secondary batteries

Abstract

To solve such a problem that, in the case where a secondary battery is repetitively curved, portions which tend to cause deterioration such as cracks or breakages are, for example, a positive electrode tab and a negative electrode tab, and this is because these portions are narrow projected portions, and tend to have low mechanical strength against repetitive curving in some cases.SOLUTION: In a secondary battery, a positive electrode tab and a negative electrode tab are provided in portions relatively less affected by curving. More specifically, the secondary battery includes a positive electrode, a positive electrode lead electrically connected to the positive electrode, a negative electrode, a negative electrode lead electrically connected to the negative electrode, a separator, and an exterior body wrapping the positive electrode, the negative electrode, and the separator. The positive electrode, the separator, the negative electrode, and the exterior body can be curved in a first direction. The positive electrode lead and the negative electrode lead are drawn from opposite sides of the exterior body, respectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, relating to the manufacture or composition of matter, especially One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, an imaging device, or any of these devices. In particular, one aspect of the present invention relates to a secondary battery and a driving method thereof. and a method for producing a secondary battery. [Background technology]

[0002] In recent years, wearable devices have been actively developed. Because of its properties, it follows the curves of the body or curves in accordance with the movement of the body. Therefore, the secondary batteries installed in wearable devices should also be As with other housings, flexible secondary batteries are being developed.

[0003] For example, Patent Document 1 discloses a sheet-like electricity storage device that can be bent and a battery mounted on the battery. An electronic device is disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2013 / 0108907 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of flexible secondary batteries, the exterior is usually made of flexible materials such as laminated film. A flexible material is used, and a portion of the positive electrode lead electrically connected to the positive electrode, and A part of the negative electrode lead electrically connected to the negative electrode is drawn out to the outside of the outer casing. The thin, extended part that electrically connects to the positive electrode lead is called the positive electrode tab. The thin, extended part of the negative electrode that electrically connects to the negative electrode lead is called the negative electrode tab.

[0006] When the secondary battery is repeatedly bent, it is prone to deterioration such as cracks and breakage. The positive and negative electrode tabs are the most important parts. These parts are elongated and thin. It is thinner than the electrode part where the active material is formed, and has low physical strength against repeated bending. This is because the signal tends to be weak.

[0007] Therefore, one aspect of the present invention provides a secondary battery with a novel structure. The present invention provides a secondary battery having a novel structure.

[0008] Another embodiment of the present invention is a novel power storage device, an electronic device equipped with a novel secondary battery, or the like. The objective of this study is to provide the following: It is to be noted that one embodiment of the present invention does not necessarily solve all of these problems. Problems other than these will be obvious from the description, drawings, claims, etc. It is not possible to extract other issues from the description, drawings, claims, etc. It is possible to do this. [Means for solving the problem]

[0009] In order to achieve the above object, in one aspect of the present invention, a positive electrode tab and a negative electrode tab are provided in a manner that prevents the influence of bending. It should be installed in a location with relatively little reverberation.

[0010] When a secondary battery is bent in a single axis direction, the difference between the inner diameter and the outer diameter at the end in the bending direction Therefore, the displacement between the adjacent current collectors is most likely to be large. The negative electrode tab is provided so as to avoid the side having the end in the curved direction.

[0011] More specifically, one aspect of the present invention is a battery comprising a positive electrode, a positive electrode lead electrically connected to the positive electrode, a negative electrode, a negative electrode lead electrically connected to the negative electrode, a separator, and a positive electrode, a negative electrode, and a separator. and an exterior covering the positive electrode, the separator, the negative electrode, and the exterior covering are arranged in a first direction. The positive electrode lead and the negative electrode lead are arranged on opposite sides of the outer casing. It is a secondary battery that is drawn from the side.

[0012] In the above, the positive electrode tab portion electrically connects the positive electrode and the positive electrode lead, and the negative electrode and the negative electrode lead are electrically connected to each other. The second direction connecting the electrode lead and the negative electrode tab portion to which the electrode lead is electrically connected is perpendicular to the first direction. It is preferable that the direction is such that [Effects of the Invention]

[0013] It is possible to provide a secondary battery with a novel structure. More specifically, a novel flexible secondary battery It is possible to provide a secondary battery having such a structure.

[0014] Alternatively, it is possible to provide a new power storage device, an electronic device equipped with a new secondary battery, etc. The description of these effects does not preclude the existence of other effects. It is not necessary for one aspect of the present invention to have all of these effects. The results will be self-evident from the description, drawings, claims, etc. Other effects can be extracted from the drawings, claims, etc. [Brief explanation of the drawings]

[0015] [Figure 1] 1A to 1C are a top view, a perspective view, and a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 2] FIG. 1 is a cross-sectional view illustrating a positive electrode active material that can be used in a secondary battery. [Figure 3] 1 is a cross-sectional view illustrating a conductive additive and the like that can be used in a secondary battery. [Figure 4] 1A and 1B are a top view and a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 5] 1A and 1B are a top view and a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 6] 1A to 1C are a top view, a perspective view, and a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 7] 1 is a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 8] 1A and 1B are a perspective view and a cross-sectional view illustrating an example of the configuration of a secondary battery. [Figure 9] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 10] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 11] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 12] 1A to 1C are diagrams illustrating a method for manufacturing a secondary battery. [Figure 13] FIG. 2 is a block diagram illustrating a battery control unit of a power storage device. [Figure 14] FIG. 2 is a conceptual diagram illustrating a battery control unit of a power storage device. [Figure 15] FIG. 2 is a circuit diagram illustrating a battery control unit of a power storage device. [Figure 16] FIG. 2 is a circuit diagram illustrating a battery control unit of a power storage device. [Figure 17] FIG. 2 is a conceptual diagram illustrating a battery control unit of a power storage device. [Figure 18] FIG. 2 is a block diagram illustrating a battery control unit of a power storage device. [Figure 19] 6 is a flowchart illustrating processing by a battery control unit of the power storage device. [Figure 20] 1A to 1C illustrate examples of electronic devices. [Figure 21] 1A to 1C illustrate examples of electronic devices. [Figure 22] 1A to 1C illustrate examples of electronic devices. [Figure 23] 1A to 1C illustrate examples of electronic devices. [Figure 24] 1A to 1C illustrate examples of electronic devices. [Figure 25] 1A to 1C illustrate examples of electronic devices. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. The present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0017] "Electrically connected" means that the connection is made via "something that has some kind of electrical effect." Here, "something that has some kind of electrical effect" means an electrical signal between connected objects. There are no particular restrictions as long as it allows the exchange of numbers.

[0018] The position, size, range, etc. of each component shown in the drawings are not necessarily the actual size for ease of understanding. Therefore, the disclosed invention may not necessarily represent the position, size, range, etc. Furthermore, the present invention is not limited to the position, size, range, etc. disclosed in the drawings, etc.

[0019] Ordinal numbers such as "first," "second," and "third" are used to avoid confusion of components. is.

[0020] The words "film" and "layer" may be used interchangeably depending on the situation. For example, the term "conductive layer" can be replaced with "conductive film." ". Alternatively, for example, the term "insulating film" may be used. It may be possible to change the term to "insulating layer."

[0021] (Embodiment 1) In this embodiment, a structure example of a secondary battery according to one embodiment of the present invention will be described with reference to FIGS. 1 to 8. We will explain about this.

[0022] [1.1. Typical configuration] The secondary battery 100 shown in FIG. 1(A1) includes a positive electrode 111, a positive electrode 112 electrically connected to the positive electrode 111, and a positive electrode 113. a negative electrode lead 121, a negative electrode 115, a negative electrode lead 125 electrically connected to the negative electrode 115, a separator The separator 103, the positive electrode 111, the negative electrode 115, and the separator 103 are covered with an exterior body 107. The positive electrode lead 121 and the negative electrode lead 125 each have a sealing layer 120. The secondary battery 100 has an electrolyte solution 104 in the area covered by the exterior body 107 .

[0023] The positive electrode 111, separator 103, and negative electrode 115 of the secondary battery 100 are shown in FIG. 1(B1), 1(B2) and 1(B3). The cross-sectional view of the positive electrode 111 taken along the line A1-A2 in FIG. 1(C) is shown. The negative electrode 115 has an active material layer 102. The positive electrode active material layer 102 has a positive electrode active material. The negative electrode current collector 105 and the negative electrode active material layer 106 are provided. The positive electrode active material layer 102 on the positive electrode current collector 101 is connected to the negative electrode current collector via a separator 103. The negative electrode active material layer 106 on the current collector 105 overlaps with the negative electrode active material layer 106 on the current collector 105 .

[0024] The secondary battery 100 can be curved in a first direction 201 as shown in FIG. 1(A2). Cut.

[0025] The positive electrode lead 121 and the negative electrode lead 125 are drawn out from opposite sides of the exterior body 107. When the secondary battery 100 is bent in a single axis direction, the inner The difference between the diameter and the outer diameter is the most likely to cause the largest misalignment between adjacent current collectors. The positive electrode tab and the negative electrode tab are provided so as to avoid the side having the end in the curved direction of the exterior body 107. In this specification, the end of the exterior body 107 refers to the area from the end of the exterior body 107 to the This refers to a range of 10% of the length of 107.

[0026] In addition, a tab portion of the positive electrode 111 where the positive electrode 111 and the positive electrode lead 121 are electrically connected, The negative electrode 115 and the negative electrode lead 125 are electrically connected to each other. The direction of the secondary battery 100 is defined as a second direction 202. In the secondary battery 100 of FIG. 201.

[0027] As shown in FIGS. 1(A1) and 1(B1), the positive electrode 111 has a shape with a notch in one part. This is because the positive electrode 111 and the negative electrode 115 are preferably connected to each other in order to prevent short-circuiting. When the cathode 111 and the anode 115 are stacked, the cathode 111 is provided in the portion close to the tab of the anode 115. This is because it is preferable not to do so.

[0028] By using the secondary battery 100 having the configuration shown in FIG. 1(A1), the tab portion of the positive electrode 111 and The tab portion of the negative electrode 115 can be provided at a location that is relatively less affected by bending. Therefore, it is possible to suppress deterioration of the secondary battery 100. It can be set to 00.

[0029] In addition, the above-described configuration is applicable to the secondary battery 100 that is elongated in the first direction, which is the direction of curvature. Therefore, the length of the exterior body 107 in the first direction 201 is It is preferable that the length is at least twice the length of the second direction 202, and more preferably at least three times the length. preferable.

[0030] The secondary battery 100 includes a positive electrode 111, a negative electrode 115, a separator 103, an electrolyte 104, Materials that can be used for the exterior body 107 will be described.

[0031] [1.2. Positive electrode] The positive electrode 111 is composed of a positive electrode current collector 101 and a positive electrode active material layer 10 formed on the positive electrode current collector 101. It consists of 2 etc.

[0032] The positive electrode current collector 101 is made of metal such as stainless steel, gold, platinum, aluminum, titanium, etc. It is possible to use materials that are highly conductive and do not undergo significant chemical changes, such as these alloys. In addition, the heat resistance of silicon, titanium, neodymium, scandium, molybdenum, etc. can be improved. Aluminum alloys containing elements that increase the reaction rate can be used. Alternatively, the metal element may be formed of a metal element that reacts with silicon to form a silicide. The metal elements forming the , tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The electric body 101 may be in the form of a foil, a plate (sheet), a mesh, a punched metal, an expanded metal, or the like. The positive electrode current collector 101 may have a thickness of 5 μm to 30 μm. It is also preferable to use graphite or the like on the surface of the positive electrode current collector 101. An undercoat layer may be provided.

[0033] The positive electrode active material layer 102 contains a positive electrode active material and a binder (binder) for increasing the adhesion of the positive electrode active material. The positive electrode active material layer 102 may contain an indium ion, a conductive additive for increasing the conductivity of the positive electrode active material layer 102, or the like.

[0034] The positive electrode active material used in the positive electrode active material layer 102 may have an olivine-type crystal structure or a layered rock salt-type There are composite oxides with a crystalline structure or a spinel-type crystalline structure. , for example, LiFeO2, LiCoO2, LiNiO2, LiMn2O4, V2O5, C Compounds such as r2O5 and MnO2 are used.

[0035] In particular, LiCoO2 has a large capacity and is more stable in the air than LiNiO2. It is preferable because it has advantages such as being more thermally stable than LiNiO2.

[0036] In addition, lithium-containing materials with a spinel-type crystal structure containing manganese, such as LiMn2O4, The material contains a small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x M x O2(0 <x<1 ) (M=Co, Al, etc.)) can improve the characteristics of the secondary battery using this. This is preferable.

[0037] In addition, the positive electrode active material is a compound having the composition formula Li a Mn b M c O dLithium-manganese can be expressed as A manganese composite oxide can be used. Here, element M is selected from elements other than lithium and manganese. The selected metal element, silicon, or phosphorus is preferably used, and nickel is preferred. Further, it is more preferable that the value is 0.0 <a / (b+c)<2、かつc>and 0.26 during discharge. It is preferable that the lithium manganese composite oxide satisfies the condition of ≦(b+c) / d<0.5. refers to an oxide containing at least lithium and manganese, and does not contain chromium, cobalt, aluminum, Sodium, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, At least one element selected from the group consisting of titanium, niobium, silicon, and phosphorus In addition, lithium ion batteries having different properties between the surface layer and the center portion, as will be described later, may be used. To make manganese composite oxide, Li 1.68 Mn 0.8062 Ni 0.318 O3 It is particularly preferable to use a lithium manganese composite oxide represented by the composition formula: Here, Li 1.68 Mn 0.8062 Ni 0.318 Lithium with the formula O3 Manganese-manganese composite oxide is a compound whose ratio (molar ratio) of the amount of raw materials is Li2CO3:MnCO 3: Lithium manganese oxide formed by adjusting NiO=0.84:0.8062:0.318 Therefore, the lithium manganese composite oxide has the composition formula Li 1.6 8Mn 0.8062 M 0.318 It is expressed as O3, but the composition may deviate from this. For example, the composition formula is Li a Mn b M c O d (1.5 <a<1.8、0.6<b<1、0.1< ​c<0.5, d=3).

[0038] The lithium manganese composite oxide has an average particle size of, for example, 5 nm or more and 50 μm or less. The average particle size is preferably determined by SEM (scanning electron microscope) or TEM. It can be measured by observation using a laser or by a particle size distribution analyzer using the laser diffraction and scattering method. The specific surface area can be measured by a gas adsorption method.

[0039] In addition, if the lithium manganese composite oxide has different properties between the surface layer and the center, it can achieve high capacity. The lithium manganese alloy has different properties between the surface layer and the center. An example of a cross section of a composite oxide particle is shown in FIG.

