Secondary battery

Abstract

To provide a secondary battery resistant to external force by solving the problem in which, in a case where a film is used in a package of a secondary battery, the film is less strong than a metal can and a current collector disposed in a region surrounded by the package or an active material layer provided on a surface of the current collector, for example, may be damaged by an external force.SOLUTION: A buffer material is provided in a region surrounded by a package in a secondary battery. Specifically, the buffer material is disposed around a current collector and housed so that a sealing part of the package (film) is disposed outside the buffer material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In this specification, the term "electronic device" refers to any device that has a secondary battery. Electro-optical devices having a secondary battery, and information terminal devices having a secondary battery are all electronic devices. [Background technology]

[0003] Electronic devices that are carried by users or worn by users are being actively developed. For example, Patent Document 1 describes a thin portable book.

[0004] Electronic devices carried by users or worn by users operate using secondary batteries as their power source. It is desirable for users to use portable electronic devices for long periods of time, and for this reason, large-capacity If a large-capacity secondary battery is built into an electronic device, Therefore, it is necessary to develop a small or thin type that can be built into portable electronic devices. Development of large-capacity secondary batteries is underway.

[0005] Secondary batteries are constructed using a metal can as an exterior body, and contain an electrolyte and the like inside the metal can. It has become a success. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 15796 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0007] When a metal can is used as the exterior body, there is a problem that the weight of the secondary battery itself increases. To realize a thin secondary battery, it is difficult to manufacture a thin metal can by molding. It is also difficult to fabricate a secondary battery using a thin metal can.

[0008] The exterior is made of a laminate of metal foil (aluminum, stainless steel, etc.) and resin (thermal adhesive resin). When a film containing cellulose ether (also called a laminate film) is used, it is possible to reduce the energy consumption compared to secondary batteries that use metal cans. Furthermore, a thin secondary battery can be manufactured. The objective of the present invention is to provide a new power storage device, a new secondary battery, etc. The description does not preclude the existence of other problems. It is not necessary to solve all of these problems. Problems other than these can be solved by the specification, drawings, and claims. It is self-evident from the description of the claims, etc., and is based on the description of the specification, drawings, claims, etc. From this, it is possible to extract other issues. [Means for solving the problem]

[0009] When a film is used as the exterior of a secondary battery, the strength of the film is weaker than that of a metal can, and the external When a force is applied from the current collector or the current collector surface, There is a risk of damaging the active material layer provided on the current collector. The secondary battery is provided with a protrusion (also called an electrode tab) for When the electrode is bent, damage such as cracks may occur around the protruding part (electrode tab part) of the current collector. This can lead to damage to the secondary battery.

[0010] In the secondary battery, a buffer material is provided in the area surrounded by the exterior body. The cushioning material is placed on the package, and the sealing part of the exterior body (film) is placed on the outside of the cushioning material. In order to increase the capacity, the area surrounded by the exterior body contains a current collector that serves as the positive electrode, A plurality of units each having at least a separator and a current collector serving as a negative electrode are stacked. The buffer material is provided between the outermost current collector and the exterior body. The thickness of the buffer material is thicker than that of the current collector. The cushioning material may be a rolled sheet made of the same material as the separator.

[0011] The shape of the cushioning material can be flat, rod-shaped, or spherical (e.g., plastic beads, glass beads). For example, a sheet-shaped plastic film is slip-molded. Furthermore, a plurality of buffer materials may be stored in the area surrounded by the exterior body. For example, a fibrous thread (glass) may be used as a cushioning material. Alternatively, a bundle of multiple fibers (spunbonded fibers) may be used. A woven aggregate (woven fabric) like this may also be used. Also, a rolled or rolled shape of a sheet-like material may be used. A folded sheet material may also be used. A thin, flat cushioning material (plastic film) is placed on the outside so that it overlaps with the current collector. One of the configurations disclosed in this specification is a film and a The area surrounded by the film includes a first current collector, an active material layer, a second current collector, and a buffer material. It is a secondary battery, and the cushioning material is a plastic film. The area of ​​the plastic film is , which is wider than the overlapping area of ​​the first current collector and the second current collector.

[0012] In addition, when the outer shape of the current collector and the frame-shaped buffer material are interlocked, a flat shape that combines them is formed. The device is stored in an area surrounded by the exterior body so that the shape is approximately rectangular. Even if the collector and the frame-shaped cushioning material are not in contact in the enclosed area, the periphery of the exterior body is sealed by thermocompression. In this case, the boundary between the current collector and the frame-shaped buffer material becomes unclear from the outside. The exterior of the pond is thinned by thermocompression at the periphery, and the laminate (first current collector, separator) is in the center. The thickness is greater than the periphery because of the presence of a second collector, a second current collector, etc., and there is a gap between the center and the periphery. The outer surface of the secondary battery is thicker than the outer edge due to the placement of cushioning material. A first lead electrode electrically connected to the first current collector of the laminate is protruding and exposed, and a second A second lead electrode electrically connected to the current collector is also protruded and exposed.

[0013] The materials for the buffer material include insulators (plastic, rubber (natural rubber, synthetic rubber), glass, It is preferable that the material used as the buffer material is a material having elasticity (e.g., nonwoven fabric, paper, etc.). Synthetic rubber, such as silicone rubber, fluororubber, chloroprene rubber, nitrile butadiene rubber, ethylene propylene rubber, styrene butadiene rubber, etc.) are preferred. The buffer material has a higher elastic modulus than the separator. Porous materials having bubbles inside the material (for example, polystyrene foam and the above-mentioned synthetic rubber materials) The material may be a sheet of sponge rubber made of a material such as a cushioning material. A gelling material may be used instead.

