Power storage device

Abstract

To provide a sheet-shaped power storage device that can be curved or bent in at least a uniaxial direction.SOLUTION: A power storage device includes a power storage element including: a plurality of sheet-shaped flexible positive electrodes each having one end fixed to a positive electrode tab, a plurality of sheet-shaped flexible negative electrodes each having one end fixed to a negative electrode tab, and a plurality of sheet-shaped flexible separators. The positive electrodes and the negative electrodes are overlapped on each other with each separator interposed between one positive electrode and one negative electrode. The power storage element is sealed in an exterior package with flexibility.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electricity storage device and a manufacturing method thereof. [Background technology]

[0002] In recent years, the use of consumer electronic devices such as mobile phones, smartphones, and game consoles has become increasingly 2. Description of the Related Art Lithium secondary batteries are widely used as power sources and as power storage devices.

[0003] In addition to long life and high capacity, such electrical equipment requires lightweight, compact, and easy-to-design exteriors. In order to secure the degree of freedom, the need for a flexible sheet-like storage device has been raised. By realizing a flexible sheet-shaped electricity storage device, The strap of a watch, clothing, thin electrical equipment, and other curved or bent parts and thicknesses It is possible to install the power storage device even in the thin part.

[0004] Conventional non-aqueous secondary batteries, such as lithium secondary batteries, are generally made of sheet-shaped aluminum or other materials. A positive electrode mixture containing a positive electrode active material that absorbs and releases lithium ions is applied to both sides of the positive electrode current collector. The positive electrode is made of a thin film of copper, and the negative electrode is made of a sheet of copper or other material. The positive electrode and the negative electrode are coated with a negative electrode mixture containing a negative electrode active material. A plurality of layers are wound with a capacitor sandwiched between them to form a wound body, and a positive electrode is attached to each of the predetermined portions of the positive electrode and the negative electrode. The positive and negative tabs are connected, and then this is wrapped in a cylindrical, square, coin-shaped, or other exterior body. The positive electrode, separator, and negative electrode are all flexible. Although it is a component, once the winding is formed and sealed in a container, the shape is fixed and it can be bent freely. The flexibility of the lithium secondary battery is completely lost. It is not possible to provide the degree of freedom to change the shape of the lithium secondary battery in the curved or bent parts of the electrical equipment. Setting up a pond is difficult.

[0005] Therefore, solid-state secondary batteries such as those disclosed in Patent Document 1 have been actively researched. Solid-state secondary batteries replace conventional non-aqueous electrolytes with inorganic or organic solid electrolytes. In other words, a positive electrode active material, a solid electrolyte, a negative electrode active material, and a negative electrode current collector are placed on the positive electrode current collector. The body is thin and flexible. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-123081 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the electrolyte layer of a solid-state secondary battery must also be thin, and the solid-state secondary battery must be curved or bent. In particular, when the solid secondary battery is used, a short circuit easily occurs between the positive and negative electrodes. The battery is made entirely of solid material, so repeated bending of the battery can prevent the film from peeling off and Cracks occur in each film, making it difficult to form a sheet-shaped battery. There is none.

[0008] In addition, the solid electrolyte used in solid secondary batteries has various issues, and it has not yet been put to practical use. do not have.

[0009] Therefore, one aspect of the present invention is to provide a method for producing a solid-state secondary battery using a conventional non-aqueous electrolyte without using a solid-state secondary battery. The structure of the non-aqueous secondary battery is utilized to bend or curve in at least one axial direction. A sheet-shaped electricity storage device is provided. [Means for solving the problem]

[0010] One aspect of the present invention is a flexible sheet-like electrode, one end of which is fixed to a positive electrode tab. A plurality of positive electrodes and a plurality of flexible sheet-like electrodes each having one end fixed to a negative electrode tab. and a plurality of flexible sheet-like separators. The positive and negative electrodes are stacked alternately with a plurality of separators sandwiched between them, and the storage element is made of flexible The power storage device is enclosed in an exterior body having the above structure.

[0011] In addition, one aspect of the present invention is a flexible sheet having one end fixed to a positive electrode tab. A flexible sheet-like battery is provided with multiple positive electrodes in the shape of a tube, each of which has one end fixed to a negative electrode tab. and a flexible sheet-like separator. The positive and negative electrodes are stacked alternately with a separator between them, and the storage element is made of a flexible outer It is a power storage device enclosed in a housing.

