Lithium ion secondary battery

Abstract

To increase the efficiency of the reaction of reducing graphene oxide under a mild condition, and improve the cycle characteristics and rate characteristics of a storage battery in the manufacturing of a storage battery electrode containing graphene as a conductive auxiliary agent.SOLUTION: In a manufacturing method of a storage battery electrode, a first mixture including an active material, a graphene oxide, and a solvent is formed, a reducing agent is added to the first mixture, the graphene oxide is reduced to make a second mixture, a binder is mixed with the second mixture to prepare a third mixture, the third mixture is applied to a current collector, and the solvent is evaporated to form an active material layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to an electrode for a storage battery, a method for manufacturing the same, a storage battery, and an electronic device. 。

[0002] Note that one aspect of the present invention is not limited to the above technical field. One aspect of the invention disclosed in this specification or the like relates to an article, a method, or a manufacturing method. One aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, as a more specific technical field of one aspect of the present invention disclosed in this specification, semiconductor devices, display devices, light-emitting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods can be cited as an example. ufacture, or a composition of matter. Therefore, more specifically, as the technical field of one aspect of the present invention disclosed in this specification, semiconductor devices, display devices, light-emitting devices, power storage devices, storage devices, their driving methods, or their manufacturing methods can be cited as an example. can be cited as an example.

Background Art

[0003] With the remarkable spread of recent portable electronic devices such as mobile phones, smartphones, e-book terminals (e-books), and portable game machines, there is an increasing demand for miniaturization and large capacity of secondary batteries, which are their driving power sources. As secondary batteries used in portable electronic devices, non-aqueous secondary batteries represented by lithium-ion secondary batteries having advantages such as high energy density and large capacity are widely used. As a secondary battery used in portable electronic devices, non-aqueous secondary batteries represented by lithium-ion secondary batteries having advantages such as high energy density and large capacity are widely used. are widely used.

[0004] Lithium-ion secondary batteries are widely popular because they have high energy density among non-aqueous secondary batteries. Lithium-ion secondary batteries include a positive electrode containing an active material such as lithium cobalt oxide (LiCoO2) or lithium iron phosphate (LiFePO4), a negative electrode containing an active material such as graphite capable of occluding and releasing lithium ions, and ethylene carbonate or diethyl carbonate. Dissolve an electrolyte composed of a lithium salt such as LiBF4 or LiPF6 in an organic solvent such as toluene It is composed of a non-aqueous electrolyte or the like. The charge and discharge of a lithium-ion secondary battery is carried out by Lithium ions in the secondary battery move between the positive electrode and the negative electrode through the non-aqueous electrolyte, and lithium Ions are inserted and desorbed into the active materials of the positive and negative electrodes.

[0005] In the positive electrode or the negative electrode, a binder (also referred to as a binder) is mixed in order to bind the active material to the active material and the active material layer to the current collector. As the binder, a polymer organic compound such as insulating polyvinylidene fluoride (PV dF) is generally used, so the electrical conductivity is extremely low. Therefore, when the ratio of the binder is increased with respect to the amount of the active material, the ratio of the amount of the active material in the electrode relatively decreases As a result, the discharge capacity of the secondary battery decreases.

[0006] Therefore, by mixing a conductive aid such as acetylene black (AB) or graphite (carbon) particles, the electrical conductivity between the active materials or between the active material layer and the current collector is improved. This enables the provision of an active material layer having high electrical conductivity (see Patent Document 1).

[0007] In addition, electrodes containing graphene as a conductive aid have been developed. Patent Document 2 discloses a method for manufacturing an electrode having a step of reducing GO (also abbreviated as GO (Graphene Oxide)) after mixing GO, an active material, and a binder . By this manufacturing method, it is possible to provide an active material layer having high electrical conductivity with a small amount of conductive aid .

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] [Problems to be Solved by the Invention]

[0009] In order to improve the performance of a storage battery having graphene as a conductive assistant, there is a demand for developing a method for manufacturing an electrode capable of sufficiently reducing graphene oxide. Further, in order to facilitate mass production of the storage battery, simplification of the method for manufacturing the electrode is demanded. Therefore, an aspect of the present invention is to provide a method for manufacturing an electrode for a storage battery capable of efficiently reducing graphene oxide. Another aspect of the present invention is to provide a method for manufacturing an electrode for a storage battery having a small internal resistance. Another aspect of the present invention is to improve the cycle characteristics of the storage battery. Another aspect of the present invention is to improve the rate characteristics of the storage battery.

[0010]

[0011] Another aspect of the present invention is to simplify the method for manufacturing an electrode for a storage battery containing graphene as a conductive assistant. Another aspect of the present invention is to provide a method for manufacturing an electrode for a storage battery for reducing graphene oxide under mild conditions. Another aspect of the present invention is to simplify the method for manufacturing the storage battery.

[0012] Another aspect of the present invention is to provide an electrode for a storage battery having a uniform thickness. Another aspect of the present invention is to provide an electrode for a storage battery and a storage battery having high strength.

[0013] Alternatively, one aspect of the present invention is to provide a novel electrode, a novel storage battery, or a method for manufacturing a novel electrode and the like. It should be noted that the description of these problems does not preclude the existence of other problems. It should be noted that one aspect of the present invention does not necessarily need to solve all of these problems. Also, in one aspect of the present invention, at least one of the above problems is solved . Other problems will become apparent from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other problems from the descriptions in the specification, drawings, claims, etc.

Means for Solving the Problems

[0014] One aspect of the present invention is to form a first mixture having an active material, graphene oxide, and a solvent, add a reducing agent to the first mixture to form a second mixture, mix a binder with the second mixture to form a third mixture, and apply the third mixture to a current collector and evaporate the solvent to form an active material layer, which is a method for manufacturing an electrode for a storage battery.

[0015] Also, one aspect of the present invention is a method for manufacturing an electrode for a storage battery, wherein in the above configuration, the solvent is evaporated by heating at a temperature of room temperature or higher and 100 °C or lower.

[0016] Also, one aspect of the present invention is an electrode for a storage battery having a current collector and an active material layer, wherein the active material layer has an active material, a conductive auxiliary agent having graphene, a binder, and a reducing agent.

[0017] Also, one aspect of the present invention is an electrode for a storage battery having a current collector and an active material layer, wherein the active material layer has an active material, a conductive auxiliary agent having graphene ​​​​An electrode for a storage battery having a conductive aid with raffene, a binder, and an oxidation derivative of a reducing agent It is.

[0018] Also, one aspect of the present invention has a first electrode and a second electrode, and the first electrode is each of the above It is an electrode having the configuration, the first electrode has a function of operating as one of a positive electrode or a negative electrode, and the The second electrode is a storage battery having a function of operating as the other of a positive electrode or a negative electrode.

[0019] Also, one aspect of the present invention is an electronic device equipped with the storage battery having the above configuration, a display panel, a light source, an operation key, a speaker , or a microphone.

[0020] In each of the above configurations, the reducing agent is preferably at least one of ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, sodium borohydride (NaBH4), lithium aluminum hydride (Li AlH4), or N,N-diethylhydroxylamine. It is preferable that it is any one of Preferably.

Advantages of the Invention

[0021] According to one aspect of the present invention, graphene oxide contained in the active material layer can be efficiently reduced. Also, according to one aspect of the present invention, a network of three-dimensional electrical conduction paths can be constructed in the active material layer. Due to the above effects, one aspect of the present invention can provide an electrode with a small internal resistance. Also, one aspect of the present invention can improve the cycle characteristics of the storage battery. Also, one aspect of the present invention can improve the rate characteristics of the storage battery. It can be.

[0022] Also, according to one aspect of the present invention, the manufacturing method of an electrode containing graphene as a conductive aid is simplified. It can be done. Further, according to one aspect of the present invention, reducing graphene oxide under mild conditions A method for manufacturing an electrode can be provided. Due to the above effects, one aspect of the present invention simplifies the manufacturing method of a storage battery It can be done.

[0023] Further, according to one aspect of the present invention, it is possible to suppress the mixture for forming the active material layer from becoming strongly basic Further, according to one aspect of the present invention, it is possible to suppress the aggregation of the active material in the active material layer Further, one aspect of the present invention can suppress the gelation of the binder Due to the above effects, one aspect of the present invention can provide an electrode having an active material layer with a uniform thickness Further, one aspect of the present invention can provide an electrode and a storage battery with high strength It can be done.

[0024] Further, according to one aspect of the present invention, a novel electrode, a novel storage battery, or a manufacturing method of a novel electrode, etc. can be provided. It should be noted that the description of these effects does not prevent the existence of other effects It should be noted that one aspect of the present invention does not necessarily have to have all of these effects It should be noted that other effects will be obvious from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc. It should be noted that other effects will be obvious from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc. It should be noted that other effects will be obvious from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc. It can be done.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Mode for Carrying Out the Invention

[0026] Hereinafter, embodiments will be described with reference to the drawings. However, the embodiments can be implemented in many different ways, and it will be easily understood by those skilled in the art that the form and details thereof can be varied in various ways without departing from the spirit and scope thereof. Therefore, the present invention

[0027] is not to be construed as being limited to the content described in the following embodiments. One reference sign is commonly used among different drawings, and repeated explanations thereof are omitted. Also, when referring to similar functions, the hatching patterns may be the same and may not be particularly labeled.

[0028] In each of the figures described in this specification, the size of each component such as the thickness and area of a film, layer, substrate, etc. may be exaggerated for the sake of clarity of individual explanations. Therefore, each component is not necessarily limited to its size, nor is it limited to the relative size between each component.

[0029] In this specification, etc., ordinal numbers such as first, second, etc. are used for convenience and do not indicate the order of processes or the order of lamination, etc. Therefore, for example, "the first " can be appropriately replaced with "the second" or "the third", etc. for explanation. Also, the ordinal numbers described in this specification, etc. and the ordinal numbers used to identify an aspect of the present invention may not match.

[0030] (Embodiment 1) In this embodiment, an electrode for a storage battery according to an aspect of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2(A) shows a perspective view of the electrode, FIG. 2(B) shows a plan view of the active material layer, and FIGS. 2(C) and 3 show a longitudinal sectional view of the active material layer.

[0031] FIG. 2(A) is a perspective view of the electrode 200. In FIG. 2(A), the electrode 200 is shown in a rectangular sheet shape, but the shape of the electrode 200 is not limited thereto, and any shape can be appropriately selected. In FIG. 2(A), the active material layer 202 is formed only on one surface of the current collector 201, but the active material layer 202 may be formed on both surfaces of the current collector 201. Also, the active material layer 20 ​It is not necessary to form it on the entire surface of the current collector 201, and a non-coated area such as an area for connecting to the tab may be provided as appropriate. The area is provided as appropriate.

[0032] For the current collector 201, metals such as stainless steel, gold, platinum, zinc, iron, copper, aluminum, titanium, etc., and alloys thereof, which have high conductivity and do not alloy with carrier ions such as lithium, can be used. Also, an aluminum alloy added with elements such as silicon, titanium, neodymium, scandium, molybdenum, etc., which improve heat resistance, can be used. Alternatively, it may be formed of a metal element that reacts with silicon to form a silicide. As the metal element that reacts with silicon to form a silicide, there are zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The current collector 201 can appropriately use shapes such as foil, plate (sheet), net, punching metal, expanded metal, etc. The current collector 201 is preferably one having a thickness of 10 μm or more and 30 μm or less. Also, an undercoat layer may be provided on the surface of the current collector 201 using graphene or the like.

[0033] Figures 2(B) and 2(C) are schematic diagrams showing the top surface and longitudinal cross-section of the active material layer 202, respectively. The active material layer 202 includes graphene 204 as a conductive aid, granular active material 203, and a binder (also referred to as a binder, not shown). The active material layer 202 may have a conductive aid other than graphene (also referred to as a second conductive aid, not shown).

[0034] As shown in the top view of the active material layer 202 shown in Figure 2(B), a plurality of granular active materials 203 are a plurality of It is coated by graphene 204. A single sheet-like graphene 204 is connected to a plurality of granular active materials 203. In particular, since graphene 204 is sheet-like, it can make surface contact so as to wrap a part of the surface of the granular active material 203. Different from granular conductive aids such as acetylene black that make point contact with the active material, graphene 204 enables surface contact with low contact resistance. Therefore, without increasing the amount of the conductive aid, the electrical conductivity between the granular active material 203 and graphene 204 can be improved. A plurality of granular active materials 203 are connected. In particular, since graphene 204 is sheet-like, it can make surface contact so as to wrap a part of the surface of the granular active material 203. Different from granular conductive aids such as acetylene black that make point contact with the active material, graphene 204 enables surface contact with low contact resistance. Therefore, without increasing the amount of the conductive aid, the electrical conductivity between the granular active material 203 and graphene 204 can be improved. A plurality of graphene 204s are also in surface contact with each other. This is because graphene oxide with extremely high dispersibility in a polar solvent is used in the formation of graphene 204. To remove the solvent by evaporating it from the mixture containing uniformly dispersed graphene oxide and reduce the graphene oxide to graphene, the graphene 204 remaining in the active material layer 202 partially overlaps and is dispersed to the extent of making surface contact with each other.

[0035] As a result, an electrical conduction path is formed in the active material layer 202. In the top view of the active material layer 202 shown in FIG. 2(B), graphene 204 does not necessarily overlap with other graphene only on the surface of the active material layer 202. A part of graphene 204 is provided between the active material layers 202. Also, since graphene 204 is an extremely thin film (sheet) composed of a single layer of carbon molecules or a stack of these, it covers and contacts a part of the surface of each individual granular active material 203 as if tracing the surface. The part that is not in contact with the active material 203 bends between a plurality of granular active materials 203, forming wrinkles or being stretched and in a taut state.

[0036] In the top view of the active material layer 202 shown in FIG. 2(B), graphene 204 does not necessarily overlap with other graphene only on the surface of the active material layer 202. A part of graphene 204 is provided between the active material layers 202. Also, since graphene 204 is an extremely thin film (sheet) composed of a single layer of carbon molecules or a stack of these, it covers and contacts a part of the surface of each individual granular active material 203 as if tracing the surface. The part that is not in contact with the active material 203 bends between a plurality of granular active materials 203, forming wrinkles or being stretched and in a taut state. The part that is not in contact with the active material 203 bends between a plurality of granular active materials 203, forming wrinkles or being stretched and in a taut state. ​​​

[0037] In the longitudinal section of the active material layer 202, as shown in FIG. 2(C), inside the active material layer 202 sheet-like graphene 204 is dispersed in a substantially uniform manner. In FIG. 2(C), the graphene 204 is schematically represented by a thick line, but actually has a thickness of a single layer or multiple layers of carbon molecules and is a thin film. Similar to the description of the upper surface of the active material layer 202, a plurality of graphene 20 4 is formed so as to wrap or cover a plurality of granular active materials 203, and thus are in surface contact with each other. Also, the graphene 204s are in surface contact with each other to form a network for electrical conduction by a plurality of graphene 204s. A schematic diagram obtained by further enlarging FIG. 2(C) is FIG. 3. The graphene 204 covers the surface of a plurality of granular active materials 203, and the graphene also contacts each other to form a network .

[0038] As shown in FIGS. 2(B), 2(C) and 3, a plurality of sheet-like graphene 204s are three-dimensionally dispersed inside the active material layer 202, and they are in surface contact with each other to form a three-dimensional electrical conduction network. Also, each graphene 2 04 covers a plurality of granular active materials 203 and is in surface contact.

[0039] Graphene 204 is formed by reducing graphene oxide using a reducing agent in the method for manufacturing an electrode for a storage battery described in Embodiment 2. In the method for manufacturing the electrode for the storage battery, since a reducing agent is used when forming the active material layer 202, a reducing agent may remain in the active material layer 202. Also, the reducing agent is the same as that for reducing graphene oxide It is oxidized at times. Therefore, the active material layer 202 may contain a derivative (hereinafter referred to as the oxidation derivative of the reducing agent) generated by the oxidation of the reducing agent.

[0040] The presence of a reducing agent or an oxidation derivative of the reducing agent in the active material layer 202 can be detected by means of analysis such as EDX (Energy Dispersive X-ray spectrometry) analysis, XPS (X-ray Photoelectron Spectroscopy), or ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry).

[0041] Examples of the reducing agent include ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, sodium borohydride (NaBH4), lithium aluminum hydride (LiAlH4), or N,N-diethylhydroxylamine, or derivatives thereof. In particular, ascorbic acid and hydroquinone are preferred in terms of high safety due to their weaker reducing power compared to hydrazine and sodium borohydride and ease of industrial use.