[0040] As shown in Figure 2(A), the lithium manganese composite oxide (LiMA) has different properties between the surface and the center. The compound preferably has a first region 331, a second region 332, and a third region 333. Preferably, the second region 332 contacts at least a part of the outside of the first region 331. The outer region 333 is closer to the surface of the particle. It is preferable to have a region that coincides with the surface of the manganese composite oxide particle.

[0041] As shown in FIG. 2B, the first region 331 is an area that is not covered by the second region 332. The second region 332 may have an area that is not covered by the third region 333. Also, for example, the first region 331 may have a region where the third region 333 is in contact with the first region 331. In addition, the first region 331 may be either the second region 332 or the third region 333. It may also have areas that are not covered.

[0042] The second region 332 preferably has a different composition than the first region 331 .

[0043] For example, the first region 331 may have lithium, manganese, the element M, and oxygen, and the second region 332 has lithium, manganese, the element M and oxygen, and the lithium of the first region 331, The atomic ratio of manganese, element M, and oxygen is expressed as a1:b1:c1:d1, and the second region The atomic ratio of lithium, manganese, element M, and oxygen in region 332 is a2:b2:c2:d Here, d1÷(b1+c1) is preferably 2.2 or more. It is preferable that the ratio is 2.3 or more, and more preferable that the ratio is 2.35 or more and 3 or less. It is preferable that d2÷(b2+c2) is less than 2.2, and it is preferable that it is less than 2.1. It is more preferable that the ratio is 1.1 or more and 1.9 or less, and it is even more preferable that the ratio is 1.1 or more and 1.9 or less.

[0044] The manganese contained in the second region 332 is different from the manganese contained in the first region 331. The element M contained in the second region 332 may have a valence of 0.01 to 0.01. The element M may have a different valence from the element M.

[0045] More specifically, the first region 331 is made of lithium manganese having a layered rock salt type crystal structure. The second region 332 is preferably a composite oxide. It is preferable that the lithium manganese composite oxide is a lithium manganese composite oxide.

[0046] Here, if there is a spatial distribution in the composition of each region or the valence of elements, for example, The composition and valence of each of the regions are evaluated, and the average value is calculated. stomach.

[0047] A transition layer may also be provided between the second region 332 and the first region 331. A transition layer is, for example, a region where the composition changes continuously or stepwise. The transition layer is a region where the crystal structure changes continuously or stepwise. The second region 3 is a region where the lattice constant of the crystal changes continuously or stepwise. A mixed layer may be provided between the first region 32 and the second region 331. Here, the mixed layer may be, for example, a layer of different The mixed layer refers to a mixture of two or more crystals having different crystal orientations. For example, it refers to a mixture of two or more crystals with different crystal structures. For example, this refers to the case where two or more crystals with different compositions are mixed together.

[0048] The third region 333 preferably contains carbon. Carbon has high electrical conductivity, so it is preferable to cover the third region 333 with carbon. By using the coated particles in the electrodes of secondary batteries, it is possible to lower the resistance of the electrodes, for example. The coating layer may include graphene or graphene oxide, and may be reduced. The graphene and reduced graphene oxide may be It has excellent electrical properties, such as high conductivity, as well as high flexibility and mechanical strength. It has excellent physical properties.

[0049] The thickness of the coating layer is preferably 0.4 nm or more and 40 nm or less.

[0050] Alternatively, the third region 333 may have a metal compound. For example, cobalt, aluminum, nickel, iron, manganese, titanium, zinc, lithium, carbon Examples of metal compounds include oxides and fluorides of these metals. be ridiculed.

[0051] The third region 333 is more stable than the first region 331 and the second region 332 in terms of the ease of oxidation / reduction or the crystal structure with respect to battery reactions such as charging and discharging. It is preferable that it is.

[0052] Alternatively, a composite material (general formula LiMPO4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II))) can be used. Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFe Ni a Ni b PO4, LiFe a [[ID=...]] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​In particular, LiFePO4 is safe, stable, has high capacity density, and can be extracted during initial oxidation (charging). It satisfies the requirements for a positive electrode active material in a balanced manner, such as the presence of lithium ions. ,preferable.

[0054] Or, the general formula Li (2-j) MSiO4 (M is Fe(II), Mn(II), Co( A composite material such as one or more of Ni(II), Ni(II), 0≦j≦2) can be used. Formula Li (2-j) A typical example of MSiO4 is Li (2-j) FeSiO4, Li (2 -j) NiSiO4, Li (2-j) CoSiO4, Li (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j ) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (k+l is 1 or less, 0 <k<1、0<l<1)、Li (2-j) Fe m N i n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m 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 (where r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc., lithium compounds can be used as materials and so on.

[0055] [[ID=十七]]Also, as the positive electrode active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, M n, Ti, V, Nb, X = S, P, Mo, W, As, Si) of the general formula can be used. As the NASICON-type compound, there are Fe2(MnO4)3, F e2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the positive electrode active material, Li 2MPO4F, Li2MP2O, Li5MO4 (M = Fe, Mn) of the general formula compounds, perovskite-type fluorides such as NaFeF3, FeF3, etc., metal chalcogenides (sulfides, selenides, tellurides) such as TiS2, MoS2, etc oxides having a reverse spinel-type crystal structure such as LiMVO4, vanadium oxide systems (V2O5, V6O [[ID=3」]]O8, etc.), manganese oxides, organic sulfur compounds, etc. can be used as materials.

[0056] In addition, when the carrier ion is an alkali metal ion other than lithium ion or an alkaline earth metal ion ion, as the positive electrode active material, instead of lithium, an alkali metal (e.g., sodium lithium, potassium, etc.), an alkaline earth metal (e.g., calcium, strontium, barium ium, beryllium, magnesium, etc.) can be used. For example, NaFeO2, Na2 / 3 [Fe 1 / 2 Mn 1 / 2 It should be noted that there may be some inaccuracies in the translation due to the complexity of the chemical terms and the possible errors in the original text format. It is recommended to double-check with a professional in the relevant field.​​​]O2 as a positive electrode active material. It can be used.

[0057] Furthermore, a combination of the above materials may be used as the positive electrode active material. A solid solution of a combination of these materials can be used as the positive electrode active material. Co 1 / 3 Mn 1 / 3 Ni 1 / 3 A solid solution of O2 and Li2MnO3 was used as the positive electrode active material. It is possible.

[0058] Although not shown, a conductive material such as a carbon layer may be provided on the surface of the positive electrode active material layer 102. The conductivity of the electrode can be improved by providing a conductive material such as a carbon layer. For example, the carbon layer covering the positive electrode active material layer 102 may be formed by adding glucose or the like when baking the positive electrode active material. It can be formed by mixing carbohydrates.

[0059] The average particle size of the primary particles of the granular positive electrode active material layer 102 is 50 nm or more and 100 μm or less. It is recommended to use the following.

[0060] As the conductive additive, for example, a carbon material, a metal material, or a conductive ceramic material is used. In addition, a fibrous material may be used as the conductive additive. The content of the conductive additive is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less. % or less is more preferable.

[0061] The conductive additive can form an electrically conductive network in the electrode. This allows the electrical conduction path between the positive electrode active materials to be maintained. By adding the agent, an active material layer having high electrical conductivity can be realized.

[0062] Examples of the conductive additive include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fiber. Examples of carbon fibers that can be used include mesophase pitch carbon fibers. Carbon fibers such as isotropic pitch-based carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tube can be produced by, for example, vapor phase growth method. For example, carbon black (acetylene black (AB) etc.), graphite particles Carbon materials such as graphene and fullerene can be used. Metal powders and fibers such as nickel, aluminum, silver, and gold, as well as conductive ceramic materials, etc. It can be used.

[0063] Flaky graphene has excellent electrical properties, such as high conductivity, as well as flexibility and functionality. Graphene has excellent physical properties, such as mechanical strength, and is therefore used as a conductive additive. This makes it possible to increase the number of contact points and the contact area between the active materials.

[0064] In this specification, graphene refers to a single-layer graphene or a graphene having 2 to 100 layers. Single-layer graphene is a graphene consisting of a single atomic layer of carbon molecules with π bonds. Graphene oxide refers to a compound in which the graphene is oxidized. When graphene is formed by reducing graphene oxide, Not all of the oxygen contained in the graphene is released, and some of the oxygen remains in the graphene. When oxygen is present, the oxygen fraction is 2 atom percent of the total graphene as measured by XPS. % or more and 11 atomic % or less, preferably 3 atomic % or more and 10 atomic % or less c% or less.

[0065] Graphene allows for surface contact with low contact resistance, and is conductive even when thin. The conductivity is so high that even a small amount can efficiently form a conductive path within the active material layer.

[0066] When using an active material with a small average particle size, for example, an active material with a particle size of 1 μm or less, The area is large, and more conductive paths connecting the active materials are required. Graphene has extremely high conductivity and can efficiently form conductive paths even in small amounts. It is particularly preferred to use

[0067] An example of a cross-sectional structure in which graphene is used as a conductive additive in a positive electrode active material layer will be described below. Note that graphene may be used as a conductive additive in the negative electrode active material layer.

[0068] 3 shows a vertical cross-sectional view of the positive electrode active material layer 102. The positive electrode active material layer 102 is made of granular positive electrode active material. The conductive material 322 is a conductive material, graphene 321 is a conductive material, and a binder (not shown) is a conductive material. (including without limitation)

[0069] In the vertical cross section of the positive electrode active material layer 102, as shown in FIG. 3, the inside of the positive electrode active material layer 102 In FIG. 3, the graphene 321 is dispersed uniformly. 321 is shown in bold, but in reality it has a thickness of a single layer or multiple layers of carbon molecules. The plurality of graphenes 321 are arranged so as to wrap the plurality of particles of the positive electrode active material 322. The positive electrode active material 322 is formed so as to cover or to be stuck on the surface of the positive electrode active material 322. In addition, the graphene 321 also makes surface contact with each other. By doing so, multiple graphenes321 form a three-dimensional electrical conduction network. do.

[0070] This is because graphene oxide, which has extremely high dispersibility in polar solvents, is used to form graphene 321. The dispersion medium is evaporated and removed from the suspension containing uniformly dispersed graphene oxide. The graphene oxide is reduced to form graphene, and the graphene oxide is removed from the positive electrode active material layer 102. Graphene 321 is dispersed to the extent that it overlaps partially and is in surface contact with each other, The reduction of graphene oxide is carried out by, for example, heat treatment. Alternatively, a reducing agent may be used.

[0071] Therefore, unlike granular conductive additives such as acetylene black, which come into point contact with the active material, graphite Since the 321 allows for surface contact with low contact resistance, the amount of conductive additive is increased. The positive electrode active material 322 and the graphene 321 are electrically connected to each other without any problem. Therefore, by increasing the ratio of the positive electrode active material 322 in the positive electrode active material layer 102, This makes it possible to increase the discharge capacity of the secondary battery.

[0072] In addition, graphene is bonded to itself to form a mesh-like graphene (hereafter referred to as graphene network). When the active material is covered with a graphene net, Fennet can also function as a binder between particles. The amount of electrode can be reduced or eliminated, reducing the electrode volume and The ratio of active material to weight can be increased, i.e., the capacity of the secondary battery can be increased. It can be done.

[0073] The electrode used in the secondary battery of one embodiment of the present invention can be manufactured by various methods. When forming an active material layer on a current collector using a coating method, the active material, binder, and conductive additive are separated. A dispersion medium (also called a solvent) is mixed to make a paste, which is then applied to the current collector. After that, if necessary, pressure such as roll press or plate press can be used. It may be compacted by pressing using a shrinking method.

[0074] Examples of the dispersion medium include water, N-methylpyrrolidone (NMP), and dimethylformamide. From the viewpoint of safety and cost, water can be used. It is preferable to use

[0075] The binder preferably contains, for example, a water-soluble polymer. For example, polysaccharides can be used. Examples of polysaccharides include carboxymethyl cellulose. CMC, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose cellulose derivatives such as diacetyl cellulose and regenerated cellulose, and starch, etc. It is possible.

[0076] In addition, styrene-butadiene rubber (SBR), styrene-isoprene Styrene rubber, acrylonitrile butadiene rubber, butadiene rubber, fluororubber, It is preferable to use rubber materials such as ethylene-propylene-diene copolymers. It is more preferable to use the rubber material in combination with the water-soluble polymer described above.

[0077] Alternatively, the binder may be polystyrene, polymethyl acrylate, or polymethyl methacrylate. Polymethylmethacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), poly Ethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, Polytetrafluoroethylene, polyethylene, polypropylene, isobutylene, polyethylene Polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylonite Polyvinyl (PAN), Polyvinyl chloride, Ethylene propylene diene polymer, Polyacetic acid It is preferable to use materials such as vinyl, polymethyl methacrylate, and nitrocellulose. .

[0078] Two or more of the above binders may be used in combination.

[0079] The content of the binder relative to the total amount of the positive electrode active material layer 102 is 1 wt % or more and 10 wt % or less. It is preferable that the content of the hydroxybenzoate is 2 wt% or more and 8 wt% or less, more preferable that the content of the hydroxybenzoate is 3 wt% or more and 5 wt% or less. In addition, the content of the conductive additive relative to the total amount of the positive electrode active material layer 102 is preferably 1 wt % or more. The content is preferably from 1 to 10 wt%, more preferably from 1 to 5 wt%.

[0080] When the positive electrode active material layer 102 is formed by a coating method, the positive electrode active material, the binder, and the conductive additive are mixed. The positive electrode paste (slurry) is prepared by mixing the above, and is then applied onto the positive electrode current collector 101 and dried. That's fine.

[0081] [1.3. Negative electrode] The negative electrode 115 is composed of a negative electrode current collector 105 and a negative electrode active material layer 10 formed on the negative electrode current collector 105. It consists of 6 etc.

[0082] The negative electrode current collector 105 is made of metals such as stainless steel, gold, platinum, iron, copper, titanium, and the like, and Use materials such as alloys that are highly conductive and do not alloy with carrier ions such as lithium. In addition, heat-resistant materials such as silicon, titanium, neodymium, scandium, and molybdenum can be used. An aluminum alloy containing an element that improves the resistance can be used. 5 is a foil, plate (sheet), mesh, punched metal, expanded metal, etc. The negative electrode current collector 105 has a thickness of 5 μm or more and 30 μm or less. It is also preferable to use a material that is coated with graphite or the like on the surface of the negative electrode current collector 105. A dark coat layer may be provided.

