured as follows: When the power supply from the main power source or commercial power source is stopped, As an uninterruptible power supply capable of performing the above-described functions, a storage battery using the storage battery electrode according to one embodiment of the present invention is used. Alternatively, the electronic equipment may be connected to the main power supply or commercial power supply. The present invention is applicable to an auxiliary power supply for supplying power to electronic devices in parallel with the supply of power. A storage battery using the storage battery electrode according to one aspect of the present invention can be used.

[0176] FIG. 15 shows a specific configuration of the electronic device. In FIG. 15, a display device 700 is 7A and 7B illustrate examples of electronic devices using a storage battery 704 that uses a storage battery electrode according to one embodiment of the present invention. Specifically, the display device 700 corresponds to a display device for receiving TV broadcasts, and includes a housing 701, a display unit, 702, a speaker unit 703, and a storage battery 704. A storage battery 704 using electrodes is provided inside the housing 701. It can receive power from a power source or use power stored in a storage battery 704. Therefore, even when power is not supplied from the commercial power source due to a power outage, The storage battery 704 using the storage battery electrode according to one embodiment of the present invention is used as an uninterruptible power supply. Then, the display device 700 becomes available for use.

[0177] The display unit 702 may be a liquid crystal display device, a light emitting device having a light emitting element such as an organic EL element in each pixel, or the like. Device, electrophoretic display, DMD (Digital Micromirror Device) e), PDP (Plasma Display Panel), FED (Field E A semiconductor display device such as a mission display can be used.

[0178] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. , including all display devices for displaying information.

[0179] In FIG. 15, a stationary lighting device 710 is equipped with a storage battery electrode according to one embodiment of the present invention. This is an example of an electronic device using a storage battery 713. Specifically, the lighting device 710 is 15, the storage battery 713 is mounted in the housing 71. 1 and a light source 712 are provided inside a ceiling 714. However, the storage battery 713 may be provided inside the housing 711. The lighting device 710 is It can receive power from a commercial power source, or use the power stored in the storage battery 713. Therefore, even when power cannot be supplied from the commercial power source due to a power outage, The storage battery 713 using the storage battery electrode according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 710 to be used.

[0180] Although FIG. 15 illustrates a fixed lighting device 710 provided on the ceiling 714, In the storage battery using the storage battery electrode according to one embodiment of the present invention, the ceiling 714 is not necessarily provided with a protective film, for example, a protective film is provided on the side wall 7 15, it can also be used for a fixed lighting device provided on a floor 716, a window 717, etc. It can also be used as a tabletop lighting device.

[0181] The light source 712 may be an artificial light source that artificially obtains light using electricity. Specifically, incandescent lamps, fluorescent lamps and other discharge lamps, and light-emitting elements such as LEDs and organic EL elements An example of the artificial light source is a lamp.

[0182] In FIG. 15, an air conditioner having an indoor unit 720 and an outdoor unit 724 is 1 is an example of an electronic device using a storage battery 723 that uses the storage battery electrode according to one embodiment of the present invention. In other words, the indoor unit 720 includes a housing 721, an air outlet 722, a storage battery 723, etc. 7 illustrates a case where the storage battery 723 is provided in the indoor unit 720, 3 may be provided in the outdoor unit 724. Alternatively, both the indoor unit 720 and the outdoor unit 724 may be provided. On the other hand, a storage battery 723 may be provided. Alternatively, power stored in the storage battery 723 can be used. In particular, when the storage battery 723 is provided in both the indoor unit 720 and the outdoor unit 724, Even when power cannot be supplied from a commercial power source due to reasons such as By using the storage battery 723 with electrodes as an uninterruptible power supply, the use of air conditioners This becomes possible.

[0183] In Figure 15, we take an example of a separate type air conditioner consisting of an indoor unit and an outdoor unit. Although the figure shows an integrated air conditioner that has the functions of both the indoor unit and the outdoor unit in a single housing, A storage battery using a storage battery electrode according to one embodiment of the present invention can also be used in the partitioner.

