Non-aqueous secondary battery

Abstract

To provide a novel separator structure in a secondary battery.SOLUTION: A non-aqueous secondary battery includes a positive electrode, a negative electrode, an electrolytic solution, a first separator, and a second separator, and the first separator and the second separator are provided between the positive electrode and the negative electrode, the first separator has a first hole and the second separator has a second hole. The first hole and the second hole have different sizes. Alternatively, the volume ratio of the first holes in the first separator is different from the volume ratio of the second holes in the second separator.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to a nonaqueous secondary battery and a method for producing the same.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one aspect relates to an article, a method, or a manufacturing method. One aspect of the present invention is a process, machine, manufacture, or composition. Therefore, the present invention more specifically disclosed herein The technical field of one embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, The driving method thereof or the manufacturing method thereof can be given as an example. [Background technology]

[0003] In recent years, secondary batteries such as lithium-ion secondary batteries, lithium-ion capacitors, air batteries, fuel cells, etc. Various types of electricity storage devices, such as fuel cells, have been actively developed (Patent Documents 1 to 3). In particular, lithium-ion secondary batteries, which have high output and high energy density, are used in mobile phones and smartphones. Mobile phones, notebook personal computers and other portable information terminals, portable music players, digital Cameras and other electrical equipment, medical equipment, hybrid vehicles (HEVs), electric vehicles (EVs) ), or next-generation clean energy vehicles such as plug-in hybrid vehicles (PHEVs), Stationary power storage devices, etc. are rapidly growing with the development of the semiconductor industry and the increasing demand for energy conservation. Demand for these materials has expanded, and they have become indispensable in modern society.

[0004] A lithium ion secondary battery, which is one type of non-aqueous secondary battery, is composed of a positive electrode, a negative electrode, a separator, and In general, a lithium ion secondary battery has a non-aqueous electrolyte, a non-aqueous electrolyte, and an exterior body that covers these. In this case, a positive electrode that absorbs and releases lithium ions is attached to both sides of a positive electrode current collector made of aluminum or the like. The positive electrode is coated with a positive electrode mixture containing active material, and the negative electrode current collector is made of copper or other material. Lithium ions are applied to both sides of the negative electrode current collector. The negative electrode is coated with a negative electrode mixture containing a negative electrode active material that absorbs and releases ions. The positive and negative electrodes are insulated by sandwiching a separator between them, and the positive and negative electrodes are The exterior body is electrically connected to the positive and negative terminals attached to the battery. It has a fixed shape. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2012 / 165358 Brochure [Patent Document 2] US Patent Application Publication No. 2012 / 0002349 [Patent Document 3] International Publication No. WO2009 / 131180 Brochure Summary of the Invention [Problem to be solved by the invention]

[0006] The separator is placed between the positive and negative electrodes and serves to prevent the two electrodes from coming into direct contact. When the two electrodes of a lithium-ion secondary battery come into direct contact with each other, a large, uncontrollable current flows between the electrodes. This may cause a large amount of heat and lead to safety issues. Even if this does not occur, self-discharge will occur and the battery's functionality will be impaired.

[0007] In addition, in the manufacturing process or charge / discharge process of a lithium-ion secondary battery, Some of the carrier ions are precipitated on the surface of the negative electrode and become irreversible components, impairing the function of the battery. Furthermore, as the deposition of lithium progresses, it grows into whisker-like structures. However, depending on the properties of the separator, the structure may pass through the separator holes and connect the two electrodes. This can lead to problems, too.

[0008] In order for the battery to function, the separator must have the ability to retain the electrolyte. The separator must also be ion conductive. Ion conductivity is closely related to the properties of the pores in the separator layer.

[0009] Separators are generally made of porous materials, and the separator The size and shape of the pores formed in the separator layer and the ratio of the pore volume to the separator layer (porosity) are different. The larger the size of the separator pores or the higher the volume ratio of the pores (porosity) The higher the temperature, the better the ionic conductivity, but the lower the insulation function between the electrodes. When whiskers are generated, the whiskers penetrate the separator. On the other hand, the deposition of lithium and other elements leads to the formation of The above-mentioned irreversible components are liberated in the form of lumps, or active material particles are liberated from the active material layer. The pores in the separator are less likely to be blocked by the particles, and ionic conductivity is more likely to be maintained.

[0010] The size and amount of pores formed in the separator are determined by the material and method of forming the separator. However, in order to obtain a separator having a desired ionic conductivity and mechanical strength, The selection of materials and forming methods must be carefully considered. However, the separator material and There are limitations to the selection of forming methods, and it is not easy to form a separator with the desired properties. do not have.

[0011] Furthermore, in the case of a flexible lithium-ion secondary battery, the secondary battery can be easily moved in response to changes in shape. Various stresses are generated inside the secondary battery. If the secondary battery does not have a structure to relieve such stresses, If the battery is not fully charged, shear fracture will easily occur at some point in the secondary battery, causing it to lose its function as a secondary battery. is lost.

[0012] In view of the above, one aspect of the present invention is to provide a secondary battery that can achieve a desired temperature while preventing direct contact between the electrodes. It is an object of the present invention to provide a separator having the above ionic conductivity and mechanical strength. Another object is to ensure long-term reliability.

[0013] Another embodiment of the present invention is a lithium ion secondary battery having a novel separator structure. Another object of one embodiment of the present invention is to provide a novel power storage device or the like. One of our goals is to provide

[0014] Another embodiment of the present invention is a secondary battery having a function of being able to change its shape, that is, a shape-changing secondary battery. It is an object of the present invention to provide a flexible secondary battery. Another objective is to provide a new separator that can withstand shape changes in ponds.

[0015] The description of these problems does not preclude the existence of other problems. It is not necessary for the embodiment to solve all of these problems. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0016] The configuration of one embodiment of the invention disclosed in this specification includes a positive electrode, a negative electrode, an electrolyte, and a first separator. The first separator and the second separator are connected to a positive electrode and a negative electrode. The first separator has a first hole, and the second separator has a second hole. The battery is a nonaqueous secondary battery having two holes, the first hole and the second hole having different sizes.

[0017] The first separator and the second separator may have different thicknesses.

[0018] Another embodiment of the present invention disclosed in this specification is a battery comprising a positive electrode, a negative electrode, an electrolyte, and a first separator. The first separator is a positive electrode, a second separator, and a third separator. and the negative electrode, and the second separator is provided between the first separator and the positive electrode. a third separator is provided between the first separator and the negative electrode; The first separator has a first hole, the second separator has a second hole, and the third separator has a second hole. The separator has a third hole, and the first hole is a non-aqueous bilayer having a different size from the second hole and the third hole. Next battery.

[0019] Another embodiment of the present invention disclosed in this specification is a battery comprising a positive electrode, a negative electrode, an electrolyte, and a first separator. The first separator is a positive electrode, a second separator, and a third separator. and the negative electrode, and the second separator is provided between the first separator and the positive electrode. a third separator is provided between the first separator and the negative electrode; The first separator has a first hole, the second separator has a second hole, and the third separator has a second hole. The separator has a third hole, and the first hole is a non-aqueous secondary battery larger than the second hole and the third hole. It is a pond.

[0020] Another embodiment of the present invention disclosed in this specification is a battery comprising a positive electrode, a negative electrode, an electrolyte, and a first separator. The first separator is a positive electrode, a second separator, and a third separator. and the negative electrode, and the second separator is provided between the first separator and the positive electrode. a third separator is provided between the first separator and the negative electrode; The first separator has a first hole, the second separator has a second hole, and the third separator has a second hole. The actuator has a third hole, and the first hole, the second hole, and the third hole are non-contact holes having different sizes. It is an aqueous secondary battery.

[0021] In addition, the nonaqueous secondary battery according to one embodiment of the present invention disclosed in this specification includes a first separator. It is preferable that the thickness of the first separator is different from the thickness of the second separator and the thickness of the third separator. Furthermore, the thickness of the first separator is smaller than the thickness of the second separator and the thickness of the third separator. It is more preferable that the thickness of the insulating film be smaller than the thickness of the insulating film.