[0083] The negative electrode active material layer 106 contains, in addition to the negative electrode active material, a binder (binder) for increasing the adhesion of the negative electrode active material. The negative electrode active material layer 106 may contain an indium ion or a conductive additive for increasing the conductivity of the negative electrode active material layer 106. The binder and conductive additive materials used in the active material layer are the same as those used in the positive electrode active material layer. The materials of the conductive additives can be taken into consideration.

[0084] The negative electrode active material is a material that can dissolve and deposit lithium or undergo a reversible reaction with lithium ions. Materials that can be used include lithium metal, carbon-based materials, alloy-based materials, etc. can.

[0085] Lithium metal has a low oxidation-reduction potential (-3.045 V vs. the standard hydrogen electrode) and is lightweight and and high specific capacity per volume (3860mAh / g and 2062mAh / cm, respectively) 3 ) and is therefore preferable.

[0086] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). Examples include carbon nanotubes, graphene, and carbon black.

[0087] Graphite includes mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch. These include artificial graphite such as spheroidized artificial graphite, and natural graphite such as spheroidized natural graphite.

[0088] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It exhibits a low potential similar to that of lithium metal (0.1V to 0.3V vs. Li / Li + This allows the lithium-ion secondary battery to exhibit a high operating voltage. Graphite has a relatively high capacity per unit volume, a small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to aluminum metals.

[0089] In addition to the carbon materials mentioned above, the negative electrode active material is also made of a material that undergoes alloying and dealloying reactions with carrier ions. Therefore, an alloy material capable of carrying out charge and discharge reactions can be used. In the case of lithium ions, examples of alloy materials include Mg, Ca, Al, Si, and Ge. , Sn, Pb, As, Sb, Bi, Ag, Au, Zn, Cd, Hg, and In, etc. A material containing at least one of these elements can be used. Silicon in particular has a theoretical capacity of 4200mAh / g, which is dramatically high. It is preferable to use silicon as the active material. , for example, Mg2Si, Mg2Ge, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. do.

[0090] In addition, the negative electrode active material is SiO, SnO, SnO2, titanium dioxide (TiO2), lithium Sodium titanium oxide (Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), Niobium pentoxide (Nb2O5), tungsten oxide (WO2), molybdenum oxide (MoO2 ) and other oxides can be used.

[0091] SiO refers to silicon oxide powder containing silicon-rich portions, and SiO y (2>y>0). For example, SiO can be expressed as Si2O3, Si3O4, or S Materials containing one or more selected from i2O, Si powder and silicon dioxide (SiO2 SiO also contains mixtures of other elements (carbon, nitrogen, iron, aluminum, copper, titanium). It may contain elements such as silicon, calcium, and manganese. i, including a plurality selected from polycrystalline Si, Si2O3, Si3O4, Si2O, and SiO2 SiO is a colored material. SiO is not SiO x (X is 2 or more) If present, they are colorless and transparent or white, making them distinguishable. After a secondary battery is fabricated using SiO, the SiO becomes an oxidant by repeated charging and discharging. When it is oxidized, it may be transformed into SiO2.

[0092] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) And preferable.

[0093] When a composite nitride of lithium and a transition metal is used, the negative electrode active material contains lithium ions, The positive electrode active material is a combination of materials such as V2O5 and Cr3O8 that do not contain lithium ions. It is preferable that a material containing lithium ions is used as the positive electrode active material. By first removing the lithium ions contained in the positive electrode active material, As the lithium-transition metal nitride, a complex nitride of lithium and a transition metal can be used.

[0094] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not undergo an alloying reaction with the negative electrode active material may be used. Further materials that undergo a reaction include Fe2O3, CuO, Cu2O, RuO2, and Cr2O Third order oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, G Nitrides such as e3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3 This also occurs with fluorides such as those listed above. Since the potential of the above fluorides is high, they are not suitable for use as positive electrode active materials. That's fine.

[0095] When the negative electrode active material layer 106 is formed by a coating method, the negative electrode active material and the binder are mixed together to form the negative electrode active material layer 106. An electrode paste (slurry) may be prepared, applied to the negative electrode current collector 105, and then dried.

[0096] Graphene may be formed on the surface of the negative electrode active material layer 106. When silicon is used, the volume due to the absorption and release of carrier ions during the charge and discharge cycle is Since the change in the negative electrode current collector 105 is large, the adhesion between the negative electrode active material layer 106 and the negative electrode current collector 105 is reduced, and the charge / discharge Therefore, the surface of the negative electrode active material layer 106 containing silicon is When graphene is formed on silicon, the volume of silicon changes during the charge-discharge cycle. In addition, it is possible to suppress a decrease in the adhesion between the negative electrode current collector 105 and the negative electrode active material layer 106. This is preferable because it reduces deterioration of the pond characteristics.

[0097] In addition, a coating of an oxide or the like may be formed on the surface of the negative electrode active material layer 106. The film formed by the decomposition of the electrolyte releases the charge consumed during its formation. In contrast, a film of oxide or the like is formed on the negative electrode active material in advance, and irreversible capacity is formed. By providing it on the surface of the layer 106, it is possible to suppress or prevent the occurrence of irreversible capacity. .

[0098] The coating that coats the negative electrode active material layer 106 may contain niobium, titanium, vanadium, tungsten, or the like. aluminum, tungsten, zirconium, molybdenum, hafnium, chromium, aluminum or or silicon oxide film, or a film containing one of these elements and lithium Such a coating can be formed on the negative electrode by the decomposition products of conventional electrolytes. This film is sufficiently dense compared to the coating formed on the surface.

[0099] For example, niobium oxide (Nb2O5) has an electrical conductivity of 10 -9 Low S / cm and high insulation Therefore, the niobium oxide film prevents the electrochemical decomposition reaction between the negative electrode active material and the electrolyte. On the other hand, the lithium diffusion coefficient of niobium oxide is 10 -9 cm 2 / sec, which is high It has lithium ion conductivity, which allows lithium ions to pass through. Silicon oxide or aluminum oxide may also be used.

[0100] The film that covers the negative electrode active material layer 106 can be formed by, for example, a sol-gel method. The sol-gel method is a method in which a solution of metal alkoxides and metal salts is subjected to hydrolysis and polymerization. This method involves creating a gel that loses fluidity through a condensation reaction, and then baking this gel to form a thin film. The sol-gel method is a method for forming thin films from a liquid phase, so the raw materials are mixed homogeneously at the molecular level. For this reason, the raw material for the metal oxide film at the solvent stage can be mixed with a negative electrode active material such as graphite. By adding the active material, it is possible to easily disperse the active material in the gel. A coating can be formed on the surface of the electrode active material layer 106. By using this coating, This can prevent the battery capacity from decreasing.

[0101] [1.4. Separator] The separator 103 may be made of a material such as cellulose or polypropylene (PP). , polyethylene (PE), polybutene, nylon, polyester, polysulfone, polya Uses porous insulators such as chlorine nitrile, polyvinylidene fluoride, and tetrafluoroethylene. In addition, nonwoven fabrics such as glass fiber and composites of glass fiber and polymer fiber can be used. A diaphragm may also be used.

[0102] [1.5. Electrolyte] The solvent of the electrolyte solution 104 used in the secondary battery 100 is preferably an aprotic organic solvent. , for example, ethylene carbonate (EC), propylene carbonate (PC), butylene Carbonate, chloroethylene carbonate, vinylene carbonate, gamma-butyrolactone γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (D EC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone oxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran One of tetrahydrofuran, sulfolane, sultone, etc., or two or more of these can be used in combinations and ratios of:

[0103] In addition, by using a polymer material that gels as a solvent for the electrolyte, safety against leakage is improved. Furthermore, it is possible to make the secondary battery thinner and lighter. Representative examples include silicone gel, acrylic gel, acrylonitrile gel, polyethylene gel, etc. Polypropylene oxide gel, polypropylene oxide gel, fluorine polymer gel, etc. be.

[0104] In addition, a flame-retardant and non-volatile ionic liquid (room-temperature molten salt) was used as the solvent for the electrolyte. Or by using multiple batteries, even if the internal temperature rises due to an internal short circuit or overcharging of the secondary battery, This can prevent the secondary battery from exploding or catching fire.

[0105] In addition, when lithium ions are used as a carrier, the electrolyte to be dissolved in the solvent is , such as LiPF6, LiClO4, LiAsF6, LiBF4, LiAlCl4, Li SCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 , Li2B 12 Cl1 2, LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2 F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2 ), LiN(C2F5SO2)2, or two or more of these lithium salts Any combination and ratio may be used.

[0106] In addition, the electrolyte used in secondary batteries is free from granular dust and elements other than the constituent elements of the electrolyte (hereinafter referred to as simple substances). It is preferable to use a highly purified electrolyte solution with a low content of impurities. Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less. It is more preferable that the content of vinylene carbonate in the electrolyte is 0.01% or less. Additives such as cellulose may also be added.

[0107] 1.6. Exterior Body There are various types of secondary battery structures. In this embodiment, the outer casing 107 is formed The film for forming the exterior body 107 is a metal film (aluminum). aluminum, stainless steel, nickel steel, etc.), plastic film made of organic materials, Hybrid materials that contain organic materials (such as organic resins and fibers) and inorganic materials (such as ceramics) Material film, carbon-containing inorganic film (carbon film, graphite film, etc.) A single layer film selected from the above or a laminated film made up of a plurality of these metal films is used. is easy to emboss, and when recesses or protrusions are formed by embossing, Since the surface area of ​​the exterior body 107 that comes into contact with the heat source increases, the heat dissipation effect is excellent.

[0108] In addition, when the shape of the secondary battery 100 is changed by applying an external force, the outside of the secondary battery 100 When external bending stress is applied to the exterior body 107, a part of the exterior body 107 is deformed or partially destroyed. By forming a recess or a protrusion on the exterior body 107, The strain caused by the applied stress can be alleviated. The reliability of the strain can be improved. It is a measure of deformation that indicates the displacement of a material point within an object. This reduces the effects of strain caused by applying external force to the secondary battery to within an acceptable range. Therefore, a highly reliable secondary battery can be provided.

[0109] [2. Variation 1] In FIG. 1, the second direction 202 connecting the tab portion of the positive electrode 111 and the tab portion of the negative electrode 115 is Although an example in which the direction is perpendicular to the first direction 201 that can be bent is shown, However, the present invention is not limited to this example, and the first direction and the second direction may be any direction other than parallel to each other.

[0110] An example of a secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 4(A1). 0, the first direction 201 and the second direction 202 are not perpendicular to each other. The battery 100 also has a tab for the positive electrode 111 and a tab for the negative electrode 115 that are relatively resistant to the influence of bending. It can be installed in a small number of places.

[0111] The positive electrode lead 121, the negative electrode lead 125, the tab of the positive electrode 111, and the tab of the negative electrode 115 For other details, please refer to the description of Figure 1.

[0112] [3. Variation 2] In addition, in FIG. 1, the positive electrode 111, the negative electrode 115, the separator 103, and the exterior body 107 are arranged in a substantially rectangular shape. However, one embodiment of the present invention is not limited to this.

[0113] An example of a secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 4(A2). 0, the positive electrode 111, the negative electrode 115, the separator 103, and the outer casing 107 are substantially oval. In the secondary battery 100 of FIG. 4(A2), the tab portion of the positive electrode 111 and the tab portion of the negative electrode 115 The second direction 202 connecting the two parts is perpendicular to the first direction 201 that can be curved. The secondary battery 100 having such a structure also has a tab for the positive electrode 111 and a tab for the negative electrode 112. The 15 tabs can be placed in areas that are less susceptible to bending.

[0114] The shapes of the positive electrode 111, the negative electrode 115, the separator 103, and the exterior body 107 are the same as those shown in FIG. Please refer to the explanatory notes regarding the above.

[0115] [4. Variation 3] An example of the secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 4(B1). The cross-sectional view taken along line -B2 is shown in FIG. 4(B2).

[0116] The secondary battery 100 in FIG. 4(B1) includes a positive electrode 111, a negative electrode 115, a separator 103, and an outer The housing 107 has a plurality of holes 211. The secondary battery 100 shown in FIG. 1, it is suitable for electronic devices that require holes, such as the band of a watch-type device. Therefore, the capacity of the secondary battery 100 can be increased. do.

[0117] The shapes of the positive electrode 111, the negative electrode 115, the separator 103, and the exterior body 107 are the same as those shown in FIG. Please refer to the explanatory notes regarding the above.

[0118] [5. Variation 4] An example of a secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 5(A). The positive electrode 111, the negative electrode 115, the separator 103, and the outer casing 107 can be curved. The length connecting the tab portion of the positive electrode 111 and the tab portion of the negative electrode 115 is longer than the length in the first direction 201 that can be The length in the second direction 202 is long. The tab of the negative electrode 115 and the tab of the negative electrode 116 can be provided at a location where the influence of the bending is relatively small. do.

[0119] The shapes of the positive electrode 111, the negative electrode 115, the separator 103, and the exterior body 107 are the same as those shown in FIG. Please refer to the explanatory notes regarding the above.

[0120] [6. Variation 5] An example of a secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 5(B1). The positive electrode 111 and the separator 103 of the battery 100 are shown in FIG. The negative electrode 115 is shown in FIG. 5(B3). A cross-sectional view of C2 is shown in FIG.

[0121] In the secondary battery 100 of FIG. 5(B1), the separator 103 is provided so as to cover the positive electrode 111. In this case, even if the positive electrode 111 does not have a notch, a short circuit between the positive electrode 111 and the negative electrode 115 can be prevented. It can be prevented.

[0122] In addition to the shape of the separator 103, the description of FIG. 1 can be taken into consideration. .

[0123] [7. Variation 6] An example of a secondary battery 100 different from that shown in FIG. 1 is shown in FIG. 6(A). The secondary battery 100 shown in FIG. 6(A) is 6(A) has a plurality of positive electrodes 111 and a plurality of negative electrodes 115. 6(C) is a perspective view showing the stacking order of the positive electrode 111 and the negative electrode 115 of the secondary battery 100. 6(B) shows a cross-sectional view taken along the dashed dotted line D1-D2 in FIG.

[0124] The secondary battery 100 shown in FIG. 6 includes a positive electrode 101 having a positive electrode active material layer 102 on one side of a positive electrode current collector 101. and four negative electrodes 115 each having a negative electrode active material layer 106 on one side of a negative electrode current collector 105. In addition, a separator 103 is provided so as to cover the positive electrode 111.

[0125] By having a plurality of positive electrodes 111 and a plurality of negative electrodes 115, the capacity of the secondary battery 100 can be increased. It can be made easier.

[0126] As shown in FIG. 6(C), the surfaces of the positive electrodes 111 that do not have the positive electrode active material layer are connected to each other by a separator. The negative electrodes 115 are arranged so as to face each other with the negative electrode active material layer 103 interposed therebetween, and the surfaces of the negative electrodes 115 which do not have the negative electrode active material layer are in contact with each other. The positive electrode 111 and the negative electrode 115 are laminated so as to form a layer.