[0012] The positive electrode is a flexible sheet-shaped (strip-shaped) positive electrode current collector and a positive electrode active material on both sides of the positive electrode current collector. The positive electrode itself is thus in the form of a sheet and is flexible. Similarly, the negative electrode is a flexible sheet-like negative electrode current collector and a negative electrode active material on both sides of the sheet. The negative electrode itself is thus in the form of a sheet and is flexible. However, when the positive electrode mixture layer or the negative electrode mixture layer is made of only the respective active materials, The positive electrode mixture layer and the negative electrode mixture layer refer to layers each made of only the active material. By stacking the positive electrode and the negative electrode with a separator interposed therebetween, charge / discharge capacity can be achieved.

[0013] Charge / discharge capacity can be increased by stacking positive and negative electrodes alternately with a separator between them. On the other hand, when the number of layers is increased, the thickness of the energy storage element increases. Even if the structure is made, it becomes difficult to bend or curve the storage element. Therefore, it may be difficult to apply it to portable electrical devices. The number of layers may be appropriately determined depending on the charge / discharge capacity and the degree of lightness or flexibility to be achieved. For example, the total number of stacked positive and negative electrodes each with a thickness of 20 μm to 100 μm The number of sheets is preferably 5 or more, and more preferably 10 to 50.

[0014] The separator separates the positive and negative electrodes and retains the electrolyte to ensure ionic conductivity between the positive and negative electrodes. In addition to having the conventional functions of protecting the positive electrode and The surface that comes into contact with the negative electrode has the function of sliding smoothly. It is preferable to use a material that has low sliding friction (low coefficient of friction) with respect to the positive electrode or negative electrode. It is also preferable to use a non-adhesive material. For example, polypropylene or polytetrafluoroethylene Oroethylene (trade name: Teflon (registered trademark)) can be used. The surfaces of these materials may be subjected to a surface treatment to reduce physical or chemical sliding friction. stomach.

[0015] The flexible sheet-like positive electrode has a positive electrode current collector made of a conductive material at one end. The positive electrode tab is physically fixed to the positive electrode. On the other hand, the other end is not fixed, resulting in Only one end of the electrode is fixed to the positive electrode tab. Multiple sheet-shaped positive electrodes are stacked flat on top of each other. Since the positive electrodes are fixed to the positive electrode tabs in a row, the positive electrodes are fixed to the positive electrode tabs in a sheet-like manner. The structure resembles a book or notebook, with multiple sheets glued together. The positive tab is The power supply may be directly led out to the exterior of the electrical device, or may be connected to other components, and the components may be connected to other components. It may be led out to the outside of the exterior body.

[0016] Similarly, the flexible sheet-like negative electrode has a negative electrode current collector made of a conductive material at one end. The negative electrode tab is physically fixed to the negative electrode. On the other hand, the other end is not fixed. Only one end of the negative electrode is fixed to the negative electrode tab. The negative electrode tab is fixed to the negative electrode tab in parallel to each other. The negative electrode tab is directly connected to the exterior of the exterior body of the power storage device. The component may be connected to another component and the component may be led out to the outside of the outer casing.

[0017] The positive and negative electrodes, one end of which is fixed to a tab, sandwich a separator between them to form a charge / discharge capacity. The positive and negative electrodes are stacked alternately so that they overlap each other. The separator applied may be a plurality of sheets or may be a continuous sheet.

[0018] The electric storage element having the above-mentioned structure has a structure in which the surface of the overlapping sheet-like positive and negative electrodes is When an external force is applied in the direction of the positive and negative electrodes, the ends of the positive and negative electrodes Since the positive and negative electrodes are not fixed except for the separator surface, they can slide and move on the separator surface. For this reason, the storage element can be deformed by using, for example, a laminate film. By enclosing the battery in a flexible exterior body, the battery is flexible in at least one axial direction. can be formed. Effect of the Invention

[0019] To provide a sheet-like electricity storage device having high capacity and flexibility in at least one axial direction. It is possible. [Brief description of the drawings]

[0020] [Figure 1] 1A and 1B are diagrams illustrating a power storage element. [Diagram 2] 1A and 1B are diagrams illustrating a power storage element. [Diagram 3] 1A and 1B are diagrams illustrating a power storage device. [Figure 4] 1A and 1B are diagrams illustrating a power storage device. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 1 is a diagram illustrating an electrical device. [Figure 8] FIG. 1 is a diagram illustrating an electrical device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the embodiments will be described with reference to the drawings. It is possible to carry out the present invention in various forms without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications may be made to the details of the present invention. However, the present invention should not be construed as being limited to the description of the following embodiments.

[0022] In each figure described in this specification, the size of each component, the thickness of the film, or the area is not shown for clarity. The figures may be exaggerated for illustrative purposes and are not necessarily limited to that scale. There is none.

[0023] (Embodiment 1) In this embodiment, a lithium ion battery having high capacity and flexibility in at least one axial direction is used. A power storage device typified by a secondary battery will be described with reference to FIG.