[0042] The reducing agent becomes an oxidation derivative of the reducing agent by the reaction of reducing graphene oxide. Here, as an example, the redox reaction of ascorbic acid will be described. Ascorbic acid is oxidized to dehydroascorbic acid. Therefore, when ascorbic acid is used as the reducing agent, dehydroascorbic acid may remain in the active material layer 202 as an oxidation derivative of the reducing agent. Also, not limited to the case where ascorbic acid is used as the reducing agent, an oxidation derivative of the reducing agent may remain in the active material layer 202.

[0043] Graphene is a carbon material having a crystal structure in which the hexagonal skeleton formed by carbon extends in a planar shape. It is. Graphene is obtained by extracting a single atomic plane of graphite crystal, and has amazing characteristics in electrical, mechanical or chemical properties. Therefore, high-mobility field-effect transistors, highly sensitive sensors, highly efficient solar cells, transparent conductive films for the next generation etc. are expected to be applied in various fields and have attracted attention.

[0044] In this specification, graphene includes single-layer graphene or multi-layer graphene with 2 layers or more and 100 layers or less. Single-layer graphene refers to a sheet of a one-atomic layer of carbon molecules having π bonds. In addition, graphene oxide refers to a compound obtained by oxidizing the above-mentioned graphene. When reducing graphene oxide to form graphene, not all of the oxygen contained in graphene oxide needs to be desorbed, and some oxygen may remain in the graphene. By using the method for manufacturing an electrode for a storage battery described in Embodiment Form 2, the reaction efficiency of the reduction reaction of graphene oxide can be increased. When oxygen is contained in graphene, the proportion of oxygen is 2 atomic% or more and 20 atomic% or less of the entire graphene when measured by XPS, preferably 3 atomic% or more and 10 atomic% or less. As described above, a plurality of sheet-like graphenes 204 are three-dimensionally dispersed inside the active material layer 202, and by their surface contact with each other, a three-dimensional electrical conductivity network is formed. Therefore, by increasing the reaction efficiency of the reduction reaction of graphene oxide, the internal resistance of the active material layer 202 and the electrode 200 can be reduced.

[0045] ​​​Graphene oxide can be produced using an oxidation method called the Hummers method. In the Hummers method, a sulfuric acid solution of potassium permanganate, hydrogen peroxide water, etc. are added to graphite powder to cause an oxidation reaction to produce a mixed solution containing graphite oxide. Graphite oxide is bonded with functional groups such as epoxy groups, carbonyl groups, carboxyl groups , and hydroxyl groups due to the oxidation of the carbon in graphite. Therefore, the interlayer distance of multiple graphene layers becomes longer compared to that of graphite, and it becomes easier to form thin flakes by separating the layers. Next, ultrasonic vibration is applied to the mixed solution containing graphite oxide to cleave the graphite oxide with a long interlayer distance, separate the graphene oxide, and produce a mixed solution containing graphene oxide . Then, by removing the solvent from the mixed solution containing graphene oxide, powdered graphene oxide can be obtained.

[0046] Graphene oxide may also be formed by appropriately adjusting the amount of an oxidizing agent such as potassium permanganate. For example, by increasing the amount of the oxidizing agent with respect to the graphite powder, the degree of oxidation of graphene oxide (the atomic ratio of oxygen to carbon) can be increased. Therefore, according to the amount of graphene oxide to be produced, the amount of the oxidizing agent with respect to the raw material graphite powder may be determined.

[0047] Note that the production of graphene oxide is not limited to the Hummers method using a sulfuric acid solution of potassium permanganate. For example, the Hummers method using nitric acid, potassium chlorate, or sodium nitrate, etc., or a method for producing graphene oxide other than the Hummers method may be appropriately used.

[0048] In addition to the addition of ultrasonic vibration, the thinning of graphite oxide flakes may also be carried out by irradiation with microwaves, radio waves, or thermal plasma, or by the application of physical stress.

[0049] The prepared graphene oxide has epoxy groups, carbonyl groups, carboxyl groups, hydroxyl groups, etc. In a polar solvent, graphene oxide interacts with the polar solvent because the oxygen of these functional groups is negatively charged. On the other hand, different graphene oxides repel each other and are difficult to aggregate. Therefore, in a polar solvent, graphene oxide is likely to be uniformly dispersed.

[0050] Also, the length of one side of graphene oxide (also referred to as flake size) is 50 nm or more and 100 μm or less, preferably 800 nm or more and 20 μm or less. By controlling the flake size of graphene oxide, the flake size of graphene in the active material layer can be controlled. When the flake size of graphene is larger than the average particle size of the granular active material 203, it is easier to make surface contact with a plurality of active materials 203, and it is easier to connect graphene to each other. Therefore, it is effective in improving the electrical conductivity of the active material layer 202.

[0051] The active material 203 is a granular active material composed of secondary particles having an average particle size and a particle size distribution, which are obtained by pulverizing, granulating, and classifying a fired product obtained by mixing and firing raw material compounds at a predetermined ratio by appropriate means. Therefore, in FIGS. 2(B) and 2(C), the active material 203 is schematically shown as a sphere, but it is not limited to this shape.

[0052] When the electrode 200 is used as the positive electrode of the storage battery, as the active material 203, lithium ions ​​Materials that allow insertion and desorption of ions can be used. For example, olivine type crystal structures, Lithium manganese composite oxide having a layered rock salt type crystal structure or a spinel type crystal structure etc.

[0053] Examples of lithium-containing composite phosphates having an olivine structure include those represented by the general formula LiMPO4(M The elements are Fe(II), Mn(II), Co(II), and Ni(II). Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, Li CoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, Li Fe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4(a+b is 1 or less bottom, 0 <a<1、0<b<1)、LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4(c+d+e is less than 1, 0 <c<1、0<d< 1, 0 <e<1)、LiFe f Ni g Co h Mn i PO4(f+g+h+i is less than 1, 0 <f<1、0<g<1、0<h<1、0<i<1)等が挙げられる。

[0054] In particular, LiFePO4 has the following features: safety, stability, high capacity density, high potential, and low initial oxidation (charging). It preferably satisfies the requirements for the active material, such as the presence of leachable lithium ions, in a well-balanced manner. Therefore, it is preferable.

[0055] Examples of the lithium-containing complex silicate having a layered rock salt-type crystal structure include, for example, LiCoO 2, LiNiO2, LiMnO2, Li2MnO3, LiNi 0.8 Co 0.2 O2, etc. NiCo-based (general formula: LiNi x Co 1-x O2 (0 < x < 1)), LiNi 0.5 M n 0.5 O2, etc. of NiMn-based (general formula: LiNi x Mn 1-x O2 (0 < x < 1)), LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, etc. of NiMnCo-based (also referred to as NMC. General formula is LiNi x Mn y Co 1-x-y O2 (x > 0, y > 0, x + y < 1)) can be mentioned. Furthermore, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li2MnO3-Li MO2 (M = Co, Ni, Mn), etc. can also be mentioned.

[0056] In particular, LiCoO2 is preferable because it has advantages such as a large capacity, being more stable in the air compared to LiNiO2, and being thermally more stable compared to Li NiO2.

[0057] Examples of the lithium manganese composite oxide having a spinel-type crystal structure include, for example, LiMn 2O4, Li 1+x Mn 2-x O4 (0 < x < 2), LiMn 2-x Al x O4 (0 < x < 2), LiMn 1.5 Ni0.5 Examples include O4, etc.

[0058] When a small amount of lithium nickelate (LiNiO2, LiNi M 1-x M x O2 (0 < x < 1) (M = C o, Al, etc.) is mixed with a lithium manganese composite oxide having a spinel-type crystal structure such as LiMn2O4, it has advantages such as suppressing the elution of manganese and suppressing the decomposition of the electrolytic solution, which is preferable. Moreover, as the positive electrode active material, a composite oxide represented by the general formula Li

[0059] MSiO4 (M is one or more of Fe(II), Mn (2-j) (II), Co(II), Ni(II), and j is 0 or more and 2 or less) can be used. Representative examples of the general formula Li MSiO4 include Li MSiO4. (2-j) MSiO4 are Li ( 2-j) FeSiO4, Li (2-j) NiSiO4, Li (2-j) CoSiO4, L i (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l <1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4( r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. can be mentioned.

[0060] Also, as the positive electrode active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, M n, Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) represented by the general formula can be used. As the NASICON type compound, Fe2(MnO4) 3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. can be mentioned. Also, as the positive electrode active material compounds represented by the general formula of Li2MPO4F, Li2MP2O7, Li5MO4 (M = Fe, Mn), perovskite type fluorides such as FeF3, metal chalcogenides (sulfides, selenides, tellurides) such as TiS2, MoS2, etc., lithium vanadium-containing composite oxides having a reverse spinel type crystal structure such as LiMVO4, vanadium oxide-based compounds( V2O5, V6O V2O5, V6O 13 materials such as LiV3O8, manganese oxides, organic sulfur compounds, etc. can be used.

[0061] The particle size of the positive electrode active material is preferably, for example, 5 nm or more and 100 μm or less.

[0062] Also, as the positive electrode active material, the composition formula Li x Mn y M zO w The lithium manganese composite oxide represented by this can also be used. Here, the element M is selected from elements other than lithium and manganese a metal element, or silicon or phosphorus, preferably nickel. Also, x / (y + z) is 0 or more and less than 2, z is greater than 0, and (y + z) / w preferably satisfies 0.26 or more and less than 0.5. The lithium manganese composite oxide refers to an oxide containing at least lithium and manganese, and may contain at least one element selected from the group consisting of chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium , copper, titanium, niobium, silicon, and phosphorus. Also, the lithium manganese composite oxide preferably has a layered rock salt-type crystal structure. Also, the lithium manganese composite oxide may have a layered rock salt type crystal structure and a spinel type crystal structure. Also, the lithium manganese composite oxide preferably has an average particle diameter of 5 nm or more and 50 μm or less, for example.

[0063] In addition, when the carrier ion is an alkali metal ion or an alkaline earth metal ion other than a lithium ion, as the positive electrode active material, in the above lithium compound and lithium manganese composite oxide, an alkali metal (for example, sodium, potassium, etc.) or an alkaline earth metal (for example, calcium, strontium, barium, beryllium , magnesium, etc.) may be used instead of lithium.

[0064] Also, when the electrode for a storage battery to be manufactured is used as the negative electrode of the storage battery, as the active material 203 ​​, using a material capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium can do.

[0065] Examples of materials capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium include carbon-based materials. Examples of carbon-based materials include graphite, graphitizable carbon (soft carbon ), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black, etc.

[0066] Examples of graphite include artificial graphite such as mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch -based artificial graphite, etc., and natural graphite such as spheroidized natural graphite.

[0067] Graphite shows a potential as low as that of lithium metal (0.1 V or more and 0.3 V or less vs. Li / Li + ) when lithium ions are inserted into graphite (when forming a lithium-graphite intercalation compound). As a result, lithium-ion secondary batteries can exhibit a high operating voltage. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, small volume expansion, low cost, and high safety compared to lithium metal, so it is preferable.

[0068] In addition, as materials capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium there are, for example, materials containing at least one of Ga, Si, Al, Ge, Sn, Pb, Sb, Bi, Ag, Zn, Cd, In, etc. that can be used. Such elements have a larger capacity compared to carbon, and in particular, silicon has a high theoretical capacity of 4200 mAh / g. Examples of materials using such elements include, for example, Mg2Si, Mg2Ge, Mg2Sn, S nS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3S n, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, Co Sb3, InSb and SbSn etc. exist.

[0069] Also, as the negative electrode active material, SiO, SnO, SnO2, titanium dioxide, lithium titanate compounds, lithium-graphite intercalation compounds, niobium pentoxide, tungsten oxide or molybdenum oxide oxides such as etc. can be used.

[0070] Also, as the negative electrode active material, Li3N-type structured Li 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 The lithium-ion secondary battery using N shows a large charge-discharge capacity (900 mAh / g , 1890 mAh / cm 3 ), so it is preferable.

[0071] When using a lithium-transition metal complex nitride, since the negative electrode active material contains lithium ions, it can be combined with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material, which is preferable. When using a material containing lithium ions as the positive electrode active material, even in this case, by previously desorbing the lithium ions contained in the positive electrode active material, a lithium-transition metal complex nitride can be used as the negative electrode active material.

[0072] Also, a material that undergoes a conversion reaction can be used as the negative electrode active material. For example , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc., lithium A transition metal oxide that does not undergo an alloying reaction may be used as the negative electrode active material. As materials in which a conversion reaction occurs, furthermore, oxides such as Fe2O3, CuO, Cu2O, RuO2, Cr2O3, sulfides such as CoS, NiS, CuS, nitrides such as Zn3N2, Cu3N, Ge3N4, phosphides such as NiP2, FeP2, CoP3, and fluorides such as FeF3, BiF3 can also be used. For materials in which a conversion reaction occurs, furthermore, oxides such as Fe2O3, CuO, Cu2O, RuO2, Cr2O 3, sulfides such as CoS 0.89 , NiS, CuS, nitrides such as Zn3N2, Cu3N, G e3N4, phosphides such as NiP2, FeP2, CoP3, and fluorides such as FeF3, BiF3 can also be used.

[0073] The granular active material 203 preferably has an average primary particle diameter of 500 nm or less, more preferably 50 nm or more and 500 nm or less, when measured by, for example, a laser diffraction particle size distribution analyzer. For the graphene 204 to make surface contact with a plurality of the granular active materials 203, the side length of the graphene 204 is preferably 50 nm or more and 100 μm or less, more preferably 800 nm or more and 20 μm or less. When measured with a laser diffraction particle size distribution analyzer, it is preferably 500 nm or less, more preferably 50 nm or more and 500 nm or less, and it is preferred to use it. To make surface contact with a plurality of the granular active materials 203, the graphene 204 has a side length of 50 nm or more and 100 μm or less, more preferably 800 nm or more and 20 μm or less, and it is preferable to have such dimensions.

[0074] As the binder included in the active material layer 202, in addition to typical polyvinylidene fluoride (PVdF), polyimide, polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, or nitrocellulose can be used. In addition to typical polyvinylidene fluoride (PVdF), polyimide, polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, or nitrocellulose can be used.

[0075] Furthermore, the active material layer 202 may have a second conductive aid. When the active material layer 202 has graphene and a second conductive aid, the three-dimensional network of electrical conduction in the active material layer can be made into a more complex shape. Therefore, during the use of the power storage device, the electric in the active material layer 202, and a more complex shape can be formed for the three-dimensional network of electrical conduction in the active material layer. Therefore, during the use of the power storage device, the electricity in the active material layer 202 It is possible to suppress the disconnection of the air conduction path. As the second conductive auxiliary agent, for example, natural graphite, artificial graphite such as mesocarbon microbeads, or carbon fibers can be used. Also, metal powders or metal fibers such as copper, nickel, aluminum, silver, and gold, or conductive ceramic materials can be used.

[0076] As the carbon fibers, for example, carbon fibers such as mesophase pitch-based carbon fibers and isotropic pitch-based carbon fibers can be used. Also, as the carbon fibers, carbon nanofibers, carbon nanotubes, etc. can be used. Further, as the carbon fibers, vapor-grown carbon fibers (VGCF:Vapor-Grown Carbon Fiber) (registered trademark) can be used. The representative values of VGCF (registered trademark) are a fiber diameter of 150 nm, a fiber length of 10 μm or more and 20 μm or less, a true density of 2 g / cm 3 2

[0077] It can be done.

[0078] Also, a granular material can be used as the conductive aid. Representative examples of the granular material include acetylene black with a diameter of 3 nm or more and 500 nm or less, and carbon black such as Ketjen black (registered trademark), etc. can be used.

[0079] Flaky, needle-shaped, or fibrous conductive aids serve to connect the active materials and suppress the deterioration of the battery. Also, these materials function as a structure for maintaining the shape of the active material layer 202 or as a buffer material. Functioning as a structure for maintaining the shape of the active material layer 202 or as a buffer material means that when the expansion and contraction of the active material are repeated, or when the secondary battery is bent, etc., peeling between the current collector and the active material is less likely to occur. Also, instead of the above materials, carbon black such as acetylene black and Ketjen black (registered trademark) can be used, but using VGCF (registered trademark) is preferable because the strength for maintaining the shape of the active material layer 202 can be increased. When the strength for maintaining the shape of the active material layer 202 is increased, deterioration due to deformation such as bending of the secondary battery can be prevented.