[0127] By using such a layering order, the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer are stacked side by side. The metal-metal contact surface is formed between the active material layer and the separator. The coefficient of friction can be reduced compared to the contact surface.

[0128] Therefore, when the secondary battery 100 is bent, the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer are brought into contact with each other. By sliding, the stress caused by the difference between the inner and outer diameters of the curve can be released. This can suppress deterioration of the secondary battery 100. In addition, the secondary battery 100 can be made highly reliable. It is possible.

[0129] FIG. 7(A) shows an example of lamination of a positive electrode 111 and a negative electrode 115, which is different from that shown in FIG. 6. In FIG. 7(A), Two positive electrodes 111 each having a positive electrode active material layer 102 on both sides of a positive electrode current collector 101, and a negative electrode current collector Four negative electrodes 115 each having a negative electrode active material layer 106 on one side of the negative electrode 105 are stacked. Even with such a configuration, the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer are in contact with each other, i.e., the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer are in contact with each other. A contact surface can be created.

[0130] FIG. 7(B) shows an example of lamination of the positive electrode 111 and the negative electrode 115, which is different from that shown in FIG. 6. In FIG. 7(B), Two positive electrodes 111 each having a positive electrode active material layer 102 on both sides of a positive electrode current collector 101, and a negative electrode current collector Two negative electrodes 115 each having a negative electrode active material layer 106 on one side of the negative electrode current collector 105, 7B, a negative electrode 115 having a negative electrode active material layer 106 is laminated on the negative electrode 115. By providing active material layers on both sides of the body, the capacity per unit volume of the secondary battery 100 can be increased. It is possible.

[0131] FIG. 7C shows an example of lamination of the positive electrode 111 and the negative electrode 115, which is different from that shown in FIG. 6. In FIG. 7C, , a polymer-containing electrolyte solution is used as the electrolyte solution 104, and a set of a positive electrode 111, a negative electrode 115, The separator 103 is bonded with the electrolyte 104. When the secondary battery 100 is bent, the positive electrode 111 and the negative electrode 115 where the battery reaction takes place slide. This can suppress the following.

[0132] In addition, the surfaces of the positive electrodes 111 that do not have the positive electrode active material layer and the surfaces of the negative electrodes 115 that do not have the negative electrode active material layer are This allows for a large number of metal-to-metal contact surfaces, i.e., surfaces that do not have a metal-to-metal bond. When 100 is bent, the contact surfaces slide, and the difference between the inner and outer diameters of the bend creates a This allows the stress generated to be released.

[0133] This makes it possible to further suppress the deterioration of the secondary battery 100. It can be a secondary battery 100.

[0134] In the example of FIG. 7(C), the polymer contained in the electrolytic solution 104 is, for example, polyethylene oxy. Polyvinylidene fluoride, polyacrylate, polymer An acrylate-based polymer can be used. It is preferable to use a polymer that can gel 04. Polyvinylidene fluoride polymers are polymers containing polyvinylidene fluoride (PVDF). This refers to poly(vinylidene fluoride-hexafluoropropylene) copolymers and the like.

[0135] The above polymers can be determined by using an FT-IR (Fourier transform infrared spectrophotometer) or the like. For example, polyvinylidene fluoride polymers can be analyzed by FT-IR. The spectrum shows absorption indicating C—F bonds. The FT-IR spectrum shows absorption indicative of a C≡N bond.

[0136] The same steps as those described in the description of FIG. 1 are repeated except that a plurality of positive electrodes 111 and a plurality of negative electrodes 115 are stacked. Please refer to the attached.

[0137] [8. Variation 7] FIG. 8 shows an example of a secondary battery 100 having a positive electrode 111 and a negative electrode 115 with different lengths from those shown in FIG. The external appearance of the secondary battery 100 in a curved state is shown in FIG. 8(A). The cross-sectional views of the dashed line E1-E2 are shown in Figure 8(B) and Figure 8(C). 8(B) is a cross-sectional view of the secondary battery 100 in a curved state, and FIG. 8(C) is a cross-sectional view of the secondary battery 100 in a curved state. 8(C) and 8(D), the positive electrode 111, the negative electrode 115, and the separator 103 are selectively shown. vinegar.

[0138] The positive electrode 111 and the negative electrode 115 of the secondary battery 100 shown in FIG. 8 are, as shown in FIG. 8(B), When the secondary battery 100 is bent, the electrode on the inner diameter side is positioned closer to the bending direction than the electrode on the outer diameter side. It is shortened.

[0139] With this configuration, the secondary battery 100 can be curved with a certain curvature as shown in FIG. 8(C). When the electrode is bent, the ends of the positive electrode 111 and the negative electrode 115 can be aligned. The entire area of ​​the positive electrode active material layer 102 of the electrode 111 is covered with the negative electrode active material of the negative electrode 115. Therefore, the positive electrode active material of the positive electrode 111 can be disposed in an unnecessary manner. Therefore, the capacity per volume of the secondary battery 100 can be increased. This configuration allows the secondary battery 100 to be used with a large capacity. This is especially useful when the zero curvature is fixed.

[0140] The same steps as those described in the description of FIG. 1 are repeated except that a plurality of positive electrodes 111 and a plurality of negative electrodes 115 are stacked. Please refer to the attached.

[0141] Note that one embodiment of the present invention has been described in this embodiment. However, the present invention is not limited to these. For example, in one embodiment of the present invention, the positive electrode lead and the negative electrode lead are each Although an example in which the wires are drawn out from the opposing sides has been shown, one embodiment of the present invention is not limited to this. In some cases, or depending on the situation, one aspect of the present invention is to For example, in one aspect of the present invention, the secondary battery may be curved. However, one embodiment of the present invention is not limited to this. Alternatively, in one aspect of the present invention, the secondary battery may be deformed as needed, such as by bending or stretching, depending on the situation. Or, for example, in some cases, Alternatively, depending on the situation, in one aspect of the present invention, the secondary battery may be left in an uncurved state. For example, one embodiment of the present invention is applied to a lithium ion secondary battery. However, one aspect of the present invention is not limited to this. Accordingly, one aspect of the present invention is to provide a battery for various secondary batteries, lead acid batteries, lithium ion polymer secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, silver oxide zinc batteries, silver oxide zinc batteries, solid state batteries, air batteries, primary batteries, capacitors, Alternatively, the present invention may be applied to an electric double layer capacitor, a lithium ion capacitor, etc. For example, in some cases or depending on the situation, one aspect of the present invention is a lithium ion It does not have to be applied to secondary batteries.

[0142] In addition, a secondary battery having the features of the representative example and the modified example shown in this embodiment in combination is also available. It can also be a pond.

[0143] (Embodiment 2) In this embodiment, a method for manufacturing a secondary battery according to one embodiment of the present invention will be described with reference to FIGS. As an example, a method for manufacturing a secondary battery 100 shown in FIG. 6 will be described.

[0144] [1. Prepare the negative electrode] First, the negative electrode active material layer 106 is formed on the negative electrode current collector 105 and processed into the shape of the negative electrode 115. (Figure 9(A)).

[0145] [2. Prepare the positive electrode and cover it with a separator] Next, a positive electrode active material layer 102 is formed on the positive electrode current collector 101 and processed into the shape of a positive electrode 111. Next, the positive electrode 111 is sandwiched between the folded separator 103 (FIG. 9(B1)).

[0146] The outer peripheral portion of the separator 103 on the outside of the positive electrode 111 is joined to form a bag-shaped separator. The outer periphery of the separator 103 is bonded with an adhesive or the like. Alternatively, ultrasonic welding or heat fusion may be used.

[0147] In this embodiment, polypropylene is used as the separator 103. The outer periphery of the glass plate is bonded by heating. The bonded portion 103a is shown in FIG. 9(B2). The positive electrode 111 can be covered with a separator 103. The separator 103 is a positive electrode active material. It is only necessary to form the layer so as to cover the porous layer 102 , and it is not necessary to cover the entire positive electrode 111 .

[0148] Although the separator 103 is bent in FIG. 9, one embodiment of the present invention is not limited to this. For example, the positive electrode 111 may be sandwiched between two separators. The joint 103a may be formed so as to surround most of the four sides.

[0149] The outer periphery of the separator 103 is joined with gaps at regular intervals. The bonding may be performed in a dotted manner.

[0150] Alternatively, joining may be performed on only one side of the outer periphery. Alternatively, joining may be performed on only two sides of the outer periphery. Alternatively, joining may be performed on the four sides of the outer periphery. The edges can be made even.

[0151] 6 and 9, the positive electrode 111 is covered with the separator 103. However, one embodiment of the present invention is not limited thereto. For example, the negative electrode 115 may be used instead of the positive electrode 111. may be covered with a separator 103.

[0152] [3. Stacking the positive and negative electrodes] Next, the positive electrode 111 and the negative electrode 115 are stacked (FIG. 10(A)). Four positive electrodes 111 each having a positive electrode active material layer 102 formed on one side, and four negative electrode active material layers 106 formed on the other side. These are stacked in a stack of four negative electrodes 115. The negative electrode 115 is disposed so that the porous layer 106 faces the separator 103. The negative electrode active material layers are arranged so that the surfaces on which the negative electrode active material layers are not formed are in contact with each other.

[0153] [4. Connect the positive and negative leads] Next, the positive electrode tabs of the plurality of positive electrode current collectors 101 and the positive electrode lead 121 having the sealing layer 120 are , and ultrasonic waves are applied while pressure is applied to create an electrical connection (ultrasonic welding).

[0154] Furthermore, the lead electrodes are subject to stress caused by external force applied after the secondary battery 100 is manufactured. Therefore, when ultrasonically welding the positive electrode lead 121, a protrusion is used. Alternatively, the positive electrode tab may be sandwiched between bonding dies, forming a curved portion on the positive electrode tab separate from the connection area. By providing the portion, stress generated when external force is applied after the secondary battery 100 is manufactured can be absorbed. Therefore, the reliability of the secondary battery 100 can be improved.

[0155] Furthermore, the positive electrode tab is not limited to being curved, and the material of the positive electrode current collector may be stainless steel or the like. The thickness of the positive electrode current collector is set to 10 μm or less, which is sufficient for the production of secondary batteries. It may also be configured to facilitate relaxation of stress that occurs when an external force is applied later.

[0156] Of course, it goes without saying that a plurality of these may be combined to alleviate the stress concentration on the positive electrode tab. do not have.

[0157] Similarly to the positive electrode current collector 101, the negative electrode tabs of the negative electrode current collectors 105 and the sealing layer 120 The negative electrode lead 125 having the same is electrically connected by ultrasonic welding (FIG. 10(B)).

[0158] [5. Cover the positive and negative electrodes with an outer casing] Next, the film used for the exterior body is folded to sandwich the positive electrode 111 and the negative electrode 115 (FIG. 11(A) )).

[0159] Next, two sides of the folded and overlapped film are joined by thermocompression bonding to form a positive electrode 111 and a negative electrode 112. The electrode 115 is covered with the exterior body 107 (FIG. 11(B)). In FIG. 11(B), two sides of the exterior body 107 are shown. The area where the positive electrode lead is bonded by thermocompression is shown as a bonded area 107a. The negative electrode lead 121 and the negative electrode lead 125 overlap with the sealing layer 120 .

[0160] [6. Inject the electrolyte and seal] Next, the electrolyte 104 is poured into the unsealed side of the exterior body 107 (FIG. 12(A)). Then, the remaining side of the exterior body 107 is sealed while vacuuming, heating and pressurizing. These operations should be carried out in an oxygen-free environment, such as by using a glove box. The vacuuming can be performed using a vacuum sealer, a liquid injection sealer, etc. By sandwiching it between two heatable bars, it can be heated and pressurized. The conditions are, for example, a vacuum of 60 kPa, heating at 190°C, and pressure of 0.1 MPa. At this time, pressure may be applied to the positive and negative electrodes from above the exterior body 107. By applying pressure, air bubbles that may have been mixed in when the electrolyte was injected can be removed from between the positive and negative electrodes. Cut.

[0161] Through the above steps, the secondary battery 100 can be fabricated (FIG. 12(B)).

[0162] This embodiment mode can be implemented in appropriate combination with other embodiment modes and examples. be.

[0163] (Embodiment 3) A battery control device that can be used in combination with a secondary battery including the negative electrode described in the above embodiment Battery Management Unit (BMU), and the battery For transistors suitable for the circuits constituting the control unit, please refer to Figures 13 to 19. In this embodiment, a battery of a power storage device having battery cells connected in series will be described. The control unit will now be described.

[0164] When multiple battery cells connected in series are repeatedly charged and discharged, This causes variations in the charge and discharge characteristics, resulting in different capacities (output voltages) for each battery cell. In a series of battery cells, the total discharge capacity depends on the battery cell with the smallest capacity. If there is a difference in the capacity of each battery cell, the overall capacity of the battery will be reduced when it is discharged. If charging is performed based on the battery cell with the smallest capacity, there is a risk of insufficient charging. If charging is performed based on a larger battery cell, there is a risk of overcharging.

[0165] Therefore, the battery control unit of the power storage device having battery cells connected in series is It also has the function of reducing variations in capacity between battery cells, which can cause overcharging. The circuit configuration to equalize the capacitance variation between the capacitors can be a resistor type, a capacitor type, or an inverter type. There are other methods such as inductor type, but here we use a transistor with a small off-current to reduce capacitance variations. An example of a circuit configuration that can align the above will be described below.

[0166] As a transistor with low off-state current, a transistor having an oxide semiconductor in a channel formation region is OS transistors with low off-state current are preferred for power storage devices. By using it in the circuit configuration of the battery control unit of the device, the amount of charge leaking from the battery is reduced, This can suppress the decrease in capacity over time.

[0167] The oxide semiconductor used in the channel formation region is In-M-Zn oxide (M is Ga, Sn, Y, Zr, La, Ce, or Nd) is used to form an oxide semiconductor film. In the target, if the atomic ratio of 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 It is preferable that z1 / y1 is 1 or more and 6 or less, and more preferably 1 or more and 6 or less. When the upper limit is 6 or less, a CAAC-OS film is easily formed as the oxide semiconductor film.

[0168] Here, the CAAC-OS film will be described.

[0169] The CAAC-OS film is one of oxide semiconductor films having a plurality of crystal parts aligned along the c-axis.