[0014] In addition, as the material of the buffer material, a conductive material can be used as long as the surface has an insulating surface. For example, the surface of carbon fiber coated with organic resin can be used as a buffer material. An inorganic insulating film, such as oxide silicon, is applied to the surface of a metal foil (aluminum foil, copper foil, stainless steel foil, etc.). It is possible to use a silicon film formed on the surface of a metal foil or a metal foil coated with an organic resin. can.

[0015] In a secondary battery, by providing a buffer material in the area surrounded by the exterior body, the current collector, etc. It can be stored in a stable position. In addition, when the secondary battery is bent into a desired shape, it can be easily folded into the desired shape. The cushioning material can also be curved, which helps the secondary battery maintain its curved shape. It is also possible to provide a function to limit the secondary battery from bending more than necessary. The buffer material can also function as the skeleton of the secondary battery.

[0016] Furthermore, the buffer material is not limited to being provided in the area surrounded by the exterior body, and a part of the buffer material may be exposed. In this case, the buffer material itself is a part of the exterior body, i.e., the sealing portion. It functions as one of the materials.

[0017] In addition, depending on the type of electronic device, the secondary battery installed in the electronic device may be bent, so cushioning materials may also be used. It is desirable that the material be flexible, and it is desirable that the material be flexible as a buffer material. Even if the electrolyte inside the battery decreases over time, it will not bend due to the buffer material. This can prevent the secondary battery from being damaged by impact or from changing in appearance. When an impact is applied, the shock is concentrated at one point because there is a buffer material in the area surrounded by the exterior body. This reduces the risk of the secondary battery being bent locally, preventing damage to the secondary battery. This can be prevented.

[0018] Alternatively, in one embodiment of the present invention, a first current collector that functions as a positive electrode is provided in a region surrounded by an exterior body. and a second current collector functioning as a negative electrode. It is an electric body.

[0019] A power storage unit according to one embodiment of the present invention has a curvature radius of 10 mm or more, preferably 30 mm or more. The film that is the exterior of the storage battery is made up of one or two sheets. In the case of a storage battery having a laminated structure, the cross-sectional structure of the curved battery is the exterior body. The structure is sandwiched between two curves of film.

[0020] Here, the radius of curvature of a surface will be explained with reference to FIG. 7. In FIG. 7(A), In a plane 1701 cutting the surface 1700, a curved surface that is included in the surface 1700 is A part of the line 1702 is approximated as an arc of a circle, and the radius of the circle is the radius of curvature 1703. is the center of curvature 1704. FIG. 7B shows a top view of the curved surface 1700. FIG. 7C shows A cross-sectional view of a curved surface 1700 cut by a plane 1701 is shown. The radius of curvature of the curve that appears in the cross section varies depending on the angle of the plane and the cutting position. However, in this specification and the like, the smallest radius of curvature is taken as the radius of curvature of the surface.

[0021] The battery is made of two films sandwiching the contents 1805, including electrodes and electrolyte, between them. When the capacitor is bent, the radius of curvature of the film 1801 on the side closer to the center of curvature 1800 of the capacitor is 1 802 is smaller than the radius of curvature 1804 of the film 1803 on the side farther from the center of curvature 1800. If the capacitor is bent to make the cross section arc-shaped, the center of curvature is close to 180° (Fig. 8(A)). The surface of the film is subjected to compressive stress, and the surface of the film far from the center of curvature 180° is subjected to tension. The pattern formed on the surface of the exterior body is made up of recesses or protrusions. When formed, even if compressive stress or tensile stress is applied, the effect of strain is not Therefore, the electric storage unit can be prevented from being damaged by the heat generated by the outer casing on the side closer to the center of curvature. The deformation can be carried out within a range in which the radius of curvature is 10 mm or more, preferably 30 mm or more.

[0022] The cross-sectional shape of the electricity storage unit is not limited to a simple arc shape, and may be a shape that includes a partial arc. For example, the shape shown in FIG. 8(C), a wavy shape (FIG. 8(D)), an S-shape, etc. When the curved surface of the power storage unit has a shape with multiple centers of curvature, The two exterior bodies are connected at the surface with the smallest curvature radius among the curvature radii at each center. The radius of curvature of the outer casing closer to the center of curvature is 10 mm or more, preferably 30 mm or more. The storage battery can be deformed within this range.

[0023] Note that one embodiment of the present invention can be applied to various power storage devices. Examples of the electrical device include a battery, a primary battery, a secondary battery, a lithium ion secondary battery (lithium (including ion polymer secondary batteries), lithium-air batteries, etc. Another example of the device is a capacitor. A capacitor such as a lithium ion capacitor is created by combining a positive electrode with an electric double layer positive electrode. It is also possible to configure a passive [Effects of the Invention]

[0024] The degree to which a secondary battery is deformed by the application of external force, i.e., the degree to which the internal structure of the secondary battery is deformed. The deformation of the battery can be adjusted by adjusting the material and placement of the cushioning material. Even if it is bent, the cushioning material prevents bending to the extent that the internal structure is not destroyed. Therefore, the buffer material protects the internal structure from damage caused by external bending forces. It is also possible to provide a new power storage device, a new secondary battery, etc. The description of these effects does not preclude the existence of other effects. An embodiment of the present invention does not necessarily have to have all of these effects. The effects are self-evident from the description, drawings, claims, etc. Other effects can be extracted from the descriptions in the drawings, claims, etc. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic view illustrating an external appearance of one embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing a configuration example of a region surrounded by an exterior body according to one embodiment of the present invention. [Figure 3] 1A and 1B are schematic views illustrating an appearance and a configuration example of one embodiment of the present invention. [Figure 4] 1A and 1B are a schematic external view and an X-ray photograph illustrating a configuration example of one embodiment of the present invention. [Figure 5] 1 is a perspective view of an appearance of an electronic device illustrating one embodiment of the present invention. [Figure 6] 1A to 1C illustrate electronic devices. [Figure 7] FIG. 4 is a diagram illustrating the radius of curvature of a surface. [Figure 8] FIG. 1 is a diagram illustrating a cross section of a power storage unit. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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. Furthermore, 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.