[0024] A lithium secondary battery is a secondary battery that uses lithium ions as carrier ions. In addition, carrier ions that can be used instead of lithium ions include sodium ions. Alkali metal ions such as thorium and potassium, calcium, strontium, barium, etc. Examples of the ions include alkaline earth metal ions, beryllium ions, and magnesium ions.

[0025] FIG. 1A is a cross-sectional view illustrating a power storage element included in a power storage device described in this embodiment. In the present invention, the electric storage element is a structure for explaining the arrangement and connection of the positive and negative electrodes. It is a term used for convenience in explaining the composition of the positive electrode, negative electrode, separator, positive electrode tab and negative electrode. In FIG. 1A, the energy storage element 100 is a structure having a plurality of sheet-like positive electrodes. 101, a plurality of sheet-shaped negative electrodes 103, a plurality of sheet-shaped separators 102, and a positive electrode It has a positive electrode tab 104 and a negative electrode tab 105.

[0026] Although not shown here, the positive electrode 101 is a positive electrode current collector made of a conductive material and a resistor on both sides of the positive electrode current collector. A positive electrode mixture layer that contains a positive electrode active material that absorbs and releases lithium ions or that is made of only a positive electrode active material. Similarly, the negative electrode 103 has at least a negative electrode current collector made of a conductive material and A negative electrode that contains a negative electrode active material that absorbs and releases lithium ions on both sides or that consists only of a negative electrode active material. The electrode material layer has at least an electrode mixture layer.

[0027] The positive electrode 101 and the negative electrode 103 used in the electricity storage device of this embodiment are bent in at least one axial direction. The positive electrode 101 is a sheet-like electrode having flexibility that allows it to be bent or curved. The positive electrode current collector is made of a flexible conductive material. The layer is curved or bent in accordance with the curvature or bending of the positive electrode current collector. In order to achieve this, the material was selected taking into consideration the mechanical strength and adhesion to the positive electrode current collector, and the film thickness was designed appropriately. The same applies to the negative electrode 103.

[0028] These sheet-like positive electrode 101 and negative electrode 103 are stacked with a separator 102 interposed therebetween. By stacking the positive electrode 101 and the negative electrode 103, a charge / discharge capacity can be formed. The area of ​​the electrodes is directly reflected in the charge and discharge capacity. In this case, the area of ​​the sheet-shaped positive electrode 101 and negative electrode 103 may be increased. Depending on the application of the device, the area of ​​the sheet-shaped electrodes may be limited. In this case, A similar effect can be obtained by increasing the number of pole layers.

[0029] In this embodiment, the charge / discharge capacity is determined by dividing the positive electrode 101 and the negative electrode 10 with a separator therebetween. On the other hand, if the number of layers is increased too much, the Since the thickness of the element 100 is increased, even if the configuration of the present invention is implemented, the element 100 is likely to bend or curve. In addition, the weight of the storage element increases, making it difficult to apply it to portable electrical equipment. Therefore, the number of stacked positive electrodes 101 and negative electrodes 103 is determined based on the charge / discharge characteristics of the formed positive electrodes 101 and negative electrodes 103. It is advisable to design them appropriately according to the volume and the degree of lightness or flexibility. For example, A stack of a positive electrode 101 having a thickness of 20 μm or more and 100 μm or less, a negative electrode 103, and two separators The number of laminated layers is set to 5 or more, preferably 10 to 50. The positive electrode mixture layer and the negative electrode current collector are each 10 μm thick, and the positive electrode mixture layer and the negative electrode mixture layer are each 100 μm thick. If the separator is 20 μm thick, the total thickness will be 240 μm. In this case, the storage element will be 12 mm thick. Therefore, in order to ensure the flexibility of the storage element, It is preferable to keep the number below this.

[0030] The separator 102 separates the positive electrode 101 from the negative electrode 103 and retains the electrolyte between the positive and negative electrodes. In addition to having the conventional functions of ensuring ionic conductivity, When the electrode is placed on the positive electrode 101, the surface in contact with the negative electrode 103 has a function of sliding smoothly. The separator 102 has low sliding friction with the contacting positive or negative electrode (low friction It is preferable to use a material with a high modulus of adhesion and a non-adhesive material. For example, polypropylene and polytetrafluoroethylene can be used. These materials may be used with surface treatments that reduce the sliding friction physically or chemically. good.

[0031] In this embodiment, the separator 102 has a planar shape similar to that of the positive electrode 101 and the negative electrode 103. The electrode 102 has a sheet-like shape having a substantially uniform shape and is arranged substantially parallel to the positive electrode 101 and the negative electrode 103. Therefore, the positive electrode 101 and the negative electrode 103 form a positive electrode. The separators 102 are used in the number of spaces between the electrodes and the negative electrodes.