[0022] In addition, in the non-aqueous secondary battery according to one embodiment of the present invention, the electrolyte is lithium. In addition, the nonaqueous solution according to one embodiment of the present invention disclosed in this specification may have a cation. The aqueous secondary battery may further have a flexible exterior body, and the nonaqueous secondary battery may have a flexible exterior body. It may have a property of

[0023] In a non-aqueous secondary battery, a multi-layer separator is provided between a positive electrode and a negative electrode, and each layer of the separator When the pore sizes of the separators are different, the properties of the entire multilayer structure are It is determined by the properties and thickness of the material, the ratio of the volume of the holes per unit volume, etc. The material, thickness, and pore volume ratio per unit volume of each separator are each set to a predetermined value. However, by setting the properties of each separator in various ways, it is possible to obtain a multi-layer structure. This makes it possible to precisely set the separator characteristics of the entire structure.

[0024] For example, when a separator with a given thickness is provided between a positive electrode and a negative electrode, A first separator with a high pore volume ratio and large, thick pores; When a separator laminate is provided with a second separator having a low ratio of fluorine and small and thin pores, While obtaining high ionic conductivity from the first separator, The separator can be one that has electrolyte retention properties.

[0025] If a separator of a given thickness is made only of the material that constitutes the first separator, ion conduction High conductivity and ability to prevent whiskers from connecting the two electrodes Furthermore, the separator has low mechanical strength. If the separator is made of only the material that constitutes the second separator, whisker-like lithium It can prevent the deposits (whiskers) from connecting the two electrodes, but it has low ionic conductivity. Furthermore, when lump-shaped deposits are generated, if the size of the holes is small, the deposits can easily penetrate the holes. The pores are blocked by the cations, resulting in a decrease in ionic conductivity.

[0026] There are limitations to the materials and properties that can be used for separators, and it is difficult to manufacture the necessary separators. It may be difficult to form a separator using multiple layers of different materials rather than using a single material. Combining separators of the above provides a wider range of separator properties to choose from.

[0027] In addition, when the flexible secondary battery is deformed, the separators provided in the multi-layer structure In this case, the stress generated in the separator can be alleviated by the sliding between the layers. Therefore, if the separator is provided in multiple layers, the secondary battery has high resistance to deformation. A structure having a multi-layer separator is suitable for a secondary battery having flexibility.

[0028] Furthermore, in flexible secondary batteries, whiskers grow from the negative electrode and form two The whiskers penetrate the separator interface and connect the two separators. In this state, when friction occurs between the separators due to the change in shape of the secondary battery, whisker-like The whiskers cannot withstand the friction and are sheared at the separator interface, causing destruction. Therefore, it is necessary to prevent a connection (short circuit) between the two electrodes caused by whiskers. It is also possible.

[0029] The exterior body of the flexible secondary battery according to one embodiment of the present invention preferably has a curvature radius of 10 mm or more. The film, which is the exterior body of the secondary battery, can be deformed with a radius of curvature of 30 mm or more. The battery is made up of one or two sheets. In the case of a laminated secondary battery, The cross-sectional structure of the battery is such that it is sandwiched between two curved film exterior bodies.

[0030] The radius of curvature of a surface will be described with reference to FIG. 17. In FIG. 17(A), a curved surface 1700 In the plane 1701 that cuts the sphere, a part of the curve 1702, which is the shape of the curved surface, is approximated to an arc of a circle. The radius of the circle is the radius of curvature 1703, and the center of the circle is the center of curvature 1704. FIG. 17(B) shows a top view of the curved surface 1700. FIG. 17(C) shows the curved surface 1700 on the plane 1701. When cutting a curved surface with a plane, the shape of the curved surface changes depending on the plane. The radius of curvature of the curves will be different, but the surface will be classified as the curve with the smallest radius of curvature. When a surface is cut by a plane, the radius of curvature of the curve, which is the cross-sectional shape of the surface, is called the radius of curvature of the surface. do.

[0031] The secondary battery, which consists of two films as exterior bodies and contains battery materials (1805) such as electrodes and electrolyte, is curved. When the secondary battery is rotated, the radius of curvature of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery 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. (Figure 18(A)). If the secondary battery is bent to make the cross section arc-shaped, the center of curvature is 1800. The surface of the film close to the center of curvature 1800 is subjected to compressive stress, and the surface of the film far from the center of curvature 1800 is subjected to compressive stress. Tensile stress is applied to the surface of the exterior body (Fig. 18(B)). When a pattern is formed, even if compressive or tensile stress is applied, the deformation does not occur. Therefore, the secondary battery is placed on the side close to the center of curvature. The exterior body can be deformed within a range in which the radius of curvature is 10 mm or more, preferably 30 mm or more. Cut.

[0032] The cross-sectional shape of the secondary battery 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. 18(C), a wavy shape (FIG. 18(D)), an S-shape, etc. In the case where the curved surface of the secondary battery has a shape having a plurality of centers of curvature, Among the radii of curvature at the centers of curvature of the two surfaces, the surface with the smallest radius of curvature is The radius of curvature of the exterior body closer to the center of curvature of the exterior body is 10 mm or more, preferably 30 mm or more. The secondary battery can be deformed within the above range. Effect of the Invention

[0033] One aspect of the present invention is to provide a secondary battery having a desired ion conduction property while preventing direct contact between the electrodes. It is possible to provide a separator having excellent mechanical strength and long-term reliability. This makes it possible to achieve this.

[0034] Another embodiment of the present invention is a lithium ion secondary battery having a novel separator structure. Another embodiment of the present invention is to provide a novel power storage device or the like. Break.

[0035] Another embodiment of the present invention is a secondary battery having a function of being able to change its shape, that is, a shape-changing secondary battery. It is possible to provide a secondary battery having flexibility. It is also possible to provide a novel separator that is resistant to shape changes.

[0036] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. Effects other than these may also be included. The above is self-evident from the description, drawings, claims, etc. Other effects can be extracted from the claims and other descriptions. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the present invention. [Diagram 2] Schematic cross-sectional view showing shearing of a whisker-like structure. [Diagram 3] FIG. 2 is a cross-sectional schematic diagram showing a current collector and an active material. [Figure 4] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram illustrating a coin-type secondary battery. [Figure 6] FIG. 2 is a diagram illustrating a stacked secondary battery. [Figure 7] FIG. 2 is a diagram illustrating a cylindrical secondary battery. [Figure 8] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 9] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 10] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 11] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 12] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 13] 1A to 1C are diagrams illustrating electronic devices. [Figure 14] 1A to 1C are diagrams illustrating electronic devices. [Figure 15] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the present invention. [Figure 16] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of the present invention. [Figure 17] FIG. [Figure 18] 1A and 1B are diagrams illustrating a secondary battery having flexibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, an embodiment of the present invention will be described in detail with reference to the 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 is not limited to the description of the following embodiments. It is not something that can be done.

[0039] In each of the drawings described in this specification, the sizes of the positive electrode, negative electrode, active material layer, exterior body, etc. The dimensions of each component, such as thickness, may be exaggerated for clarity of illustration. Therefore, each component is not necessarily limited by its size, and the relative size between each component is not necessarily limited by its size. The size is not limited.

[0040] In addition, in this specification, ordinal numbers such as 1st, 2nd, 3rd, etc. are used for convenience. It does not indicate the order of the processes or the vertical positional relationship. In the above explanation, "the first" can be replaced with "the second" or "the third", etc. as appropriate. In addition, the ordinal numbers described in this specification and the like and the ordinal numbers used to specify one aspect of the present invention The ordinal numbers used may not match.

[0041] In addition, in the configuration of the present invention described in this specification, etc., the same parts or parts having similar functions The same reference numerals are used in common between different drawings, and the repeated explanations are omitted. When referring to parts having similar functions, the same hatch pattern is used and no special reference numerals are attached. There may not be.