[0027] In each drawing described in this specification, the size of each component, the thickness of a layer, or the area is The figures may be exaggerated or abbreviated for clarity. This is not limited to rules.

[0028] In this specification, ordinal numbers such as "first" and "second" are used to avoid confusion of components. It does not indicate any order or ranking such as the order of processes or stacking. In addition, even if a term is not accompanied by an ordinal number in this specification, etc., it is possible to avoid confusion of the constituent elements. To avoid this, ordinal numbers may be used in the claims.

[0029] (Embodiment 1) FIG. 1(A) shows an example of a schematic diagram of a power storage unit. An example is shown in Figure 2(A).

[0030] The power storage unit 100 of one embodiment of the present invention includes a positive electrode 101, a separator 103, and an outer casing 107. The power storage unit has at least a negative electrode 102, a buffer material 110, and an electrolyte solution. There are various structures, but in this embodiment, a film is used to form the exterior body 107.

[0031] The film for forming the exterior body 107 is a metal film (aluminum, stainless steel, nickel, Nickel steel, gold, silver, copper, titanium, nichrome, iron, tin, tantalum, niobium, molybdenum, zinc metal foils (metals or alloys such as vanadium, zinc, etc.), plastic foils made from organic materials, Hybrid materials including films, organic materials (such as organic resins and fibers) and inorganic materials (such as ceramics) Lid material film, carbon-containing inorganic film (carbon film, graphite film) A single layer film selected from the following or a laminated film made up of a plurality of these is used.

[0032] In this embodiment, the buffer material 110 is a sheet-like plastic having an area larger than that of the positive electrode 101. In this embodiment, the buffer material 110 is made of a separator 10. The plastic film is thicker than that of the buffer material 110. The buffer material 110 has slits. Furthermore, the buffer material 110 is not limited to a rectangular shape, and may have four rounded corners. If the shape of the buffer material 110 has sharp corners, the corners may be caught by the exterior body when the power storage unit is bent. To prevent this, chamfering the corners of the cushioning material 110 can improve reliability. The buffer material 110 is made of an insulating material, for example. PP, PE, PET, PBT and other polyesters, nylon 6, nylon 66 and other For example, an inorganic vapor deposition film or paper may be used.

[0033] By providing a buffer material 110 in the area surrounded by the exterior body of the power storage unit, the current collector and other components are placed in a stable position. When bending the power storage unit into a desired shape, the cushioning material must also be bent to achieve the desired shape. This can also contribute to maintaining the bent shape of the electricity storage unit. It can also have a function to prevent the storage battery from bending more than necessary. The battery can also function as a skeleton of the power storage unit. By providing the shock absorber 110, the influence of strain caused by applying force from outside the power storage unit can be tolerated. Therefore, it is possible to provide a highly reliable electricity storage unit.

[0034] Furthermore, by providing the buffer material 110 in the area surrounded by the exterior body of the power storage unit, the surface of the buffer material 110 If the surface is smooth, the current collector and the soft plastic film that are in contact with the surface of the cushioning material 110 can be easily removed. The exterior body that comes into contact with the surface of the shock absorber 110 slides, providing a storage battery that is resistant to repeated bending. You can also do this.

[0035] The positive electrode 101 is formed by forming a positive electrode active material layer on one or both sides of a current collector (such as aluminum). The negative electrode 102 includes a current collector (copper or the like) on one side or The term "negative electrode" includes those in which a negative electrode active material layer is provided on both sides. The positive electrode 101 is electrically connected to the positive electrode lead 104, and the negative electrode 102 is electrically connected to the negative electrode lead 105. The positive electrode lead 104 and the negative electrode lead 105 are electrically connected. A part of the positive electrode lead 104 and a part of the negative electrode lead 105 are connected to the outer casing. The charge and discharge of the electricity storage unit 100 are performed by the positive electrode lead 104 and This is done via the negative electrode lead 105.

[0036] Here, the flow of current during charging of a secondary battery will be explained using Figure 1(B). When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of current are in the same direction. In secondary batteries that use lithium, the anode (positive electrode) and cathode (cathode) is switched, and the oxidation reaction and reduction reaction are switched, so the reaction potential The electrode with a higher reaction potential is called the positive electrode, and the electrode with a lower reaction potential is called the negative electrode. Whether charging, discharging, or applying a reverse pulse current, Even when an electric current flows through it, the positive electrode is called the "positive electrode" or "+ electrode (plus electrode)" and the negative electrode is called the "positive electrode" or "+ electrode (plus electrode)". This is called the "negative electrode" or "-electrode (minus electrode)." When using the terms anode (positive electrode) and cathode (negative electrode), the following occurs during charging and discharging: This can be confusing as the anode and cathode are opposites. The term "cathode" will not be used in this specification. When using the terms cathode and positive electrode, specify whether they are charging or discharging. It will also be noted whether it corresponds to the negative pole (negative pole) or the positive pole (positive pole).