[0032] The planar shape of the sheet-like positive electrode 101 is, for example, a long rectangle. The shape can be freely selected depending on the application, such as the electrical equipment in which the device is installed. For example, a trapezoid Any two-dimensional shape having a certain area, such as a triangle, polygon, circle, or ellipse, may be used. At one end of the positive electrode 101, the positive electrode current collector is physically connected to a positive electrode tab 104 made of a conductive material. If the planar shape of the positive electrode 101 is, for example, a rectangle, one of the short sides of the rectangle is The end portion may be formed by partially disposing the plurality of positive electrodes 101 even in other planar shapes. For fixing, any point can be one end, while the other end is fixed. As a result, only one end of the positive electrode 101 is fixed to the positive electrode tab 104.

[0033] In this manner, the positive electrode tabs 101 are arranged in parallel to one another so that the sheet-like positive electrodes 101 overlap each other. 4, the plurality of sheet-like positive electrodes 1 fixed to the positive electrode tab 104 are bundled together. 01 is a structure similar to a book or notebook, consisting of multiple sheets glued to a spine.

[0034] Similarly, the negative electrode 103 has a negative electrode current collector connected at one end to a negative electrode tab 1 made of a conductive material. On the other hand, the other end is not fixed, so the negative electrode 1 Only one end of the negative electrode 103 is fixed to the negative electrode tab 105. The negative electrode tabs 105 are fixed to and bundled in parallel to each other so that the negative electrode tabs 105 are aligned in parallel to each other.

[0035] The positive electrode tab 104 and the negative electrode tab 105 are connection terminals for inputting and outputting electric power. The positive electrode tab 104 and the negative electrode tab 105 function as a positive electrode terminal and a negative electrode terminal, respectively. A conductive material with low resistance is used. The element 100 is entirely immersed in an electrolyte (not shown), and is therefore made of a material that is non-reactive with the electrolyte. The positive electrode tab 104 and the negative electrode tab 105 are made of, for example, stainless steel, gold, platinum, etc. Metals such as zinc, iron, copper, aluminum, and titanium, as well as alloys of these metals, can be used. The positive electrode tab 104 and the negative electrode tab 105 are led out directly to the outside of the exterior body of the power storage device. However, it is necessary to connect it to another conductive part, and the other conductive part is led out to the outside of the exterior body. Good too.

[0036] As described above, each of the flexible sheet-like electrodes, one end of which is fixed to the positive electrode tab 104, and a flexible positive electrode 101, each of which has one end fixed to a negative electrode tab 105. The structure is such that a plurality of sheet-like negative electrodes 103 are alternately laminated with separators 102 sandwiched between them. The energy storage element 100 and the energy storage device including the energy storage element 100 have at least In other words, the positive electrode 101 of the energy storage element 100 and the separator 102 can be flexible in one axial direction. The positive electrode 101 and the negative electrode 103 are not fixed to each other. Since the separator 102 is only in surface contact with the separator 102, when an external force is applied, The positive electrode 101 and the negative electrode 103, which are flexible, slide on the surface of the separator 102. During this movement, the positive electrode 101 and the negative electrode 102 can move in a direction that absorbs or relieves the force. Since the electrode 103 and the separator 102 are both flexible sheets, Therefore, the laminated structure of the positive electrode 101, the negative electrode 103, and the separator 102 is deformed by the external force. Since the entire structure of the energy storage element 100 is curved or bent in response to an external force, The material can also have flexibility in one axial direction.

[0037] The uniaxial direction is the surface where the positive electrode 101, the negative electrode 103, and the separator 102 are superimposed on each other. "at least one axial direction" refers to a direction including the perpendicular direction. A force is applied from above or below to the generally sheet-shaped energy storage element 100 according to this embodiment. In this case, the energy storage element 100 is bent or curved upward or downward in response to the applied force. When a force in a twisting direction is applied to the electric storage element 100, the electric storage element 1 00 means that it can also deform in the torsional direction.

[0038] For example, in FIG. 1B, when a force is applied from below the energy storage element 100, In this case, the positive electrode 101, the negative electrode 103, and the separator 102 are The positive electrode 101 is pushed upward in an arch shape, and the separator 102 in contact with it The negative electrode 103 slides along the surface and moves to the left, while the negative electrode 103 slides along the surface of the separator 102 that is in contact with it. The battery element 100 slides along the surface and moves to the right. As a result, the battery element 100 takes on an upwardly convex warped shape. The flexibility of the storage element is such that the storage element absorbs or reduces external forces through such an action. The battery is provided with a high charge / discharge capacity and maintains a high charge / discharge capacity.