[0080] The active material layer 202 shown above preferably contains 80 wt% or more and 95 wt% or less of the active material 203, 0.1 wt% or more and 8 wt% or less of graphene, and 1 wt % or more and 10 wt% or less of the binder with respect to the total weight of the active material layer 202. Also, when the active material layer 202 has a second conductive aid, it is preferable that the total weight of graphene and the second conductive aid is 0.1 wt% or more and 8 wt% or less with respect to the total weight of the active material layer 202.

[0081] As shown in this embodiment, graphene 204 having an average particle diameter larger than that of the granular active material 203 is dispersed in the active material layer 202 so as to be in surface contact with one or more other adjacent graphene 204s and in surface contact so as to wrap a part of the surface of the granular active material 203. Thus, it is possible to provide a battery electrode including an active material layer having a high filling amount and a high density with a small amount of conductive assistant. In this embodiment, one aspect of the present invention has been described. Or, in other embodiments, one aspect of the present invention is described. However, one aspect of the present invention is not limited to these. That is, in this embodiment and other embodiments, since various aspects of the invention are described, one aspect of the present invention is not limited to a specific aspect. For example, as one aspect of the present invention, an example in the case where graphene is applied to a battery electrode has been shown, but one aspect of the present invention is not limited to this. Depending on the case or the situation, graphene or graphene oxide may be used as an electrode for a supercapacitor which is a capacitor having a very large capacitance, as an oxygen reduction electrode catalyst, as a material for a dispersion liquid having lower friction than lubricating oil, as a transparent electrode for a display device, a solar cell, etc., as a gas barrier material, as a polymer material having high mechanical strength and low weight, as a material for a highly sensitive nanosensor for detecting uranium or plutonium contained in radioactive contaminated water, or as a material for removing radioactive substances. Or for example, depending on the case or the situation, as one aspect of the present invention, graphene may not be applied to the battery electrode.

[0082]

[0083] ​​​​​​​​​​​​​​​​This embodiment can be implemented in appropriate combination with other embodiments.

[0084] (Embodiment 2) In this embodiment, a method for manufacturing the electrode 200 including the active material layer 202 using the active material, conductive assistant, and binder exemplified in Embodiment 1 will be described with reference to FIG. 1. First, the active material, graphene oxide, and a solvent are kneaded to form a first mixture (step

[0085] S101). At this time, a second conductive assistant may be added. As the active material, graphene oxide, and the second conductive assistant, the materials described in Embodiment 1 can be used. As the solvent for forming the mixture, a polar solvent can be used. For example, methanol

[0086] , ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DM F), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), or a mixture of any one or more of these can be used. In particular, NMP is preferable because it can well disperse graphene oxide. Next, by performing solid kneading (kneading in a high-viscosity state) on the first mixture, aggregation of graphene oxide and the active material can be loosened. Also, since the oxygen of the functional group in graphene oxide has a negative charge in a polar solvent, it is difficult for different graphene oxides to aggregate. Therefore, the active material and graphene oxide can be more uniformly dispersed.

[0087] Next, a reducing agent is added to and mixed with the first mixture to reduce graphene oxide and form a second mixture (step S102). The reducing agent is dissolved in a small amount of solvent and then added to the first mixture.

[0088] ​​​​​​ When added to the compound, it is preferable as it facilitates mixing. By this step, graphene oxide can be reduced to graphene. Note that not all of the oxygen contained in graphene oxide needs to be removed, and some oxygen may remain in the graphene.

[0089] As the reducing agent, the materials described in Embodiment 1 can be used.

[0090] As the solvent for dissolving the reducing agent, a solvent with high solubility of the reducing agent and low boiling point can be used. For example, water, methanol, ethanol, etc. can be used.

[0091] The mixture added with the reducing agent may be heated at 30°C or higher and 200°C or lower, preferably 50°C or higher and 100°C or lower. Heating can promote the reduction reaction of graphene oxide. Note that the atmosphere is not particularly limited.

[0092] Note that graphene oxide can be reduced by heating the mixture having graphene oxide without adding a reducing agent. However, in order to sufficiently reduce graphene oxide by heating, heating at a high temperature is required. Therefore, due to limitations such as the heat resistance temperature of the materials or devices used for electrode fabrication, graphene oxide cannot be heated to a sufficiently high temperature, and the reduction may be insufficient. On the other hand, in one aspect of the present invention, by adding a reducing agent, graphene oxide can be reduced without heating at a high temperature. Therefore, it can be said that the efficiency of the reaction for reducing graphene oxide under mild conditions can be enhanced by the method shown in Step S102.

[0093] The weight of the reducing agent is 5 wt% or more with respect to the weight of graphene oxide contained It is preferably set at a ratio of 500 wt% or less. Further, the weight of the reducing agent may be changed according to the degree of oxidation of the graphene oxide used in step S101.

[0094] Here, when a high-density active material is used, the density of the active material layer 202 may increase. Examples of the high-density active material include lithium manganese composite oxides represented by the composition formula Li Mn x Mn y M z O w and LiCoO2, LiNi Mn 1 / 3 Mn 1 / 3 Co 1 / 3 O2 and the like such as NiMnCo systems. When the reduction treatment of graphene oxide is performed after forming the active material layer 202, there may be a case where graphene oxide cannot be sufficiently reduced. This is presumably because the voids in the active material layer 202 are very few and the reducing agent does not sufficiently penetrate deep into the active material.

[0095] On the other hand, in one aspect of the present invention, as shown in step S102, graphene oxide is reduced by adding a reducing agent to the first mixture before forming the active material layer. By adding a reducing agent to the first mixture, the reducing agent spreads widely in the mixture, so that the graphene oxide contained in the second mixture can be reduced with high reaction efficiency. Therefore, in the subsequent step S10 4, an active material layer 202 in which graphene oxide is reduced with high reaction efficiency can be formed.

[0096] In addition, compared with the case where graphene oxide is reduced for each electrode after electrode fabrication, adding a reducing agent to the first mixture to reduce graphene oxide can reduce a large amount of graphene oxide at once. There may be a case where raffinate can be reduced. That is, one aspect of the present invention is the simplification of the process and it can be said that it is a method capable of improving mass productivity.

[0097] In addition, when a basic active material is used as the active material, there is a case where the second mixture becomes basic In this case, in the subsequent step S103, when PVdF is added to the second mixture PVdF may gel and it may be difficult to uniformly knead the third mixture. On the other hand, even when a basic active material is used as the active material, in step S102 if an acid is added as a reducing agent, it is possible to suppress the second mixture from becoming strongly basic Therefore, in the subsequent step S103, gelation of PVdF can be suppressed so that a uniformly kneaded third mixture can be produced. Therefore, an active material layer in which the binder is uniformly distributed can be formed, and an electrode having a uniform thickness can be produced In addition, an electrode having high strength and being difficult to be destroyed by, for example, external impact can be produced

[0098] Examples of the basic active material include lithium x manganese y M z O w manganese composite oxide represented by etc.

[0099] Examples of the acid that can be used as a reducing agent include ascorbic acid, hydroquinone, etc.

[0100] In addition, when an active material unstable to an acid or a binder is used, it is more preferable to use a base as a reducing agent in step S102 Examples of the active material unstable to an acid include ​​​For example, LiCoO2, LiFePO4, etc. can be mentioned. Also, a binder unstable to an acid includes, for example, SBR, etc. Also, a base that can be used as a reducing agent includes, for example, hydrazine, dimethylhydrazine, sodium borohydride, or N, N - diethylhydroxylamine, etc.

[0101] Thus, in one aspect of the present invention, by using an acid as a reducing agent, a basic active material and a binder that gels in a mixture of strong basicity are combined to produce an electrode having a uniform thickness or a high - strength electrode. Also, by using a base as a reducing agent it is also possible to produce an electrode using an active material unstable to an acid or a binder. By applying one aspect of the present invention the range of selection of materials used for the active material and the binder and their combinations is broad which is preferable.

[0102] Here, the second mixture may be heated at 20°C or higher and 80°C or lower for 5 minutes or longer and 10 hours or shorter under a reduced - pressure atmosphere to perform an operation of removing the solvent added together with the reducing agent.

[0103] Next, a binder is added to the second mixture and kneaded to form a third mixture (also referred to as a paste) (step S103). As the binder, the materials described in Embodiment 1 can be used .

[0104] Next, the third mixture is applied to a current collector and the solvent is evaporated to form an active material layer . More specifically, the third mixture and the current collector are heated at 20°C or higher and 1 70°C or lower for 1 minute or longer and 10 hours or shorter to evaporate the solvent contained in the third mixture As a result, an active material layer can be formed. The atmosphere is not particularly limited.

[0105] Through the above steps, an electrode 200 having an active material layer 202 in which the active material 203 and graphene 204 are uniformly dispersed can be fabricated. After this step, a pressing process may be performed on the electrode 200.

[0106] As described in this embodiment, by adding a reducing agent to a first mixture containing an active material, graphene oxide, and a solvent and heating, graphene oxide can be reduced under mild conditions . In addition, the efficiency of the reaction for reducing graphene oxide can be enhanced. Further, a third mixture is fabricated using a second mixture containing graphene, applied to a current collector, and the solvent is evaporated to fabricate an electrode containing graphene as a conductive aid under mild conditions . In addition, an electrode having a uniform thickness can be fabricated. Further, an electrode having high strength and being difficult to be broken by an external impact can be fabricated. Therefore, by fabricating a storage battery using the method for manufacturing an electrode described in this embodiment , the cycle characteristics and rate characteristics of the storage battery can be improved. In addition, the manufacturing method of the storage battery can be simplified . Further, a storage battery having high strength and being difficult to be broken by an external impact, for example, can be fabricated .

[0107] This embodiment can be implemented in appropriate combination with other embodiments.

[0108] (Embodiment 3) In this embodiment, the structure of a storage battery using an electrode for a storage battery fabricated by the manufacturing method shown in Embodiment 2 will be described with reference to FIGS. 4 to 7.

[0109] (Coin-shaped battery) Figure 4(A) is an external view of a coin-shaped (single-layer flat type) battery, and Figure 4(B) is a cross-sectional view thereof. It is a sectional view.

[0110] The coin-shaped battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 3 02 that also serves as a negative electrode terminal, which are insulated and sealed with a gasket 303 made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact therewith. Also, the negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact therewith. Between the positive electrode active material layer 306 and the negative electrode active material layer 309, there are a separator 310 and an electrolytic solution (not shown).

[0111] At least one of the positive electrode 304 or the negative electrode 307 can be manufactured using the method for manufacturing an electrode for a battery according to one aspect of the present invention shown in Embodiment 2.

[0112] The configuration of the positive electrode active material layer 306 or the negative electrode active material layer 309 in the case where the manufacturing method of the electrode for a battery shown in Embodiment 2 is not used for either the positive electrode 304 or the negative electrode 307 is shown.

[0113] The positive electrode active material layer 306 may have, in addition to the positive electrode active material, a binder (binder) for enhancing the adhesion of the positive electrode active material, a conductive aid for enhancing the conductivity of the positive electrode active material layer 306, and the like.

[0114] As the positive electrode active material, the binder, and the conductive aid, the materials described in Embodiment 1 can be used.

[0115] The negative electrode active material layer 309 has, in addition to the negative electrode active material, a binder (binder) for enhancing the adhesion of the negative electrode active material, The negative electrode active material layer 309 may also have a conductive assistant or the like for enhancing the conductivity of the negative electrode active material layer 309.

[0116] As the negative electrode active material, the binder, and the conductive assistant, the materials described in Embodiment 1 can be used. This is possible.

[0117] In addition, a film such as an oxide may be formed on the surface of the negative electrode active material layer 309. During charging, a film formed by decomposition of the electrolytic solution or the like cannot release the amount of charge consumed during its formation, and forms an irreversible capacity. On the other hand, by providing a film such as an oxide on the surface of the negative electrode active material layer 309 in advance, the generation of the irreversible capacity can be suppressed or prevented. For the negative electrode active material layer 309, .

[0118] As the film covering such a negative electrode active material layer 309, an oxide film of any one of niobium, titanium, vanadium, tantalum, tungsten, zirconium, molybdenum, hafnium, chromium, aluminum or silicon, or an oxide film containing any one of these elements and lithium can be used. Such a film is a sufficiently dense film compared to a film formed on the surface of the negative electrode by decomposition products of a conventional electrolytic solution. For example, niobium pentoxide (Nb2O5) has a low electrical conductivity of 10 S / cm and exhibits high insulation. Therefore, the niobium oxide film inhibits the electrochemical decomposition reaction of the electrolytic solution or the like that occurs when the negative electrode active material and the electrolytic solution come into contact during charging. On the other hand, the lithium diffusion coefficient of niobium oxide is 10 cm

[0119] / sec, and it has high lithium ion conductivity. -9 S / cm and is low, showing high insulation. For this reason, the niobium oxide film inhibits the electrochemical decomposition reaction of the electrolytic solution or the like that occurs when the negative electrode active material and the electrolytic solution come into contact during charging. On the other hand, the lithium diffusion coefficient of niobium oxide is 10 cm -9 / sec, and it has high lithium ion conductivity. 2 Therefore, it is possible to permeate lithium ions. In addition, silicon oxide and aluminum oxide can also be used. Minyum may also be used.

[0120] For forming a film that coats the negative electrode active material layer 309, for example, the sol-gel method can be used. The sol-gel method is a method in which a solution composed of a metal alkoxide, a metal salt, etc. is made into a gel that has lost its fluidity through a hydrolysis reaction and a polycondensation reaction, and this gel is fired to form a thin film. Since the sol-gel method is a method for forming a thin film from a liquid phase, the raw materials can be homogeneously mixed at the molecular level. Therefore, by adding a negative electrode active material such as graphite to the raw material of the metal oxide film at the solution stage, the active material can be easily dispersed in the gel. In this way, a film can be formed on the surface of the negative electrode active material layer 309. By using this film, a decrease in the capacity of the storage body can be prevented.

[0121] As the separator 310, an insulator having pores, such as cellulose (paper), polypropylene, or polyethylene, can be used.

[0122] As the electrolyte, in addition to an electrolyte containing a supporting electrolyte, a solid electrolyte or a gel electrolyte in which a part of the electrolyte is gelled can be used.

[0123] As the supporting electrolyte, a material having carrier ions can be used. Representative examples of the supporting electrolyte include lithium salts such as LiPF6, LiClO4, LiAsF6, LiBF4, LiCF3SO3, Li(CF3SO2)2N, and Li(C2F5SO2)2N. These electrolytes may be used alone, or two or more of them may be used in any combination and ratio.

[0124] ​​​​​​​In addition, when the carrier ions are alkali metal ions or alkaline earth metal ions other than lithium ions, in the above lithium salts, an alkali metal (such as sodium or potassium) or an alkaline earth metal (such as calcium, strontium, barium, beryllium, magnesium, etc.) may be used instead of lithium as the electrolyte.

[0125]

[0125] Examples include aromatic cations such as imidazolium cations and pyridinium cations. Examples of the anions constituting the ionic liquid include monovalent amide-based anions, monovalent methide-based anions, fluorosulfonic acid anions, perfluoroalkylsulfonic acid anions, tetrafluoroborate, perfluoroalkylborate, hexafluorophosphate, or perfluoroalkylphosphate.

[0126] Alternatively, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as a sulfide-based or oxide-based material, or a solid electrolyte having a polymer material such as a PEO (polyethylene oxide)-based material can be used. When using a solid electrolyte, it is not necessary to install a separator or a spacer. Also, since the entire battery can be solidified, there is no risk of leakage and the safety is dramatically improved.

[0127] For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, and titanium, alloys of these metals, alloys of these metals with other metals (e.g., stainless steel, etc.), laminates of these metals, laminates of these metals with the aforementioned alloys (e.g., stainless steel / aluminum, etc.), and laminates of these metals with other metals (e.g., nickel / iron / nickel, etc.) that have corrosion resistance against liquids such as the electrolytic solution during charge and discharge of the secondary battery can be used. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 307. The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated with the electrolyte, and as shown in Fig. 4(B), with the positive electrode can 301 facing downwards, the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode can 302 are laminated in this order, and the positive electrode can 301 and the negative electrode can 302 are connected via the gasket 303.

[0128] ​​​​​​​​​​​ Press to manufacture the coin-shaped battery 300.