[0037] A charger is connected to the two terminals shown in FIG. 1(B), and the power storage unit 100 is charged. As the charging of the power storage unit 100 progresses, the potential difference between the electrodes increases. The current flows from the external terminal (positive electrode lead 104) to the positive electrode current collector (positive electrode 101) and enters the electricity storage unit 1. In the 00, the current flows from the positive electrode 101 to the negative electrode 102, and from the negative electrode to the outside of the storage battery 100. The direction of the current flowing toward the negative terminal (negative lead 105) is defined as the positive direction. The direction of the current is the direction in which the current flows.

[0038] In this embodiment, for the sake of simplicity, a pair of positive electrode 101 and negative electrode 102 is enclosed in an outer casing. In order to increase the capacity of the electricity storage body, it is possible to store a plurality of sets of positive electrodes 101 and The negative electrode 102 may be housed in an exterior body 107 .

[0039] As shown in FIG. 2(A), the exterior body 107 contains a buffer material 110, a positive electrode 101, and a separator. 2A shows an example in which a cathode 103 and an anode 102 are arranged. For clarity, the exterior body 107, the positive electrode lead 104, and the negative electrode lead 105 are not shown.

[0040] 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.

[0041] In this embodiment, the power storage unit is configured such that, for example, the thickness of the separator 103 is about 15 μm. the positive electrode 101 current collector is about 10 μm or more and about 40 μm or less, and the positive electrode active material layer the negative electrode active material layer is about 50 μm or more and about 100 μm or less, and the negative electrode active material layer is about 50 μm or more and about 100 μm or less, The current collector of the negative electrode 102 has a thickness of about 5 μm or more and about 40 μm or less.

[0042] In addition, in FIG. 2(A), an example in which a sheet-like separator is used as the separator 103 is shown, but a bag-like separator may be used. Alternatively, one separator may be folded and a positive electrode placed between the folded separators. The electrode (or negative electrode) may be located inside the exterior body 107.

[0043] The position of the buffer material 110 is not limited to that shown in FIG. 2(A). For example, as shown in FIG. 2(B), A buffer material 110 may be provided on the side in contact with the negative electrode 102 as shown.

[0044] The number of buffer materials 110 is not limited to one, and multiple buffer materials may be used. In this way, the positive electrode 101 and the separator are disposed between the first buffer material 110a and the second buffer material 110b. The cathode 103 and the anode 102 may be configured.

[0045] The positive electrode active material used in the positive electrode active material layer of the electricity storage unit 100 may have an olivine type crystal structure, a layered structure, or the like. There are composite oxides with rock salt crystal structures or spinel crystal structures. As a substance, for example, LiFeO2, LiCoO2, LiNiO2, LiMn2O4, V2O 5, compounds such as Cr2O5, MnO2, etc. are used.

[0046] Alternatively, a composite material (general formula LiMPO4, where M is Fe(II), Mn(II), Co(II) Representative examples of the general formula LiMPO4 include: Examples include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, and LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4(a+b is less than 1, 0 <a<1、0<b<1)、LiF e c Nid Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO 4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g C o h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 <i < 1) and the like lithium compounds can be used as materials.

[0047] Or, a composite material such as the general formula Li (2-j) MSiO4 (M is one or more of Fe(II), Mn(II), Co( II), Ni(II), 0 ≦ j ≦ 2) and the like can be used. General formula Li (2-j) MSiO4 representative examples include 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 in Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (where m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1) , Li (2-j) Fe r Ni s Co t Mn u SiO4 (where r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. Lithium compounds can be used as materials and so on.

[0048] Also, as the positive electrode active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, M n, Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) represented by the general formula of the sodium[[ID=4�]] silicon type compound can be used. Examples of the NASICON type compound include Fe2(MnO4) 3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the positive electrode active material , compounds represented by the general formula of Li₂MPO₄F, Li₂MP₂O₇, Li₅MO₄ (M = Fe, Mn) , perovskite type fluorides such as NaFeF3, FeF3, metal chalcogenides (sulfides, selenides, tellurides) such as TiS2, Mo S2, etc., oxides having an inverse spinel type crystal structure such as LiMVO4, vanadium oxide systems (V2O5, V6O 13 , L iV3O8, etc.), manganese oxides, organic sulfur compounds, etc. can be used as materials.

[0049] Note that the carrier ion is an alkali metal ion other than lithium ion, an alkaline earth metal In the case of ions, instead of lithium, an alkali metal (e.g., sodium) is used as the positive electrode active material. alkaline earth metals (e.g., calcium, strontium, barium, etc.), Alternatively, metals such as aluminum, beryllium, or magnesium may be used.

[0050] The separator 103 is made of cellulose (paper) or polypropylene with holes. An insulator such as polyethylene can be used.

[0051] The electrolyte solution uses a material that has lithium ions as the electrolyte, and the carrier ions are mobile. Representative examples of electrolytes are LiPF6, LiClO4, LiAsF6, and LiBF4 , LiCF3SO3, Li(CF3SO2)2N, Li(C2F5SO2)2N, etc. These electrolytes may be used alone or in any combination of two or more. It may be used in any combination and ratio.

[0052] The solvent of the electrolyte solution is a material in which carrier ions can move. As the solvent, an aprotic organic solvent is preferred. Representative examples of the aprotic organic solvent include: Ethylene carbonate (EC), propylene carbonate, dimethyl carbonate, diene Diethyl carbonate (DEC), γ-butyrolactone, acetonitrile, dimethoxyethane , tetrahydrofuran, etc., and one or more of these can be used. By using a polymer material that gels as a solvent for the electrolyte, safety against leakage etc. is improved. Furthermore, it is possible to make the storage battery thinner and lighter. Representative polymer materials that can be gelled are Examples include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide There are gels made from hydroxyl groups, polypropylene oxide gels, and fluorine polymer gels. In addition, one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts) are used as the solvent for the electrolyte. By using multiple batteries, even if the internal temperature rises due to an internal short circuit or overcharging of the battery, This can prevent the battery from exploding or catching fire. Ionic liquid is a salt in a fluid state. Ionic liquids contain cations and anions, and have high ion mobility (conductivity). Ionic liquids include ions containing ethylmethylimidazolium (EMI) cations. Liquid, or N-methyl-N-propylpiperidinium (PP 13 ) cation-containing ions Examples include liquids.