[0039] Here, the distance between the positive electrode tab 104 and the negative electrode tab 105 is approximately fixed. Even when an external force is applied to the energy storage element 100, the positive electrode tab 104 and the negative electrode tab 105 The distance between the positive electrode 101 and the negative electrode tab 105 or the negative electrode 103 and the positive electrode tab 106 is approximately constant. The positive electrode tab 104 and the negative electrode tab 105 are in contact with each other and do not cause an electrical short circuit. By significantly increasing the distance between the positive electrode 101 and the negative electrode 103, the overlapping area between the positive electrode 101 and the negative electrode 103 is reduced. The charge / discharge capacity is not significantly reduced, and the positive electrodes 10 bound by the positive electrode tabs 104 1 and the negative electrode 103 bound by the negative electrode tab 105 may come off, causing the overlapping portion to be lost. Neither.

[0040] In addition, the shape of the energy storage element 100 once bent depends on the selection of materials for the positive and negative electrodes constituting the energy storage element. By selecting this option, the original shape can be restored.

[0041] As an embodiment different from the present embodiment, the energy storage element 100 does not use the separator 102. In the embodiment, a liquid electrolyte is inserted between the energy storage element 100 in a curved or bent state. By solidifying it, the flexibility is lost, but the curved or bent shape is retained. It is possible to manufacture a power storage device having such a shape.

[0042] Therefore, the electric storage element 100 is made of a sheet-like positive electrode 101 and a sheet-like negative electrode 103 that overlap each other. When force is applied, the ends of the positive electrode 101 and the negative electrode 103 are connected to the positive electrode tab 104 or the negative electrode tab 105, respectively. The positive electrode 101 and the negative electrode 102 are not fixed except for one end connected to the electrode tab 105. The pole 103 can be deformed by sliding on the surface of the separator 102. Therefore, the storage element 100 is sealed in a flexible exterior body using, for example, a laminate film. By inserting the insulating film, it is possible to form a power storage device that is flexible in at least one axial direction.

[0043] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0044] (Embodiment 2) In this embodiment, the separators in the energy storage element described in the first embodiment are formed into a continuous An example of the separator will be described with reference to FIG.

[0045] FIG. 2A is a diagram illustrating a power storage element 200 included in the power storage device shown in this embodiment. 2A is a cross-sectional view of the energy storage element 200. In FIG. A plurality of sheet-like negative electrodes 203, a common separator 202, and a positive electrode tab 204. , and a negative electrode tab 205.

[0046] The structure of the energy storage element 200 is similar to the structure of the energy storage element 100 described in the first embodiment. 2, except that separator 202 is a single continuous sheet.

[0047] That is, one end of a plurality of flexible sheet-like positive electrodes 201 is fixed to a positive electrode tab 204. On the other hand, one end of a plurality of flexible sheet-like negative electrodes 203 is fixed to a negative electrode tab 205. The positive electrodes 201 and the negative electrodes 203 are connected to one common separator 20. The separators 202 are stacked alternately with the separator 202 sandwiched between them. As shown in the figure, the cross section is arranged between the positive electrode 201 and the negative electrode 203 in a meandering shape. do.

[0048] In this way, even if the separator 202 is made of a single continuous sheet, As shown in FIG. 1, the flexibility of the energy storage element 200 can be ensured. For example, When an external force is applied from below the positive electrode 201 and the negative electrode 203, the separator 2 The separator 202 slides on the surface of the separator 202 and moves to the right or left, respectively. Because it is a flexible sheet, external force can cause the sheet to bend upwards, but the separator 202 has a low coefficient of sliding friction with the positive electrode 201 and the negative electrode 203 and is non-adhesive. There is no change in response to sliding of the electrode 201 or the negative electrode 203.

[0049] As described above, similarly to the first embodiment, the energy storage element 200 in the present embodiment is also flexible. In particular, in the structure shown in this embodiment, the separator 202 Since it is continuous, the end portion facing the end portion fixed to the positive electrode tab 204 or the negative electrode tab 205 The ends of the positive electrode 201 and the negative electrode 203 located at the position are wrapped in the separator 202. The positive electrode 201 is electrically connected to the negative electrode tab 205, or the negative electrode 203 is electrically connected to the positive electrode tab 204. It is possible to structurally prevent short circuits.

[0050] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0051] (Embodiment 3) In this embodiment, a power storage device using the power storage element described in Embodiment 1 or 2 will be described. This will be described with reference to FIG. 3 and FIG.

[0052] 3A and 3B show the energy storage element 100 shown in the first embodiment or the energy storage element 100 shown in the second embodiment. 1 is a perspective view illustrating an energy storage device having the energy storage element 200 shown in FIG.