[0184] In FIG. 15, an electric refrigerator-freezer 730 uses a storage battery electrode according to one embodiment of the present invention. This is an example of an electronic device using a storage battery 734. Specifically, the electric refrigerator-freezer 730 has a housing 731, a refrigerator compartment door 732, a freezer compartment door 733, a storage battery 734, etc. In FIG. A storage battery 734 is provided inside the housing 731. The electric refrigerator-freezer 730 is powered by a commercial power source. It can receive power from a power source or use power stored in a battery 734. Therefore, even when power cannot be supplied from the commercial power source due to a power outage or other reasons, By using a storage battery 734 using the storage battery electrode according to one embodiment as an uninterruptible power supply, The freezer refrigerator 730 will be available for use.

[0185] Among the above-mentioned electronic devices, high-frequency heating devices such as microwave ovens and electric rice cookers are Equipment requires high power for a short period of time, so it supplements the power that cannot be supplied by commercial power. A storage battery using a storage battery electrode according to one embodiment of the present invention is used as an auxiliary power source for This prevents the commercial power breaker from tripping when electronic devices are in use.

[0186] In addition, during times when electronic devices are not in use, especially when the total amount of power that can be supplied by the commercial power supplier is low, During times when the percentage of electricity actually used (called the electricity usage rate) is low, By storing electricity in the reservoir, it is possible to prevent the rate of electricity usage from increasing outside of the above time periods. For example, in the case of an electric refrigerator-freezer 730, when the temperature is low, the refrigerator compartment door 732 and the freezer During the night when the room door 733 is not opened or closed, power is stored in the storage battery 734. During the daytime when the temperature rises and the refrigerator door 732 and the freezer door 733 are opened and closed, By using the storage battery 734 as an auxiliary power source, it is possible to keep the power usage rate low during the day.

[0187] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0188] (Embodiment 6) Next, a portable information terminal, which is an example of an electronic device, will be described with reference to FIG.

[0189] 16(A) and 16(B) show a foldable tablet terminal 800. (A) shows the tablet terminal 800 in an open state. The tablet terminal 800 includes a housing 801, a display unit 802a, and a , a display unit 802b, a display mode changeover switch 803, a power switch 804, a power saving mode It has a mode changeover switch 805 and an operation switch 807.

[0190] A part of the display unit 802a can be used as a touch panel area 808a, and the displayed operation Data can be input by touching the operation key 809. For example, half of the area has a display function and the other half has a touch function. Although the display unit 802a has a configuration having a panel function, it is not limited to this configuration. For example, the entire surface of the display unit 802a may have a touch panel function. The keyboard buttons are displayed on the display unit 802b to function as a touch panel, and the display unit 802b is used as a display screen. It is possible.

[0191] Similarly to the display unit 802a, the display unit 802b can also be touched by touching a part of the display unit 802b. The area 808b of the touch panel can be used as a keyboard display switch. By touching the position where the replacement button 810 is displayed with a finger or a stylus, the display unit 80 Keyboard buttons can be displayed on 2b.

[0192] In addition, when the area 808a of the touch panel and the area 808b of the touch panel are touched at the same time, You can also input it.

[0193] A display mode changeover switch 803 is used to change the display orientation between portrait and landscape. You can select between black and white and color display. The Touch 805 detects external light during use using a light sensor built into the tablet device. The tablet device has a light sensor that can adjust the display brightness to suit the amount of light. In addition, it also incorporates other detection devices such as gyro, acceleration sensor, etc. to detect tilt. It is also acceptable to do so.

[0194] Also, FIG. 16(A) shows an example in which the display area of ​​the display unit 802b is the same as that of the display unit 802a. However, there is no particular limitation, and one size may be different from the other, and the product may be The quality may also be different. For example, one may be a display panel that can display a higher resolution image than the other. That's fine.