[0053] In addition, instead of the electrolyte solution, solid electrolytes containing inorganic materials such as sulfides and oxides, and P A solid electrolyte containing a polymer material such as EO (polyethylene oxide) can be used. When a solid electrolyte is used, there is no need to install a separator or spacer. Since the entire pond can be solidified, there is no risk of leakage, dramatically improving safety.

[0054] The negative electrode active material used in the negative electrode active material layer of the electricity storage unit 100 is a lithium-ion battery prepared by dissolution and deposition, or Materials that can insert and extract lithium ions can be used, such as lithium metal and carbon-based materials. Materials, alloy materials, etc. can be used.

[0055] 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.

[0056] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). Examples include carbon nanotubes, graphene, and carbon black.

[0057] 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.

[0058] When lithium ions are inserted into graphite (when lithium-graphite intercalation compounds are formed), It exhibits a potential as low as that of lithium metal (0.1 to 0.3 V vs. Li / Li + ).child This allows lithium-ion secondary batteries to exhibit high operating voltages. , relatively high capacity per unit volume, small volume expansion, inexpensive, and comparable to lithium metal This is preferable because it has advantages such as higher safety compared to the conventional method.

[0059] As a negative electrode active material, it is possible to carry out charge-discharge reactions by alloying and dealloying reactions with lithium. A suitable alloy material or oxide can also be used. In some cases, the alloy material may be, for example, Al, Si, Ge, Sn, Pb, Sb, Bi, There are materials containing at least one of Ag, Au, Zn, Cd, In, Ga, etc. Such elements have a large capacity compared to carbon, and silicon in particular has a theoretical capacity of 4200mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Examples of alloy materials using elements include Mg2Si, Mg2Ge, Mg2Sn, and SnS. 2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb 3, InSb, SbSn, etc. SiO refers to silicon containing silicon-rich portions. It refers to oxide powder, SiO y It can also be written as (2>y>0). For example, SiO is Materials containing one or more selected from Si2O3, Si3O4, or Si2O, and S It also includes a mixture of powder of i and silicon dioxide SiO2. SiO2 also contains other elements (carbon, nitrogen, etc.) , iron, aluminum, copper, titanium, calcium, manganese, etc.) , single crystal Si, amorphous Si, polycrystalline Si, Si2O3, Si3O4, Si2O, S SiO is a colored material. No SiO x (X is 2 or more), it is colorless, transparent, or white and can be distinguished. However, after the secondary battery is fabricated using SiO as the material for the secondary battery, it is necessary to repeatedly charge and discharge it. If SiO is oxidized by heating, it may change to SiO2.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 mentioned above. Since the potential of the fluorides is high, they are not suitable for use as positive electrode active materials. That's fine.

[0064] In addition to the above-mentioned negative electrode active material, the negative electrode active material layer contains a binder for improving the adhesion of the active material. The negative electrode active material layer may contain a binder, a conductive auxiliary agent for increasing the conductivity of the negative electrode active material layer, and the like.

[0065] Furthermore, the buffer material is not limited to being provided in the area surrounded by the exterior body, and a part of the buffer material may be exposed. When the outer periphery of the exterior body 107 is bonded by thermocompression, The adhesive area may be overlapped with a part of the sheet-like cushioning material and sealed by thermocompression. The cushioning material is fixed at the portion in contact with the adhesive area.

[0066] In this embodiment, an example of a small battery used in a portable information terminal or the like is shown, but there is no particular limitation. The present invention can be applied not only to batteries but also to large batteries to be installed in vehicles, etc.

[0067] (Embodiment 2) In the first embodiment, an example in which a sheet-shaped cushioning material is used is shown. This example shows a cushioning material with a different shape and installation position from that of Example 1.

[0068] FIG. 3(A) shows an example of a schematic diagram of a power storage unit. An example is shown in Figure 3(B). In Figure 3, the same reference numerals are used for the parts common to Figure 1. For the sake of brevity, detailed descriptions will be omitted here.

[0069] The power storage unit 300 of one embodiment of the present invention includes a positive electrode 101, a separator 103, and an outer casing 107. The negative electrode 102, the first buffer material 310a, the second buffer material 310b, and a small amount of electrolyte are It also has.

[0070] In the embodiment, the separator 1 is used as the first buffer material 310a and the second buffer material 310b. It is thicker than 03 and uses a rod-shaped elastic body (elastic material).

[0071] As shown in FIGS. 3A and 3B, a first buffer material 310a and a second buffer material 310b are The positive electrode 101, the separator 103, and the negative electrode 102 are disposed between them.

[0072] The outer periphery of the exterior body 107 is bonded by thermocompression. The film has a polypropylene layer on the surface, and only the thermo-compressed area adheres. It becomes an area.

[0073] In this embodiment, the adhesive region 311 is in contact with the first buffer material 310a, and the side surface of the power storage unit 300 is When the buffer material is placed inside the power storage unit without being exposed, The cross section is wedge-shaped to make the step around the sealing part gentler. The second buffer material 310b is in contact with the buffer material 310b, and the second buffer material 310b is exposed on the side surface of the power storage unit 300. The first buffer material 310a and the second buffer material 310b also function as sealing materials.