[0129] (Laminated battery) Figure 5 shows an external view of the laminated battery 500. Also, FIGS. 6(A) and 6(B) show the cross sections A1 - A2 and B1 - B2 indicated by the dashed line in FIG. 5. The laminated battery 500 has a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, a negative electrode current collector 504 and a negative electrode 506 having a negative electrode active material layer 505, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is installed between the positive electrode 503 and the negative electrode 506. Also, the electrolyte 508 is injected into the region surrounded by the exterior body 509.

[0130] In the laminated battery 500 shown in FIG. 5, the positive electrode current collector 501 and the negative electrode current collector 50 4 also serve as terminals for obtaining electrical contact with the outside. Therefore, a part of the positive electrode current collector 501 and the negative electrode current collector 504 are arranged to be exposed outside from the exterior body 509.

[0131] In the laminated battery 500, the exterior body 509 is provided with a flexible metal thin film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide on a film, and further, an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided as the outer surface of the exterior body on the metal thin film. A three-layer laminated film can be used. By adopting such a three-layer structure, permeation of the electrolyte and gas is blocked, insulation is ensured, and at the same time, it has electrolyte resistance.

[0132] ​​​ Cylindrical battery Next, an example of a cylindrical battery will be described with reference to FIG. 7. The cylindrical battery 600 has a positive electrode cap (battery lid) 601 on the upper surface and a battery can (outer can) 602 on the side surface and the bottom surface as shown in FIG. 7(A). The positive electrode cap and the battery can (outer can) 60 2 are insulated by a gasket (insulating packing) 610.

[0133] FIG. 7(B) is a diagram schematically showing a cross section of the cylindrical battery. Inside the hollow cylindrical battery can 6 02, a battery element is provided in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 interposed therebetween. Although not shown, the battery element is wound around a center pin . One end of the battery can 602 is closed and the other end is open. The battery can 602 is made of nickel, aluminum, titanium, etc., which have corrosion resistance against liquids such as electrolytes during charging and discharging of the secondary battery, alloys of these metals, alloys of these metals and other metals (e.g., stainless steel, etc.), laminates of these metals, laminates of these metals and the above-mentioned alloys (e.g., stainless steel / aluminum, etc.), laminates of these metals and other metals (e.g., nickel / iron / nickel, etc.). Inside the battery can 602, the battery element in which the positive electrode, the negative electrode and the separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Also, the inside of the battery can 602 where the battery element is provided is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte can be the same as that used in coin-type and laminate-type batteries.

[0134] 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 battery described above. ​​​​​​​​​​Although it suffices to do so, since the positive and negative electrodes used in the cylindrical storage battery are wound, they differ in that active materials are formed on both sides of the current collector. A positive electrode terminal (positive current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum. The positive electrode terminal 603 is resistance welded to the safety valve mechanism 612, and the negative electrode terminal 607 is resistance welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery rises above a predetermined threshold value. Also, the PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and it restricts the current amount to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO3)-based semiconductor ceramics or the like can be used. A positive electrode terminal (positive current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum. The positive electrode terminal 603 is resistance welded to the safety valve mechanism 612, and the negative electrode terminal 607 is resistance welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery rises above a predetermined threshold value. Also, the PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and it restricts the current amount to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO3)-based semiconductor ceramics or the like can be used.

[0135] In this embodiment, as the storage battery, coin-type, laminate-type, and cylindrical storage batteries are shown, but storage batteries of various shapes such as other sealed storage batteries and rectangular storage batteries can be used. Also, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which a positive electrode, a negative electrode, and a separator are wound may be used. In this embodiment, as the storage battery, coin-type, laminate-type, and cylindrical storage batteries are shown, but storage batteries of various shapes such as other sealed storage batteries and rectangular storage batteries can be used. Also, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which a positive electrode, a negative electrode, and a separator are wound may be used.

[0136] For the positive electrode or negative electrode of the coin-type storage battery 300, storage battery 500, and storage battery 600 shown in this embodiment, an electrode manufactured by the method for manufacturing an electrode for a storage battery according to one aspect of the present invention is used. Therefore, the discharge capacities of the coin-shaped battery 300, the battery 500, and the battery 600 can be increased.

[0137] In addition, in this embodiment, one aspect of the present invention has been described. However, one aspect of the present invention is not limited to these. That is, in this embodiment, various aspects of the invention are described Therefore, one aspect of the present invention is not limited to a specific aspect. For example, as one aspect of the present invention an example of applying to a lithium-ion secondary battery has been shown, but one aspect of the present invention is not limited to this In some cases, or depending on the situation, one aspect of the present invention may be various secondary batteries, for example, lead-acid batteries, lithium-ion polymer secondary batteries, nickel-metal hydride batteries, nickel cadmium batteries, nickel-iron batteries, nickel-zinc batteries, or silver oxide-zinc batteries, primary batteries, capacitors, or lithium-ion capacitors, etc. It may be applied to. It may also be applied to solid-state batteries or air batteries, etc. Or for example, depending on the case, or depending on the situation, one aspect of the present invention may not be applied to a lithium-ion secondary battery .. This embodiment can be implemented in appropriate combination with other embodiments. ..

[0138] This embodiment can be implemented in appropriate combination with other embodiments.

[0139] (Embodiment 4) A battery using an electrode for a battery according to one aspect of the present invention can be used as a power source for various electrical devices driven by electricity ..

[0140] As a specific example of an electrical device using a battery using an electrode for a battery according to one aspect of the present invention, a television, a display device such as a monitor, a lighting device, a desktop or notebook personal computer .. Computers, word processors, DVDs (Digital Versatile Disks), etc., image playback devices that play still or moving images stored on recording media such as c), portable CD players, radios, tape recorders, headphone stereos, stereos, table clocks, wall-mounted clocks, cordless phone handsets, transceivers, mobile phones, car phones, portable game machines, calculators, personal digital assistants, electronic notebooks, e-book terminals, electronic translators, voice input devices, video cameras, digital still cameras, toys, high-frequency heating devices such as electric shavers and microwave ovens, electric rice cookers, washing machines, vacuum cleaners, water heaters, fans, hair dryers, air conditioners, air conditioning equipment such as humidifiers and dehumidifiers, dishwashers, dish dryers, clothes dryers, futon dryers, electric refrigerators, freezers, refrigerator-freezers, freezers for DNA storage, flashlights, chain saws and other power tools, smoke detectors, medical devices such as dialysis devices, etc. Further, induction lamps, signal machines, belt conveyors, elevators, escalators, industrial robots, power storage systems and industrial equipment such as energy storage devices for load leveling and smart grids. Also, moving bodies propelled by electric motors using power from storage batteries are also considered to be within the scope of electrical equipment. Examples of such moving bodies include electric vehicles (EVs), hybrid vehicles (HEVs) that combine internal combustion engines and electric motors, plug-in hybrid vehicles (PHEVs), tracked vehicles that convert the tires of these types of vehicles into endless tracks, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, golf carts, small or large ships, submarines, helicopters, aircraft, rockets, artificial satellites, space exploration vehicles and planetary exploration vehicles, spaceships, etc.

[0141] Incidentally, as a main power source for supplying almost all of the power consumption, a storage battery using the electrode for a storage battery according to one aspect of the present invention can be used for the above electrical equipment. Alternatively, when the supply of power from the above main power source or commercial power source stops, the electrical equipment can use a storage battery using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply for supplying power to the electrical equipment. Alternatively, the above electrical equipment can use a storage battery using the electrode for a storage battery according to one aspect of the present invention as an auxiliary power source for supplying power to the electrical equipment in parallel with the supply of power from the above main power source or commercial power source to the electrical equipment. FIG. 8 shows a specific configuration of the above electrical equipment. In FIG. 8, the display device 700 is an example of an electrical equipment using a storage battery 704 using the electrode for a storage battery according to one aspect 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, a storage battery 704, and the like. The storage battery 704 using the electrode for a storage battery according to one aspect of the present invention is provided inside the housing 701. The display device 700 can receive power supply from a commercial power source, or can use the power stored in the storage battery 704. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 704 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the display device 700 can be used. The display unit 702 is provided with a light-emitting device having a light-emitting element such as a liquid crystal display device or an organic EL element in each pixel, an electrophoretic display device, a DMD (Digital Micromirror Devic

[0142]

[0143] ​​​​​​​​​​​​​​​e), PDP (Plasma Display Panel), FED (Field Emission Display), etc., a semiconductor display device can be used. In addition to being used for TV broadcast reception, the display device can also be used for personal computers, advertising displays, etc.

[0144] Note that the display device includes all display devices for information display, such as for personal computers and advertising displays, in addition to those for TV broadcast reception. In FIG. 8, the installed lighting device 710 is an example of an electrical device using a storage battery 713 using the electrode for a storage battery according to one aspect of the present invention. Specifically, the lighting device 710 includes a housing 711, a light source 712, a storage battery 713, etc. In FIG. 8, the case where the storage battery 713 is provided inside the ceiling 714 where the housing 711 and the light source 712 are installed is illustrated, but the storage battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used.

[0145] In FIG. 8, the installed lighting device 710 is an example of an electrical device using a storage battery 713 using the electrode for a storage battery according to one aspect of the present invention. Specifically, the lighting device 710 includes a housing 711, a light source 712, a storage battery 713, etc. In FIG. 8, the case where the storage battery 713 is provided inside the ceiling 714 where the housing 711 and the light source 712 are installed is illustrated, but the storage battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. 11, a light source 712, a storage battery 713, etc. In FIG. 8, the case where the storage battery 713 is provided inside the ceiling 714 where the housing 711 and the light source 712 are installed is illustrated, but the storage battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. 11, a light source 712, a storage battery 713, etc. In FIG. 8, the case where the storage battery 713 is provided inside the ceiling 714 where the housing 711 and the light source 712 are installed is illustrated, but the storage battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. and the light source 712 are installed is illustrated, but the storage battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. The lighting device 710 can receive power supply from a commercial power source, or can use the power stored in the storage battery 713. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. Therefore, even when power supply from a commercial power source cannot be received due to a power outage or the like, by using the storage battery 713 using the electrode for a storage battery according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used. the lighting device 710 can be used.

[0146] In FIG. 8, the installed lighting device 710 provided on the ceiling 714 is illustrated, but the storage battery using the electrode for a storage battery according to one aspect of the present invention can be used not only for the ceiling 714 but also for installed lighting devices provided on, for example, side walls 715, floors 716, windows 717, etc., and can also be used for desktop lighting devices, etc. the storage battery using the electrode for a storage battery according to one aspect of the present invention can be used not only for the ceiling 714 but also for installed lighting devices provided on, for example, side walls 715, floors 716, windows 717, etc., and can also be used for desktop lighting devices, etc. 5, floors 716, windows 717, etc., and can also be used for desktop lighting devices, etc. and can also be used for desktop lighting devices, etc.

[0147] Also, as the light source 712, an artificial light source that artificially obtains light using power can be used. . Specifically, incandescent lamps, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements are examples of the above artificial light sources. The element is cited as an example of the above artificial light source.

[0148] In FIG. 8, an air conditioner having an indoor unit 720 and an outdoor unit 724 is an example of an electric device using a storage battery 723 using an electrode for a storage battery according to an aspect of the present invention. Specifically, the indoor unit 720 has a housing 721, an air outlet 722, a storage battery 723, etc. In FIG. 8, the case where the storage battery 723 is provided in the indoor unit 720 is illustrated, but the storage battery 723 may be provided in the outdoor unit 724. Alternatively, the storage battery 723 may be provided in both the indoor unit 720 and the outdoor unit 724. The air conditioner can receive power supply from a commercial power source, and can also use the power stored in the storage battery 723. In particular, when the storage battery 723 is provided in both the indoor unit 720 and the outdoor unit 724, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the storage battery 723 using an electrode for a storage battery according to an aspect of the present invention as an uninterruptible power supply, it becomes possible to use the air conditioner.

[0149] Note that in FIG. 8, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated, but it is also possible to use a storage battery using an electrode for a storage battery according to an aspect of the present invention in an integrated type air conditioner having the functions of the indoor unit and the outdoor unit in one housing.

[0150] In FIG. 8, an electric refrigerator-freezer 730 is an example of an electric device using a storage battery 734 using an electrode for a storage battery according to an aspect of the present invention. Specifically, the electric refrigerator-freezer 730 has a housing 7 ​​​​31, a refrigerator door 732, a freezer door 733, a storage battery 734, etc. A 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 the battery 734 or use the power stored in the battery 734. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention can be used in one embodiment. By using a storage battery 734 using the storage battery electrodes according to the present invention as an uninterruptible power source, Warehouse 730 will be available for use.

[0151] Among the above-mentioned electrical appliances, high-frequency heating devices such as microwave ovens, electric rice cookers, etc. The equipment requires high power for a short period of time. Therefore, the equipment supplements the power that cannot be supplied by commercial power sources. A storage battery using the storage battery electrode according to one embodiment of the present invention is used as an auxiliary power source for This can prevent the commercial power breaker from tripping when electrical equipment is in use.

[0152] In addition, during periods when electrical equipment is not being used, especially during periods when the total amount of power that can be supplied by the commercial power supplier is low, During times when the proportion of electricity actually used (called the electricity usage rate) is low, By storing electricity in the pond, it is possible to prevent the power usage rate from increasing outside the above-mentioned 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.

[0153] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0154] (Embodiment 5) Next, a portable information terminal, which is an example of an electric device, will be described with reference to FIG. 9.

[0155] FIGS. 9(A) and 9(B) show a foldable tablet terminal 800. FIG. 9(A) shows the open state, and the tablet terminal 800 includes a housing 801, a display unit 802a, a display unit 802b, a display mode switch 803, a power switch 804, a power saving mode switch 805, and an operation switch 807.

[0156] A part of the display unit 802a can be a touch panel area 808a, and data can be input by touching the displayed operation key 809. Note that, as an example, in the display unit 802a, a configuration in which half of the area has only a display function and the other half has a touch panel function is shown, but the present invention is not limited to this configuration. It is also possible that the entire area of the display unit 802a has a touch panel function. For example, the entire surface of the display unit 802a can be used to display keyboard buttons to serve as a touch panel, and the display unit 802b can be used as a display screen.

[0157] Similarly, in the display unit 802b, a part of the display unit 802b can be a touch panel area 808b. Also, by touching the position where the keyboard display changeover button 810 of the touch panel is displayed with a finger or a stylus, etc., keyboard buttons can be displayed on the display unit 802b.

[0158] Also, simultaneous touch input can be performed on the touch panel area 808a and the touch panel area 808b. ​​​​​​​​​​

[0159] In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor. In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor. In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor. In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor. In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor. In addition, the display mode switch 803 can select to switch the display orientation such as vertical display or horizontal display, and can also switch between black and white display and color display. The power saving mode switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet terminal during use. The tablet terminal may incorporate other detection devices such as sensors for detecting inclination, such as a gyroscope and an acceleration sensor, in addition to the optical sensor.

[0160] In addition, FIG. 9(A) shows an example where the display areas of the display units 802b and 802a are the same, but it is not particularly limited, and the sizes of one side and the other side may be different, and the display quality may also be different. For example, one may be a display panel capable of performing higher-definition display than the other. In addition, FIG. 9(A) shows an example where the display areas of the display units 802b and 802a are the same, but it is not particularly limited, and the sizes of one side and the other side may be different, and the display quality may also be different. For example, one may be a display panel capable of performing higher-definition display than the other. In addition, FIG. 9(A) shows an example where the display areas of the display units 802b and 802a are the same, but it is not particularly limited, and the sizes of one side and the other side may be different, and the display quality may also be different. For example, one may be a display panel capable of performing higher-definition display than the other. In addition, FIG. 9(A) shows an example where the display areas of the display units 802b and 802a are the same, but it is not particularly limited, and the sizes of one side and the other side may be different, and the display quality may also be different. For example, one may be a display panel capable of performing higher-definition display than the other.

[0161] FIG. 9(B) shows a closed state. The tablet terminal 800 includes a housing 801, a solar cell 811, a charge / discharge control circuit 850, a battery 851, and a DCDC converter 852. FIG. 9(B) shows a closed state. The tablet terminal 800 includes a housing 801, a solar cell 811, a charge / discharge control circuit 850, a battery 851, and a DCDC converter 852. Note that FIG. 9(B) shows a configuration having a battery 851 and a DCDC converter 852 as an example of the charge / discharge control circuit 850. The battery 851 has a storage battery using the electrode for a storage battery according to one aspect of the present invention described in the above embodiment. Note that FIG. 9(B) shows a configuration having a battery 851 and a DCDC converter 852 as an example of the charge / discharge control circuit 850. The battery 851 has a storage battery using the electrode for a storage battery according to one aspect of the present invention described in the above embodiment. Note that FIG. 9(B) shows a configuration having a battery 851 and a DCDC converter 852 as an example of the charge / discharge control circuit 850. The battery 851 has a storage battery using the electrode for a storage battery according to one aspect of the present invention described in the above embodiment.