[0170] Transmission Electron Microscope (TEM) A bright-field image and a combined analysis image of the diffraction pattern of the CAAC-OS film were obtained by using a microscope. By observing the TEM image, multiple crystalline regions can be identified. On the other hand, high-resolution TEM images also reveal clear boundaries between crystalline parts, i.e., grain boundaries. Therefore, the CAAC-OS film is It can be said that the decrease in electron mobility caused by grain boundaries is unlikely to occur.

[0171] When a high-resolution TEM image of the cross section of the CAAC-OS film was observed from a direction approximately parallel to the sample surface, It can be seen that the metal atoms are arranged in layers in the crystalline part. Each layer of metal atoms is The CAAC-OS film is formed on a surface (also called a surface to be formed) or on a surface that reflects the unevenness of the surface. The CAAC-OS film has a shape and is aligned parallel to the surface on which the film is formed or the upper surface.

[0172] On the other hand, a high-resolution TEM image of the plane of the CAAC-OS film was observed from a direction approximately perpendicular to the sample surface. It was confirmed that the metal atoms in the crystals were arranged in a triangular or hexagonal shape. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

[0173] X-ray diffraction (XRD) was performed on the CAAC-OS film. For example, a CAAC-OS film with InGaZnO4 crystals was found by structural analysis using the device. In the out-of-plane analysis, a peak was observed at a diffraction angle (2θ) of approximately 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. Therefore, the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is approximately aligned on the surface on which the film is formed or on the upper surface. You can see that it is oriented vertically.

[0174] In addition, the out-of-plane method of CAAC-OS film with InGaZnO4 crystals In the analysis by , in addition to the peak at 2θ around 31°, a peak also appeared at 2θ around 36°. The peak at 2θ around 36° is due to the presence of c-axis orientation in part of the CAAC-OS film. The CAAC-OS film contains crystals that do not have a 2θ of around 31°. It is preferable that the peak is exhibited at 2θ of around 36° and that the peak is not exhibited at 2θ of around 36°.

[0175] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. These are elements other than the main components of the oxide semiconductor film, such as silicon and transition metal elements. The elements that bond to oxygen more strongly than the metal elements that constitute the oxide semiconductor film, such as fluorine, are oxidized. By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, reducing its crystallinity. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide have an atomic radius (or molecular radius) is large, and when it is contained inside the oxide semiconductor film, The impurities contained in the oxide semiconductor film are likely to disturb the atomic arrangement and cause a decrease in crystallinity. Objects can act as carrier traps or carrier sources.

[0176] The CAAC-OS film is an oxide semiconductor film with a low density of defect states. Oxygen vacancies in the semiconductor film can become carrier traps or trap hydrogen, It can be a source of carrier generation.

[0177] Low impurity concentration and low defect level density (low oxygen vacancies) are called high purity intrinsic or The term "substantially highly purified intrinsic" refers to a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film. Since there are fewer carrier generation sources, the carrier density can be reduced. The transistor using the oxide semiconductor film has electrical characteristics ( It is also called normally-on.) It is rare for it to become a high-purity intrinsic or substantially high-purity The intrinsic oxide semiconductor film has few carrier traps. Transistors using this film have little fluctuation in electrical characteristics and are highly reliable. Note that it takes time for the charges trapped in the carrier traps in the oxide semiconductor film to be released. The impurity concentration is high and the charge is stable for a long time, so the charge may behave like a fixed charge. Therefore, a transistor using an oxide semiconductor film with a high density of defect states has unstable electrical characteristics. This may occur.

[0178] In addition, transistors using CAAC-OS films show improved electrical characteristics when irradiated with visible light or ultraviolet light. The fluctuation is small.

[0179] Note that an OS transistor is a transistor having silicon in a channel formation region (Si transistor). Since the band gap is larger than that of a semiconductor (transistor), dielectric breakdown does not occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated. For the above reasons, in the power storage device, a battery control unit applied to such a battery cell The above-mentioned OS transistor is suitable for the circuit configuration.

[0180] FIG. 13 shows an example of a block diagram of a power storage device. The power storage device BT00 shown in FIG. A terminal pair BT01, a terminal pair BT02, a switching control circuit BT03, and a switching circuit BT0 4, a switching circuit BT05, a transformer control circuit BT06, and a transformer circuit BT07, and a battery unit BT08 including a plurality of connected battery cells BT09.

[0181] In addition, in the power storage device BT00 of FIG. 13, the terminal pair BT01 and the terminal pair BT02 are A switching control circuit BT03, a switching circuit BT04, a switching circuit BT05, and a transformer control The part consisting of the circuit BT06 and the transformer circuit BT07 is called the battery control unit. It is possible.

[0182] The switching control circuit BT03 controls the operations of the switching circuits BT04 and BT05. Specifically, the switching control circuit BT03 controls the measured voltage of each battery cell BT09. Based on the voltage, the battery cells to be discharged (discharge battery cell group) and the battery cells to be charged (charge battery group) are selected. Determine the pond cell group.

[0183] Furthermore, the switching control circuit BT03 controls the determined discharge battery cell group and charge battery cell group. The control signal S1 and the control signal S2 are output based on the group. This control signal S1 connects the terminal pair BT01 and the discharge battery cell group. The control signal S2 is a signal that controls the switching circuit BT04 so as to connect the This control signal S2 is output to the switching circuit BT05. This is a signal that controls the switching circuit BT05 to connect the group.

[0184] The switching control circuit BT03 includes the switching circuits BT04, BT05, and Considering the configuration of the transformer circuit BT07, between the terminal pair BT01 and the discharge battery cell group or between the terminal Control is performed so that terminals of the same polarity are connected between the slave pair BT02 and the charging battery cell group. A signal S1 and a control signal S2 are generated.

[0185] The operation of the switching control circuit BT03 will now be described in detail.

[0186] First, the switching control circuit BT03 measures the voltage of each of the plurality of battery cells BT09. The switching control circuit BT03 then selects, for example, the battery cell BT09 having a voltage equal to or higher than a predetermined threshold. High voltage battery cells (high voltage cells), battery cells BT09 with voltages below a certain threshold are classified as low voltage It is determined to be a battery cell (low voltage cell).

[0187] There are various methods for determining whether a cell is a high-voltage cell or a low-voltage cell. For example, the switching control circuit BT03 selects the battery with the highest current among multiple battery cells BT09. The voltage of each battery cell BT0 is determined based on the voltage of the battery cell BT09 with the highest or lowest voltage. 9 may be a high-voltage cell or a low-voltage cell. In this case, the switching control circuit BT03 determines whether the voltage of each battery cell BT09 is equal to or greater than a predetermined ratio of the reference voltage. By doing so, it is possible to determine whether each battery cell BT09 is a high-voltage cell or a low-voltage cell. Then, the switching control circuit BT03 switches between the discharging battery cell group and the charging battery cell group based on the result of this judgment. Determine the pond cell group.

[0188] In addition, among the multiple battery cells BT09, high voltage cells and low voltage cells are mixed in various states. For example, the switching control circuit BT03 can select the voltage between high-voltage cells and low-voltage cells. The part with the most high-voltage cells connected in series is the discharge battery cell group. The switching control circuit BT03 charges the part with the most low-voltage cells connected in series. The switching control circuit BT03 detects whether the battery cells are close to being overcharged or overdischarged. Even if the battery cell group BT09 is preferentially selected as a discharge battery cell group or a charge battery cell group, good.

[0189] An example of the operation of the switching control circuit BT03 in this embodiment will now be described with reference to FIG. FIG. 14 is a diagram for explaining an example of the operation of the switching control circuit BT03. For convenience of explanation, FIG. 14 shows an example in which four battery cells BT09 are connected in series. Reveal.

[0190] First, in the example of FIG. 14(A), if the voltages of the battery cells a to d are voltages Va to Vd, then , Va=Vb=Vc>Vd. In other words, three consecutive high voltages The high-voltage cells a to c and one low-voltage cell d are connected in series. The control circuit BT03 determines three consecutive high-voltage cells a to c as a discharge battery cell group. In addition, the switching control circuit BT03 determines the low voltage cell d as the charging battery cell group. .

[0191] Next, the example of FIG. 14B shows a case where the relationship is Vc>Va=Vb>>Vd. That is, between two consecutive low voltage cells a and b, one high voltage cell c, and one over-discharge In this case, the switching control circuit BT03 is configured as follows: The high-voltage cell c is determined as the discharge battery cell group. Since the high-voltage cell d is close to over-discharge, it is the low-voltage cell a and b that are the two consecutive low-voltage cells. The pressure cell d is determined as the charging battery cell group with priority.

[0192] Finally, the example of FIG. 14(C) shows a case where the relationship Va>Vb=Vc=Vd holds. 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 BT03 determines the high voltage cell a as the discharge battery cell group. The switching control circuit BT03 also determines whether to charge three consecutive low-voltage cells b to d. Determined as a battery cell group.

[0193] The switching control circuit BT03 determines the results as shown in the examples of FIGS. 14(A) to 14(C). Based on this, information indicating the discharge battery cell group to which the switching circuit BT04 is connected is set. The control signal S1 and information indicating the charging battery cell group to which the switching circuit BT05 is connected are set. The control signal S2 thus determined is sent to the switching circuit BT04 and the switching circuit BT05. Each is output.

[0194] The above is a detailed explanation of the operation of the switching control circuit BT03.

[0195] The switching circuit BT04 is responsive to the control signal S1 output from the switching control circuit BT03. The connection destination of the terminal pair BT01 is set to the discharge battery cell determined by the switching control circuit BT03. Set it to the rule group.

[0196] The terminal pair BT01 is composed of a pair of terminals A1 and A2. In this case, either one of the terminals A1 and A2 is connected to the most upstream (high voltage) of the discharge battery cell group. The other end is connected to the positive terminal of the battery cell BT09 located at the top of the discharge battery cell group. By connecting it to the negative terminal of the battery cell BT09 located downstream (low potential side), The switching circuit BT04 is set to the connection destination of the pair BT01. The position of the discharged battery cell group can be recognized using the obtained information.

[0197] The switching circuit BT05 is responsive to the control signal S2 output from the switching control circuit BT03. The connection destination of the terminal pair BT02 is determined by the switching control circuit BT03. Set it to the rule group.

[0198] The terminal pair BT02 is composed of the pair of terminals B1 and B2. In this case, either one of the terminals B1 and B2 is connected to the most upstream (high voltage) of the charging battery cell group. The other end is connected to the positive terminal of the battery cell BT09 located at the top of the charging battery cell group. By connecting it to the negative terminal of the battery cell BT09 located downstream (low potential side), The connection destination of the BT02 is set. The switching circuit BT05 is set by the control signal S2. The position of the charging battery cell group can be recognized using the obtained information.

[0199] 15 and 16 are circuit diagrams showing examples of the configuration of the switching circuits BT04 and BT05. Shown in 6.

[0200] In FIG. 15, the switching circuit BT04 includes a plurality of transistors BT10 and buses BT11 and BT12. The bus BT11 is connected to the terminal A1. 2 is connected to the terminal A2. One of them is alternately connected to buses BT11 and BT12. The other of the sources or drains of the plurality of transistors BT10 is connected to two adjacent It is connected between battery cells BT09.

[0201] Among the multiple transistors BT10, the transistor BT10 located at the most upstream position The other of the source and drain is connected to the positive electrode of the battery cell BT09 located at the most upstream of the battery module BT08. The transistor BT10 located at the most downstream position is connected to the terminal. The other of the source and drain of the transistor BT10 is located at the most downstream of the battery section BT08. It is connected to the negative terminal of the battery cell BT09.

[0202] The switching circuit BT04 controls the control signal S1 to be applied to the gates of the plurality of transistors BT10. In response, one of the plurality of transistors BT10 connected to the bus BT11 and and one of the plurality of transistors BT10 connected to T12 are brought into a conductive state. By doing so, the discharge battery cell group and the terminal pair BT01 are connected. The positive terminal of the battery cell BT09, which is located most upstream in the group of cells, is connected to the terminal A1 or A2 of the terminal pair. 2. In addition, the battery cell located most downstream in the discharge battery cell group is connected to either The negative terminal of the BT09 terminal is the other of the terminals A1 or A2 of the terminal pair, i.e., the positive terminal The terminal that is not connected to the

[0203] It is preferable to use an OS transistor for the transistor BT10. Since the off-state current of the capacitor is small, it reduces the amount of charge leaking from battery cells that do not belong to the discharge battery cell group. This prevents the capacitance from decreasing over time. Therefore, the output voltage of the discharged battery cell group is large. Even if the transistor BT10 is not in a conductive state, the battery cell BT09 and the terminal pair It is possible to insulate the BT01.

[0204] In addition, in FIG. 15, the switching circuit BT05 includes a plurality of transistors BT13 and a current control The bus BT15 and the bus BT16 are connected to the switch BT14. 16 is disposed between the plurality of transistors BT13 and the current control switch BT14. The sources or drains of the plurality of transistors BT13 are alternately connected to each other. The buses BT15 and BT16 are connected to the plurality of transistors BT13. The other of the source and drain is connected between two adjacent battery cells BT09. are.

[0205] Among the multiple transistors BT13, the transistor BT13 located at the most upstream The other of the source and drain is connected to the positive electrode of the battery cell BT09 located at the most upstream of the battery module BT08. The transistor BT13 located at the most downstream position is connected to the terminal. The other of the source and drain of the transistor BT13 is located at the most downstream of the battery section BT08. It is connected to the negative terminal of the battery cell BT09.

[0206] The transistor BT13 is an OS transistor, similar to the transistor BT10. Since the OS transistor has a small off-state current, it is preferable that the OS transistor does not belong to the rechargeable battery cell group. This reduces the amount of charge leaking from the battery cell and prevents the capacity from decreasing over time. In addition, OS transistors are less likely to experience dielectric breakdown when high voltages are applied. Transistor BT that remains non-conductive even when the voltage for charging the battery cell group is large. The battery cell BT09 to which the terminal pair BT02 is connected can be insulated from the terminal pair BT02.

[0207] The current control switch BT14 has a switch pair BT17 and a switch pair BT18. One end of the switch pair BT17 is connected to the terminal B1. The end is branched by two switches, one of which is connected to bus BT15 and the other The switch pair BT16 is connected to the bus BT16. One end of the switch pair BT18 is connected to the terminal B2. The other end of the switch pair BT18 is branched into two switches, while The switch is connected to bus BT15, and the other switch is connected to bus BT16. .

[0208] The switches included in the switch pair BT17 and the switch pair BT18 are transistors BT10 Similarly to the transistor BT13, an OS transistor is preferably used.

[0209] The switching circuit BT05 switches the transistor BT13 and the current control By controlling the combination of on / off states of the switch BT14, the charging battery cell group and terminal pair BT02.

[0210] As an example, the switching circuit BT05 connects the charging battery cell group and the terminal pair BT0 as follows: Connect 2.