[0195] FIG. 16(B) shows the tablet terminal 800 in a closed state, and the tablet terminal 800 includes a housing 801, a solar cell 811, a charge / discharge control circuit 850, a battery 851, and a DC / DC converter 852 16B, a battery 851, a DCD The battery 851 is the same as the above embodiment. The present invention has a storage battery using the storage battery electrode according to one embodiment of the present invention described above.

[0196] The tablet terminal 800 can be folded in half, so when not in use, the housing 801 can be closed. Therefore, the display units 802a and 802b can be protected, and the display units 802a and 802b can be To provide a tablet terminal 800 that is highly durable and reliable from the viewpoint of long-term use. This can be done.

[0197] In addition, the tablet terminals shown in Figs. 16(A) and 16(B) can store various information. Functions that display information (still images, videos, text images, etc.), calendars, dates, or times, etc. The function to display the information on the display unit, and the function to operate or edit the information displayed on the display unit by touch input. It has the function of controlling the processing by various software (programs), etc. This can be done.

[0198] The solar cell 811 attached to the surface of the tablet terminal supplies power to the touch panel, display, and The solar cell 811 can supply the power to a display unit, a video signal processing unit, etc. The battery 851 can be efficiently charged by providing the charger 801 on one or both sides. It can be concluded that

[0199] The configuration and operation of the charge / discharge control circuit 850 shown in FIG. 16B will be described with reference to FIG. 16C. 16C shows a solar cell 811, a battery 851, DC-DC converter 852, converter 853, switches SW1 to SW3, table The display unit 802 includes a battery 851, a DC-DC converter 852, and a converter The charge / discharge control circuit 850 shown in FIG. 16(B) is configured with a power supply 853 and switches SW1 to SW3. This is the corresponding location.

[0200] First, an example of operation when power is generated by solar cell 811 using external light will be described. The power generated by the solar cell is converted to a voltage to charge the battery 851. The voltage is increased or decreased by the converter 852. When power from 811 is used, switch SW1 is turned on and the converter 853 is turned on. The voltage is increased or decreased to the voltage required for the display unit 802. When not displaying, turn SW1 off and SW2 on to charge the battery 851. The configuration may be such that:

[0201] The solar cell 811 is shown as an example of a power generating means, but is not particularly limited thereto. Other power generation methods such as piezoelectric elements (piezoelectric elements) and thermoelectric elements (Peltier elements) For example, the power may be transmitted and received wirelessly (contactlessly). It is possible to combine a non-contact power transmission module that charges by transmitting power to the battery, or other charging methods. It may also be composed.

[0202] Furthermore, a storage battery using the storage battery electrode according to one embodiment of the present invention described in the above embodiment may be provided. It goes without saying that the electronic device is not particularly limited to the one shown in FIG. 16 as long as it is equipped with such a device.

[0203] (Embodiment 7) Furthermore, an example of a mobile object, which is an example of an electronic device, will be described with reference to FIG.

[0204] The storage battery described in the previous embodiment can be used as the control battery. The battery can be charged by external power supply using plug-in technology or wireless power supply. In addition, if the moving object is an electric railway vehicle, it can be supplied with power from overhead wires or conductive rails. It can be charged.

[0205] 17(A) and (B) show an example of an electric vehicle. The electric vehicle 860 has a battery. The power of the battery 861 is output by a control circuit 862. The force is adjusted and supplied to the driving device 863. The control circuit 862 includes a ROM (not shown), It is controlled by a processing unit 864 having RAM, a CPU, etc.

[0206] The drive unit 863 is a DC motor or an AC motor alone, or a combination of a motor and an internal combustion engine. The processing device 864 is configured to receive operation information (acceleration , deceleration, stopping, etc.) and driving information (uphill and downhill slopes, load information on the drive wheels, etc.) The control circuit 862 outputs a control signal based on the input information such as The control signal from the processing unit 864 adjusts the electrical energy supplied from the battery 861. In case an AC motor is installed, the output of the drive unit 863 is controlled by adjusting the speed. However, it also has a built-in inverter that converts direct current to alternating current.