[0162] Since the tablet terminal 800 is foldable in two, the housing 801 can be closed when not in use. Therefore, the display units 802a and 802b can be protected, and a tablet terminal 800 with excellent durability and reliability from the viewpoint of long-term use can be provided. Since the tablet terminal 800 is foldable in two, the housing 801 can be closed when not in use. Therefore, the display units 802a and 802b can be protected, and a tablet terminal 800 with excellent durability and reliability from the viewpoint of long-term use can be provided. Since the tablet terminal 800 is foldable in two, the housing 801 can be closed when not in use. Therefore, the display units 802a and 802b can be protected, and a tablet terminal 800 with excellent durability and reliability from the viewpoint of long-term use can be provided. Since the tablet terminal 800 is foldable in two, the housing 801 can be closed when not in use. Therefore, the display units 802a and 802b can be protected, and a tablet terminal 800 with excellent durability and reliability from the viewpoint of long-term use can be provided.

[0163] In addition, the tablet terminals shown in Figs. 9(A) and 9(B) can store various information ( Functions for displaying still images, videos, text images, etc., and for displaying calendars, dates, or times, etc. A function to display information on the display unit, and a touch input device to operate or edit the information displayed on the display unit by touch input. It has the ability to control processing by various software (programs), etc. can.

[0164] 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 processor, or the like. The battery 851 can be efficiently charged by providing a charger on one or both sides of the battery 801. It can be said that it is completed.

[0165] The configuration and operation of the charge / discharge control circuit 850 shown in FIG. 9B are shown in FIG. FIG. 9C shows a solar cell 811, a battery 851, and a , a DC-DC converter 852, a converter 853, switches SW1 to SW3, a display unit 8 02, battery 851, DCDC converter 852, converter 8 53, switches SW1 to SW3 correspond to the charge / discharge control circuit 850 shown in FIG. This is the location.

[0166] First, an example of operation in which 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 converter 852 steps up or steps down the voltage. When the power from 811 is used, switch SW1 is turned on, and the converter 853 will step up or step down the voltage to the required voltage for the display unit 802. Also, when the display unit 802 is not performing a display, SW1 can be turned off and SW2 can be turned on to charge the battery 851. This is how it should be configured. When the display unit 802 is not performing a display, SW1 can be turned off and SW2 can be turned on to charge the battery 851. This is how it should be configured.

[0167] Note that the solar cell 811 is shown as an example of a power generation means, but it is not particularly limited. Other power generation means such as piezoelectric elements (piezoelectric devices) and thermoelectric conversion elements (Peltier elements) can also be used to charge the battery 851. For example, a contactless power transmission module that wirelessly (non - contact) transmits and receives power for charging, or a configuration that combines other charging means, can also be used. Note that the solar cell 811 is shown as an example of a power generation means, but it is not particularly limited. Other power generation means such as piezoelectric elements (piezoelectric devices) and thermoelectric conversion elements (Peltier elements) can also be used to charge the battery 851. For example, a contactless power transmission module that wirelessly (non - contact) transmits and receives power for charging, or a configuration that combines other charging means, can also be used. Note that the solar cell 811 is shown as an example of a power generation means, but it is not particularly limited. Other power generation means such as piezoelectric elements (piezoelectric devices) and thermoelectric conversion elements (Peltier elements) can also be used to charge the battery 851. For example, a contactless power transmission module that wirelessly (non - contact) transmits and receives power for charging, or a configuration that combines other charging means, can also be used. Note that the solar cell 811 is shown as an example of a power generation means, but it is not particularly limited. Other power generation means such as piezoelectric elements (piezoelectric devices) and thermoelectric conversion elements (Peltier elements) can also be used to charge the battery 851. For example, a contactless power transmission module that wirelessly (non - contact) transmits and receives power for charging, or a configuration that combines other charging means, can also be used. Note that the solar cell 811 is shown as an example of a power generation means, but it is not particularly limited. Other power generation means such as piezoelectric elements (piezoelectric devices) and thermoelectric conversion elements (Peltier elements) can also be used to charge the battery 851. For example, a contactless power transmission module that wirelessly (non - contact) transmits and receives power for charging, or a configuration that combines other charging means, can also be used.

[0168] Also, it goes without saying that if a storage battery using the electrode for a storage battery according to one aspect of the present invention described in the above - mentioned embodiment is provided, it is not particularly limited to the electrical device shown in FIG. 9. Also, it goes without saying that if a storage battery using the electrode for a storage battery according to one aspect of the present invention described in the above - mentioned embodiment is provided, it is not particularly limited to the electrical device shown in FIG. 9.

[0169] (Embodiment 6) Furthermore, an example of a moving body, which is an example of an electrical device, will be described with reference to FIG. 10.

[0170] The storage battery described in the previous embodiment can be used as a battery for control. The control battery can be charged by external power supply by plug - in technology or non - contact power supply. When the moving body is an electric railway vehicle, it can be charged by power supply from an overhead wire or a conductive rail (conductive rail). The storage battery described in the previous embodiment can be used as a battery for control. The control battery can be charged by external power supply by plug - in technology or non - contact power supply. When the moving body is an electric railway vehicle, it can be charged by power supply from an overhead wire or a conductive rail (conductive rail). The storage battery described in the previous embodiment can be used as a battery for control. The control battery can be charged by external power supply by plug - in technology or non - contact power supply. When the moving body is an electric railway vehicle, it can be charged by power supply from an overhead wire or a conductive rail (conductive rail). The storage battery described in the previous embodiment can be used as a battery for control. The control battery can be charged by external power supply by plug - in technology or non - contact power supply. When the moving body is an electric railway vehicle, it can be charged by power supply from an overhead wire or a conductive rail (conductive rail).

[0171] FIGS. 10(A) and (B) show an example of an electric vehicle. The electric vehicle 860 has a battery It is equipped with a battery 861. The power of the battery 861 is adjusted by a control circuit 862 and supplied to a drive device 863. The control circuit 862 is controlled by a processing device 864 having a ROM, RAM, CPU, etc. (not shown). The drive device 863 is configured by combining a DC motor or an AC motor alone, or a motor and an internal combustion engine.

[0172] The processing device 864 outputs a control signal to the control circuit 862 based on input information such as the operation information (acceleration, deceleration, stop, etc.) of the driver of the electric vehicle 860 and information during traveling (information such as uphill and downhill, load information applied to the drive wheels, etc.). The control circuit 862 adjusts the electrical energy supplied from the battery 861 according to the control signal of the processing device 864 and controls the output of the drive device 863. When an AC motor is installed, although not shown, an inverter for converting DC to AC is also built in. The battery 861 can be charged by external power supply using plug-in technology. For example, the battery 861 is charged from a commercial power supply through a power plug. The charging can be performed by converting it to a DC constant voltage having a certain voltage value through a conversion device such as an AC / DC converter.

[0173] By mounting a storage battery using the electrode for a storage battery according to one aspect of the present invention as the battery 861, it is possible to contribute to increasing the capacity of the battery and improving convenience. In addition, if the characteristics of the battery 861 are improved and the battery 861 itself can be made smaller and lighter, it contributes to reducing the weight of the vehicle, so that the fuel efficiency can be improved. .

[0174] ​​​​​​​Note that the present invention is not limited to the above-described electric devices as long as the storage battery according to one embodiment of the present invention is included. Needless to say, that is not the case.

[0175] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0176] (Embodiment 7) A battery cell including the material described in the above embodiment (for example, the battery cell described in the third embodiment) A battery control unit (Battery Manager) that can be used in combination with the A battery control unit (BMU) and a circuit suitable for the circuit constituting the battery control unit The transistor will be described with reference to FIGS. A battery control unit for a power storage device having battery cells connected in a series will be described.

[0177] When multiple battery cells connected in series are repeatedly charged and discharged, the characteristics between the battery cells The capacity (output voltage) varies depending on the variation in the The total discharge capacity depends on the battery cells with smaller capacity. Also, if charging is performed based on a battery cell with a smaller capacity, the charging In addition, if charging is performed based on the battery cell with the larger capacity, it may result in overcharging. There is a risk that this may happen.

[0178] Therefore, the battery control unit of the power storage device having battery cells connected in series is It has the function of aligning the capacity variation between battery cells, which can cause overcharging. The circuit configuration for aligning the capacitance variation between the resistors, capacitors, or inductors can be used. There are other methods such as the transistor method, but here we use a transistor with a small off-current to reduce the variation in capacitance. An example of a circuit configuration that can be aligned will be described.

[0179] As a transistor with a small off-current, a transistor having an oxide semiconductor in a channel formation region (OS transistor) is preferable. By using an OS transistor with a small off-current in the circuit configuration of the battery control unit of the power storage device, the amount of charge leaking from the battery cell can be reduced, and a decrease in capacitance over time can be suppressed. and a decrease in capacitance over time can be suppressed. and a decrease in capacitance over time can be suppressed.

[0180] As the oxide semiconductor used in the channel formation region, In-M-Zn oxide (M is Ga, Sn, Y, Zr, La, Ce, or Nd) is used. In the target used for forming the oxide semiconductor film, when the atomic ratio of the metal elements is In:M:Zn = x1:y1:z1, 、 x1 / y1 is 1 / 3 or more and 6 or less, and further 1 or more and 6 or less, and z1 / y1 is 1 / 3 or more and 6 or less, and further 1 or more and 6 or less is preferable. Note that by setting z1 / y1 to 1 or more and 6 or less, a CAAC-OS film is likely to be formed as the oxide semiconductor film.

[0181] Here, the CAAC-OS film will be described.

[0182] The CAAC-OS film is one of the oxide semiconductor films having a plurality of crystal parts oriented in the c-axis direction.

[0183] By observing a composite analysis image (also referred to as a high-resolution TEM image) of a bright-field image and a diffraction pattern of the CAAC-OS film with a transmission electron microscope (TEM: Transmission Electron Micro scope), a plurality of crystal parts can be confirmed. On the other hand, from the high-resolution TEM image, a clear boundary between crystal parts, that is, a grain boundary (grain boundary) Also called undary. It cannot be confirmed. Therefore, it can be said that the CAAC-OS film is less likely to cause a decrease in electron mobility due to grain boundaries.

[0184] When observing the high-resolution TEM image of the cross-section of the CAAC-OS film from a direction substantially parallel to the sample surface, In the crystal part, it can be confirmed that metal atoms are arranged in layers. Each layer of metal atoms reflects the unevenness of the surface (also referred to as the surface to be formed) or the upper surface of the CAAC-OS film and is arranged parallel to the surface to be formed or the upper surface of the CAAC-OS film.

[0185] On the other hand, when observing the high-resolution TEM image of the plane of the CAAC-OS film from a direction substantially perpendicular to the sample surface, it can be confirmed that in the crystal part, metal atoms are arranged in a triangular or hexagonal shape. However, no regularity is found in the arrangement of metal atoms between different crystal parts.

[0186] When performing structural analysis on the CAAC-OS film using an X-ray diffraction (XRD) device, for example, in the out-of-plane method analysis of a CAAC-OS film having a crystal of InGaZnO4, a peak may appear near a diffraction angle (2θ) of 31°. This peak is attributed to the (009) plane of the crystal of InGaZnO4. Therefore, it can be confirmed that the crystal of the CAAC-OS film has c-axis orientation, and the c-axis is oriented in a direction substantially perpendicular to the surface to be formed or the upper surface.

[0187] In addition, in the out-of-plane method analysis of a CAAC-OS film having a crystal of InGaZnO4, in addition to the peak near 2θ of 31°, a peak also appears near 2θ of 36°. may occur. The peak near 2θ = 36° indicates that a part of the CAAC-OS film contains crystals without c-axis orientation. The CAAC-OS film preferably shows a peak near 2θ = 31° and does not show a peak near 2θ = 36°. and does not show a peak near 2θ = 36°.

[0188] The CAAC-OS film is an oxide semiconductor film with a low impurity concentration. Impurities are elements other than the main components of the oxide semiconductor film, such as hydrogen, carbon, silicon, and transition metal elements. In particular, elements with a stronger binding force with oxygen than the metal elements constituting the oxide semiconductor film, such as silicon, will disrupt the atomic arrangement of the oxide semiconductor film by taking oxygen from the oxide semiconductor film, leading to a decrease in crystallinity. Moreover, heavy metals such as iron and nickel, argon, carbon dioxide, etc., have a large atomic radius (or molecular radius), so when contained inside the oxide semiconductor film, they will disrupt the atomic arrangement of the oxide semiconductor film and become a factor in reducing crystallinity. Note that impurities contained in the oxide semiconductor film may sometimes serve as carrier traps or carrier generation sources.

[0189] In addition, the CAAC-OS film is an oxide semiconductor film with a low defect level density. For example, oxygen vacancies in the oxide semiconductor film may serve as carrier traps or become carrier generation sources by capturing hydrogen.

[0190] A low impurity concentration and a low defect level density (few oxygen vacancies) are referred to as high-purity intrinsic or substantially high-purity intrinsic. An oxide semiconductor film with high-purity intrinsic or substantially high-purity intrinsic has few carrier generation sources, so the carrier density can be lowered. Therefore, a transistor using the oxide semiconductor film has electrical characteristics with a negative threshold voltage ( ​​​It is also less likely to become (also known as normally-on). In addition, an oxide semiconductor film with high-purity intrinsic or substantially high-purity intrinsic has few carrier traps. Therefore, a transistor using such an oxide semiconductor film has small fluctuations in electrical characteristics and becomes a highly reliable transistor. Incidentally, the charge trapped in the carrier trap of the oxide semiconductor film takes a long time to be released and may behave like a fixed charge. Therefore, a transistor using an oxide semiconductor film with a high impurity concentration and a high defect level density may have unstable electrical characteristics. In addition, a transistor using a CAAC-OS film has small fluctuations in electrical characteristics due to irradiation with visible light or ultraviolet light. Incidentally, since an OS transistor has a larger bandgap than a transistor having silicon in the channel formation region (Si transistor), breakdown is less likely to occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated.

[0191] In the circuit configuration of the battery control unit applied to such a battery cell in a power storage device, it is suitable to be composed of the aforementioned OS transistors.

[0192] In addition, an OS transistor has a larger bandgap than a transistor having silicon in the channel formation region (Si transistor). Therefore, breakdown is less likely to occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated. In the circuit configuration of the battery control unit applied to such a battery cell in a power storage device, it is suitable to be composed of the aforementioned OS transistors.

[0193] FIG. 11 shows an example of a block diagram of a power storage device. The power storage device 1000 shown in FIG. 11 includes a terminal pair 1001, a terminal pair 1002, a switching control circuit 1003, a switching circuit 100 4, a switching circuit 1005, a voltage control circuit 1006, a voltage circuit 1007, and a battery unit 1008 including a plurality of battery cells 1009 connected in series.

[0194] Also, in the power storage device 1000 of FIG. 11, the part constituted by the terminal pair 1001, the terminal pair 1002, the switching control circuit 1003, the switching circuit 1004, the switching circuit 1005, the voltage control circuit 1006, and the voltage conversion circuit 1007 can be referred to as a battery control unit. The switching control circuit 1003 controls the operations of the switching circuit 1004 and the switching circuit 1005. Specifically, based on the voltage measured for each battery cell 1009, the switching control circuit 1003 determines the battery cells to be discharged (discharge battery cell group) and the battery cells to be charged (charge battery cell group). Furthermore, based on the determined discharge battery cell group and charge battery cell group, the switching control circuit 1003 outputs a control signal S1 and a control signal S2. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. can be.

[0195] Moreover, the switching control circuit 1003 generates the control signal S1 and the control signal S2 such that terminals of the same polarity are connected between the terminal pair 1001 and the discharge battery cell group or between the terminal pair 1002 and the charge battery cell group, taking into account the configurations of the switching circuit 1004, the switching circuit 1005, and the voltage conversion circuit 1007. Specifically, the switching control circuit 1003 controls the operations of the switching circuit 1004 and the switching circuit 1005. Specifically, based on the voltage measured for each battery cell 1009, the switching control circuit 1003 determines the battery cells to be discharged (discharge battery cell group) and the battery cells to be charged (charge battery cell group). Based on the voltage measured for each battery cell 1009, the switching control circuit 1003 determines the battery cells to be discharged (discharge battery cell group) and the battery cells to be charged (charge battery cell group). Furthermore, based on the determined discharge battery cell group and charge battery cell group, the switching control circuit 1003 outputs a control signal S1 and a control signal S2. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group.