[0211] The switching circuit BT05 controls the control signal S2 to be applied to the gates of the plurality of transistors BT13. In response, the positive terminal of the battery cell BT09 located most upstream in the charging battery cell group is connected. The switching circuit BT05 turns on the transistor BT13 connected to the In response to the control signal S2 applied to the gate of the transistor BT13, The switching transistor connected to the negative terminal of the most downstream battery cell BT09 Set BT13 to conductive state.

[0212] The polarity of the voltage applied to terminal pair BT02 is the same as that of the discharge battery cell group connected to terminal pair BT01. The method of charging the battery cell group may vary depending on the configuration of the transformer circuit BT07. To allow current to flow in the same direction, the terminals of the same polarity must be connected between the terminal pair BT02 and the charging battery cells. Therefore, the current control switch BT14 is controlled by the control signal S2 as follows: Depending on the polarity of the voltage applied to terminal pair BT02, switch pair BT17 and switch pair BT It is controlled to switch between each of the 18 connection destinations.

[0213] As an example, a voltage is applied to the terminal pair BT02 such that terminal B1 is positive and terminal B2 is negative. At this time, the most downstream battery cell BT09 of the battery module BT08 If the battery cell group is a charging battery cell group, the switch pair BT17 switches the battery cell group by the control signal S2. The positive terminal of the switch pair BT17 is connected to the positive terminal of the switch pair BT09. The switch connected to bus BT16 is turned on, and the bus BT1 of switch pair BT17 is turned on. On the other hand, the switch pair BT18 is in the OFF state when the control signal S2 This controls the connection to the negative terminal of the battery cell BT09. The switch connected to the bus BT15 of the switch pair BT18 is turned on, and The switch connected to the bus BT16 of T18 is turned off. Between the BT02 and the charging battery cell group, terminals with the same polarity are connected. The direction of the current flowing from the BT02 slave pair is controlled so that it charges the battery cell group. will be done.

[0214] Also, the current control switch BT14 is connected to the switching circuit BT05, not the switching circuit BT In this case, the current control switch BT14 may be included in the control signal S1. By controlling the polarity of the voltage applied to the terminal pair BT01, the voltage applied to the terminal pair BT02 can be controlled. The current control switch BT14 controls the polarity of the voltage applied to the terminal pair BT02. This controls the direction of current flowing from the battery to the charging battery cell group.

[0215] FIG. 16 shows a configuration example of the switching circuit BT04 and the switching circuit BT05, which is different from that shown in FIG. FIG.

[0216] In FIG. 16, the switching circuit BT04 includes a plurality of transistor pairs BT21 and a bus BT24. and a bus BT25. The bus BT24 is connected to the terminal A1. BT25 is connected to the terminal A2. Each of them is branched by the transistor BT22 and the transistor BT23. One of the source and drain of BT22 is connected to the bus BT24. One of the source and drain of the resistor BT23 is connected to the bus BT25. The other ends of the transistor pairs BT21 are connected between two adjacent battery cells BT09. Among the multiple transistor pairs BT21, the transistor located at the most upstream The other end of the transistor pair BT21 is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery section BT08. Also, the most downstream of the plurality of transistor pairs BT21 is connected to the pole terminal. The other end of the transistor pair BT21 is connected to the battery cell BT0 located at the most downstream of the battery section BT08. 9 is connected to the negative terminal.

[0217] The switching circuit BT04 switches between the transistor BT22 and the transistor BT30 in response to the control signal S1. By switching the conductive / non-conductive state of BT23, the connection of the transistor pair BT21 is The connection destination is switched to either terminal A1 or terminal A2. If T22 is conductive, transistor BT23 is non-conductive and is connected to terminal On the other hand, if the transistor BT23 is in a conducting state, the transistor BT22 The transistors BT22 and BT23 are in a non-conducting state and are connected to the terminal A2. Which of the switches BT23 is turned on is determined by a control signal S1.

[0218] Two transistor pairs BT21 are used to connect the terminal pair BT01 to the discharge battery cell group. In detail, the connection destination of the two transistor pairs BT21 is determined based on the control signal S1. By determining the terminal pair BT01 and the terminal pair BT02, the discharge battery cell group is connected to the terminal pair BT01. One of the two transistor pairs BT21 is connected to terminal A1, and the other is connected to terminal A2 by the control signal S1.

[0219] The switching circuit BT05 includes a plurality of transistor pairs BT31, a bus BT34, and a bus BT The bus BT34 is connected to the terminal B1. The bus BT35 has One end of each of the plurality of transistor pairs BT31 is connected to the terminal B2. The output is branched by the transistor BT32 and the transistor BT33. One end of the branched signal is connected to a bus BT34. One end of the branch is connected to a bus BT35. The other end of each is connected between two adjacent battery cells BT09. Among the changeover switch pairs BT31, the changeover switch pair BT31 located at the most upstream The other end is connected to the positive terminal of the battery cell BT09 located at the most upstream position of the battery unit BT08. In addition, among the plurality of transistor pairs BT31, the transistor pair BT located at the most downstream The other end of the terminal 31 is connected to the negative terminal of the battery cell BT09 located at the most downstream side of the battery unit BT08. It is being done.

[0220] The switching circuit BT05 switches between the transistor BT32 and the transistor BT33 in response to the control signal S2. By switching the conductive / non-conductive state of BT33, the connection of the transistor pair BT31 is The connection destination is switched to either terminal B1 or terminal B2. If T32 is conductive, transistor BT33 is non-conductive and is connected to terminal Conversely, if the transistor BT33 is in a conducting state, the transistor BT32 The transistors BT32 and BT33 are in a non-conducting state and are connected to the terminal B2. Which of the switches BT33 is turned on is determined by a control signal S2.

[0221] Two transistor pairs BT31 are used to connect the terminal pair BT02 to the charging battery cells. In detail, the connection destination of the two transistor pairs BT31 is determined based on the control signal S2. By determining the terminal pair BT02, the charging battery cell group is connected to the terminal pair BT02. One of the two transistor pairs BT31 is connected to terminal B1, and the other is connected to terminal B2 by the control signal S2.

[0222] The two transistor pairs BT31 are connected to the terminal pair BT02. Specifically, terminal B1 is positive and terminal B2 is negative. When such a voltage is applied to the terminal pair BT02, the upstream transistor pair BT31 , the transistor BT32 is in a conducting state and the transistor BT33 is in a non-conducting state. On the other hand, the downstream transistor pair BT31 is controlled by the control signal S2. The transistor BT33 is controlled to be in a conductive state and the transistor BT32 is controlled to be in a non-conductive state. It is controlled by the signal S2. Also, the voltage that makes the terminal B1 negative and the terminal B2 positive is When a voltage is applied to the terminal pair BT02, the upstream transistor pair BT31 The control is performed so that the transistor BT33 is in a conducting state and the transistor BT32 is in a non-conducting state. On the other hand, the downstream transistor pair BT31 is controlled by the transistor The control signal S2 is supplied to the transistor BT32 so that the transistor BT32 is in a conducting state and the transistor BT33 is in a non-conducting state. In this way, the same voltage is applied between the terminal pair BT02 and the charging battery cell group. The terminals with the same polarity are connected together. The direction of the current flowing from the terminal pair BT02 is The battery cells are controlled to charge.

[0223] The transformer control circuit BT06 controls the operation of the transformer circuit BT07. , the number of battery cells BT09 included in the discharge battery cell group and the number of battery cells BT09 included in the charge battery cell group Based on the number of cells BT09, a transformer signal S3 is generated to control the operation of the transformer circuit BT07. and outputs it to the transformer circuit BT07.

[0224] The number of battery cells BT09 included in the discharge battery cell group is equal to the number of battery cells BT09 included in the charge battery cell group. If the number of battery cells is greater than the number of BT09, an excessively large charging voltage will be applied to the charging battery cell group. Therefore, the transformer control circuit BT06 is The transformer circuit BT07 is used to lower the discharge voltage (Vdis) to a level that allows the cells to be charged. It outputs a control transformer signal S3.

[0225] In addition, the number of battery cells BT09 included in the discharging battery cell group is If the number of battery cells is less than or equal to the number of BT09, the charge required to charge the battery cell group is Therefore, the voltage transformer control circuit BT06 detects excess voltage in the charging battery cell group. The voltage transformer circuit is designed to boost the discharge voltage (Vdis) within a range where a large charge voltage is not applied to the The transformer outputs a transformer signal S3 that controls the circuit BT07.

[0226] The voltage value that constitutes an excessively high charging voltage is the voltage value of the battery cell BT08 used in the battery module BT08. The voltage can be determined in consideration of the product specifications of 09. The stepped-down voltage is applied to the terminal pair BT02 as a charging voltage (Vcha).

[0227] Here, an example of the operation of the transformer control circuit BT06 in this embodiment is shown in FIGS. 17(A) to 17(C). 17(A) to 17(C) show the discharges explained in FIGS. 14(A) to 14(C). An example of the operation of the voltage transformer control circuit BT06 corresponding to the battery cell group and the charge battery cell group will be explained. 17(A) to 17(C) are conceptual diagrams for illustrating the battery control unit BT41. As described above, the battery control unit BT41 has the terminal pair BT01 and the terminal pair B T02, a switching control circuit BT03, a switching circuit BT04, and a switching circuit BT0 5, a voltage transformation control circuit BT06, and a voltage transformation circuit BT07.

[0228] In the example shown in FIG. 17(A), three consecutive high voltages are applied as described in FIG. 14(A). Cells a to c and one low-voltage cell d are connected in series. In this case, as shown in FIG. As explained above with reference to the example of the switching control circuit BT03, the switching control circuit BT03 controls the high voltage cells a to c to the discharge voltage. The low-voltage cell d is determined as the battery cell group, and the low-voltage cell d is determined as the charging battery cell group. The control circuit BT06 is based on the number of battery cells BT09 included in the discharge battery cell group. , based on the ratio of the number of battery cells BT09 included in the charging battery cell group, the discharge voltage (Vdi Calculate the conversion ratio N from the current (V) to the charging voltage (Vcha).

[0229] The number of battery cells BT09 included in the discharge battery cell group is equal to the number of battery cells BT09 included in the charge battery cell group. If the number of battery cells is greater than the number of BT09, the discharge voltage is directly applied to the terminal pair BT02 without being transformed. When this voltage is applied, a voltage is applied to battery cell BT09 in the charging battery cell group via terminal pair BT02. There is a possibility that excessive voltage will be applied. Therefore, in the case shown in FIG. Therefore, the charging voltage (Vcha) applied to the terminal pair BT02 must be lower than the discharging voltage. Furthermore, in order to charge the battery cell group, the charging voltage must be It must be greater than the total voltage of the included battery cells BT09. Therefore, the voltage transformer control circuit B T06 is the charging voltage when the number of battery cells BT09 included in the discharge battery cell group is used as the reference. The conversion ratio N is set to be larger than the ratio of the number of battery cells BT09 included in the battery cell group.

[0230] The transformer control circuit BT06 determines the number of battery cells BT09 included in the discharge battery cell group as a standard. When the conversion ratio N is 1, the ratio of the number of battery cells BT09 included in the charging battery cell group is At this time, the charging voltage is preferably set to be about 10% or more higher than the voltage of the charging battery cell group. However, the charging voltage is actually equal to the voltage of the charging battery cell group. The control circuit BT06 controls the voltage of the charging battery cell group to be equal to the charging voltage according to the conversion ratio N. This current flows to charge the battery cell group. The set value will be used.

[0231] In the example shown in FIG. 17(A), the number of battery cells BT09 included in the discharge battery cell group is 3. Since the number of battery cells included in the charging battery cell group is one, the voltage transformer control circuit The BT06 calculates a conversion ratio N that is slightly larger than 1 / 3. BT06 converts the discharge voltage into a charge voltage by converting the discharge voltage into a charge voltage according to the conversion ratio N. The transformer circuit BT07 then outputs the voltage signal S3 to the transformer circuit BT07. The charging voltage applied to the terminal pair BT02 is then applied to the terminal pair BT02. The battery cell BT09 included in the charging battery cell group is charged by the charging voltage.

[0232] In the examples shown in FIG. 17(B) and FIG. 17(C), as in FIG. 17(A), the conversion ratio N In the examples shown in FIG. 17(B) and FIG. 17(C), the The number of battery cells BT09 included in the charging battery cell group is less than or equal to the number of battery cells BT09 included in the charging battery cell group. Therefore, the conversion ratio N is 1 or more. The transformer outputs a transformer signal S3 that boosts the applied voltage and converts it into a charging voltage.

[0233] The transformer circuit BT07 adjusts the discharge voltage applied to the terminal pair BT01 based on the transformer signal S3. The transformer circuit BT07 converts the converted charging voltage into a charging voltage. 2. Here, the transformer circuit BT07 connects the terminal pair BT01 and the terminal pair BT02. This allows the transformer circuit BT07 to be electrically isolated from the lowest discharged battery cell group. The absolute voltage of the negative terminal of the battery cell BT09 located downstream and the most downstream of the charging battery cells This prevents a short circuit due to a difference in absolute voltage between the negative terminal of the battery cell BT09 located at the Then, as described above, the transformer circuit BT07 converts the sum of the discharged battery cell groups into the sum of the discharged battery cells based on the transformer signal S3. The discharge voltage, which is the measured voltage, is converted into the charge voltage.

[0234] The transformer circuit BT07 is, for example, an isolated DC (Direct Current)-DC In this case, the transformer control circuit BT06 is an isolated DC- The signal that controls the on / off ratio (duty ratio) of the DC converter is the transformer signal S3. By outputting this voltage, the charging voltage converted by the transformer circuit BT07 is controlled.

[0235] In addition, there are various types of isolated DC-DC converters, including flyback, forward, and RCC ( Ring Choke Converter type, push-pull type, half-block type There are various types of inverters, such as full-bridge and ridge types, depending on the desired output voltage. The appropriate method is selected based on the results.

[0236] The configuration of the transformer circuit BT07 using an isolated DC-DC converter is shown in Figure 18. The C-DC converter BT51 has a switch unit BT52 and a transformer unit BT53. The switch BT52 is a switch that switches the operation of the isolated DC-DC converter on and off. For example, MOSFET (Metal-Oxide-Semiconductor tor Field-Effect Transistor) and bipolar transistor The switch unit BT52 is realized by using a transformer or the like. Based on the transformer signal S3 that controls the on / off ratio, the isolated DC-DC converter The switch BT51 is periodically switched between the on and off states. Various configurations are possible depending on the type of isolated DC-DC converter used. BT53 converts the discharge voltage applied from the terminal pair BT01 into a charge voltage. The transformer section BT53 operates in conjunction with the on / off state of the switch section BT52. The discharge voltage is converted into a charge voltage according to the on / off ratio. This charge voltage is In the switching period of 2, the longer the ON time, the larger the capacitance becomes. The voltage is increased as the ON time of the switch unit BT52 is shorter in the switching period. When using an isolated DC-DC converter, the transformer part BT53 Internally, terminal pair BT01 and terminal pair BT02 can be isolated from each other.