[0207] The battery 861 can be charged by an external power supply using plug-in technology. For example, the battery 861 can be charged from a commercial power source through a power plug. It is converted into a constant DC voltage with a constant voltage value through a conversion device such as an AC / DC converter. The battery 861 can be formed by using a storage battery electrode according to one embodiment of the present invention. By installing a storage battery using this technology, it is possible to contribute to increasing the battery capacity, improving convenience. In addition, the improvement of the characteristics of the battery 861 allows the battery 861 If the device itself can be made smaller and lighter, it will contribute to reducing the vehicle's weight, thereby improving fuel efficiency. .

[0208] Note that the electronic devices including the storage battery of one embodiment of the present invention are not limited to the above-described electronic devices. Needless to say, that is not the case.

[0209] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0210] Hereinafter, one embodiment of the present invention will be described in detail using an example. The results of producing a positive electrode by the method shown in embodiment 2 will be described. The present invention is not limited to the above examples.

[0211] (Preparation of graphene oxide) Three types of graphene oxide were produced using different processes and designated as graphene oxide A to C. The electrode was fabricated without performing step S12. Graphene oxide was used as Comparative Example 1 to prepare an electrode in the same manner.

[0212] First, a dispersion of graphene oxide (hereinafter referred to as graphene oxide dispersion) was prepared by the following method. First, 4 g of graphite was mixed with 138 mL of concentrated sulfuric acid to prepare a mixture. Next, 10 g of potassium permanganate was added to the mixture while stirring in an ice bath. The mixture was then removed from the ice bath and stirred at about 25°C for 4.5 hours to give an oxidized gram. A mixture A containing phytoes was obtained.

[0213] Next, 276 mL of water was added to the graphite oxide-containing mixture A while stirring in an ice bath. Next, the mixture was stirred in an oil bath at approximately 98°C for 15 minutes to react, and then the mixture was stirred. To the mixture, 400 mL of water and 30 mL of hydrogen peroxide solution (concentration 30 wt%) were added to remove unreacted The potassium permanganate was deactivated to obtain mixed solution B.

[0214] Next, suction-filter the mixed solution B using a membrane filter with a pore size of 0.45 μm. A precipitate was obtained by adding 3.5% hydrochloric acid to the precipitate and stirring the mixture, which was then filtered by suction. A precipitate containing graphite oxide was obtained.

[0215] The precipitate containing graphite oxide was mixed with 4 L of water, and the mixture was subjected to a 40 kHz frequency test. Ultrasonic waves were applied at 9000 rpm for 1 hour to obtain a dispersion containing graphene oxide. The precipitated graphene oxide was collected by centrifugation at 400°C.

[0216] The obtained graphene oxide was dispersed in alcohol and stirred at 30°C using an evaporator. The obtained sample was crushed in an automatic mortar and then placed under reduced pressure to remove the acid. The alcohols used were ethanol, methanol, 1-propanol, and 1-propanol. The graphene oxides A, B, and C were prepared using propyl alcohol. I chose Gen C.

[0217] In the preparation of Comparative Example 1, the obtained graphene oxide was evaporated at 30°C using an evaporator. The mixture was stirred for 5 hours under reduced pressure. The obtained sample was crushed in a dancing mill and then further reduced pressure. Comparative Example 1 was produced by placing it under pressure.

[0218] Comparative Example 1 and solid graphene oxides A to C 13 The C NMR spectrum is shown in Figure 6. In the spectra of Laphenes A to C, the intensity of the peak at 73 ppm is higher than that of Comparative Example 1. In the spectra of graphene oxide B and C, the peak at 63 ppm was A decrease in the intensity of the peaks at 73 ppm and 63 ppm was also observed. These are derived from the carbon of the epoxy group and the carbon bonded to the hydroxyl group, respectively. In the spectrum of phenyl A, peaks at 63 ppm and 19 ppm are due to the ethoxy group. In the spectrum of graphene oxide B, a methoxy group-derived peak was observed at 53 ppm. In addition, in the spectrum of graphene oxide C, there was a peak at 69 ppm. , 27 ppm, and 12.5 ppm, peaks attributable to the 1-propoxy group were present.