[0196] Furthermore, based on the determined discharge battery cell group and charge battery cell group, the switching control circuit 1003 outputs a control signal S1 and a control signal S2. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. Furthermore, based on the determined discharge battery cell group and charge battery cell group, the switching control circuit 1003 outputs a control signal S1 and a control signal S2. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. The control signal S1 is output to the switching circuit 1004. This control signal S1 is a signal for controlling the switching circuit 1004 to connect the terminal pair 1001 and the discharge battery cell group. Also, the control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. The control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group. The control signal S2 is output to the switching circuit 1005. This control signal S2 is a signal for controlling the switching circuit 1005 to connect the terminal pair 1002 and the charge battery cell group.

[0197] Moreover, the switching control circuit 1003 generates the control signal S1 and the control signal S2 such that terminals of the same polarity are connected between the terminal pair 1001 and the discharge battery cell group or between the terminal pair 1002 and the charge battery cell group, taking into account the configurations of the switching circuit 1004, the switching circuit 1005, and the voltage conversion circuit 1007. Moreover, the switching control circuit 1003 generates the control signal S1 and the control signal S2 such that terminals of the same polarity are connected between the terminal pair 1001 and the discharge battery cell group or between the terminal pair 1002 and the charge battery cell group, taking into account the configurations of the switching circuit 1004, the switching circuit 1005, and the voltage conversion circuit 1007. Moreover, the switching control circuit 1003 generates the control signal S1 and the control signal S2 such that terminals of the same polarity are connected between the terminal pair 1001 and the discharge battery cell group or between the terminal pair 1002 and the charge battery cell group, taking into account the configurations of the switching circuit 1004, the switching circuit 1005, and the voltage conversion circuit 1007. Moreover, the switching control circuit 1003 generates the control signal S1 and the control signal S2 such that terminals of the same polarity are connected between the terminal pair 1001 and the discharge battery cell group or between the terminal pair 1002 and the charge battery cell group, taking into account the configurations of the switching circuit 1004, the switching circuit 1005, and the voltage conversion circuit 1007.

[0198] Details of the operation of the switching control circuit 1003 will be described.

[0199] First, the switching control circuit 1003 measures the voltage of each of the plurality of battery cells 1009. Then the switching control circuit 1003 determines, for example, a battery cell 1009 having a voltage equal to or higher than a predetermined threshold as a high-voltage battery cell (high-voltage cell), and a battery cell 1009 having a voltage lower than the predetermined threshold as a low-voltage battery cell (low-voltage cell).

[0200] Note that various methods can be used to determine the high-voltage cells and the low-voltage cells. For example, the switching control circuit 1003 may determine whether each battery cell 1009 is a high-voltage cell or a low-voltage cell based on the voltage of the battery cell 1009 having the highest or lowest voltage among the plurality of battery cells 1009. In this case, the switching control circuit 1003 determines whether the voltage of each battery cell 1009 is equal to or higher than a predetermined ratio with respect to the reference voltage, etc., so as to determine whether each battery cell 1009 is a high-voltage cell or a low-voltage cell. Then the switching control circuit 1003 determines a discharge battery cell group and a charge battery cell group based on this determination result. Note that among the plurality of battery cells 1009, high-voltage cells and low-voltage cells may be mixed in various states. For example, the switching control circuit 1003 may set, as the discharge battery cell group, a portion in which the high-voltage cells are most continuously connected in series while the high-voltage cells and the low-voltage cells are mixed. Also, the switching control circuit 1003 may set, as the charge battery cell group, a portion in which the low-voltage cells are most continuously connected in series. Further, the switching control circuit 1003 may preferentially select a battery cell 1009 close to overcharge or over-discharge as the discharge battery cell group or the charge battery cell group. Then the switching control circuit 1003 determines a discharge battery cell group and a charge

[0201] battery cell group based on this determination result. Note that among the plurality of battery cells 1009, high-voltage cells and low-voltage cells may be mixed in various states. For example, the switching control circuit 1003 may set, as the discharge battery cell group, a portion in which the high-voltage cells are most continuously connected in series while the high-voltage cells and the low-voltage cells are mixed. Also, the switching control circuit 1003 may set, as the charge battery cell group, a portion in which the low-voltage cells are most continuously connected in series. Further, the switching control circuit 1003 may preferentially select a battery cell 1009 close to overcharge or over-discharge as the discharge battery cell group or the charge battery cell group. control circuit 1003 may set, as the charge battery cell group, a portion in which the low-voltage cells are most continuously connected in series. Also, the switching control circuit 1003 may preferentially select a battery cell 1009 close to overcharge or over-discharge as the discharge battery cell group or the charge battery cell group. battery cell group. Also, the switching control circuit 1003 may preferentially select a battery cell 1009 close to overcharge or over-discharge as the discharge battery cell group or the charge battery cell group. This is also possible.

[0202] Here, an operation example of the switching control circuit 1003 in the present embodiment will be described with reference to FIG. 12. FIG. 12 is a diagram for explaining an operation example of the switching control circuit 1003. For the sake of convenience of explanation, in FIG. 12, a case where four battery cells 1009 are connected in series will be described as an example.

[0203] First, in the example of FIG. 12(A), assuming that the voltages of battery cells a to d are voltage Va to voltage Vd, it shows a case where Va = Vb = Vc > Vd. That is, three consecutive high-voltage cells a to c and one low-voltage cell d are connected in series. In this case, the switching control circuit 1003 determines the three consecutive high-voltage cells a to c as the discharge battery cell group. Also, the switching control circuit 1003 determines the low-voltage cell d as the charge battery cell group.

[0204] Next, in the example of FIG. 12(B), it shows a case where Vc > Va = Vb >> Vd. That is, two consecutive low-voltage cells a and b, one high-voltage cell c, and one low-voltage cell d near over-discharge are connected in series. In this case, the switching control circuit 1003 determines the high-voltage cell c as the discharge battery cell group. Also, the switching control circuit 1003 preferentially determines, not the two consecutive low-voltage cells a and b, but the low-voltage cell d near over-discharge as the charge battery cell group.

[0205] Finally, in the example of FIG. 12(C), it shows a case where Va > Vb = Vc = Vd. That is, one high-voltage cell a and three consecutive low-voltage cells b to d are connected in series. In this case, the switching control circuit 1003 determines the high-voltage cell a as the discharge battery cell group. Also, the switching control circuit 1003 determines three consecutive low-voltage cells b to d as the charge battery cell group.

[0206] Based on the determined results as in the examples of FIGS. 12(A) to (C) above, the switching control circuit 1003 sets the control signal S1 indicating the discharge battery cell group which is the connection destination of the switching circuit 1004, and the control signal S2 indicating the charge battery cell group which is the connection destination of the switching circuit 1005, and outputs them to the switching circuit 1004 and the switching circuit 1005 respectively.

[0207] The above is the explanation regarding the details of the operation of the switching control circuit 1003.

[0208] The switching circuit 1004 sets the connection destination of the terminal pair 1001 to the discharge battery cell group determined by the switching control circuit 1003 according to the control signal S1 output from the switching control circuit 1003.

[0209] The terminal pair 1001 is composed of paired terminals A1 and A2. The switching circuit 1004 connects one of these terminals A1 and A2 to the positive terminal of the battery cell 1009 located most upstream (high-potential side) in the discharge battery cell group, and the other to the negative terminal of the battery cell 1009 located most downstream (low-potential side) in the discharge battery cell group, thereby setting the connection destination of the terminal pair 1001. Note that the switching circuit 1004 can recognize the position of the discharge battery cell group using the information set in the control signal S1.

[0210] ​​​​​​​​​​​The switching circuit 1005 sets the connection destination of the terminal pair 1002 to the rechargeable battery cell group determined by the switching control circuit 1003 according to the control signal S2 output from the switching control circuit 1003. Among the battery cells, the one located closest to the upstream (higher potential side) in the rechargeable battery cell group is set.

[0211] The terminal pair 1002 is composed of a pair of terminals B1 and B2. The switching circuit 1005 connects one of the terminals B1 and B2 to the positive terminal of the battery cell 1009 located closest to the upstream (higher potential side) in the rechargeable battery cell group, and connects the other to the negative terminal of the battery cell 1009 located closest to the downstream (lower potential side) in the rechargeable battery cell group, thereby setting the connection destination of the terminal pair 1002. Note that the switching circuit 1005 can recognize the position of the rechargeable battery cell group using the information set in the control signal S2. Among the battery cells, the one located closest to the upstream (higher potential side) in the rechargeable battery cell group is set. Among the battery cells, the one located closest to the upstream (higher potential side) in the rechargeable battery cell group is set.

[0212] Circuit diagrams showing configuration examples of the switching circuit 1004 and the switching circuit 1005 are shown in FIGS. 13 and 14. In FIG. 13, the switching circuit 1004 has a plurality of transistors 1010, and buses 1011 and 1012. The bus 1011 is connected to the terminal A1. Also, the bus 1012 is connected to the terminal A2. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009.

[0213] In FIG. 13, the switching circuit 1004 has a plurality of transistors 1010, buses 1011 and 1012. The bus 1011 is connected to the terminal A1. Also, the bus 1012 is connected to the terminal A2. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009. The bus 1011 is connected to the terminal A1. Also, the bus 1012 is connected to the terminal A2. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009. The bus 1011 is connected to the terminal A1. Also, the bus 1012 is connected to the terminal A2. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009. One of the sources or drains of the plurality of transistors 1010 is connected to the buses 1011 and 1012 alternately at every other one. Also, the other of the sources or drains of the plurality of transistors 1010 is connected between every two adjacent battery cells 1009.

[0214] Among the plurality of transistors 1010, the other of the source or drain of the transistor 1010 located closest to the upstream is connected to the positive electrode of the battery cell 1009 located closest to the upstream in the battery unit 1008. Among the plurality of transistors 1010, the other of the source or drain of the transistor 1010 located closest to the upstream is connected to the positive electrode of the battery cell 1009 located closest to the upstream in the battery unit 1008. It is connected to a terminal. Among the plurality of transistors 1010, the transistor at the most downstream position has the other of its source or drain connected to the negative terminal of the battery cell 1009 located at the most downstream of the battery unit 1008.

[0215] The switching circuit 1004, according to the control signal S1 applied to the gates of the plurality of transistors 1010, conducts one of the plurality of transistors 1010 connected to the bus 1011 and one of the plurality of transistors 1010 connected to the bus 1 012 respectively, thereby connecting the discharge battery cell group and the terminal pair 1001. As a result, the positive terminal of the battery cell 1009 located most upstream in the discharge battery cell group is connected to either terminal A1 or A 2 of the terminal pair. Also, the negative terminal of the battery cell 1009 located most downstream in the discharge battery cell group is connected to the other of terminals A1 and A2 of the terminal pair, that is, the terminal not connected to the positive terminal. 2 of the terminal pair. It is preferably an OS transistor. Since the OS transistor has a small off-current, it can reduce the amount of charge leaking from battery cells not belonging to the discharge battery cell group and suppress the decrease in capacity over time. Also, the OS transistor is less likely to experience dielectric breakdown when a high voltage is applied. Therefore, even when the output voltage of the discharge battery cell group is large, the battery cell 1009 to which the non-conducting transistor 1010 is connected and the terminal pair 1001 can be insulated.

[0216] For the transistor 1010, it is preferable to use an OS transistor. Since the OS transistor has a small off-current, it can reduce the amount of charge leaking from battery cells not belonging to the discharge battery cell group and suppress the decrease in capacity over time. Also, the OS transistor is less likely to experience dielectric breakdown when a high voltage is applied. Therefore, even when the output voltage of the discharge battery cell group is large, the battery cell 1009 to which the non-conducting transistor 1010 is connected and the terminal pair 1001 can be insulated. 1001 can be insulated. 1001 can be insulated. 1001 can be insulated.

[0217] Also, in FIG. 13, the switching circuit 1005 includes a plurality of transistors 1013 and a current control It has switch 1014, bus 1015, and bus 1016. Buses 1015 and 10 16 are arranged between a plurality of transistors 1013 and current control switch 1014 . One of the source or drain of the plurality of transistors 1013 is alternately connected to buses 1015 and 1016 every other one . Also, the other of the source or drain of the plurality of transistors 1013 is connected between two adjacent battery cells 1009 .

[0218] Among the plurality of transistors 1013, the other of the source or drain of the transistor 1013 located most upstream is connected to the positive electrode terminal of the battery cell 1009 located most upstream in the battery unit 1008 . Also, among the plurality of transistors 1013, the other of the source or drain of the transistor 1013 located most downstream is connected to the negative electrode terminal of the battery cell 1009 located most downstream in the battery unit 1008 .

[0219] Similar to transistor 1010, it is preferable to use an OS transistor for transistor 1013 . Since the OS transistor has a small off-current, it can reduce the amount of charge leaking from battery cells not belonging to the rechargeable battery cell group and suppress the decrease in capacity over time . Also, the OS transistor is less likely to suffer dielectric breakdown when a high voltage is applied. Therefore, even if the voltage for charging the rechargeable battery cell group is large, the battery cell 1009 and terminal pair 1002 to which the non-conducting transistor 10 13 is connected can be insulated .

[0220] The current control switch 1014 has switch pair 1017 and switch pair 1018. The s ​One end of switch pair 1017 is connected to terminal B1. Also, the other end of switch pair 1017 branches out at two switches, one of which is connected to bus 1015 and the other switch is connected to bus 1016. One end of switch pair 1018 is connected to terminal B2. Also, the other end of switch pair 1018 branches out at two switches, one of which is connected to bus 1015 and the other switch is connected to bus 1016.

[0221] The switches of switch pair 1017 and switch pair 1018 preferably use OS transistors, similar to transistor 1010 and transistor 1013.

[0222] Switching circuit 1005 controls the combination of the on / off states of transistor 1013 and current control switch 1014 according to control signal S2, thereby connecting the rechargeable battery cell group to terminal pair 1002.

[0223] Switching circuit 1005 connects the rechargeable battery cell group to terminal pair 100 2 as follows as an example.

[0224] Switching circuit 1005 turns on the transistor 1013 connected to the positive terminal of the battery cell 1009 located most upstream in the rechargeable battery cell group according to the control signal S2 applied to the gates of the plurality of transistors 1013. Also, switching circuit 1005 turns on the transistor 1013 connected to the negative terminal of the battery cell 1009 located most downstream in the rechargeable battery cell group according to the control signal S2 applied to the gates of the plurality of transistors 1013.

[0225] ​​​​​​ The polarity of the voltage applied to terminal pair 1002 can vary depending on the discharge battery cell group connected to terminal pair 1001 , and the configuration of the transformer circuit 1007. Also, in order to allow current to flow in the charging direction of the rechargeable battery cell group, it is necessary to connect terminals of the same polarity between terminal pair 1002 and the rechargeable battery cell group . Therefore, the current control switch 1014 is controlled by the control signal S2 to switch the connection destinations of switch pair 1017 and switch pair 10 18 according to the polarity of the voltage applied to terminal pair 1002 11 respectively .

[0226] As an example, a state will be described in which a voltage is applied to terminal pair 1002 such that terminal B1 is the positive electrode and terminal B2 is the negative electrode . At this time, when the lowermost battery cell 1009 of the battery unit 1008 is the rechargeable battery cell group, switch pair 1017 is controlled by the control signal S2 to be connected to the positive electrode terminal of the battery cell 1009. That is, the switch connected to bus 1016 of switch pair 1017 is turned on, and the switch connected to bus 10 15 of switch pair 1017 is turned off. On the other hand, switch pair 1018 is controlled by the control signal S2 to be connected to the negative electrode terminal of the battery cell 1009. That is , the switch connected to bus 1015 of switch pair 1018 is turned on, and the switch connected to bus 10 16 of switch pair 1018 is turned off. In this way , terminals of the same polarity are connected between terminal pair 1002 and the rechargeable battery cell group. Thus , the direction of the current flowing from terminal pair 1002 is controlled to be the direction of charging the rechargeable battery cell group .

[0227] ​​Also, the current control switch 1014 may be included in the switching circuit 1004 instead of the switching circuit 10 05. In this case, the current control switch 1014 controls the polarity of the voltage applied to the terminal pair 1002 by controlling the polarity of the voltage applied to the terminal pair 1001 in response to the control signal S1. Then, the current control switch 1014 controls the direction of the current flowing from the terminal pair 100 2 to the rechargeable battery cell group.