[0042] In this specification, the pores of the separator refer to a layer or film having a separator material. The separator refers to the area that does not have separator material. The separator also refers to the holes. The term may refer to the pores as a single unit or may refer to the pores and the separator material separately. There is no particular limitation as to whether the shape is directional or isotropic. Whether or not a hole penetrates the layer having the separator material, whether or not the hole is surrounded by the separator material There is no limitation as to whether the separator is a closed space or not. In the secondary battery, the pores are partially or entirely filled with the electrolyte. .

[0043] In addition, the contents described in the description of the embodiment of the present invention can be used in appropriate combination. Cut.

[0044] (Embodiment 1) A method for manufacturing a lithium-ion secondary battery according to one embodiment of the present invention will be described with reference to FIG. First, a positive electrode current collector 110, a positive electrode active material layer 112, and a first separator 100, a second separator 101, a negative electrode active material layer 113, and a negative electrode current collector 111 are stacked. The cross-sectional view of the current collector and the active material layer is shown in FIG. The active material layer can be formed on both sides of the current collector, and the secondary battery can have a laminated structure. It is Noh.

[0045] FIG. 1 is an enlarged schematic cross-sectional view of a first separator 100 and a second separator 101. 1(B) and 1(C). The first separator 100 and the second separator 101 are Each of the first and second holes 104 and 105 has a different size. The ratio of the volume of the first pores 104 in the separator 100 to the volume of the second pores 101 is The volume ratio of the second pores 105 is different from that of the separator in the schematic diagram. In this paper, the pores are expressed as gaps between the fibers, but the structure of the separator is not limited to a fiber structure. isn't it.

[0046] Furthermore, as shown in FIG. 1(A), the thickness of the first separator 100 and the second separator 101 Therefore, the ionic conductivity, mechanical strength, insulating performance, etc. of the separator are different. The first separator 100 and the second separator 101 have different characteristics. Even if a product is manufactured using the same materials, different characteristics can be obtained by changing the manufacturing method or conditions. may be given.

[0047] The separator material can be paper, nonwoven fabric, glass fiber, or nylon (polyamide). ), Vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin However, it is necessary to use synthetic fibers such as polyester and polyurethane, which do not dissolve in the electrolyte solution described below. It is necessary to select the right material.

[0048] More specifically, the separator material may be, for example, a fluorine-based polymer or a polyethylene terephthalate. oxide, polypropylene oxide, etc., polyethers such as polyethylene and polypropylene, etc. Polyolefin, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate Polymethyl acrylate, polyvinyl alcohol, polymethacrylonitrile, polyvinyl Nyl acetate, polyvinylpyrrolidone, polyethyleneimine, polybutadiene, poly ethylene, polyisoprene, polyurethane polymers and their derivatives, cellulose, paper, One material selected from nonwoven fabric and glass fiber can be used alone or in combination of two or more materials. can.

[0049] The separator has the following functions: insulation to prevent contact between the two electrodes, ability to retain electrolyte, and ion conductivity. As a method for producing a membrane that functions as a separator, a method for stretching the membrane has been proposed. For example, a molten polymer material is spread and allowed to dissipate heat, and the resulting film is called a membrane. There is a stretching method in which holes are formed by stretching in two parallel axial directions. The separators used are limited in the size of the pores and the thickness of the membrane due to the materials used and the mechanical strength of the membrane. There are limitations.

[0050] In this embodiment, the first separator 100 and the second separator 101 are The first separator can be fabricated by a stretching method and used in a secondary battery. The material constituting the first separator 100 and the second separator 101 may be the above-mentioned materials or materials other than those mentioned above. One or more materials can be selected and used, depending on the film formation conditions and stretching conditions, etc. The characteristics of the membrane, such as the size of the pores in the membrane, the volume ratio of the pores (also called the porosity), and the membrane thickness, are then The first separator 100 and the second separator 110 each have different characteristics. By using the film 101 in combination with the film 102, the cell of the secondary battery is improved compared to when one of the films is used alone. This allows you to select from a wide variety of parameter performance options.

[0051] For example, the second separator 101 has smaller pores than the first separator 100. The ratio of the volume of the pores in the membrane (porosity) is small, and the membrane is thin. When the separator 100 and the second separator 101 are used together as a separator for a secondary battery, The second step is to improve the insulation performance to prevent Li whiskers from connecting the positive and negative electrodes. The thick first separator 100 ensures high ionic conductivity. That is, the first separator 100 and the second separator 101 can be It is also possible to give each of them a different function.

[0052] Furthermore, even when a deformation stress is applied to the secondary battery, the first separator 100 and the second separator At the interface with the separator 101, the two separators slide against each other to relieve stress. Therefore, the structure using two separators is suitable for the separator of a flexible secondary battery. Furthermore, it is also suitable for the structure of a flexible secondary battery, in which a whisker-like structure (a whisker-like structure) is formed from the negative electrode. When the crystalline structure (Iscar) 108 grows and breaks through the interface between the two separators (Figure 2(A) When friction occurs between the separators due to the change in shape of the secondary battery, whisker-like structures (weaves) form. The Iscar 108 cannot withstand the sliding and is sheared and destroyed at the separator interface. In order to prevent a connection (short circuit) between the two electrodes due to the whisker-like structure 108, The white arrows in Fig. 2(B) indicate the sliding of both separators. Represents movement.

[0053] As a method for fabricating a structure with two separators, a membrane containing the separator material is A method of stretching two layers and forming holes in both layers is considered. The conditions of the stretching process applied to the two layers are the same, so the size of the holes formed is similar, and each cell The porosity of the pores in the separator may also be similar. However, it may be difficult to provide different performances to each of the data. In an embodiment according to the present invention, the separator laminate produced by the method is not necessarily It is not something to be excluded.

[0054] The method of assembling two separators into a secondary battery is to first combine the two separators and then It is possible to sandwich the film between the positive and negative electrodes as described above. It is also possible to place one separator on each of the positive and negative electrodes and then combine them. The first separator and the second separator are placed on the other side, and the other of the positive electrode or the negative electrode is placed on the other side. A cross-sectional schematic diagram of a secondary battery having two separators is shown in Figure 1(A). .

[0055] The second separator 101 is in the form of a sheet or a thin film having a size capable of covering both sides of the negative electrode. If the negative electrode is formed in an envelope shape and wrapped in a separator, the negative electrode The second separator can protect the negative electrode from mechanical damage, making it easier to handle the negative electrode. The first separator 100 is sandwiched between the negative electrode wrapped in the separator 101 and the positive electrode active material layer 112. The battery is then inserted into an exterior body 120 and impregnated with an electrolyte solution 121 to form a secondary battery. As shown in FIG. 15, the second separator 101 is formed into an envelope shape. FIG. 15(A) shows the cross-sectional structure of a secondary battery made by using a pair of a positive electrode and a negative electrode. The cross-sectional structure of the battery is shown, but multiple pairs of positive and negative electrodes can be used to create a stacked secondary battery. As shown in FIG. 15(B), an electrode active material is formed on both sides of a collector to form an envelope-shaped separator. The cross-sectional structure of the stacked secondary battery is shown.

[0056] As described later, the first separator and the second separator are used in a secondary battery having flexibility. The mounting brackets are not fixed in place because they may slide.

[0057] The negative electrode will be described with reference to FIG. In this embodiment, the material used for the negative electrode active material layer 113 is The process of forming a negative electrode using a carbon-based material will be described below. The negative electrode active material is a granular active material. Therefore, in FIG. 3(A), Although the negative electrode active material is shown in a circular shape, the shape is not limited to this. Although several sizes are shown, the sizes may vary. The process is described below.

[0058] As the negative electrode active material, carbon-based materials include graphite, easily graphitizable carbon (soft carbon), and Graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black For graphite, mesocarbon microbeads (MCMB) and coke-based artificial There are graphite, artificial graphite such as pitch-based artificial graphite, and natural graphite such as spherical natural graphite. Lead comes in a variety of shapes, including flakes and spheres.