[0053] 3A shows a power storage device 400 in an initial shape that is not curved or bent. In the figure, the power storage device 400 is in the form of a thin rectangular sheet having long and short sides. The opposing short sides are provided with a positive electrode tab 402a and A negative electrode tab 402b is provided inside the power storage device 400. The energy storage element 100, 200 shown in the second embodiment is enclosed together with an electrolyte. 2a and the negative electrode tab 402b are integral with the positive electrode tab or the negative electrode tab of the storage element, respectively. , or connected as a separate component.

[0054] The power storage device 400 has an exterior body 401 that encapsulates the power storage element and the electrolyte. 1 is a flexible bag-like container for accommodating the energy storage elements 100 and 200 and an electrolyte in a sealed state. However, it is necessary to use a material that has a certain strength as an exterior of the sheet-shaped electricity storage device 400. In addition, it is also required that the battery has resistance to the electrolyte contained therein. The exterior body 401 is made of, for example, polyethylene, polypropylene, polycarbonate, etc. The inner surface of the membrane is made of a material such as carbide, ionomer, or polyamide, and is coated with aluminum, stainless steel, or other materials. A thin metal film made of a material having excellent flexibility, such as copper, nickel, etc., is then applied to the thin metal film. Three-layer structure with an insulating synthetic resin film made of polyamide resin, polyester resin, etc. on the outer surface A laminate film of this structure can be used. By using such a three-layer structure, It blocks the permeation of liquids and gases, ensures insulation, and is resistant to electrolytes.

[0055] The solute of the electrolyte is a material having carrier ions. Typical examples of the solute of the electrolyte are: , LiClO4, LiAsF6, LiBF4, LiPF6, Li(C2F5SO2)2N Lithium salts include:

[0056] In addition, the carrier ion is an alkali metal ion other than the lithium ion, an alkaline earth metal ion, etc. In the case of ions, beryllium ions, or magnesium ions, the above In the lithium salt, an alkali metal (e.g., sodium or potassium) is used instead of lithium. Alkaline earth metals (e.g., calcium, strontium, barium, etc.), Lithium or magnesium may also be used.

[0057] As the solvent for the electrolyte, a material capable of transporting carrier ions is used. The solvent is preferably an aprotic organic solvent. Representative examples of the aprotic organic solvent include , Ethylene carbonate (EC), Propylene carbonate, Dimethyl carbonate, Di Ethyl 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. In addition, it is possible to make the lithium secondary battery thinner and lighter. Representative examples of materials include silicone gel, acrylic gel, acrylonitrile gel, and poly Ethylene oxide, polypropylene oxide, fluorine-based polymers, etc. As the solvent for the solution, one or more ionic liquids (room temperature molten salts) that are flame-retardant and non-volatile are used. By using the battery several times, the internal temperature of the lithium secondary battery may rise due to an internal short circuit or overcharging. This also makes it possible to prevent the lithium secondary battery from exploding or catching fire.

[0058] In FIG. 3A, the power storage device 400 has a rectangular shape in plan view, but may have a trapezoid, polygon, circle, or ellipse shape. Any shape can be designed and implemented as long as it has a certain area. .

[0059] In addition, in FIG. 3(A), the positive electrode tab 402a and the negative electrode tab 402b are provided on opposing sides. However, wiring etc. can be routed from the storage element and arranged side by side. It is also possible.

[0060] Next, FIG. 3B shows the power storage device 400 in a curved or bent state. In FIG. In other words, the power storage device 400 is curved so as to be convex upward on the positive electrode tab 402a side, and the negative electrode tab 4 The side of the electrode 402b is curved so as to be convex downward. As described in the first or second embodiment, the storage element built into the 00 is The positive or negative electrode slides in the direction of the line segment connecting the positive and negative tabs. It is possible to bend the battery while maintaining the discharge capacity. As a result, the power storage device 400 is shaped as shown in FIG. It can bend like this.

[0061] Note that the power storage device 400 shown in this embodiment is In addition to bending or curving in one axial direction, it can also tolerate a certain degree of twisting. This is because the positive and negative electrodes are open except for one end, ensuring freedom of movement. .

[0062] Next, the internal structure of the power storage device 400 according to the present embodiment will be described with reference to FIGS. This will be explained using:

[0063] FIG. 4A is a cross-sectional view of the power storage device 400, showing an enlarged view of the positive electrode and its vicinity. Since the negative electrode portion and the negative electrode portion have roughly symmetrical structures in the schematic diagram, the negative electrode portion is not shown in the figure. is omitted.