[0228] FIG. 14 is a circuit diagram showing a configuration example of the switching circuit 1004 and the switching circuit 1005, which is different from FIG. 13.

[0229] In FIG. 14, the switching circuit 1004 has a plurality of transistor pairs 1021, a bus 1024 and a bus 1025. The bus 1024 is connected to the terminal A1. Also, the bus 1025 is connected to the terminal A2. One end of each of the plurality of transistor pairs 1021 branches into a transistor 1022 and a transistor 1023, respectively. One of the source or drain of the transistor 1022 is connected to the bus 1024. Also, one of the source or drain of the transistor 1023 is connected to the bus 1025. Also, the other ends of the plurality of transistor pairs are connected between two adjacent battery cells 1009, respectively. Note that, among the plurality of transistor pairs 1021, the other end of the transistor pair 1021 located at the most upstream is connected to the positive terminal of the battery cell 1009 located at the most upstream of the battery unit 1008. Also, among the plurality of transistor pairs 1021, the other end of the transistor pair 1021 located at the most downstream is connected to the negative terminal of the battery cell 1009 located at the most downstream of the battery unit 1008.

[0230] ​​​​​​​​ The switching circuit 1004 switches the conduction / non-conduction states of the transistor 1022 and the transistor 1023, and thereby switches the connection destination of the transistor pair 1021 to either the terminal A1 or the terminal A2. Specifically, if the transistor 1 022 is in the conduction state, the transistor 1023 is in the non-conduction state, and the connection destination of the transistor pair 1021 becomes the terminal A1. On the other hand, if the transistor 1023 is in the conduction state, the transistor 1022 is in the non-conduction state, and the connection destination of the transistor pair 1021 becomes the terminal A2 . Whether the transistor 1022 or the transistor 1023 is in the conduction state is determined by the control signal S1.

[0231] To connect the terminal pair 1001 and the discharge battery cell group, two transistor pairs 1021 are used . Specifically, based on the control signal S1, the connection destinations of the two transistor pairs 1021 are respectively determined, and thereby the discharge battery cell group and the terminal pair 1001 are connected. The connection destination of each of the two transistor pairs 1021 is controlled by the control signal S1 such that one becomes the terminal A1 and the other becomes the terminal A2.

[0232] The switching circuit 1005 includes a plurality of transistor pairs 1031, and a bus 1034 and a bus 10 35. The bus 1034 is connected to the terminal B1. Also, the bus 1035 is connected to the terminal B2. One end of each of the plurality of transistor pairs 1031 branches into a transistor 1032 and a transistor 1033 respectively. One of the source or drain of the transistor 1032 is connected to the bus 1034. Also, the transistor 103 One of the source or drain of 3 is connected to the bus 1035. Also, a plurality of The other ends of the transistor pairs 1031 are respectively connected between two adjacent battery cells 1009. Among the plurality of transistor pairs 1031, the other end of the transistor pair 1 031 located at the most downstream is connected to the negative terminal of the battery cell 1009 located at the most downstream of the battery unit 1008. Among the plurality of transistor pairs 1031, the other end of the transistor pair 1031 located at the most upstream is connected to the negative terminal of the battery cell 1009 located at the most upstream of the battery unit 1008. are.

[0233] The switching circuit 1005 switches the conduction / non-conduction states of the transistor 1032 and the transistor 1033, thereby switching the connection destination of the transistor pair 1031 to either the terminal B1 or the terminal B2. Specifically, if the transistor 1 032 is in the conduction state, the transistor 1033 is in the non-conduction state, and the connection destination of the transistor pair 1031 becomes the terminal B1. Conversely, if the transistor 1033 is in the conduction state, the transistor 1032 is in the non-conduction state, and the connection destination of the transistor pair 1031 is the terminal B2 . Which of the transistor 1032 and the transistor 1033 is in the conduction state is determined by the control signal S2. is determined by the control signal S2.

[0234] To connect the terminal pair 1002 and the rechargeable battery cell group, two transistor pairs 1031 are used . Specifically, based on the control signal S2, the connection destinations of the two transistor pairs 1031 are respectively determined, whereby the rechargeable battery cell group and the terminal pair 1002 are connected. Two The connection destinations of the two transistor pairs 1031 are such that one becomes the terminal B1 and the other becomes the terminal . B2 by the control signal S2.

[0235] The two transistor pairs 1031 are connected to terminal pairs 1002. Specifically, terminal B1 is the positive terminal and terminal B2 is the negative terminal. When such a voltage is applied to the terminal pair 1002, the upstream transistor pair 1031 Therefore, the transistor 1032 is turned on and the transistor 1033 is turned off. On the other hand, the downstream transistor pair 1031 is controlled by the control signal S2. The transistor 1033 is controlled to be in a conductive state and the transistor 1032 is controlled to be in a non-conductive state. It is controlled by the signal S2. Also, the voltage at terminal B1 becomes negative and the voltage at terminal B2 becomes positive. When a voltage is applied to terminal pair 1002, the upstream transistor pair 1031 The control circuit 1034 controls the transistor 1033 so that the transistor 1033 is in a conducting state and the transistor 1032 is in a non-conducting state. On the other hand, the downstream transistor pair 1031 is controlled by the transistor A control signal S2 is supplied to the transistor 1032 so that the transistor 1032 is in a conducting state and the transistor 1033 is in a non-conducting state. In this way, the same The terminals with polarity are connected to each other. The direction of the current flowing from the terminal pair 1002 is the charging direction. The battery cell group is controlled in a charging direction.

[0236] The transformer control circuit 1006 controls the operation of the transformer circuit 1007. , the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group Based on the number of cells 1009, a transformer signal S3 is generated to control the operation of the transformer circuit 1007. The converted signal is output to the transformer circuit 1007.

[0237] In addition, when the number of battery cells 1009 included in the discharge battery cell group is larger than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to prevent an excessively large charging voltage from being applied to the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step down the discharge voltage (Vdis) within a range where the rechargeable battery cell group can be charged. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is larger than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to prevent an excessively large charging voltage from being applied to the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step down the discharge voltage (Vdis) within a range where the rechargeable battery cell group can be charged. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is larger than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to prevent an excessively large charging voltage from being applied to the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step down the discharge voltage (Vdis) within a range where the rechargeable battery cell group can be charged.

[0238] In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group. In addition, when the number of battery cells 1009 included in the discharge battery cell group is equal to or less than the number of battery cells 1009 included in the rechargeable battery cell group, it is necessary to ensure the charging voltage required to charge the rechargeable battery cell group. Therefore, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 for controlling the voltage conversion circuit 1007 to step up the discharge voltage (Vdis) within a range where an excessive charging voltage is not applied to the rechargeable battery cell group.

[0239] In addition, the voltage value for the excessive charging voltage can be determined in view of the product specifications of the battery cells 1009 used in the battery unit 1008. Also, the voltage stepped up and down by the voltage conversion circuit 1007 is applied to the terminal pair 1002 as the charging voltage (Vcha). In addition, the voltage value for the excessive charging voltage can be determined in view of the product specifications of the battery cells 1009 used in the battery unit 1008. Also, the voltage stepped up and down by the voltage conversion circuit 1007 is applied to the terminal pair 1002 as the charging voltage (Vcha). In addition, the voltage value for the excessive charging voltage can be determined in view of the product specifications of the battery cells 1009 used in the battery unit 1008. Also, the voltage stepped up and down by the voltage conversion circuit 1007 is applied to the terminal pair 1002 as the charging voltage (Vcha).

[0240] Here, an operation example of the voltage conversion control circuit 1006 in the present embodiment will be described with reference to FIGS. 15(A) to (C). FIGS. 15(A) to (C) are conceptual diagrams for explaining an operation example of the voltage conversion control circuit 1006 corresponding to the discharge battery cell group and the rechargeable battery cell group described with reference to FIGS. 12(A) to (C). Note that FIGS. 15(A) to (C) show the battery control unit 1041 in the figure. Here, an operation example of the voltage conversion control circuit 1006 in the present embodiment will be described with reference to FIGS. 15(A) to (C). FIGS. 15(A) to (C) are conceptual diagrams for explaining an operation example of the voltage conversion control circuit 1006 corresponding to the discharge battery cell group and the rechargeable battery cell group described with reference to FIGS. 12(A) to (C). Note that FIGS. 15(A) to (C) show the battery control unit 1041 in the figure. Here, an operation example of the voltage conversion control circuit 1006 in the present embodiment will be described with reference to FIGS. 15(A) to (C). FIGS. 15(A) to (C) are conceptual diagrams for explaining an operation example of the voltage conversion control circuit 1006 corresponding to the discharge battery cell group and the rechargeable battery cell group described with reference to FIGS. 12(A) to (C). Note that FIGS. 15(A) to (C) show the battery control unit 1041 in the figure. Here, an operation example of the voltage conversion control circuit 1006 in the present embodiment will be described with reference to FIGS. 15(A) to (C). FIGS. 15(A) to (C) are conceptual diagrams for explaining an operation example of the voltage conversion control circuit 1006 corresponding to the discharge battery cell group and the rechargeable battery cell group described with reference to FIGS. 12(A) to (C). Note that FIGS. 15(A) to (C) show the battery control unit 1041 in the figure. is shown. The battery control unit 1041 includes a terminal pair 1001, a terminal pair 1002, a switching control circuit 1003, a switching circuit 1004, a switching circuit 1005, a voltage conversion control circuit 1006, and a voltage conversion circuit 1007.

[0241] In the example shown in FIG. 15(A), as described in FIG. 12(A), three consecutive high-voltage cells a to c and one low-voltage cell d are connected in series. In this case, as described using FIG. 12(A), the switching control circuit 1003 determines the high-voltage cells a to c as the discharge battery cell group and determines the low-voltage cell d as the charge battery cell group. Then, the voltage conversion control circuit 1006 calculates a conversion ratio N from the discharge voltage (Vdis) to the charge voltage (Vcha) based on the ratio of the number of battery cells 1009 included in the charge battery cell group with respect to the number of battery cells

[0242] 1009 included in the discharge battery cell group when the number of battery cells 1009 included in the discharge battery cell group is larger than the number of battery cells 1009 included in the charge battery cell group, if the discharge voltage is directly applied to the terminal pair 1002 without voltage conversion, an excessive voltage may be applied to the battery cells 1009 included in the charge battery cell group via the terminal pair 1002. Therefore, in the case shown in FIG. 15(A), it is necessary to step down the charge voltage (Vcha) applied to the terminal pair 1002 below the discharge voltage. Furthermore, in order to charge the charge battery cell group, the charge voltage needs to be greater than the total voltage of the battery Set the conversion ratio N to be larger than the ratio of the number of battery cells 1009 included in the battery cell group.

[0243] The voltage conversion control circuit 1006 is based on the number of battery cells 1009 included in the discharging battery cell group. When this is the case, it is preferable to increase the conversion ratio N by about 1% or more and 10% or less with respect to the ratio of the number of battery cells 1009 included in the charging battery cell group. At this time, the charging voltage becomes higher than the voltage of the charging battery cell group, but actually the charging voltage becomes equal to the voltage of the charging battery cell group. However, since the voltage conversion control circuit 1006 makes the voltage of the charging battery cell group equal to the charging voltage according to the conversion ratio N, a current for charging the charging battery cell group will flow. This current becomes the value set in the voltage conversion control circuit 1006. However, since the voltage conversion control circuit 1006 makes the voltage of the charging battery cell group equal to the charging voltage according to the conversion ratio N, a current for charging the charging battery cell group will flow. This current becomes the value set in the voltage conversion control circuit 1006. However, since the voltage conversion control circuit 1006 makes the voltage of the charging battery cell group equal to the charging voltage according to the conversion ratio N, a current for charging the charging battery cell group will flow. This current becomes the value set in the voltage conversion control circuit 1006. However, since the voltage conversion control circuit 1006 makes the voltage of the charging battery cell group equal to the charging voltage according to the conversion ratio N, a current for charging the charging battery cell group will flow. This current becomes the value set in the voltage conversion control circuit 1006. This current becomes the value set in the voltage conversion control circuit 1006.

[0244] In the example shown in FIG. 15(A), since the number of battery cells 1009 included in the discharging battery cell group is 3 and the number of battery cells 1009 included in the charging battery cell group is 1, the voltage conversion control circuit 1006 calculates a value slightly larger than 1 / 3 as the conversion ratio N. Then, the voltage conversion control circuit 1006 steps down the discharging voltage according to the conversion ratio N and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002. and the number of battery cells 1009 included in the charging battery cell group is 1, the voltage conversion control circuit 1006 calculates a value slightly larger than 1 / 3 as the conversion ratio N. Then, the voltage conversion control circuit 1006 steps down the discharging voltage according to the conversion ratio N and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002. and the number of battery cells 1009 included in the charging battery cell group is 1, the voltage conversion control circuit 1006 calculates a value slightly larger than 1 / 3 as the conversion ratio N. Then, the voltage conversion control circuit 1006 steps down the discharging voltage according to the conversion ratio N and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002. and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002. and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002. and outputs a voltage conversion signal S3 for converting it into a charging voltage to the voltage conversion circuit 1007. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 1002. Then, the battery cells 1009 included in the charging battery cell group are charged by the charging voltage applied to the terminal pair 1002.

[0245] Also, in the examples shown in FIGS. 15(B) and 15(C), the conversion ratio N is calculated in the same manner as in FIG. 15(A). In the examples shown in FIGS. 15(B) and 15(C), the number of battery cells 1009 included in the discharging battery cell group is less than or equal to the number of battery cells 1009 included in the charging battery cell group. Also, in the examples shown in FIGS. 15(B) and 15(C), the conversion ratio N is calculated in the same manner as in FIG. 15(A). In the examples shown in FIGS. 15(B) and 15(C), the number of battery cells 1009 included in the discharging battery cell group is less than or equal to the number of battery cells 1009 included in the charging battery cell group. Also, in the examples shown in FIGS. 15(B) and 15(C), the conversion ratio N is calculated in the same manner as in FIG. 15(A). In the examples shown in FIGS. 15(B) and 15(C), the number of battery cells 1009 included in the discharging battery cell group is less than or equal to the number of battery cells 1009 included in the charging battery cell group. Therefore, the conversion ratio N is greater than 1. Thus, in this case, the voltage conversion control circuit 1006 outputs a voltage conversion signal S3 that boosts the discharge voltage and converts it into a charging voltage.

[0246] Based on the voltage conversion signal S3, the voltage conversion circuit 1007 converts the discharge voltage applied to the terminal pair 1001 into a charging voltage. Then, the voltage conversion circuit 1007 applies the converted charging voltage to the terminal pair 100 2. Here, the voltage conversion circuit 1007 electrically insulates between the terminal pair 1001 and the terminal pair 1002. Thereby, the voltage conversion circuit 1007 prevents a short circuit caused by the difference between the absolute voltage of the negative electrode terminal of the battery cell 1009 located at the lowest current position in the discharge battery cell group and the absolute voltage of the negative electrode terminal of the battery cell 1009 located at the most downstream position in the charging battery cell group. Further more, as described above, the voltage conversion circuit 1007 converts the total voltage of the discharge battery cell group, which is the discharge voltage, into a charging voltage based on the voltage conversion signal S3. In addition, for the voltage conversion circuit 1007, for example, an isolated DC (Direct Current)-DC converter or the like can be used. In this case, the voltage conversion control circuit 1006 controls the charging voltage converted by the voltage conversion circuit 1007 by outputting a signal for controlling the on / off ratio (duty ratio) of the isolated DC-DC

[0247] converter as the voltage conversion signal S3. Note that isolated DC-DC converters include the flyback method, the forward method, the RCC ( Ringing Choke Converter) method, the push-pull method, the half-bridge

[0248] method, the full-bridge method, etc. However, an appropriate method is selected according to the magnitude of the target output voltage.

[0249] The configuration of the transformer circuit 1007 using an isolated DC-DC converter is shown in FIG. 16. The isolated D C-DC converter 1051 includes a switch section 1052 and a transformer section 1053. The switch section 1052 is a switch that switches the on / off operation of the isolated DC-DC converter. For example, it is implemented using a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a bipolar transistor, or the like. Also, the switch section 1052 is based on a transformer control signal S3 output from the transformer control circuit 1006 for controlling the on / off ratio, and periodically switches the on state and the off state of the isolated DC-DC converter 1051. Note that the switch section 1052 can have various configurations depending on the type of isolated DC-DC converter used. The transformer section 1053 converts the discharge voltage applied from the terminal pair 1001 into a charging voltage. Specifically, the transformer section 1053 operates in conjunction with the on / off state of the switch section 1052 and converts the discharge voltage into a charging voltage according to its on / off ratio. This charging voltage increases as the time in the on state is longer during the switching period of the switch section 1052. Note that when using an isolated DC-DC converter, inside the transformer section 1053, the terminal pair 1001 and the terminal pair 1002 can be insulated from each other.