[0059] In addition to carbon-based materials, lithium-ion batteries can be used as negative electrode active materials, and can be charged and discharged by alloying and dealloying reactions with lithium. Materials capable of undergoing reactions can also be used. For example, Ga, Si, Al, Ge, Materials containing at least one of Sn, Pb, Sb, Bi, Ag, Zn, Cd, In, etc. These elements have a large capacity compared to carbon, and silicon in particular has a theoretical The capacity is as high as 4200mAh / g, which is preferable. , for example, Mg2Si, Mg2Ge, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. do.

[0060] In addition, the negative electrode active material is SiO, SnO, SnO2, titanium dioxide (TiO2), lithium 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 is Co, Ni or Cu) can be used. For example, Li2 .6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) This is preferable.

[0062] When a composite nitride of lithium and transition metals is used, the negative electrode active material contains lithium ions, The positive electrode active material is made of V2O5, Cr3O8, etc., which do not contain lithium ions. Even when 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, lithium is released as the negative electrode active material. A double nitride of ammonium 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. For example, Lithium oxide (LiO), 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 in which the reaction occurs include Fe2O3, CuO, Cu2O, RuO2, and Cr2O. 3rd 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

[0064] For example, the particle size of the negative electrode active material is preferably 50 nm or more and 100 μm or less. .

[0065] Acetylene black (AB), graphite particles, and carbon black are used as conductive additives for the electrodes. Carbon nanotubes, graphene, fullerene, etc. can be used.

[0066] The conductive additive can form an electronic conduction network in the electrode. This makes it possible to maintain a path of electrical conduction between the negative electrode active materials. By adding an electric assistant, it is possible to realize a negative electrode active material layer 113 having high electronic conductivity. This can be done.

[0067] In addition to the typical polyvinylidene fluoride (PVDF), polyimide is also used as a binder. , polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene poly styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, Polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. It is possible.

[0068] The content of the binder relative to the total amount of the negative electrode active material layer 113 is 1 wt % or more and 10 wt % or less. is preferable, 2 wt% or more and 8 wt% or less is more preferable, and 3 wt% or more and 5 wt% or less is even more preferable. It is more preferable that the content of the conductive assistant with respect to the total amount of the negative electrode active material layer 113 is 1 wt % or less. The content is preferably from 1 wt % to 10 wt %, and more preferably from 1 wt % to 5 wt %.

[0069] Next, a negative electrode active material layer 113 is formed on the negative electrode current collector 111. When forming the porous layer 113, a negative electrode active material, a binder, a conductive assistant, and a dispersion medium are mixed to form an electrode. A negative electrode paste (slurry) is prepared, applied to the negative electrode current collector 111, and dried. If necessary, a pressing process may be carried out later.

[0070] In this embodiment, a copper metal foil is used as the negative electrode current collector 111, and a mesoporous slurry is used. Bon microbeads are mixed with polyvinylidene fluoride (PVDF) as a binder. The above is used.

[0071] The negative electrode current collector 111 may be made of any of stainless steel, gold, platinum, zinc, iron, copper, titanium, and tantalum. Metals such as these and their alloys have high electrical conductivity and can be alloyed with carrier ions such as lithium. In addition, metals that react with silicon to form silicides can be used. The metal element that reacts with silicon to form silicide is di- Ru, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum The negative electrode current collector 111 may be in the form of a foil or a plate (seal). Shapes include metal, net, cylinder, coil, punched metal, expanded metal, etc. The negative electrode current collector 111 has a thickness of 5 μm or more and 30 μm or less. It is also advisable to use graphite or the like on a part of the surface of the electrode current collector. A coating layer may be provided.

[0072] Through the above steps, a negative electrode for a lithium ion secondary battery can be produced.

[0073] The positive electrode is composed of at least a positive electrode active material layer 112 and a positive electrode current collector 110. In this embodiment, the material used for the positive electrode active material layer 112 is lithium iron phosphate. The process of forming a positive electrode using LiFePO4 is described below. In the positive electrode active material, a granular active material is used. The positive electrode active material is shown in a circular shape, but the shape is not limited to this. Although the positive electrode active material is shown as having a uniform size, the positive electrode active material may have size variation. The process for forming the poles is described below.

[0074] The positive electrode active material is a material capable of inserting and extracting carrier ions such as lithium ions. For example, an olivine type crystal structure, a layered rock salt type crystal structure, or a spinel type crystal structure can be used. Examples of such materials include lithium-containing materials having a tetracyclic crystal structure.

[0075] Lithium-containing materials with an olivine structure (general formula LiMPO4 (M is Fe(II), Mn( Representative examples of LiFePO4, Li NiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a C o b PO4, LiFe a Mn b PO4, LiNi a Co bPO4, LiNi a Mn b PO 4 (a + b is less than or equal to 1, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, Li Fe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is less than or equal to 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is less than or equal to 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. exist.

[0076] In particular, lithium iron phosphate (LiFePO4) is preferable because it satisfies well the requirements for a cathode active material, such as safety, stability, high capacity density, high potential, and the presence of lithium ions that can be extracted during initial oxidation (charging). For example, as a lithium-containing material having a layered rock salt-type crystal structure, there are lithium cobaltate (LiCoO2), LiNiO2, LiMnO2, Li2MnO3, LiNi

[0077] (LiCoO2), LiNiO2, LiMnO2, Li2MnO3, LiNi 0.8 Co 0.2 O2, etc. of the NiCo system (general formula is LiNi x Co 1-x O2 (0 < x < 1)), L iNi 0.5 Mn 0.5 O2, etc. of the NiMn system (general formula is LiNi x Mn 1-x O2 (0 < x < 1)), LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, etc. of the NiMnCo system (also referred to as NMC. General formula is LiNi also. General formula is LiNix Mn y Co 1-x-y O2(x>0, y>0, x+y<1 In addition, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li2 Other examples include MnO3-LiMO2 (M is Co, Ni or Mn).

[0078] In particular, LiCoO2 has a large capacity and is more stable in air than LiNiO2. and is preferable since it has advantages such as being more thermally stable than LiNiO2.

[0079] Examples of lithium-containing materials having a spinel-type crystal structure include LiMn2O4, L i 1+x Mn 2-x O4, Li(MnAl)2O4, LiMn 1.5 Ni 0.5 O4 and others Some examples include:

[0080] A lithium-containing material having a spinel-type crystal structure containing manganese, such as LiMn2O4, A small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x MO2 (M=Co, Al, etc.) ) is preferably mixed because it has the advantage of suppressing the elution of manganese and the decomposition of the electrolyte. I wish.

[0081] In addition, the positive electrode active material is a compound having the general formula Li (2-j) MSiO4 (M is Fe(II), Mn (II), Co(II), or Ni(II) (j is 0 to 2) The general formula Li (2-j) A typical example of MSiO4 is Li ( 2-j) FeSiO4, Li (2-j) NiSiO4, Li (2-j)CoSiO4, L i (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4( r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. are mentioned.

[0082] Also, as the positive electrode active material, A x M2(XO4)3 (A is Li, Na, or Mg) (M is Fe, Mn, Ti, V, Nb, or Al) (X is S, P, Mo, W, As, or , Si) can be used. Nasicon-type compound Examples include Fe2(MnO4)3, Fe2(SO4)3, and Li3Fe2(PO4)3. Examples of the positive electrode active material include Li2MPO4F, Li2MP2O7, and Li5M Compounds represented by the general formula O4 (M is Fe or Mn), perobic compounds such as NaF3 and FeF3 Skite-type fluorides, metal chalcogenides such as TiS2 and MoS2 (sulfides, selenides , tellurides), lithium-containing materials having an inverse spinel crystal structure such as LiMVO4, Vanadium oxides (V2O5, V6O 13 , LiV3O8, etc.), manganese oxides, organic Materials such as sulfur compounds can be used.