[0074] The first buffer material 310a and the second buffer material 310b are made of a material that is more durable than a separator. Use a material with a higher elastic modulus than the material itself. For example, use rubber (natural rubber, synthetic rubber, etc.). It is preferable to select a material that is unlikely to undergo a chemical reaction when in contact with the electrolyte. In this case, silicone rubber is used, which is resistant to chemical reactions when it comes into contact with the electrolyte. The materials used for the first buffer material 310a and the second buffer material 310b are It is preferable to coat or surface treat the electrode with a material that has high solvent resistance to the electrolyte.

[0075] The first buffer material 310a and the second buffer material 310b are made of a material suitable for thermocompression bonding. A material that adheres by this method is used.

[0076] By providing the first buffer material 310a and the second buffer material 310b, the power storage unit 300 can be bent. However, the film of the exterior body is configured to be less likely to wrinkle at the outer periphery of the power storage unit 300. It is possible.

[0077] In order to increase the capacity of the electricity storage unit 300, the positive electrode 101, the separator 103, the negative electrode 104, When multiple combinations of layers in 02 are stacked and stored in an exterior body, the total thickness becomes thicker. This causes a difference in thickness between the outer casing and the peripheral area, resulting in a step in the film. In order to reduce the shock, a first buffer material 310a and a second buffer material 310b may be provided. preferable.

[0078] In addition, by increasing the length of the first buffer material 310a and the second buffer material 310b, When bending the electricity storage unit 300, a space may be provided so that the current collector and the like can slide. stomach.

[0079] Also, an example in which two elastic bodies, a first buffer material 310a and a second buffer material 310b, are used has been shown. However, there is no particular limitation, and a single U-shaped elastic material may be used as the cushioning material. A single elastic material may be used as the cushioning material.

[0080] This embodiment can be combined with the first embodiment. For example, the first buffer material The positive electrode 101, the separator 103, and the negative electrode 10 are disposed between the first buffer material 310a and the second buffer material 310b. 2 is positioned, and a sheet of plastic film is used as a third buffer material. The battery may be housed inside the power storage unit.

[0081] (Embodiment 3) In this embodiment, the film of the exterior body is formed with unevenness by press processing, for example, embossing. The area surrounded by the exterior body is made of a sheet-like plastic film as a cushioning material 110. Here is an example:

[0082] In this embodiment, the film surface is embossed, and a film having a pattern is used. An example of manufacturing a lithium ion secondary battery is shown in FIG. 4. In FIG. 4, the same The same reference numerals will be used to describe common parts, and for the sake of simplicity, detailed descriptions will not be given here. This will be omitted.

[0083] First, a sheet made of a flexible substrate is prepared. The sheet is a laminate, and the metal film is The adhesive layer (also called a heat seal layer) is used on one or both sides. The adhesive layer is a heat-sealable resin film containing polypropylene, polyethylene, etc. In this embodiment, the sheet has a nylon resin on the surface of an aluminum foil, The back of the foil is made of acid-resistant polypropylene film and the metal foil is laminated with polypropylene film. A sheet is used, and the sheet is cut to prepare the film.

[0084] Then, this film is embossed to form irregularities on the surface of the film, making it visible. Here, we will show an example of embossing after cutting the sheet. The order is not particularly limited, and the sheet is embossed before being cut, and then cut. Alternatively, the sheet may be folded and thermocompressed before being cut.

[0085] Embossing is a type of press processing, in which an embossing roll with an uneven surface is used. The embossing roll is pressed against the film to form irregularities on the film surface that correspond to the irregularities of the embossing roll. An embossing roll is a roll with a pattern engraved on its surface.

[0086] Furthermore, the method is not limited to using an embossing roll, and an embossing plate may also be used. In addition, the present invention is not limited to embossing, and any other processing may be used as long as a relief is formed on a part of the film. stomach.

[0087] In this embodiment, the film 411 is provided with projections and depressions on both sides to form a pattern. Fold it in the center, overlap the two corners that sandwich the bent part, and glue the three sides together. It has a sealed structure.

[0088] Next, the film 411 is folded in the center to form the state shown in FIG. 4(A).

[0089] As shown in FIG. 4(B), the secondary battery is made up of a positive electrode 101, a separator 103, and a negative electrode The positive electrode 101 and the negative electrode 102 are laminated together, and the buffer material 110 is prepared. The current collectors used are stainless steel, gold, platinum, zinc, iron, nickel, copper, aluminum, Metals such as titanium and tantalum, and their alloys, are highly conductive and have low carriers such as lithium. Materials that do not alloy with ions can be used. Also, silicon, titanium, neodymium Aluminum alloys to which elements such as scandium and molybdenum, which improve heat resistance, have been added. Gold can be used. It can also be made of a metal element that reacts with silicon to form silicide. The metal element that reacts with silicon to form silicide is zirconium. Titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten There are stainless steel, cobalt, nickel, etc. The current collectors are available in foil, plate (sheet), mesh, etc. , cylindrical, coil, punched metal, expanded metal, or other shapes may be used as appropriate. It is preferable to use a current collector having a thickness of 5 μm or more and 40 μm or less. For the sake of simplicity, a laminated assembly of a positive electrode 101, a separator 103, and a negative electrode 102 is shown here. Although an example of combining the two and storing them in one exterior body was shown, in order to increase the capacity of the secondary battery, In this embodiment, 12 combinations are stacked and stored in the exterior body. Stored in the exterior housing.

[0090] Then, two lead electrodes having a sealing layer 415 shown in FIG. 4(C) are prepared. Also called lead terminals, these are used to pull out the positive or negative electrodes of a secondary battery to the outside of the exterior film. As the lead electrodes, the positive electrode lead 104 is made of aluminum, and the negative electrode lead 1 05 uses nickel-plated copper.