[0064] The power storage device 400 includes an exterior body 401 and an energy storage element 404 sealed therein. As mentioned above, 4 is a laminate in which positive and negative electrodes are alternately stacked with a separator sandwiched between them. A plurality of positive electrodes are fixed at one end to a positive electrode tab 403, and a plurality of negative electrodes are fixed at one end to a negative electrode tab (not shown). The positive electrode tab 403 is led out to the outside of the exterior body 401. In FIG. In this case, the positive electrode tab 403 connected to multiple positive electrodes is connected to other positive electrode tabs 402, and the positive electrode tab 402 is led out to the outside of the exterior body 401. However, the structure for leading out the tab to the outside is not limited to this. For example, the positive electrode tab 403 and the positive electrode tab 402 may be led out as a single unit. Furthermore, one or more other conductive members may be provided between the positive electrode tab 403 and the positive electrode tab 402 to electrically The same applies to the negative electrode.

[0065] A support plate 406 is provided on the lower surface of the storage element 404. The support plate 406 is 403 and the bottom of the negative electrode tab (not shown). As a result, the positive electrode tab and the negative electrode tab can be fixed, and the energy storage element 404 is not curved. Even if the electrode tab is bent, the distance between the positive electrode tab and the negative electrode tab can be approximately fixed. This can cause an electrical short circuit between the positive and negative electrode tabs, or between the negative and positive electrode tabs. In addition, there is no risk of the exterior body 40 becoming too wide due to the gap between the positive electrode tab and the negative electrode tab becoming too wide. There is no risk of losing the overlap between the positive and negative electrodes inside 1.

[0066] The positive electrode, negative electrode, and separator constituting the storage element 404, and the exterior body 401 may each be Because they are flexible, depending on the material selected, they may bend due to gravity, and may bend in their initial state. Therefore, the support plate 406 may not be able to maintain a flat sheet shape. By providing it on the underside of 4, it is possible to support the power storage element 404.

[0067] The support plate is made of a material that minimizes bending due to its own weight or the fixing of the storage element 404, and is As long as the above conditions are met, the material is made of a flexible material that can bend or curve due to mechanical bending. The material may be a conductive material or an insulating material. For example, it may be a copper plate having a certain thickness. In the case where a conductive material is used for the support plate 406, the positive At least a fixed portion is required to fix the electrode tab and the negative electrode tab and to prevent short circuit between them. In addition, the support plate 406 is made of a metal core and an insulating material covering the metal core. A flexible material may be used, or a structure having a movable part in at least one axial direction may be used.

[0068] The exterior body 401 that encloses the storage element 404 and the electrolyte 405 is sealed inside. Any flexible bag-shaped storage battery that can be stored in the battery may be used, but a sheet-shaped storage battery that can be curved or bent is also acceptable. The outer casing of the device 400 has a certain strength. The exterior body 401 is also required to have resistance to electrolyte. Materials such as polyethylene, polypropylene, polycarbonate, ionomer, polyamide, etc. On the insulating film 401c made of the above, a material having excellent flexibility, such as aluminum, stainless steel, copper, or nickel, is A thin metal film 401b is provided on the thin metal film, and a polyamide resin is provided on the thin metal film as the outer surface of the exterior body. A three-layer laminate film having an insulating synthetic resin film 401a such as grease or polyester resin. Such a three-layer structure can prevent the permeation of electrolyte and gas. It blocks electrical current, ensures insulation, and is resistant to electrolyte.

[0069] FIG. 4B is a cross-sectional view of a power storage device 400 different from that in FIG. 4A. The positive electrode and negative electrode are roughly symmetrical in the schematic diagram. Due to the structure, the negative electrode portion is not shown.

[0070] In FIG. 4B, an insulating material is used for the support plate 406, and the positive electrode tab 403 is The positive electrode tab 402 is electrically connected to the positive electrode tab 402 which is led to the outside of the exterior body 401 via a wiring 407 provided in the Since the wiring 407 is in direct contact with the electrolyte 405, the reaction with the electrolyte 405 is prevented. It is necessary to select a conductive material that is less susceptible to this problem. For example, stainless steel is used for the wiring 407. Uses metals such as gold, platinum, zinc, iron, copper, aluminum, titanium, and alloys of these metals. The wiring 407 is connected to the positive electrode tabs 402 and 403 except for the terminal portion. , may be covered with an insulating material.

[0071] In the structure shown in FIG. 4(B), the positive electrode tab 402 is connected to the support plate 4 via a wiring 407. 06 and is not in direct contact with the power storage element 404, and is therefore located outside the exterior body 401. When a force is applied to the positive electrode tab 402, the force is prevented from being directly applied to the electric storage element 404. It is possible.