[0083] In addition, the carrier ions are alkali metal ions other than lithium ions, alkaline earth metal ions, etc. In the case of group ions, lithium is used instead of lithium in the above compounds and oxides as the positive electrode active material. , alkali metals (e.g., sodium and potassium), alkaline earth metals (e.g., calcium For example, tungsten, strontium, barium, beryllium, magnesium, etc. may be used. For example, NaFeO2 and Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 ]O2 and other sodium-containing The layered oxide can be used as the positive electrode active material.

[0084] In addition, a material in which a plurality of the above materials are combined may be used as the positive electrode active material. A solid solution of the above 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 is used as the positive electrode active material. It is possible.

[0085] The positive electrode active material should preferably have an average primary particle size of 50 nm to 100 μm. .

[0086] Acetylene black (AB), graphite particles, and carbon black are used as conductive additives for the electrodes. Carbon nanotubes, graphene, fullerene, etc. can be used.

[0087] The conductive additive can form an electronic conduction network in the electrode. This makes it possible to maintain a path of electrical conduction between the positive electrode active materials. By adding an electric assistant, it is possible to realize a positive electrode active material layer 112 having high electronic conductivity. This can be done.

[0088] In addition to the typical polyvinylidene fluoride (PVDF), polyimide is also used as a binder. , polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene poly styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, Uses polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. It is possible.

[0089] The content of the binder relative to the total amount of the positive electrode active material layer 112 is 1 wt % or more and 10 wt % or less. is preferable, 2 wt% or more and 8 wt% or less is more preferable, and 3 wt% or more and 5 wt% or less is even more preferable. It is more preferable that the content of the conductive assistant with respect to the total amount of the positive electrode active material layer 112 is 1 wt % or less. The content is preferably from 1 wt % to 10 wt %, and more preferably from 1 wt % to 5 wt %.

[0090] When the positive electrode active material layer 112 is formed by using a coating method, the positive electrode active material, the binder, and the conductive additive are mixed together. The agent and the dispersion medium are mixed to prepare an electrode paste (slurry), which is then applied onto the positive electrode current collector 110. In this embodiment, the negative electrode current collector 111 is made of aluminum as a main component. Metal materials are used.

[0091] The positive electrode current collector may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, or the like. Use materials that are highly conductive and do not alloy with carrier ions such as lithium, such as alloys of these. In addition, materials with high resistance such as silicon, titanium, neodymium, scandium, and molybdenum can be used. Aluminum alloys containing elements that improve thermal properties can be used. Alternatively, the silicide may be formed from a metal element that reacts with silicon to form a silicide. Metal elements that form silicide include zirconium, titanium, hafnium, and vanadium. , niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The positive electrode current collector is available in foil, plate (sheet), mesh, punched metal, expanded metal, etc. A barrel-like shape or the like can be appropriately used.

[0092] Through the above steps, a positive electrode for a lithium ion secondary battery can be produced.

[0093] The first separator, the second separator, the positive electrode, and the negative electrode obtained in this embodiment, Using the electrolyte, a thin lithium ion secondary battery can be realized. The method of assembling the separator, positive electrode, and negative electrode is as described above.

[0094] The electrolyte that can be used in the lithium ion secondary battery is a non-aqueous electrolyte that contains an electrolyte (solute). It is preferable to use an aqueous solution (solvent).

[0095] The solvent for the electrolyte is preferably an aprotic organic solvent, for example, ethylene carbonate. (EC), propylene carbonate (PC), butylene carbonate, chloroethylene Carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethicone Diethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate Methyl formate, Methyl acetate, Methyl butyrate, 1,3-dioxane, 1,4- Dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, Methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane , sultone, etc., or two or more of these may be used in any combination and ratio. It is possible.

[0096] In addition, by using a polymer material that gels as a solvent for the electrolyte, safety against leakage, etc. is improved. The safety of the lithium ion secondary battery is improved. In addition, the lithium ion secondary battery can be made thinner and lighter. Representative examples of polymeric materials that are used include silicone gel, acrylic gel, and acrylonitrile. Gel, polyethylene oxide, polypropylene oxide, fluorine-based polymer, etc. .

[0097] In addition, ionic liquids (also called room temperature molten salts), which are flame-retardant and difficult to evaporate, are used as the solvent for the electrolyte. ) is used to prevent internal short circuits in lithium-ion secondary batteries and damage caused by overcharging, etc. Even if the internal temperature rises, the lithium-ion secondary battery will not explode or catch fire. This makes it possible to improve the safety of the lithium ion secondary battery.

[0098] Examples of the electrolyte that can be dissolved in the solvent include LiPF6, LiClO4, and Li iAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO 4. Li2B 10 Cl 10 , Li2B 12 Cl 12 , LiCF3SO3, LiC4F9S O3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2 )2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, etc. Use one or more of these thium salts in any combination and ratio. can be done.

[0099] In the above electrolyte, the carrier ions are lithium ions. However, carrier ions other than lithium ions can also be used. In the case of alkali metal ions and alkaline earth metal ions, the carrier ions are In the above lithium salt, an alkali metal (e.g., sodium) may be used instead of lithium. Alkaline earth metals (e.g. calcium, strontium, barium, etc.), Aluminum, beryllium, magnesium, etc. may also be used.

[0100] In addition, the electrolyte used in secondary batteries is free of granular waste and elements other than the constituent elements of the electrolyte (hereinafter referred to as single 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. More preferably, it is 0.01% or less. Additives such as phosphate may also be added.

[0101] The positive electrode, the negative electrode, the first separator, and the second separator shown in this embodiment If a flexible material is used, the secondary battery can be made flexible. In a secondary battery having such a property, when a deformation stress is applied to the secondary battery, the first separator 1 At the interface between the separator 100 and the second separator 101, the two separators are misaligned, causing stress. can be alleviated.

[0102] 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, a lithium Air battery, lead acid battery, lithium ion polymer secondary battery, nickel-metal hydride battery, nickel nickel-cadmium battery, nickel-iron battery, nickel-zinc battery, silver oxide-zinc battery Examples of the storage device include a battery, a solid-state battery, and an air battery. For example, a negative electrode according to one embodiment of the present invention and a positive electrode of an electric double layer may be combined. It is also possible to combine them to form a capacitor such as a lithium ion capacitor. be.

[0103] Note that this embodiment mode can be freely combined with other embodiment modes.

[0104] (Embodiment 2) In this embodiment, a method for manufacturing a lithium-ion secondary battery according to one embodiment of the present invention will be described. The following will be described with reference to FIG. 4(A). First, a positive electrode current collector 110 and a positive electrode active material layer 112 are , a second separator 101, a first separator 100, a third separator 102, The figure shows a schematic cross-sectional view of a state in which a negative electrode active material layer 113 and a negative electrode current collector 111 are stacked. The active material layer can be formed on both sides of the current collector, and secondary batteries can be stacked. .

[0105] The second separator 101, the first separator 100, and the third separator 102 are Enlarged cross-sectional schematic diagrams are shown in Fig. 4(B), Fig. 4(C) and Fig. 4(D). The first separator 100, the second separator 101 and the third separator 102 are respectively formed with the first hole 10 The separator has a first hole 104, a second hole 105, and a third hole 106. Although the separator is depicted as being fibrous and the holes as gaps between the fibers, the separator structure is limited to a fibrous structure. In addition, the volume of the first pores 104 in the first separator 100 is not necessarily the same. the ratio of the volume of the second holes 105 to the volume of the second separator 101; The ratio of the volume of the third holes 106 to the volume of the separator 102 is considered to be a factor contributing to the characteristics of each separator. The size of the pores in each separator and the ratio of the pore volume (void ratio) can be considered. The ionic conductivity, mechanical strength, and other separator properties can be determined by the rate of change. Cut.