[0237] The flow of processing by power storage device BT00 in this embodiment will be described with reference to FIG. 10 is a flowchart showing the flow of processing by power storage device BT00.

[0238] First, the power storage device BT00 acquires the voltage measured for each of the plurality of battery cells BT09 (step Step S001). Then, the power storage device BT00 aligns the voltages of the plurality of battery cells BT09. It is determined whether or not the start condition of the operation is satisfied (step S002). For example, the difference between the maximum and minimum voltages measured for each of the plurality of battery cells BT09 is a predetermined value. If this start condition is not met (step S0 02:NO), the voltage of each battery cell BT09 is balanced, so the stored On the other hand, if the start condition is met (step S 002: YES), the power storage device BT00 executes a process to equalize the voltages of the battery cells BT09. In this process, the power storage device BT00 calculates the voltage of each cell based on the measured voltage of each cell. It is determined whether the battery cell BT09 is a high-voltage cell or a low-voltage cell (step S003). The power storage device BT00 determines the discharge battery cell group and the charge battery cell group based on the determination result. (Step S004). Furthermore, the power storage device BT00 sets the determined discharge battery cell group as A control signal S1 is sent to set the connection destination of the terminal pair BT01, and the determined charging battery cell group is set to the terminal A control signal S2 is generated to set the connection destination of the power storage device BT02 (step S005). The BT00 transmits the generated control signals S1 and S2 to the switching circuit BT04 and the switching circuit BT05. Then, the terminal pairs are output to the switching circuit BT05 by the switching circuit BT04. BT01 is connected to the discharge battery cell group, and the terminal pair BT02 is connected to the terminal pair BT03 by the switching circuit BT05. and the discharge battery cell group are connected (step S006). The number of battery cells BT09 included in the battery cell group and the number of battery cells included in the rechargeable battery cell group Based on the number of BT09, a transformed signal S3 is generated (step S007). The power storage device BT00 adjusts the discharge voltage applied to the terminal pair BT01 based on the transformation signal S3. The voltage is converted into a charging voltage and applied to the terminal pair BT02 (step S008). The charge of the battery cells is transferred to the charging battery cells.

[0239] In addition, in the flowchart of FIG. 19, multiple steps are listed in order, but each step The order in which the steps are executed is not limited to the order in which they are listed.

[0240] As described above, according to this embodiment, when transferring charges from the discharge battery cell group to the charge battery cell group, Like the capacitor method, the charge from the discharged battery cells is first stored and then transferred to the charged battery cells. This eliminates the need for a configuration that emits electrons into groups. This increases the charge transfer efficiency per unit time. In addition, the switching circuits BT04 and BT05 can improve the Therefore, among the discharge battery cell group and the charge battery cell group, the battery cells connected to the transformer circuit are individually Can be switched.

[0241] Furthermore, the number of battery cells BT09 included in the discharge battery cell group is determined by the transformer circuit BT07. The number of battery cells BT09 included in the charging battery cell group is determined based on the voltage applied to the terminal pair BT01. The discharge voltage is converted into a charge voltage and applied to the terminal pair BT02. Regardless of the selection of the BT09 battery cells on the side and the charging side, charge transfer can be achieved without any problems. can.

[0242] Furthermore, by using OS transistors for the transistors BT10 and BT13, As a result, leakage occurs from the battery cell BT09 that does not belong to the charging battery cell group or the discharging battery cell group. This reduces the charge amount of the battery cell BT09 that does not contribute to charging and discharging. In addition, OS transistors have the advantage over Si transistors in that they can suppress the decrease in capacitance. This causes the temperature of the battery cell BT09 to rise, However, normal operation, such as switching between conductive and non-conductive states according to the control signals S1 and S2, is also possible. This can be done.

[0243] (Fourth embodiment) In this embodiment, an example in which the secondary battery described in Embodiment 1 is mounted in an electronic device will be described. Reveal.

[0244] An example of mounting a flexible secondary battery in a wristband-type electronic device is shown in Figure 20. The armband type device 7300 can be worn on an arm 7301 and has a curved surface. The display has a display unit and a bendable secondary battery.

[0245] In addition, in the display unit, a display element, a display device which is a device having a display element, a light-emitting element, and A light-emitting device, which is a device having a light-emitting element, can be formed in various forms or can include various elements. The display element, the display device, the light-emitting element, or the light-emitting device may include, for example, an EL (electroluminescent) Electroluminescence) elements (EL elements including organic and inorganic materials, organic EL elements, inorganic EL elements), LEDs (white LEDs, red LEDs, green LEDs, blue LEDs, etc.), transistors (transistors that emit light according to the current), electron-emitting devices, liquid crystal devices, electronic ink, Electrophoretic element, Grating Light Valve (GLV), Plasma Display (PDP) ), display elements using MEMS (microelectromechanical systems), digital Digital Micromirror Device (DMD), Digital Micro Shutter (DMS), MIRASOL®, an IMOD (Interference Modulation) element shutter-type MEMS display element, optical interference-type MEMS display element, electro using wetting elements, piezoelectric ceramic displays, or carbon nanotubes In addition to these, display elements, display devices, etc. The light emitting element or light emitting device is configured to provide contrast, brightness, reflection, etc., by electrical or magnetic action. The display medium may have a variable reflectance, transmittance, etc. Examples include EL displays. is a field emission display (FED) or SED type flat panel display (SED:Surface-conduction Electron-emitter An example of a display device using a liquid crystal element is a liquid crystal display. Play (Transmissive LCD, Semi-Transmissive LCD, Reflective LCD , direct-view LCDs, projection LCDs, etc. Electronic ink, electronic powder An example of a display device using a fluid (registered trademark) or an electrophoretic element is electronic paper. In addition, when realizing a semi-transmissive liquid crystal display or a reflective liquid crystal display, In this case, it is sufficient that a part or all of the pixel electrode functions as a reflective electrode. For example, a part or all of the pixel electrodes may be made of aluminum, silver, etc. Furthermore, in this case, a memory circuit such as an SRAM can be provided under the reflective electrode. This makes it possible to further reduce power consumption. In this case, placing graphene or graphite under the LED electrodes or nitride semiconductors may Graphene or graphite may be formed into a multilayer film by stacking multiple layers. By providing graphene or graphite on the surface of the silicon substrate, a nitride semiconductor, for example, It is possible to easily form a film such as an n-type GaN semiconductor layer with crystallinity. An LED can be constructed by providing a p-type GaN semiconductor layer having a crystal structure. An AlN layer is placed between graphene or graphite and a crystalline n-type GaN semiconductor layer. The GaN semiconductor layer of the LED may be formed by MOCVD. However, by providing graphene, the GaN semiconductor layer of the LED can be grown by sputtering. It is also possible to form a film by

[0246] Furthermore, the armband device 7300 preferably has one or more functional elements, e.g. For example, sensors for force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetic Air, temperature, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity It is also possible to use sensors that include the function of measuring gradient, vibration, smell, or infrared rays. The display device may also have functional elements such as a touch panel, an antenna, a power generation element, and a speaker.

[0247] For example, the armband type device 7300 is worn on the user's arm at night and the display unit is illuminated. In addition, military personnel and security guards may wear armband-type devices on their upper arms. Wearing the 300, while crawling forward, he receives instructions from his superior in real time and You can see the display on the display of the new device. When carrying out the mission, they wear helmets on their heads, have weapons and tools in their hands, and use radios and It is difficult to use with mobile phones or head-worn devices. Military personnel and security personnel wear armbands on their upper arms. By wearing the 7300 handheld device, you can hear the sound from the microphone and other audio inputs even if your hands are full. It is useful to be able to operate the armband device 7300 by voice input or the like.

[0248] The armband device 7300 can also be used effectively in the field of sports. In races like Lasson, athletes check the time on their wristwatches, but if they don't stop swinging their arms, the time will not be recorded. It is difficult to check the swing of the arms. If the arms stop swinging, the rhythm is disrupted, which hinders the game. The armband type device 7300 is attached to the upper arm to stop the arm swing. It allows you to check the time without having to worry about your position on the course, and also allows you to check other information (your location on the course, your health, etc.) The display can also show the player's health status. Instead of using voice input, the new device can be operated and instructions can be given to the coach via the communication function. The instructions are then output by a voice output unit such as a speaker and displayed on the screen, allowing the player to confirm the instructions. It would also be useful to have the functionality to do this.

[0249] In addition, at construction sites, etc., workers wearing helmets can wear the armband-type device 7300. Wearing it on your wrist and operating it will allow you to easily communicate and obtain the location information of other people so that you can work safely. You can gain.

[0250] An example of mounting a flexible secondary battery in other electronic devices is shown in Figure 21. As an electronic device to which a secondary battery having such a shape is applied, for example, a television set (TV , or television receiver), computer monitors, digital cameras, Digital video cameras, digital photo frames, mobile phones (mobile phones, mobile phone devices) (also known as "game consoles"), portable game consoles, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Examples include machine tools.

[0251] In addition, the flexible secondary battery can be mounted on the inner or outer wall of a house or building, or on the inside or outside of a car. It is also possible to incorporate it along the curved surface of the interior or exterior of the vehicle.

[0252] FIG. 21A shows an example of a mobile phone. The mobile phone 7400 has a housing 7401. In addition to the display unit 7402 incorporated in the The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, etc. It has a battery 7407.

[0253] FIG. 21B shows the mobile phone 7400 in a bent state. When the entire device is deformed by an external force and curved, the secondary battery inside 7407 is also bent. At this time, the state of the bent secondary battery 7407 is shown in FIG. The secondary battery 7407 is a thin secondary battery. The secondary battery 7407 is bent. The secondary battery 7407 is fixed in a state where the lead electrode is electrically connected to the current collector. For example, the current collector is made of copper foil, and by alloying a part of it with gallium, The adhesion between the current collector and the active material layer is improved. This allows the secondary battery 7407 to bend. This configuration is highly reliable even when the power supply is turned on.

[0254] FIG. 21(D) shows an example of a bangle-type display device. The portable display device 7100 includes: The device includes a housing 7101, a display unit 7102, operation buttons 7103, and a secondary battery 7104. 21(E) shows the state of the bent secondary battery 7104. The secondary battery 7104 is bent. When the device is worn on the user's arm with the device attached, the housing may deform and cause damage to part of the secondary battery 7104 or The total curvature changes. The degree of curvature at any point on the curve is expressed as the radius of the corresponding circle. The value expressed is the radius of curvature, and the reciprocal of the radius of curvature is called the curvature. Specifically, the radius of curvature is The area is within the range of 40 mm to 150 mm, and the area is part of the main surface of the casing or the secondary battery 7104. The radius of curvature of the main surface of the secondary battery 7104 is 40 mm or more and 150 mm or less. High reliability can be maintained if the distance is within the range of mm or less.

[0255] In addition, bendable secondary batteries can be installed in various electronic devices with efficient space utilization. For example, the stove 7500 shown in FIG. 21(F) has a main body 7512 and a module 7511. The module 7511 is equipped with a secondary battery 7501, a motor, a fan, and an air outlet. 7511a, a thermoelectric generator. In the stove 7500, fuel is supplied from the opening 7512a. After the battery is charged and ignited, the motor of the module 7511 is powered by the power of the secondary battery 7501. By rotating the fan, outside air can be sent into the stove 7500 through the air outlet 7511a. In this way, it is possible to make a stove with strong heat because it can efficiently take in outside air. Furthermore, the heat energy obtained from the combustion of fuel is used to heat the upper grill 7513. It is possible to cook food using the heat energy generated by the thermoelectric generator in module 7511. The energy can be converted into electricity and charged into the secondary battery 7501. The power stored in the external terminal 7511b can be output from the external terminal 7511b.

[0256] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0257] (Embodiment 5) In this embodiment, the secondary battery described in the first embodiment can be mounted on an electronic device. Another example is shown below.

[0258] 22(A) and 22(B) show an example of a foldable tablet terminal. The tablet terminal 9600 shown in FIGS. 22(A) and 22(B) includes a housing 9630a, a housing a movable part 9640 connecting the housing 9630a and the housing 9630b; a display part 96 31a and a display unit 9631 having a display unit 9631b, a display mode changeover switch 962 6. Power switch 9627, power saving mode switch 9625, fastener 9629, 22A shows the tablet terminal 9600 in an open state. 22(B) shows the tablet terminal 9600 in a closed state.

[0259] The tablet terminal 9600 also includes a secondary battery inside the housing 9630a and the housing 9630b. The secondary battery 9635 is connected to the housing 9630a through a movable portion 9640. It is provided across the housing 9630b.

[0260] A part of the display unit 9631a can be used as a touch panel area 9632a. By touching the operation keys 9638, data can be input. In 1a, for example, half of the area has a display function only, and the other half The display unit 963 has a touch panel function, but is not limited to this. The entire area of ​​the display unit 96 may have a touch panel function. The entire surface of 31a is displayed as a keyboard button to serve as a touch panel, and the display part 9631b is displayed. It can be used as a screen.

[0261] In addition, in the display unit 9631b, as in the display unit 9631a, a part of the display unit 9631b The area 9632b of the touch panel can be used as the keyboard of the touch panel. By touching the area where the display switch button 9639 is displayed with your finger or a stylus, A keyboard can be displayed on the display portion 9631b.

[0262] In addition, touch panel area 9632a and touch panel area 9632b can be touched simultaneously. You can also input characters using the touchpad.

[0263] A display mode changeover switch 9626 changes the display orientation between portrait and landscape. You can select between black and white and color display. The touch 9625 detects when in use by the light sensor built into the tablet terminal 9600. The display brightness can be optimized according to the amount of external light. In addition to optical sensors, other sensors such as gyros and acceleration sensors that detect tilt are also available. The device may be built-in.

[0264] FIG. 22A shows an example in which the display area of ​​the display portion 9631b is the same as that of the display portion 9631a. However, there is no particular limitation, and one size may be different from the other, and the display For example, one display panel may be capable of displaying images with higher resolution than the other. It may also be possible to use the following.

[0265] FIG. 22(B) shows the tablet terminal in a closed state, and the tablet terminal includes a housing 9630, a solar cell 96 33, a charge / discharge control circuit 9634 including a DC / DC converter 9636. The secondary battery of one embodiment of the present invention is used as the battery 9635.