[0091] Then, the positive electrode lead 104 and the protruding portion of the positive electrode 101 are electrically connected by ultrasonic welding or the like. Then, the negative electrode lead 105 and the protruding portion of the negative electrode 102 are electrically connected by ultrasonic welding or the like. Connect to the target.

[0092] Then, in order to leave one side for the electrolyte, two sides of the film 411 are heat-pressed. During the thermocompression bonding, the sealing layer 415 provided on the lead electrode also melts, and the lead electrode and the film 411 are fixed. Then, in a reduced pressure atmosphere or an inert atmosphere, A desired amount of electrolyte is dropped onto the inside of the bag-shaped film 411. The remaining unpressurized edges of the film are sealed by thermocompression.

[0093] In this manner, the power storage unit 400 shown in FIG. 4(D) can be manufactured.

[0094] The obtained electricity storage unit 400 has a pattern with projections and depressions on the surface of the film 411 that serves as the exterior body. In addition, the end surface area is a thermocompression bonding area, and this area also has an uneven surface pattern. The unevenness of the thermocompression bonded area is smaller than that of the central part, but the stress applied when the secondary battery is bent is large. By using a structure that relieves strain caused by stress, The battery will not be damaged (exterior etc.) when bent or deformed, ensuring long-term reliability. This ensures safety.

[0095] In addition, a sample with the above configuration was prepared without adding the electrolyte and cut along the dotted line A1-A2. The X-ray photograph of this case is shown in Figure 4(E).

[0096] In Figure 4(E), there are irregularities on the exterior film and a gap between the lower exterior film and the current collector. The plastic film is not visible in the X-ray, and the gap is visible. A sheet-shaped plastic film (thickness 300 μm) is provided.

[0097] The sheet-shaped plastic film used as a cushioning material is attached to the exterior film when the power storage unit is bent. This prevents the irregularities of the film from coming into direct contact with the current collector and causing damage.

[0098] This embodiment mode can be freely combined with Embodiment Mode 1 or 2.

[0099] (Fourth embodiment) In this embodiment, a power storage unit obtained by using any one of Embodiments 1 to 3 is incorporated. An example of such an electronic device is shown below.

[0100] Examples of electronic devices that use power storage devices include head-mounted displays and goggle-type displays. display devices such as TVs (also called televisions or television receivers), desktop laptop and other personal computers, computer monitors, digital cameras, etc. digital cameras, digital video cameras, digital photo frames, electronic organizers, e-book terminals, Translators, toys, voice input devices such as microphones, electric shavers, electric toothbrushes, electronic razors High frequency heating devices such as microwave ovens, electric rice cookers, electric washing machines, electric vacuum cleaners, water heaters, electric fans, hair Dryers, air conditioning equipment such as humidifiers, dehumidifiers, and air conditioners, dishwashers, and dish dryers dryers, clothes dryers, futon dryers, electric refrigerators, electric freezers, electric refrigerator-freezers, for DNA storage Freezers, flashlights, power tools, smoke detectors, gas alarms, burglar alarms and other alarm systems, industrial equipment Industrial robots, hearing aids, cardiac pacemakers, X-ray machines, radiation detectors, electric massagers health and medical equipment such as dialysis machines and dialysis machines, mobile phones (also called mobile phones or mobile phone devices) ), portable game consoles, personal digital assistants, lighting equipment, headphones, stereos, remote controls Rollers, clocks such as table clocks and wall clocks, cordless telephone handsets, transceivers, pedometers, Portable or stationary sound reproducing devices such as calculators, digital audio players, pachinko machines, etc. Examples include large game consoles.

[0101] The power storage unit obtained by using any one of the first to third embodiments has a thin and flexible exterior. It is a film that is attached to a support structure having a curved surface, and is used to protect the support structure from a large radius of curvature. It can be deformed to follow the curved surface of the area.

[0102] In addition, flexible storage batteries can be mounted on the interior or exterior walls of houses and buildings, or on automobiles. It is also possible to incorporate it along the curved surface of the interior or exterior of the vehicle.

[0103] FIG. 5A 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, and the like. It has a body 7407.

[0104] FIG. 5B shows the mobile phone 7400 in a curved state. When the entire casing 0 is deformed by an external force and curved, the casing 7 provided inside the casing The state of the bent power storage unit 7407 is shown in FIG. The power storage unit 7407 is a laminated battery (also called a laminated battery or a film-covered battery). The power storage unit 7407 is fixed in a bent state. 07 has a lead electrode 7408 electrically connected to a current collector 7409. For example, A buffer material is provided in the area surrounded by the film of the exterior body of the power storage unit 7407. This structure has high reliability even when the mobile phone 740 is bent. 0 is the slot for inserting a SIM card and for connecting USB devices such as USB memory. A connector portion for connecting the power supply and the power source may be provided.

[0105] Figure 5(D) shows an example of a bendable mobile phone. If the mobile phone is bent in the shape shown in FIG. 5(E), it can be made into a bangle-type mobile phone. 100 includes a housing 7101, a display unit 7102, operation buttons 7103, and a power storage unit 7104. FIG. 5F shows a state of the power storage unit 7104 that can be bent. When the battery 104 is bent and worn on the user's arm, the housing is deformed and one part of the battery 7104 is The curvature of part or the whole changes. Specifically, the curvature radius is between 10 mm and 150 mm. Within this range, a part or the whole of the main surface of the housing or the power storage unit 7104 changes. 7104 has a lead electrode 7105 electrically connected to a current collector 7106. For example, a buffer material is provided in the area surrounded by the film of the exterior body of the power storage unit 7104. The structure is such that the body 7104 can maintain high reliability even if it is bent many times with its curvature changed. In this way, the mobile phone shown in Figure 5(D) can change into multiple shapes. To realize this, at least a housing 7101, a display unit 7102, and It is also desirable that the power storage unit 7104 be flexible.