[0106] Each separator can be manufactured using the materials and methods shown in the first embodiment. For example, the second separator 101 and the third separator 102 are made of the same material and by the same method. and the first separator 100 is manufactured from a different material or method. In this case, the first hole 104 of the first separator 100 is connected to the second separator 101. The first holes 104 are larger than the second holes 105, and the total area of ​​the first holes 104 in the first separator 100 is The ratio of the volume of the second hole 105 to the volume of the second separator 101 is set to be larger than the ratio of the volume of the second hole 105 to the volume of the second separator 101. , the first separator can be thicker than the second separator.

[0107] The insulating performance for preventing the connection between the positive and negative electrodes is mainly provided by the second separator 101 and the third separator 102, it is possible to ensure high ionic conductivity in the thick first separator 100. Also, the second separator 101 and the third separator 102 cover both sides of the electrodes. The separator is formed into a sheet or envelope of a size that can be used for the If the positive and negative electrodes are wrapped, the positive and negative electrodes are protected from mechanical damage during the manufacturing process of the secondary battery. This makes it possible to protect the positive electrode and the negative electrode from the influence of the second separator 101, and makes it easy to handle the positive electrode and the negative electrode. A first separator 100 is disposed between a positive electrode wrapped in a second separator 102 and a negative electrode wrapped in a third separator 102. The battery is then sandwiched between the electrodes and housed in an exterior body 120, and impregnated with an electrolyte solution 121 to form a secondary battery. FIG. 16 shows a second separator 101 and a third separator 102. The cross-sectional structure of the secondary battery fabricated in an envelope shape is shown in FIG. The cross-sectional structure of a secondary battery made using one negative electrode is shown, but the structure of a secondary battery made using multiple positive and negative electrode pairs is also shown. In FIG. 16(B), the electrode active material is applied to both sides of the current collector. The cross-sectional structure of the laminated secondary battery is shown in Fig. 1. .

[0108] The materials for the positive electrode, positive electrode active material, negative electrode, negative electrode active material, and electrolyte, and the method for producing each electrode are the same as those in the first embodiment. It is sufficient to use the one shown in the figure.

[0109] By making the separator between the positive and negative electrodes into a three-layer structure, a flexible secondary battery can be created. In this case, the stress caused by the change in shape of the secondary battery can be alleviated. The interface between the first separator 100 and the second separator 101 and the interface between the first separator 100 and the second separator 102 are At the interface with the separator 102 of the third embodiment, the two membranes can be displaced, and the shape of the membrane can be changed. It is possible to relieve stress, preventing shear fracture due to shape change in secondary batteries. It is possible to do so.

[0110] The material, thickness, and other characteristics of the second separator 101 and the third separator 102 are and the material, thickness, and other characteristics of the first separator 100. The second separator 101 and the third separator 10 2. The material, thickness, pore size, percentage of pore volume in the membrane, and other characteristics, in whole or in part By combining three separators, a secondary battery can be formed. It is possible to set the separator properties in a variety of ways. Furthermore, it is possible to set the separator in four or more layers. It is also possible to

[0111] (Embodiment 3) In this embodiment, a secondary battery using the separator shown in the first or second embodiment is constructed. The structure will be described with reference to FIGS.

[0112] (Coin-type secondary battery) FIG. 5(A) is an external view of a coin-type (single-layer flat) secondary battery, and FIG. 5(B) is an external view of the FIG.

[0113] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305. The negative electrode 307 is formed by contacting a negative electrode current collector 308. The positive electrode active material layer 306 and the negative electrode active material layer 309 are formed. Between them are separators 310a and 310b, and an electrolyte (not shown). do.

[0114] The positive electrode can 301 and the negative electrode can 302 are made of nickel or aluminum, which are resistant to corrosion by the electrolyte. Metals such as aluminum and titanium, or alloys of these and other metals (e.g., stainless steel, In order to prevent corrosion by the electrolyte, nickel or aluminum can be used. The positive electrode can 301 is a positive electrode 304, and the negative electrode can 302 is a negative electrode. 307 and electrically connected to each other.

[0115] The negative electrode 307, the positive electrode 304, the separator 310a, and the separator 310b are placed in an electrolyte. As shown in FIG. 5(B), the positive electrode can 301 is placed downward, and the positive electrode 304 and the separator 3 are placed in the positive electrode can 301. 10a, separator 310b, negative electrode 307, and negative electrode can 302 are laminated in this order, and a positive electrode can 30 1 and a negative electrode can 302 are pressure-bonded via a gasket 303 to produce a coin-type secondary battery 300. Create.

[0116] Here, the flow of current during charging of a secondary battery will be explained using FIG. 5(C). When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of electric current are in the same direction. In secondary batteries that use lithium, the anode and cathode are charged and discharged. (cathode) is switched, and the oxidation and reduction reactions are switched, so the reaction potential The electrode with the higher reaction potential is called the positive electrode, and the electrode with the lower reaction potential is called the negative electrode. In this case, even if the battery is 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 The negative electrode is called the "negative electrode" or "-electrode (minus electrode)". When the terms anode (positive electrode) and cathode (negative electrode) are used, the following occurs during charging and discharging: This can be confusing because the anode and cathode are the opposite. The term "cathode" is not used in this specification. When using the terms cathode and positive electrode, specify whether they are charging or discharging. It will also be indicated whether it corresponds to a positive pole (positive pole) or a negative pole (negative pole).

[0117] A charger is connected to the two terminals shown in FIG. 5(C) to charge the secondary battery 400. As the charging of the battery 400 progresses, the potential difference between the electrodes increases. The current flows from the external terminal of the secondary battery 400 to the positive electrode 402, and then flows through the positive electrode 40 2 through separator 403a and separator 403b toward the negative electrode 404, and The direction of current flowing from the secondary battery 400 to the external terminal of the secondary battery 400 is defined as the positive direction. The direction of the charging current is defined as the direction of the current.

[0118] (Stacked secondary battery) Next, an example of a stacked secondary battery will be described with reference to FIG.

[0119] The stacked secondary battery 500 shown in FIG. 6 has a positive electrode current collector 501 and a positive electrode active material layer 502. a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505; The battery includes separators 507a and 507b, an electrolyte 508, and an exterior body 509. A separator 507a and a separator 508 are disposed between a positive electrode 503 and a negative electrode 506 in a housing 509. The inside of the exterior body 509 is filled with an electrolyte 508. The separator may have a three-layer structure.

[0120] In the stacked secondary battery 500 shown in FIG. 6, a positive electrode current collector 501 and a negative electrode current collector 504 The positive electrode current collector 501 also serves as a terminal for electrical contact with the outside. A part of the negative electrode current collector 504 is disposed so as to be exposed to the outside from the exterior body 509 .

[0121] In the laminated secondary battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, Aluminum is deposited on a film made of a material such as polyethylene, polycarbonate, ionomer, or polyamide. A thin metal film made of aluminum, stainless steel, copper, nickel or the like having excellent flexibility is then applied to the thin metal film. On top of that, an insulating synthetic resin film such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A laminate film having a three-layer structure in which the first and second layers are laminated can be used. It blocks the permeation of electrolyte and gas, ensures insulation, and is electrolyte-resistant. .

[0122] (Cylindrical secondary battery) Next, an example of a cylindrical secondary battery will be described with reference to FIG. As shown in FIG. 7(A), 00 has a positive electrode cap (battery cover) 601 on the top surface, and The battery can (external can) 602 is disposed on the bottom surface. It is insulated from 02 by a gasket (insulating packing) 610.

[0123] Fig. 7(B) is a schematic diagram showing a cross section of a cylindrical secondary battery. On the inside of 602, a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. The separator 605 has a two-layer or three-layer structure. Although not shown, the battery element is wound around a center pin. One end is closed and the other end is open. The battery can 602 contains a material that is resistant to corrosion by the electrolyte. Metals such as nickel, aluminum, titanium, or alloys of these and other metals For example, gold (e.g., stainless steel, etc.) can be used. Therefore, it is preferable to coat the inside of the battery can 602 with nickel, aluminum, or the like. The battery element, in which the positive electrode, the negative electrode and the separator are wound, is connected to a pair of opposing insulating plates 608, 6 The inside of the battery can 602 in which the battery element is provided is filled with an electrolyte ( The electrolyte used is the same as that used in coin-type and stacked-type secondary batteries. There can be.