[0219] Therefore, graphene oxides A to C have fewer epoxy groups than Comparative Example 1, and the amount of added alcohol It was shown that an alkoxy group derived from methyl alcohol was introduced.

[0220] Next, positive electrodes having conductive additives using graphene oxides A to C and Comparative Example 1 as raw materials were assembled. We created battery cells incorporating these materials and compared their charge and discharge characteristics.

[0221] (Preparation of positive electrode) Positive electrodes were fabricated using graphene oxides A to C and Comparative Example 1. First, the positive electrode active material (Li FePO4) particles, binder (PVdF, manufactured by Kureha Chemical Co., Ltd.), and oxide as raw materials for conductive additives. Any one of graphenes A to C and comparative example 1 was mixed to prepare a mixture (also called a positive electrode paste). The compounding ratio of the positive electrode paste (LiFePO4: graphene oxide: PVdF The ratio of the positive electrode paste to the current collector (aluminum) was 93:2:5 (unit: wt%). The positive electrode was fabricated by applying the paste to the current collector, heating it under reduced pressure, and reducing it. The loading amount is 6 mg / cm 2 The reduction method of graphene oxide is either thermal reduction or chemical reduction. The original was used.

[0222] The thermal reduction treatment of graphene oxide involves heating the active material layer at 170°C under reduced pressure for 10 hours. The chemical reduction treatment of graphene oxide was carried out by treating the active material layer with a polar The test was carried out by immersing the sample in a solvent and heating it at 60°C for one hour. Ascorbic acid was dissolved as a reducing agent at a concentration of 77 mmol / L in an NMP aqueous solution. We used the following.

[0223] (Discharge characteristics) The fabricated positive electrodes were assembled into half cells, and the charge-discharge characteristics of each cell were measured. The negative electrode uses lithium metal, and the electrolyte is ethylene carbonate (EC) and diethyl carbonate. The mixture of hexafluorophosphate and decanoic acid (DEC) in a volume ratio of 1:1 was added to the solution. The solution used was lithium (LiPF6) dissolved at a concentration of 1 mol / liter.

[0224] For convenience, graphene oxide A, B, and C were used as raw materials for the conductive additive and subjected to thermal reduction treatment. The cells fabricated using the electrodes are designated as cells A, B, and C, respectively. A cell was fabricated using electrodes that had undergone chemical reduction treatment using B, C as the raw materials for the conductive additive. Let them be cells D, E, and F respectively. Also, using Comparative Example 1 as the raw material of the conductive assistant, a cell fabricated using the electrode subjected to heat reduction treatment was designated as Comparative Example 2, and a cell fabricated using the electrode subjected to chemical reduction treatment was designated as Comparative Example 3. Next, the results of evaluating the charge-discharge characteristics of the fabricated cells will be described. First, CC (constant current) charging, CCCV (constant current constant voltage) charging, and CC discharging will be described.

[0225] <CC Charging>

[0226] CC charging will be described. CC charging is a charging method in which a constant current is passed through the secondary battery throughout the charging period and the charging is stopped when a predetermined voltage is reached. Assume that the secondary battery has an equivalent circuit of internal resistance R and secondary battery capacitance C as shown in Fig. 7(A). In this case, the secondary battery voltage V is the sum of the voltage V

[0227] across the internal resistance R and the voltage V across the secondary battery capacitance C. While CC charging is being performed, as shown in Fig. 7(A), the switch is turned on and a constant current I flows through the secondary battery. During this time, since the current I is constant, according to Ohm's law V =R×I, the voltage V across the internal resistance R is also constant. On the other hand, the voltage V B across the secondary battery capacitance C increases with time. Therefore, the secondary battery voltage V R increases with time. C And when the secondary battery voltage V