[0106] In addition, the mobile phone 7100 has a slot for inserting a SIM card and a USB memory stick. A connector for connecting a USB device such as the above may be provided.

[0107] Another example of using a mobile phone is shown in Figure 5(D), where the mobile phone is folded in the center. If the center part of the mobile phone is further expanded, it can be made into the shape shown in Figure 5(G). The mobile phone is folded so that the ends overlap as shown in Figure 5(H) to make it smaller. It can be made small enough to fit in a user's pocket. Figures 5(D), 5(G), and 5(H) If only the deformation shown in FIG. 1 is observed, the power storage unit 7104 is not bent. When the device is dropped or subjected to other shocks, the thin and internally disposed power storage unit 71 The shock is also applied to the battery 7104. If the exterior is provided, these impacts can be absorbed, and a durable secondary battery can be realized. The capacitor 7104 in which a buffer material is provided in the area surrounded by the film of the body is Regardless of whether or not this is the case, a highly reliable mobile phone can be achieved.

[0108] FIG. 6(A) shows an example of a vacuum cleaner. The inside of the vacuum cleaner has a dust collection space to suck up and store dust. Therefore, it is preferable that the space occupied by the power storage unit 7604 is as small as possible. and disposing a bendable capacitor 7604 between the outer surface and the dust collection space. is useful.

[0109] The vacuum cleaner 7600 includes an operation button 7603 and a power storage unit 7604. ) shows a state of a power storage unit 7604 that can be bent. A buffer material is provided in the area surrounded by the film, and the signal strength is maintained when the power storage unit 7604 is bent. The capacitor 7604 has a lead electrode 7604 electrically connected to the negative electrode. 601 and a lead electrode 7602 electrically connected to the positive electrode.

[0110] In addition, another example of a power storage unit 7604 in which two lead electrodes are exposed on one short side of the exterior body is shown. FIG. 6C shows a state of the power storage unit 7605 that can be bent. The structure is such that the current collector or lead electrode is exposed on each of the two short sides of the exterior body. By providing a buffer material in the area surrounded by the film on the exterior of the 7605, it can be bent. and highly reliable.

[0111] 6D shows an example of an internal structure of the power storage unit 7605. As shown in FIG. It is composed of a positive electrode 101, a separator 103, and two negative electrodes 102. 103 is folded, and the positive electrode 101 is placed between them. The positive electrode active material layer is shown here as a combination of a positive electrode and two negative electrodes. In order to increase the capacity of the power storage unit 7605, a combination of more positive and negative electrodes is used. Also, a buffer material 110 is provided in contact with one of the negative electrodes 102. The buffer material 110 is It is placed in the area surrounded by the film of the power storage unit 7605, and reinforces the mechanical strength of the power storage unit 7605. It plays a role in

[0112] The thin power storage unit 7604 is manufactured by the method for manufacturing a secondary battery having a laminate structure described in Embodiment 3. It can be made by

[0113] The thin power storage unit 7604 has a laminate structure and is bent and fixed. The device 7600 has a display unit 7606 that displays the remaining power of a thin power storage unit 7604. The display surface of the display portion 7606 is curved to match the shape of the outer surface of the vacuum cleaner. The vacuum cleaner has a connection cord for connecting to an outlet, and a thin storage battery 7604. Once enough power is charged, you can use the vacuum cleaner without the cord. The thin power storage unit 7604 may be charged wirelessly without using a connection cord. By providing a buffer material in the area surrounded by the film of the exterior body of the power storage unit 7604, it is possible to improve resistance to shock. It is fast and reliable.

[0114] In addition, by installing a bendable electricity storage device in a vehicle, it is possible to Next-generation clean energy vehicles such as electric vehicles (EV) and plug-in hybrid vehicles (PHEV) It can also be used in agricultural machinery, motorized bicycles including electrically assisted bicycles, Motorcycles, electric wheelchairs, electric carts, small or large boats, submarines, fixed-wing and rotary-wing aircraft Bending for moving objects such as aircraft, rockets, satellites, space probes, planetary probes, and spacecraft It is also possible to mount a power storage unit that can be used. [Explanation of symbols]

[0115] 100 Electricity storage unit 101 Positive electrode 102 Negative electrode 103 Separator 104 Positive lead 105 Negative lead 107 Exterior body 110 Cushioning material 110a Cushioning material 110b Cushioning material 300 Electricity storage unit 310a Cushioning material 310b Cushioning material 311 Adhesive area 400 Electricity storage unit 411 Film 415 Sealing Layer 1700 curved surface 1701 Plane 1702 Curve 1703 Radius of curvature 1704 Center of curvature 1800 Center of curvature 1801 Film 1802 radius of curvature 1803 Film 1804 radius of curvature

Claims

1. A secondary battery having a first current collector, an active material layer, a second current collector, a buffer material, and a separator, the cushioning material has a sheet-like plastic film, the buffer material overlaps the first current collector and the second current collector, and is housed in a region surrounded by an exterior body; an area of ​​the buffer material is larger than an area where the first current collector and the second current collector overlap; the exterior body has a pattern formed of recesses or protrusions on its surface, When the secondary battery is bent, the cushioning material slides against the exterior body.

2. In claim 1, The buffer material is thicker than the separator.

3. In claim 1 or claim 2, The buffer material has a slit.

Images