[0124] The positive electrode 604 and the negative electrode 606 are manufactured in the same manner as the positive electrode and the negative electrode of the coin-type secondary battery described above. However, the positive and negative electrodes used in cylindrical secondary batteries are wound, so they must be wound on both sides of the current collector. The difference is that the active material is formed. The positive electrode 604 has a positive electrode terminal (positive electrode current collector lead) 603. is connected to the negative electrode 606, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. The negative electrode terminal 603 and the negative electrode terminal 607 can both be made of a metal material such as aluminum. The positive terminal 603 is connected to a safety valve mechanism 612, and the negative terminal 607 is connected to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. Electrically connected to the positive electrode cap 601 via a ture coefficient 611 The safety valve mechanism 612 is a mechanism that releases the positive electrode cap when the internal pressure of the battery increases beyond a certain threshold. The cap 601 and the positive electrode 604 are electrically disconnected. 11 is a thermal resistor whose resistance increases when the temperature rises. The PTC element contains barium titanate (Ba TiO3) based semiconductor ceramics, etc. can be used.

[0125] In this embodiment, the secondary battery is a coin type, a laminate type, and a cylindrical type. However, secondary batteries of various shapes, such as sealed secondary batteries and square secondary batteries, can also be used. In addition, a structure in which a positive electrode, a negative electrode, and a separator are laminated in multiple layers, The parater may be wound.

[0126] The coin-type secondary battery 300, the secondary battery 500, and the cylindrical secondary battery 60 shown in this embodiment 0 has multiple layers of separators with different characteristics. Therefore, the characteristics of the separators in the secondary battery Gender can be determined in a variety of ways.

[0127] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0128] (Embodiment 4) In this embodiment, structural examples of the power storage device will be described with reference to FIGS. 8, 9, 10, 11, and 12. I will use this to explain.

[0129] 8(A) and 8(B) are diagrams showing the external appearance of a power storage device. The power storage unit 913 has a label 910 attached thereto. As shown in FIG. 8B, the power storage device has a terminal 951 and a terminal 952. , and has an antenna 914 and an antenna 915 on the back of the label 910.

[0130] The circuit board 900 includes a terminal 911 and a circuit 912. The terminal 911 is connected to a terminal 951. , a terminal 952, an antenna 914, an antenna 915, and a circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is used as a control signal input terminal, a power supply terminal, etc. may also be used.

[0131] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, dielectric Alternatively, antenna 914 or antenna 915 may be used. The flat conductor may function as one of the conductors for electric field coupling. In other words, the annulus can be used as one of the two conductors of the capacitor. In this way, the electromagnetic field, the magnetic field, and the like can be detected by the antenna 914 or the antenna 915. Alternatively, power can be exchanged using an electric field.

[0132] The line width of antenna 914 is preferably larger than the line width of antenna 915. This allows the amount of power received by the antenna 914 to be increased.

[0133] The power storage device includes an antenna 914 and an antenna 915, and a layer 916 between the power storage body 913. The layer 916 has a function of shielding an electromagnetic field generated by the power storage unit 913, for example. The layer 916 may be made of, for example, a magnetic material.

[0134] The structure of the power storage device is not limited to that shown in FIG.

[0135] For example, as shown in Figs. 9(A-1) and 9(A-2), In the power storage unit 913 shown in FIG. 9, an antenna may be provided on each of a pair of opposing surfaces. FIG. 9(A-1) is an external view seen from one side of the pair of faces, and FIG. 9(A-2) is an external view seen from the top 8(A) and 8(B) are external views as viewed from the other side of the pair of surfaces. Regarding the same parts as those of the power storage device, the description of the power storage device shown in FIG. 8(A) and FIG. 8(B) will be repeated as appropriate. It can be used.

[0136] As shown in FIG. 9(A-1), a layer 916 is sandwiched between one of a pair of surfaces of a power storage unit 913, and an antenna is formed. As shown in FIG. 9(A-2), a layer 914 is provided on the other of the pair of surfaces of the power storage unit 913. An antenna 915 is provided on both sides of the layer 917. The layer 917 is, for example, a layer for storing power from a power storage unit 913. The layer 917 has a function of shielding a magnetic field. For example, a magnetic material is used for the layer 917. This can be done.

[0137] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It is possible.

[0138] Or, as shown in FIG. 9(B-1) and FIG. 9(B-2), A separate antenna may be provided on each of a pair of opposing surfaces of the power storage unit 913. FIG. 9(B-1) is an external view seen from one side of the pair of faces, and FIG. 9(B-2) is an external view seen from one side of the pair of faces. 8(A) and 8(B) are external views seen from the other side of the pair of surfaces. For the same parts as those of the power storage device shown in FIG. 8(A) and FIG. 8(B), the description of the power storage device shown in FIG. It can be used as needed.

[0139] As shown in FIG. 9(B-1), a layer 916 is sandwiched between one of a pair of surfaces of a power storage unit 913, and an antenna is formed. As shown in FIG. 9(A-2), An antenna 918 is provided on the other of the pair of surfaces, sandwiching the layer 917. The antenna 918 is, for example, For example, the antenna 918 has a function of performing data communication with an external device. For example, an antenna having a shape applicable to the antenna 914 and the antenna 915 can be applied. As a method for communication between the power storage device and other devices via the antenna 918, NFC or the like may be used. A response method that can be used between the power storage device and the external device can be applied. .

[0140] 10A, the power storage unit 913 shown in FIG. 8A and FIG. 8B may be A display device 920 may be provided. The display device 920 is electrically connected to the terminal 911 via the terminal 919. It is not necessary to provide the label 910 in the portion where the display device 920 is provided. Note that the same parts as those in the power storage device shown in FIG. The description of the power storage device in FIG. 8B can be used as appropriate.

[0141] The display device 920 displays, for example, an image indicating whether charging is in progress, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display device, an electrophotographic display device, or the like. For example, an electroluminescence (EL) display device can be used. By using the par, the power consumption of the display device 920 can be reduced.

[0142] 10B, the power storage unit 913 shown in FIG. 8A and FIG. 8B may be connected to the sensor. The sensor 921 may be electrically connected to the terminal 911 via a terminal 922. The sensor 921 may be provided on the back side of the label 910. The same parts as those in the power storage device shown in FIG. 8(A) and FIG. 8(B) are The description of the power storage device shown in 2. above can be used as appropriate.

[0143] Various sensors can be used as the sensor 921. For example, data indicating the environment in which the power storage device is placed (such as temperature) is detected, and the circuit It is also possible to store the information in the memory of the 912.

[0144] Further, a structural example of the power storage unit 913 will be described with reference to FIGS.

[0145] A power storage unit 913 shown in FIG. 11A includes a terminal 951 and a terminal 952 provided inside a housing 930. The winding body 950 is impregnated with an electrolyte inside the housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is in contact with the housing by using an insulating material or the like. 11A, the housing 930 is not in contact with the housing 930. However, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 952 are extends outside the housing 930. The housing 930 is made of a metal material (e.g., aluminum). etc.) or a resin material can be used.

[0146] The housing 930 shown in FIG. 11A may be formed of a plurality of materials. In the power storage unit 913 shown in FIG. 11(B), a housing 930a and a housing 930b are attached to each other. A wound body 950 is provided in an area surrounded by the housing 930a and the housing 930b.

[0147] The housing 930a can be made of an insulating material such as an organic resin. By using a material such as organic resin on the surface on which the electric field is formed, the electric storage body 913 can be shielded from the electric field. If the shielding of the electric field by the housing 930a is small, the inside of the housing 930 Antennas such as antenna 914 and antenna 915 may be provided in the housing 930b. For example, a metal material can be used.

[0148] The structure of the wound body 950 is shown in FIG. The electrode 932 and the separator 933 are two- or three-layered. The wound body 950 has a separator 933 sandwiched between a negative electrode 931 and a positive electrode 932. The laminated sheet is wound to form a wound body. The electrodes 932 and the separators 933 may be laminated a plurality of times.