[0228] reaches a predetermined voltage, for example, 4.1V, the charging is stopped. During this period, since the current I is constant, according to Ohm's law V R =R×I, the voltage V across the internal resistance R is also constant. On the other hand, the voltage V R across the secondary battery capacitance C increases with time. Therefore, the secondary battery voltage V increases with time. C And when the secondary battery voltage V B reaches a predetermined voltage, for example, 4.1V, the charging is stopped. And when the secondary battery voltage V

[0229] reaches a predetermined voltage, for example, 4.1V, the charging is stopped. B And when the secondary battery voltage V When CC charging stops, as shown in Fig. 7(B), the switch turns off and the current I = 0 becomes. Therefore, the voltage V R across the internal resistance R becomes 0V. Therefore, due to the absence of voltage drop across the internal resistance R B the secondary battery voltage V

[0230] During CC charging and after CC charging stops, the secondary battery voltage V B and the charging current are shown in Fig. 7(C) for an example. The secondary battery voltage V B which was rising during CC charging is shown to slightly decrease after CC charging stops.

[0231] <CCCV charging> Next, CCCV charging will be described. CCCV charging first performs charging at a predetermined voltage in CC charging, and then performs charging until the current flowing in CV (constant voltage) charging decreases, specifically until it reaches the termination current value.

[0232] During CC charging, as shown in Fig. 8(A), the switch of the constant current power supply is on and the switch of the constant voltage power supply is off, and a constant current I flows into the secondary battery. During this period, since the current I is constant, according to Ohm's law of V R = R×I, the voltage V R across the internal resistance R is also constant. On the other hand, the voltage V C across the secondary battery capacity C increases with the passage of time. Therefore B the secondary battery voltage V

[0233] And when the secondary battery voltage V B reaches a predetermined voltage, for example, 4.1V, from CC charging to C Switch to V charging. While performing CV charging, as shown in Fig. 8(B), the switch of the constant voltage power supply is on, the switch of the constant current power supply is off, and the secondary battery voltage V B becomes constant . On the other hand, the voltage V C across the secondary battery capacitance C increases with time. V B = V R + V C . Therefore, the voltage V R across the internal resistance R decreases with time. As the voltage V across the internal resistance R decreases, according to Ohm's law V R = R×I, the current I flowing through the secondary battery also decreases. R When the current I flowing through the secondary battery reaches a predetermined current, for example, a current equivalent to 0.01C

[0234] , charging is stopped. When CCCV charging is stopped, as shown in Fig. 8(C), all switches turn off and the current I = 0. Therefore, the voltage V across the internal resistance R becomes 0V R [[ID=�5]]. However, since the voltage V across the internal resistance R due to CV charging is sufficiently small R , even when the voltage drop across the internal resistance R disappears, the secondary battery voltage V hardly drops. B

[0235] Examples of the secondary battery voltage V B and the charging current during CCCV charging and after CCCV charging is stopped are shown in Fig. 8(D). It shows that even when CCCV charging is stopped, the secondary battery voltage V hardly drops. B

[0236] <CC Discharge> Next, CC discharge will be described. CC discharge is to discharge a constant current through the secondary battery throughout the discharge period Flow from the pond, secondary battery voltage V B Discharge stops when the voltage reaches a certain value, for example, 2.5V. This is a discharge method.

[0237] The secondary battery voltage V during CC discharge B An example of the charge current is shown in Figure 9. Therefore, the secondary battery voltage V B is shown to be descending.

[0238] Next, the discharge rate and charge rate will be explained. It is the relative ratio of the current during discharge and is expressed in units of C. For a battery with a rated capacity of X (Ah), In this case, the current equivalent to 1C is X(A). When discharging with a current of 2X(A), the current is 2C. If it is discharged at a current of X / 5(A), it is said to be discharged at 0.2C. The same applies to the charging rate; if you charge with a current of 2X (A), it will be charged at 2C. When charging with a current of X / 5(A), it was said to be charged at 0.2C. .