[0250] The processing flow of the power storage device 1000 in this embodiment will be described with reference to FIG. 17. FIG. 17 is a flowchart showing the processing flow of the power storage device 1000.

[0251] First, the power storage device 1000 acquires the voltages measured for each of the plurality of battery cells Step S1101). Then, the power storage device 1000 determines whether the start condition for the operation of equalizing the voltages of the plurality of battery cells 1009 is satisfied (step S1102). This start condition can be, for example, whether the difference between the maximum value and the minimum value of the voltages measured for each of the plurality of battery cells 1009 is equal to or greater than a predetermined threshold value. If this start condition is not satisfied (step S1102: NO), since the voltages of the respective battery cells 1009 are in a balanced state, the power storage device 1000 does not execute the subsequent processing. On the other hand, if the start condition is satisfied (step S1102: YES), the power storage device 1000 executes a process of equalizing the voltages of the respective battery cells 1009. In this process, the power storage device 1000 determines whether each battery cell 1009 is a high-voltage cell or a low-voltage cell based on the measured voltage for each cell (step S1103 ). Then, the power storage device 1000 determines a discharge battery cell group and a charge battery cell group based on the determination result (step S1104). Further, the power storage device 1000 generates a control signal S1 for setting the determined discharge battery cell group as the connection destination of the terminal pair 1001 and a control signal S2 for setting the determined charge battery cell group as the connection destination of the terminal pair 1002 (step S110 5). The power storage device 1000 outputs the generated control signal S1 and control signal S2 to the switching circuit 1004 and the switching circuit 1005, respectively. Then, the switching circuit 1004 connects the terminal pair 1001 to the discharge battery cell group, and the switching circuit 1005 connects the terminal pair 1002 to the discharge battery cell group (step S1106). Also, the power storage device 1000 generates a transformer signal S3 based on the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group (step S1 ). Based on the measured voltage for each cell, the power storage device 1000 determines whether each battery cell 1009 is a high-voltage cell or a low-voltage cell (step S1103 ). Then, based on the determination result, the power storage device 1000 determines a discharge battery cell group and a charge battery cell group (step S1104). Further, the power storage device 1000 generates a control signal S1 for setting the determined discharge battery cell group as the connection destination of the terminal pair 1001 and a control signal S2 for setting the determined charge battery cell group as the connection destination of the terminal pair 1002 (step S110 5). The power storage device 1000 outputs the generated control signal S1 and control signal S2 to the switching circuit 1004 and the switching circuit 1005, respectively. Then, the switching circuit 1004 connects the terminal pair 1001 to the discharge battery cell group, and the switching circuit 1005 connects the terminal pair 1002 to the discharge battery cell group (step S1106). Also, the power storage device 1000 generates a transformer signal S3 based on the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group (step S1 ). ). The power storage device 1000 outputs the generated control signal S1 and control signal S2 to the switching circuit 1004 and the switching circuit 1005, respectively. Then, the switching circuit 1004 connects the terminal pair 1001 to the discharge battery cell group, and the switching circuit 1005 connects the terminal pair 1002 to the discharge battery cell group (step S1106). Also, the power storage device 1000 generates a transformer signal S3 based on the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group (step S1 ). connects the terminal pair 1001 to the discharge battery cell group, and the switching circuit 1005 connects the terminal pair 1002 to the discharge battery cell group (step S1106). Also, the power storage device 1000 generates a transformer signal S3 based on the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group (step S1 ). ). 107). Then, based on the voltage conversion signal S3, the power storage device 1000 converts the discharge voltage applied to the terminal pair 1001 into a charging voltage and applies it to the terminal pair 1002 (step S1108 ). As a result, the charge of the discharge battery cell group is moved to the charge battery cell group. )

[0252] Also, in the flowchart of FIG. 17, although a plurality of steps are described in order, the execution order of each step is not limited to the described order.

[0253] As described above, according to the present embodiment, when moving charge from the discharge battery cell group to the charge battery cell group , a configuration such as a capacitor method, which temporarily stores the charge from the discharge battery cell group and then discharges it to the charge battery cell group is not required. Thereby, the charge transfer efficiency per unit time can be improved. Further, by the switching circuit 1004 and the switching circuit 1005 , among the discharge battery cell group and the charge battery cell group, the battery cells connected to the voltage conversion circuit can be switched individually .

[0254] Furthermore, based on the number of battery cells 1009 included in the discharge battery cell group and the number of battery cells 1009 included in the charge battery cell group, the voltage conversion circuit 1007 converts the discharge voltage applied to the terminal pair 1001 into a charging voltage and applies it to the terminal pair 1002. As a result, regardless of how the battery cells 1009 on the discharge side and the charge side are selected, charge transfer can be realized without problems .

[0255] Furthermore, by using OS transistors for the transistor 1010 and the transistor 1013 , leakage from the battery cells 1009 that do not belong to the charge battery cell group and the discharge battery cell group can be prevented ​​​​The charge amount can be reduced. As a result, the decrease in the capacity of the battery cell 1009 that does not contribute to charging and discharging can be suppressed. Also, the OS transistor has less variation in characteristics with respect to heat compared to the Si transistor. Thus, even when the temperature of the battery cell 1009 rises, normal operations such as switching between the conductive state and the non-conductive state according to the control signals S1 and S2 can be achieved. This embodiment can be implemented in appropriate combination with other embodiments.

Example

[0256] Hereinafter, an aspect of the present invention will be specifically described using examples. In this example, the results of fabricating the positive electrode by the method shown in Embodiment 2 will be described. Note that the present invention is not limited to only the following examples.

[0257] (Synthesis of the positive electrode active material) First, a lithium manganese composite oxide was synthesized as the positive electrode active material. Using Li2CO3, MnCO3, and NiO as starting materials, each was weighed so that Li2CO3:MnCO3:NiO = 0.84:0.8062:0.318 (molar ratio). Next, after adding acetone to these powders, they were mixed with a ball mill to prepare a mixed powder.

[0258] Then, heating was performed to evaporate the acetone to obtain a mixed raw material.

[0259] Next, the mixed raw material was placed in a crucible and fired to synthesize the material. Here, firing was performed under the conditions of 1000°C for 10 hours. The firing atmosphere was air, and the gas flow rate was 10 L / min.

[0260]

[0261] ​​​​​​​​​​​ Next, a crushing treatment was performed to break up the sintering of the fired particles. The crushing treatment was carried out by adding acetone to the fired particles and then mixing them with a ball mill.

[0262] Next, heating was performed to evaporate the acetone after the crushing treatment, and a lithium manganese composite oxide having nickel was obtained.

[0263] (Fabrication of Electrode A) For the fabrication of Electrode A, lithium manganese composite oxide as a positive electrode active material, L - ascorbic acid as a reducing agent, graphene oxide (GO) as a raw material for a conductive assistant, acetylene black (AB) as a second conductive assistant, PVdF as a binder, and NMP as a solvent were used. First, lithium manganese composite oxide, GO, AB, and NMP were kneaded to prepare a first mixture. Next, L - ascorbic acid dissolved in a small amount of water was added to the first mixture and kneaded, and GO was reduced by heating at 80 °C for 1 hour to prepare a second mixture. Further, PVdF was added to the second mixture and kneaded to prepare a positive electrode paste. The blending ratio of the positive electrode paste was such that lithium manganese composite oxide:graphene:AB:L - ascorbic acid:PVdF = 89:0.5:4.5:1:5 (weight ratio), and the amounts of the respective materials were adjusted. The positive electrode paste was applied to a current collector (aluminum) and heated at 250 °C to evaporate the solvent contained in the positive electrode paste, thereby fabricating Electrode A. The loading amount of the positive electrode paste on the current collector was 6 mg / cm 2

[0264] (Fabrication of Comparative Example B) For comparison, Comparative Example B was fabricated by reducing GO only by heating without using a reducing agent. First, the lithium manganese composite oxide, GO, AB, and NMP were mixed to obtain the first mixture. Next, PVdF was added to the first mixture and mixed to prepare a positive electrode. The mixture ratio of the positive electrode paste was lithium manganese composite oxide:GO. The amounts of each material were adjusted so that the ratio of AB to PVdF was 90:0.5:4.5:5. The positive electrode paste is applied to a current collector (aluminum) and heated to 250°C to evaporate the solvent. The positive electrode paste was then simultaneously reduced to prepare Comparative Example B. The dosage is 6mg / cm 2 It was decided.

[0265] (Preparation of half-cell) The prepared electrodes A and Comparative Example B were assembled into half cells, and the charge / discharge characteristics of each cell were measured. The half cell is a cell in which an active material other than Li metal is used for the positive electrode and Li is used for the negative electrode. The figure shows a lithium-ion secondary battery cell that uses lithium metal. The plate is made of polypropylene (PP) and the electrolyte is ethylene carbonate (EC). In a mixed solution of diethyl carbonate (DEC) and , lithium hexafluorophosphate (LiPF6) dissolved at a concentration of 1 mol / liter Used.

[0266] (Evaluation of cycle characteristics) The results of measuring the charge and discharge capacity are shown in FIG. 18. In FIG. 18, the vertical axis represents capacity (mAh / g). The horizontal axis represents the number of cycles. The charging conditions were constant current charging, charging rate 0.2C, and final voltage 4 The discharge conditions were constant current discharge, discharge rate 0.2C, and final voltage 2.0V. The number of cycles was measured up to 10. The cycle characteristics of the fabricated half-cell are shown. In Fig. 18(B), a comparative example B was incorporated and fabricated The cycle characteristics of the half-cell are shown.

[0267] Here, the charge rate and discharge rate will be described. The charge rate of 1C means the current value at which the cell is charged at a constant current and the charging is completed in exactly 1 hour. In this example, since the theoretical capacity of the half-cell is 150 mAh / g, 1C is 150 mA / g. Also, 0.2C means the current value at which the cell is charged at a constant current and the charging is completed in exactly 5 hours, and in the half-cell with the above-mentioned theoretical capacity, it is 30 mA / g. Similarly, the discharge rate of 1C means the current value at which the cell is discharged at a constant current and the discharging is completed in exactly 1 hour. In the half-cell fabricated in this example, 1C is 150 mA / g and 0.2C is 30 mA / g as well. There is.

[0268] As can be seen from Figs. 18(A) and (B), in the half-cell using electrode A, compared with the half-cell using comparative example B, the decrease in capacity with the increase in the number of cycles is suppressed . From this, it was found that electrode A has higher electrical conductivity than comparative example B. Therefore , by adding a reducing agent during fabrication, heating, reducing GO, and then forming the positive electrode active material layer, it is speculated that GO was reduced with high reaction efficiency and a three-dimensional network of electrical conduction paths was constructed in the active material layer.

[0269] (Evaluation of rate characteristics) Fig. 19 shows the discharge curves measured by changing the discharge rate for the half-cells fabricated by incorporating electrode A and comparative example B, respectively. The vertical axis represents voltage (V), and the horizontal axis represents charge-discharge capacity (mAh / g ) is shown. The charging conditions were constant current charging at a charging rate of 0.2C. Figure 19(A) shows the charging curve and the discharging curve when the discharging rate was 0.2C. Also, Figure 19(B) shows the charging curve and the discharging curve when the discharging rate was 0.5C. Further, Figure 19(C) shows the charging curve and the discharging curve when the discharging rate was 1.0C.

[0270] From Figures 19(A), (B), and (C), it was revealed that in the half-cell incorporating Comparative Example B, the discharge capacity and voltage significantly decreased as the discharge rate increased. On the other hand, it was found that in the half-cell incorporating Electrode A, the discharge capacity and voltage were less likely to decrease even when the discharge rate was increased. Therefore, it became clear that Electrode A had a lower resistance compared to Comparative Example B. From this, it was suggested that the efficiency of the reaction for reducing GO could be increased by reducing GO with a reducing agent before forming the positive electrode active material layer.

[0271] (Measurement of Current Interruption Method Resistance) Next, Electrode A and Comparative Example B were evaluated by measuring the current interruption method resistance. Here, the current interruption method resistance will be explained. When charging a battery and the charging is interrupted, a behavior where the voltage drops is observed. The cause of this voltage drop is the internal resistance of the battery. {( Voltage immediately after interruption) - (Voltage 3 seconds after interruption)} / Current, using this calculation formula, the ohmic component of the internal resistance of the half-cell incorporating Electrode A and the half-cell incorporating Comparative Example B was obtained and compared. The charging conditions were constant current charging at a charging rate of 0.2C. The interruption of charging was performed every time charging was carried out at 15 mA h / g. When the charging capacity of the battery reached 195 mAh / g, 210 mAh / g, 225 mAh / g, 240 mAh / g, the current was interrupted, and the internal resistance The results of calculating the ohmic component of

[0272]

Table 1

[0273] From the results in Table 1, it was found that the half-cell incorporating electrode A had a smaller internal resistance ohmic component than the half-cell incorporating Comparative Example B. From this, it became clear that electrode A had a lower resistance than Comparative Example B. Therefore, it was suggested that by adding a reducing agent when producing the positive electrode active material layer, the efficiency of the reaction for reducing GO could be increased, and an electrode with a small internal resistance ohmic component could be produced.

Explanation of symbols

[0274] S101 step S102 step S103 step S104 step 200 electrode 201 current collector 202 active material layer 203 active material 204 graphene 300 coin-type battery 301 positive electrode can 302 negative electrode 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 electrode terminal 604 Positive electrode 605 Separator 606 Negative electrode 607 Negative electrode terminal 608 Insulating plate 609 Insulating plate 610 Gasket (insulating packing) 611 PTC element 612 Safety valve mechanism 700 Display device 701 Housing 702 Display unit 703 Speaker unit 704 Storage battery 710 Lighting device 711 Housing 712 Light source 713 Storage battery 714 Ceiling 715 Side wall 716 Floor 717 Window 720 Indoor unit 721 Housing 722 Air outlet 723 Storage battery 724 Outdoor unit 730 Electric refrigerator-freezer 731 Housing 732 Refrigerator door 733 Freezer door 734 Storage battery 800 Tablet terminal 801 Housing 802 Display unit 802a Display unit 802b Display unit 803 Display mode changeover 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 Switching Button 811 Solar Cell 850 Charge and Discharge Control Circuit 851 Battery 852 DCDC Converter 853 Converter 860 Electric Vehicle 861 Battery 862 Control Circuit 863 Driving Device 864 Processing Device S1 Control Signal S2 Control Signal S3 Transformer Signal 1000 Energy Storage Device 1001 Terminal Pair 1002 Terminal Pair 1003 Switching Control Circuit 1004 Switching Circuit 1005 Switching Circuit 1006 Transformer Control Circuit 1007 Transformer Circuit 1008 Battery Unit 1009 Battery Cell 1010 Transistor 1011 Bus 1012 Bus 1013 Transistor 1014 Current Control Switch 1015 Bus 1016 Bus 1017 Switch Pair 1018 Switch Pair 1021 Transistor Pair 1022 Transistor 1023 Transistor 1024 Bus 1025 Bus 1031 Transistor pair 1032 Transistor 1033 Transistor 1034 Bus 1035 Bus 1041 Battery control unit 1051 Isolated DC-DC converter 1052 Switch section 1053 Transformer section S1101 Step S1102 Step S1103 Step S1104 Step S1105 Step S1106 Step S1107 Step S1108 Step

Claims

1. A lithium-ion secondary battery having a current collector and an active material layer, wherein the active material layer includes an active material, multilayer graphene, a binder, and a reducing agent.

2. A lithium-ion secondary battery having a current collector and an active material layer, wherein the active material layer includes an active material, multilayer graphene, a binder, and an oxidation derivative of a reducing agent.

3. The lithium-ion secondary battery according to Claim 1 or Claim 2, wherein the reducing agent is at least one of ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, sodium borohydride, lithium aluminum hydride, or N,N-diethylhydroxylamine.

4. The lithium-ion secondary battery according to any one of Claims 1 to 3, wherein the active material layer further includes a conductive aid in the form of needles, fibers, or granules.

Images