[0149] The negative electrode 931 is connected to the terminal 911 shown in FIG. 8 via one of the terminals 951 and 952. The positive electrode 932 is connected to the terminal 911 shown in FIG. Connected.

[0150] Note that this embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0151] (Embodiment 5) In this embodiment, an example of an electronic device having the secondary battery described in the previous embodiment will be described. This will be described with reference to FIG. 13 and FIG.

[0152] Examples of electronic devices that use secondary batteries include digital cameras, digital video cameras, Digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable games Examples of such electronic devices include smartphones, tablets, and audio players. 3 and 14.

[0153] FIG. 13A shows an example of a mobile phone. A mobile phone 800 is assembled in a housing 801. In addition to the built-in display unit 802, operation buttons 803, a speaker 805, a microphone 806, etc. Note that the secondary battery 804 of one embodiment of the present invention is used inside the mobile phone 800. This reduces the weight.

[0154] The mobile phone 800 shown in FIG. 13A displays information by touching a display unit 802 with a finger or the like. In addition, operations such as making a phone call or writing an email can be done from the display. This can be done by touching the display unit 802 with a finger or the like.

[0155] The screen of the display unit 802 has three main modes. The first is a display mode that mainly displays images. The first is a display mode, the second is an input mode for inputting information such as characters, and the third is a display mode. This is a display + input mode that combines the two modes, display and input mode.

[0156] For example, when making a call or composing an e-mail, the display unit 802 is used mainly for inputting characters. The user may then enter a character input mode in which the character is displayed on the screen and perform an input operation for the character.

[0157] In addition, the mobile phone 800 includes sensors for detecting tilt, such as a gyro sensor and an acceleration sensor. By providing a detection device having a sensor, the orientation of the mobile phone 800 (portrait or landscape) can be determined, The screen display on the display unit 802 can be automatically switched.

[0158] The screen mode can be changed by touching the display unit 802 or by pressing the operation button on the housing 801. The image display is performed by operating the button 803. Also, the image display is changed depending on the type of image displayed on the display unit 802. For example, if the image signal to be displayed on the display unit is video data, If there is, switch to display mode; if there is text data, switch to input mode.

[0159] In the input mode, a signal detected by the optical sensor of the display unit 802 is detected. If there is no input from the touch of the 802 for a certain period of time, the screen mode will change from input mode to The display mode may be switched to the display mode.

[0160] The display unit 802 can also function as an image sensor. By touching the device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. The display uses a backlight that emits near-infrared light or a sensing light source that emits near-infrared light. If a person has a fingerprint, it is also possible to image finger veins, palm veins, etc.

[0161] FIG. 13B shows the mobile phone 800 in a bent state. When the whole is bent by being deformed by an external force, the secondary battery 80 provided inside 4 is also bent. At this time, the state of the bent secondary battery 804 is as shown in FIG. The secondary battery 804 is a stacked type secondary battery.

[0162] FIG. 14A shows a smart watch, which includes a housing 702, a display panel 704, and operation buttons. 711, 712, a connection terminal 713, a band 721, a clasp 722, etc. Note that the weight of a smartwatch can be reduced by including a secondary battery according to one embodiment of the present invention inside the smartwatch. The housing 702 is provided with the controller according to one embodiment of the present invention described in Embodiment 3. The secondary battery may be an in-band type secondary battery (FIG. 14B). The flexible secondary battery 740 according to one embodiment of the present invention may be included in the flexible portion. The secondary battery 740 having the above structure is in a band shape and is detachable from the housing 702. Power can be supplied to the housing 702 through the positive terminal 741 and the negative terminal 742. This is possible (Figure 14(C)).

[0163] A display panel 704 mounted on a housing 702 that also serves as a bezel has a non-rectangular display area. The display panel 704 has an icon 705 representing the time, other icons 706 etc. can be displayed.

[0164] The smart watch shown in FIG. 14 can have various functions. For example, Functions for displaying various information (still images, videos, text images, etc.) on the display unit, touch panel function Functions such as displaying calendars, dates, or times, and various software (programs) A function for controlling processing by wireless communication, a function for controlling various computers by using wireless communication, Functions for connecting to a network and transmitting or receiving various data using wireless communication functions Function: A function to read out a program or data recorded on a recording medium and display it on the display unit It is possible to have the ability, etc.

[0165] In addition, a speaker and a sensor (force, displacement, position, velocity, acceleration, angular velocity) are installed inside the housing 702. , rotation speed, distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage , including the function to measure power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays ), a microphone, etc.

[0166] FIG. 13D shows an example of a bangle-type display device. The portable display device 7100 is The device includes a housing 7101 , a display unit 7102 , operation buttons 7103 , and a secondary battery 7104 . FIG. 13E shows the state of a bent secondary battery 7104.

[0167] FIG. 13F shows an example of a wristband-type display device. The wristband-type display device 7200 is a device that is mounted on a case. The armband-type display device 7200 is flexible, although not shown. The armband-type display device 7200 has a secondary battery having a flexible structure in response to a change in shape of the armband-type display device 7200. The secondary battery also changes shape.

[0168] Note that the structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. There can be. [Explanation of symbols]

[0169] 100 First separator 101 Second separator 102 Third Separator 104 First Hole 105 Second Hole 106 Third Hole 108 Whisker 110 Positive electrode current collector 111 Negative electrode current collector 112 Cathode active material layer 113 Negative electrode active material layer 120 Exterior body 121 Electrolyte 300 Secondary battery 301 Positive electrode can 302 Anode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310a Separator 310b Separator 400 Secondary battery 402 Positive electrode 403a Separator 403b Separator 404 negative electrode 500 secondary battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507a Separator 507b Separator 508 Electrolyte 509 Exterior body 600 Secondary battery 601 Positive electrode cap 602 Battery Can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating plate 610 Gasket 611 PTC element 612 Safety valve mechanism 702 Case 704 Display Panel 705 Clock icon 706 other icons 711 Operation button 712 Operation button 713 Connection terminal 721 Band 722 Clasp 730 Coin-type secondary battery 740 Flexible secondary battery 741 Positive terminal 742 Negative terminal 800 Mobile Phones 801 Case 802 Display section 803 Operation button 804 Secondary battery 805 Speaker 806 Mike 900 Circuit Board 901 Current collector 902 Electrode active material 903 Insulating particles 910 Label 911 Terminal 912 Circuit 913 Electricity storage unit 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 930a Case 930b Case 931 negative electrode 932 Positive electrode 933 Separator 951 Terminal 952 Terminal 1001 Base material 1002 Electrode active material 1003 Insulating particles 1004 Conductive film 1005 Resin film 1006 Current collector 1700 curved surface 1701 Plane 1702 Curve, which is the shape of a surface 1703 Radius of curvature 1704 Center of curvature 1800 Center of curvature 1801 Film 1802 radius of curvature 1803 Film 1804 radius of curvature 1805 Electrode / Electrolyte 7100 Portable display devices 7101 Case 7102 Display section 7103 Operation button 7104 Secondary battery 7200 Armband type display device 7201 Case 7202 Display section

Claims

[Claim 1] A positive electrode and A negative electrode; An electrolyte; a first separator having a plurality of first holes; a second separator having a plurality of second holes; a third separator having a plurality of third holes; the positive electrode, the negative electrode, the electrolytic solution, the first separator, the second separator, and the third separator each have a flexible material; the first separator is provided between the positive electrode and the negative electrode, the second separator is provided between the first separator and the negative electrode, the third separator is provided between the first separator and the positive electrode, a ratio of a volume of the plurality of first holes to a volume of the first separator is greater than a ratio of a volume of the plurality of second holes to a volume of the second separator, a ratio of a volume of the plurality of first holes to a volume of the first separator is greater than a ratio of a volume of the plurality of third holes to a volume of the third separator.

Images