[0239] In this example, the charging conditions were CCCV charging and the charging rate was 0.2 C. The discharge conditions were CC discharge, and the discharge rates were 0.2C, 0.2C, 1C, 2C, 5C, and 1 The discharge curve at a discharge rate of 10C is shown in Figure 1. Shown as 0.

[0240] 10(A) and (B) are graphs showing discharge characteristics, with the horizontal axis representing discharge capacity (mAh / g). The vertical axis shows voltage (V).

[0241] The cells A, B, and C had higher discharge capacities than the comparative example 2. In particular, the cell C had the best In addition, it was found that Cell C had a higher plateau potential than Comparative Example 2. It was.

[0242] Cells D, E, and F had higher discharge capacities than Comparative Example 3. In particular, Cell F had the best discharge capacity. The electrical properties were obtained.

[0243] As a result, an electrode was fabricated using graphene oxide with alkoxy groups as a raw material for the conductive additive. The cell using graphene oxide without alkoxy groups was made as the raw material for the conductive additive. It was found that the cell with the 1-proton electrode exhibited better discharge characteristics than the cell with the 1-proton electrode. When an electrode made of graphene oxide C prepared using polyaniline was used, the discharge characteristics were Cells C and F were fabricated with the best properties. The positive electrode active material layer, which is made by dispersing graphene oxide in a positive electrode paste, has electron conductivity. It was shown that the network was well formed.

[0244] In addition, a cell using an electrode made by thermal reduction of graphene oxide with 1-propoxy groups was developed. So, the cell using the electrode made by thermal reduction of graphene oxide without alkoxy groups Therefore, the plateau potential increased when the graphene oxide with 1-propoxy groups was heated. It was found that the electrode produced by reduction had high conductivity. The presence or absence of alkoxy groups on the graphene did not affect the plateau potential. Therefore, graphene oxide with 1-propoxy groups can be efficiently graphed by thermal reduction. It became clear that the value of the product had been reduced to

[0245] Next, the graphene oxide was reduced to RGO (Reduced Graphene Oxide). e) The electrical conductivity of RGO was evaluated by powder electrical conductivity measurement.

[0246] (Preparation of RGO) Graphene oxides A to C were kept under reduced pressure for 1 hour, then heated to 170°C and kept for 10 hours. The obtained RGO was packed into a 5 mm diameter pellet die and The pellets were produced by applying pressure for 10 minutes with a pressure pump, releasing the pressure, and then applying pressure again for 10 minutes. At this time, the pressure per unit area applied to the powder was approximately 7.5 Mgf / cm 2 It is. The pellets were designated as samples A to C. Samples A, B, and C were graphene oxide A, B, and C, respectively. The RGO was produced using C. The same reduction was carried out on Comparative Example 1, and pellets were obtained. Comparative Example 4 was prepared by this process.

[0247] For Sample A, Sample B, Sample C and Comparative Example 4, the DC four-terminal van der Pauw method The resistivity was measured using ResiTest8300 (Toyo Corporation). The results are shown in Table 1.

[0248] [Table 1]

[0249] Table 1 shows the electrical conductivities and resistivities of Comparative Example 4 and Samples A to C.

[0250] As shown in Table 1, all of Samples A to C had higher electrical conductivity than Comparative Example 4. Therefore, it can be seen that the reduction in Samples A to C is more advanced than in Comparative Example 4, and a graphene structure is formed. Therefore, graphene oxide prepared using alcohol is more stable than graphene prepared using water. This suggests that the structure is more susceptible to thermal reduction than graphene oxide.

[0251] (Comparison of reduction speed) Next, to compare the reduction rate of graphene oxide under mild conditions, we A, graphene oxide C, and Comparative Example 1 were stored for approximately 1 year and 6 months. The test was carried out in a dry room at 25°C.