[0266] In addition, since the tablet terminal 9600 can be folded in half, when not in use, the housing 9630a and The housing 9630b can be folded so that the housing 9630a and the housing 9630b overlap each other. Since the display units 9631a and 9631b can be protected, the durability of the tablet terminal 9600 can be improved. In addition, the secondary battery 9635 using the secondary battery of one embodiment of the present invention can improve durability. is flexible, and the charge / discharge capacity is not easily reduced even when repeatedly bent and stretched. This allows us to provide excellent tablet devices.

[0267] In addition, the tablet terminals shown in Figures 22(A) and 22(B) can be used in various Functions that display information (still images, videos, text images, etc.), calendars, dates, or times The function to display information on the display unit, and the function to input or edit the information displayed on the display unit. It has input functions, functions to control processing using various software (programs), etc. It is possible.

[0268] The solar cell 9633 attached to the surface of the tablet terminal supplies power to the touch panel, The solar cell 9633 can be supplied to a display unit, a video signal processor, or the like. The secondary battery 9635 can be efficiently charged by the battery 9630. Note that the secondary battery of one embodiment of the present invention can be used as the secondary battery 9635. By using this, it is possible to suppress the decrease in discharge capacity due to repeated charging and discharging, so it can be used for a long period of time. It can be a tablet terminal that can be used for a wide range of purposes.

[0269] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 22(B) are shown in FIG. A block diagram is shown in FIG. 22(C) and will be explained. In FIG. 22(C), a solar cell 9633 and a secondary battery 96 35, DC-DC converter 9636, converter 9637, switch SW1 to switch SW3, display unit 9631, secondary battery 9635, DC-DC converter 9 636, converter 9637, and switches SW1 to SW3 are shown in FIG. This corresponds to the charge / discharge control circuit 9634.

[0270] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted to a voltage to charge the secondary battery 9635. The converter 9636 increases or decreases the voltage. When power is used from the battery 9633, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying in 1, turn switch SW1 off and switch SW2 on. The secondary battery 9635 may be charged.

[0271] The solar cell 9633 is shown as an example of a power generating means, but is not particularly limited thereto. Secondary power generation by other means such as piezoelectric elements (piezoelectric elements) and thermoelectric conversion elements (Peltier elements) For example, the battery 9635 may be configured to be charged. It is also possible to combine it with a contactless power transmission module that charges the battery, or other charging means. You may do so.

[0272] In addition, the secondary battery described in the first embodiment is installed in a wearable device as shown in FIG. It can be posted.

[0273] For example, it can be mounted on a glasses-type device 400 as shown in FIG. The display device 400 has a frame 400a and a display unit 400b. By installing a secondary battery in the temple of the 400a, the weight balance is good and it can be used continuously. The eyeglass-type device 400 may have a long gap.

[0274] It can also be installed in a headset type device 401. Headset type device 401 includes at least a microphone part 401a, a flexible pipe 401b, and an earphone. The flexible pipe 401b and the earphone section 401c have a secondary battery. A pond can be provided.

[0275] It can also be mounted on a device 402 that can be attached directly to the body. A secondary battery 402b can be provided inside the thin housing 402a.

[0276] It can also be mounted on a device 403 that can be attached to clothing. A secondary battery 403b can be provided inside the thin housing 403a.

[0277] It can also be installed in a wristwatch type device 405. The wristwatch type device 405 has a display The display unit 405a or the belt unit 405b has: A secondary battery may be provided.

[0278] It can also be mounted on a belt-type device 406. The belt-type device 406 is The belt portion 406a and the wireless power receiving portion 406b are provided inside the belt portion 406a. , a secondary battery can be mounted.

[0279] Also, the secondary battery described in the first embodiment is mounted on a bracelet type device 407 as shown in FIG. 23(B). The bracelet type device 407 has two bays in a case 407a. The case 407a has a curved secondary battery 407b. The case 407a also has a curved display 407b on the surface. Regarding the display unit that can be used for the display unit 407c, The description of the display unit can be taken into consideration. The bracelet type device 407 has a connection unit 407 The hinge portion 407e can be moved around the hinge portion 407e to the connecting portion 407d. In addition, charging and the like can be performed via an external terminal provided on the connection part 407d. do.

[0280] Another example of electronic equipment is shown in FIG. 24. In FIG. 24, a display device 8000 is a display device according to one embodiment of the present invention. 8 is an example of an electronic device using a secondary battery 8004 according to an embodiment. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, and a speaker unit. The secondary battery 8004 according to one embodiment of the present invention includes a housing 8003 and a secondary battery 8004. The display device 8000 is provided inside a body 8001. The display device 8000 receives power from a commercial power source. Alternatively, the power stored in the secondary battery 8004 can be used. Even when power cannot be supplied from a commercial power source due to a power outage or the like, the present invention The display device 8000 can be used by using the secondary battery 8004 as an uninterruptible power supply. do.

[0281] The display unit 8002 includes a liquid crystal display device, an emitting device having a light emitting element such as an organic EL element in each pixel, and Device, electrophoretic display device, DMD (Digital Micromirror Device) ce), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a reflective LED (emission display) can be used.

[0282] In addition to TV broadcast reception, display devices are also used for personal computers and advertising displays. , including all display devices for displaying information.

[0283] In FIG. 24, a stationary lighting device 8100 includes a secondary battery 81 according to one embodiment of the present invention. 8101, a housing 8102, a light source 8103, and a light source 8104. 24, the secondary battery 8103 is mounted in the housing 81. 8101 and a light source 8102 are installed inside a ceiling 8104. However, the secondary battery 8103 may be provided inside the housing 8101. The device 8100 can receive power from a commercial power source or can store power in a secondary battery 8103. Therefore, if the power supply from the commercial power source is interrupted due to a power outage, etc., Even when the power is not available, the secondary battery 8103 according to one embodiment of the present invention can be used as an uninterruptible power supply. This allows the lighting device 8100 to be used.

[0284] 24 shows an example of a lighting device 8100 that is installed on a ceiling 8104. However, the secondary battery according to one embodiment of the present invention is not limited to the ceiling 8104, but may be installed on other parts such as the side wall 8105 and the floor 8106. 106, it can be used for a fixed lighting device provided in a window 8107, etc., or it can be used for a tabletop lighting device. It can also be used in lighting devices of this type.

[0285] The light source 8102 may be an artificial light source that artificially obtains light using electricity. Specifically, incandescent lamps, fluorescent lamps and other discharge lamps, and light-emitting devices such as LEDs and organic EL elements The element is an example of the artificial light source.

[0286] In FIG. 24, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electronic device using a secondary battery 8203 according to one embodiment of the present invention. The device 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, and the like. 8 illustrates an example in which the secondary battery 8203 is provided in the indoor unit 8200. The battery 8203 may be provided in the outdoor unit 8204. Both the power supply 8201 and the power supply 8204 may be provided with a secondary battery 8203. The power supply can be supplied from a commercial power source, or the power stored in the secondary battery 8203 can be used. In particular, both the indoor unit 8200 and the outdoor unit 8204 may be equipped with secondary batteries 82 If 03 is installed, when power cannot be supplied from the commercial power source due to a power outage, etc. In addition, by using the secondary battery 8203 of one embodiment of the present invention as an uninterruptible power supply, The conditioner can be used.

[0287] In Figure 24, a separate type air conditioner consisting of an indoor unit and an outdoor unit is shown. As an example, it is an all-in-one air conditioner that has the functions of both the indoor unit and the outdoor unit in a single housing. The secondary battery according to one embodiment of the present invention can also be used in the conditioner.

[0288] In FIG. 24, an electric refrigerator-freezer 8300 includes a secondary battery 8304 according to one embodiment of the present invention. Specifically, an electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator It has a storage compartment door 8302, a freezer compartment door 8303, a secondary battery 8304, etc. A secondary battery 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 is It can receive power from a commercial power source, or use the power stored in the secondary battery 8304. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 of one embodiment of the present invention as an uninterruptible power supply, It will be possible to use the 8300 freezer refrigerator.

[0289] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0290] (Embodiment 6) In this embodiment, an example is shown in which the secondary battery described in the first embodiment is mounted on a vehicle.

[0291] In addition, when secondary batteries are installed in vehicles, hybrid vehicles (HEVs), electric vehicles (EVs), Or realizing next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs) can.

[0292] 25A and 25B show examples of vehicles using one embodiment of the present invention. 400 is an electric vehicle that uses an electric motor as a power source for running; or A hybrid vehicle that can select between an electric motor and an engine as a power source for driving. By using one aspect of the present invention, a vehicle with a long driving range can be realized. The automobile 8400 also has a secondary battery. The secondary battery can power the electric motor. In addition to driving the headlights 8401 and room lights (not shown), can supply power to

[0293] In addition, the secondary battery is used to power the speedometer, tachometer, and other displays of the automobile 8400. The secondary battery can supply power to the navigation device of the automobile 8400. The present invention can provide power to semiconductor devices such as mobile terminals.

[0294] The automobile 8500 shown in FIG. 25(B) has a plug-in type secondary battery. It can be charged by receiving power from an external charging facility using a contactless power supply system or other methods. FIG. 25(B) shows the charging of electricity from a ground-mounted charging device 8021 to a storage battery mounted on an automobile 8500. The figure shows a state in which the charging device is being charged via a cable 8022. The power supply method and connector standards are applied according to the specified method such as CHAdeMO (registered trademark) or Combo. The charging device 8021 may be a charging station installed in a commercial facility. It can also be a household power source. For example, plug-in technology allows for external power supply. This allows the secondary battery installed in the car 8500 to be charged. This can be achieved by converting AC power into DC power via a conversion device such as a converter.

[0295] Although not shown, a power receiving device is mounted on the vehicle and power is supplied contactlessly from a power transmitting device on the ground. In this case, a power transmission device is installed on the road or exterior wall. By incorporating this technology, charging can be carried out not only when the vehicle is stopped but also while the vehicle is moving. This method may be used to transmit and receive power between vehicles. A solar cell may be provided to charge the secondary battery when the vehicle is stopped or running. The power can be supplied by an electromagnetic induction method or a magnetic resonance method.

[0296] Furthermore, the secondary battery installed in the vehicle can also be used as a power supply source for other purposes besides the vehicle. In this case, it is possible to avoid using commercial power sources during peak power demand periods.

[0297] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Explanation of symbols]

[0298] 100 Secondary battery 101 Positive electrode current collector 102 Cathode active material layer 103 Separator 103a Joint 104 Electrolyte 105 Negative electrode current collector 106 Negative electrode active material layer 107 Exterior body 107a Joint 111 Positive electrode 115 Negative electrode 120 sealing layer 121 Positive lead 125 Negative lead 151 Switch 152 Current Control Switch 154 Switch Pairs 201 directions 202 directions 211 holes 321 Graphene 322 Cathode active material 331 areas 332 areas 333 areas 400 Eyeglasses-type Device 400a frame 400b Display section 401 Headset-type device 401a Microphone section 401b Flexible Pipe 401c Earphone section 402 Device 402a housing 402b secondary battery 403 Device 403a housing 403b secondary battery 405 Wristwatch-type device 405a Display section 405b Belt section 406 Belt-type device 406a Belt section 406b Wireless power receiving unit 407 Bracelet-type device 407a Case 407b secondary battery 407c Display section 407d Connection 407e Hinge part 7100 Portable display devices 7101 Housing 7102 Display section 7103 Operation button 7104 Secondary battery 7300 Armband Device 7301 Arm 7400 mobile phone 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Secondary battery 7500 stove 7501 Secondary battery 7511 Module 7511a Air vent 7511b External terminal 7512 main body 7512a opening 7513 Grill 8000 display device 8001 Case 8002 Display section 8003 Speaker section 8004 Secondary battery 8021 Charging device 8022 cable 8100 Lighting equipment 8101 Housing 8102 Light source 8103 Secondary battery 8104 Ceiling 8105 Side wall 8106 beds 8107 Window 8200 indoor unit 8201 Housing 8202 Ventilation outlet 8203 Secondary battery 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Housing 8302 Refrigerator door 8303 Freezer door 8304 Secondary battery 8400 Automobiles 8401 Headlight 8500 cars 9600 tablet device 9625 Switch 9626 Switch 9627 Power Switch 9628 Operation Switch 9629 Fasteners 9630 chassis 9630a housing 9630b housing 9631 Display section 9631a Display section 9631b Display section 9632a area 9632b area 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Secondary battery 9636 DC / DC Converter 9637 Converter 9638 Operation key 9639 Button 9640 Moving parts BT00 Power storage device BT01 terminal pair BT02 terminal pair BT03 control circuit BT04 circuit BT05 circuit BT06 Transformer control circuit BT07 transformer circuit BT08 battery part BT09 Battery Cell BT10 transistor BT11 Bus BT12 Bus BT13 transistor BT14 Current Control Switch BT15 Bus BT16 Bus BT17 Switch vs. BT18 Switch vs. BT21 Transistor Pair BT22 transistor BT23 transistor BT24 Bus BT25 Bus BT31 Transistor Pair BT32 transistor BT33 transistor BT34 Bus BT35 Bus BT41 Battery Control Unit BT51 Isolated DC-DC Converter BT52 switch part BT53 transformer S1 control signal S2 control signal S3 transformer signal SW1 switch SW2 switch SW3 switch

Claims

[Claim 1] A secondary battery comprising: a plurality of positive electrodes; a positive electrode lead electrically connected to each of the plurality of positive electrodes; a plurality of negative electrodes; a negative electrode lead electrically connected to each of the plurality of negative electrodes; a separator; and an exterior body that covers the plurality of positive electrodes, the plurality of negative electrodes, and the separator, the secondary battery has long sides along a first direction and short sides along a second direction intersecting the first direction; the secondary battery is capable of being curved in the first direction; a direction connecting the positive electrode lead and the negative electrode lead intersects with the first direction; When the secondary battery is curved with a first curvature in the first direction, an end of a first electrode located on the innermost diameter side and an end of a second electrode located on the outermost diameter side among the plurality of positive electrodes and the plurality of negative electrodes are aligned, When the secondary battery is in a flat state, the first electrode has a length in the first direction that is shorter than that of the second electrode; the positive electrode lead and the negative electrode lead are drawn out from the opposing long sides of the exterior body, each of the plurality of positive electrodes has a positive electrode active material layer on one surface thereof; each of the plurality of negative electrodes has a negative electrode active material layer on one surface thereof; any two of the plurality of positive electrodes are arranged such that the surfaces not having the positive electrode active material layer face each other with the separator interposed therebetween; any two of the plurality of negative electrodes are arranged so that the surfaces not having the negative electrode active material layer face each other.

Images