[0252] Solids of graphene oxides A, C, and Comparative Example 1 after storage 13 C NMR was measured and the In Comparative Example 1, no significant change was observed in the spectrum before and after storage. After storage, graphene oxide A showed peaks of 63 ppm and 19 ppm derived from ethoxy groups. The peak disappears, and the intensity of the broad peak around 130 ppm due to the carbon in graphene increases. In addition, graphene oxide C showed 69 ppm, 27 ppm, and The intensity of the peaks at 12.5 ppm and 130 ppm decreased, and the intensity of the broad peak around 130 ppm increased. The results suggest that graphene oxides A and C were reduced during storage. Therefore, it is clear that graphene oxide with alkoxy groups is easily reduced even at room temperature. It became clear. [Explanation of symbols]

[0253] 100 Battery electrodes 101 Current collector 102 Active material layer 103 Active material 104 Graphene 106 Graphene oxide 107 Graphene oxide 108 Graphene oxide 300 Coin-type battery 301 Positive electrode can 302 Anode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior body 600 storage battery 601 Positive electrode cap 602 Battery can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating board 610 Gasket (insulating packing) 611 PTC element 612 Safety valve mechanism 700 Display device 701 Case 702 Display section 703 Speaker section 704 Storage battery 710 Lighting Equipment 711 Case 712 Light source 713 Storage battery 714 Ceiling 715 Side wall 716 beds 717 Window 720 indoor unit 721 Case 722 Ventilation vent 723 Storage battery 724 Outdoor unit 730 Electric refrigerator-freezer 731 Case 732 Refrigerator door 733 Freezer door 734 Storage Battery 800 tablet devices 801 Case 802 Display section 802a Display 802b display 803 Display mode switch 804 Power Switch 805 Power saving mode switch 807 Operation switch 808a Touch panel area 808b Touch panel area 809 Operation Key 810 Keyboard display switch button 811 Solar Cells 850 Charge / discharge control circuit 851 Battery 852 DC-DC converter 853 Converter 860 Electric Vehicles 861 Battery 862 Control circuit 863 Drive Unit 864 Processing equipment

Claims

1. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have a region that covers the active material, and constitute a three-dimensional electron conduction network in the active material layer; an active material layer having an electrical conductivity of more than 8.65 S / cm when the resistivity of the plurality of graphenes is measured by a direct current four-probe method.

2. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have a region that wraps the active material, and constitute a three-dimensional electron conduction network in the active material layer; an active material layer having an electrical conductivity of more than 8.65 S / cm when the resistivity of the plurality of graphenes is measured by a direct current four-probe method.

3. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have regions where they are attached to the active material, and form a three-dimensional electron conduction network in the active material layer; an active material layer having an electrical conductivity of more than 8.65 S / cm when the resistivity of the plurality of graphenes is measured by a direct current four-probe method.

4. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have a region that covers the active material, and form a three-dimensional electron conduction network in the active material layer; When the resistivity of the plurality of graphenes was measured by a direct current four-terminal method, the resistivity was 1.16 × 10 －１ The active material layer has a resistance lower than Ω·cm.

5. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have a region surrounding the active material, and constitute a three-dimensional electron conduction network in the active material layer; When the resistivity of the plurality of graphenes was measured by a direct current four-terminal method, the resistivity was 1.16 × 10 －１ The active material layer has a resistance lower than Ω·cm.

6. An active material layer having an active material and a plurality of graphenes, the plurality of graphenes are in surface contact with each other to form a sheet shape, have regions where they are attached to the active material, and form a three-dimensional electron conduction network in the active material layer; When the resistivity of the plurality of graphenes was measured by a direct current four-terminal method, the resistivity was 1.16 × 10 －１ The active material layer has a resistance lower than Ω·cm.

7. A secondary battery comprising the active material layer according to any one of claims 1 to 6.

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