[0072] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0073] (Embodiment 4) In this embodiment, the energy storage element described in any one of the first to third embodiments is a lithium secondary battery. The structure and manufacturing method thereof will be described below.

[0074] (Positive electrode and its manufacturing method) First, the positive electrode and the manufacturing method thereof will be described. FIG. 5(A) is a cross-sectional view of a positive electrode 500. The positive electrode 500 has a positive electrode mixture layer 502 formed on a positive electrode current collector 501.

[0075] The positive electrode current collector 501 may be made of stainless steel, gold, platinum, zinc, iron, copper, aluminum, titanium, etc. Materials with high electrical conductivity, such as metals and alloys thereof, can be used. Elements that improve heat resistance, such as titanium, neodymium, scandium, and molybdenum, are added. Aluminum alloys that react with silicon to form silicide can be used. The metal element may be a metal element that reacts with silicon to form a silicide. These include zirconium, titanium, hafnium, vanadium, niobium, tantalum, and chromium. , molybdenum, tungsten, cobalt, nickel, etc. The positive electrode current collector 501 is a foil Plate (sheet), net, punched metal, expanded metal, etc. It can be used.

[0076] The positive electrode active material used in the positive electrode mixture layer 502 is a material capable of inserting and extracting lithium ions. Materials can be used, for example, olivine type crystal structures, layered rock salt type crystal structures, or Examples of the lithium-containing composite oxide include those having a spinel type crystal structure.

[0077] Examples of lithium-containing composite oxides having an olivine structure include those represented by the general formula LiMPO4 (where M is , Fe(II), Mn(II), Co(II), Ni(II) Representative examples of the general formula LiMPO4 include LiFePO4, LiNi PO4, LiCoPO4, LiMnPO4, LiFeNi 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 1 or less, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. can be mentioned.

[0078] In particular, LiFePO4 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), and thus is preferable.

[0079] Examples of lithium-containing composite oxides having a layered rock salt crystal structure include, for example, lithium cobaltate (LiCoO2), LiNiO2, LiMnO2, Li2MnO3, LiNi 0. <000071>8Co 0.2 O2, etc. of the NiCo system (general formula is LiNi x Co 1-x O2 (0 < x < 1) )), LiNi 0.5 Mn​​0.5 O2, etc. NiMn system (general formula: LiNi x Mn 1-x O 2(0 <x<1))、LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 NiMnCo system (N Also known as MC. The general formula is LiNi x 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, Other examples include Li2MnO3-LiMO2 (M=Co, Ni, Mn).

[0080] In particular, LiCoO2 has a large capacity, is more stable in air than LiNiO2, and It is preferred because it has advantages such as being more thermally stable than NiO2.

[0081] Examples of lithium-containing composite oxides having a spinel-type crystal structure include LiMnO 4. Li 1+x Mn 2-x O4, Li(MnAl)2O4, LiMn 1.5 Ni 0.5 O 4 etc.

[0082] Lithium-containing composite oxides with spinel-type crystal structure containing manganese, such as LiMn2O4 The material contains a small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x MO2 (M=Co, A Mixing with manganese oxide, etc., has the advantage of suppressing the elution of manganese and the decomposition of the electrolyte. Yes, this is preferable.

[0083] 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), Ni(II) one or more, 0 ≦ j ≦ 2) represented by the composite oxide can be used. As a representative example of the general formula Li (2-j) MSiO4, Li (2-j ) FeSiO4, Li (2-j) NiSiO4, Li (2-j) CoSiO4, Li (2 -j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO 4, Li (2-j) Ni k Mn l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1) , Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q Si O4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. can be mentioned .

[0084] Also, as the positive electrode active material, Ax M2(XO4)3(A=Li, Na, Mg, M=Fe, M n, Ti, V, Nb, Al, X=S, P, Mo, W, As, Si) A Sikon type compound can be used. The Nasikon type compound is Fe2(MnO4) 3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. As general examples, Li2MPO4F, Li2MP2O7, and Li5MO4 (M=Fe, Mn) Compounds represented by the formula, perovskite-type fluorides such as NaF3 and FeF3, TiS2, M Metal chalcogenides (sulfides, selenides, tellurides) such as oS2, LiMVO4, etc. Lithium-containing composite oxides with an inverse spinel crystal structure, vanadium oxide-based (VO 5. V6O 13 LiV3O8, etc.), manganese oxide-based, organic sulfur-based materials, etc. This can be done.

[0085] In addition, the carrier ion is an alkali metal ion other than the lithium ion, an alkaline earth metal ion, etc. In the case of zinc ions, beryllium ions, or magnesium ions, the positive electrode mixture layer 502 is In the lithium compounds and lithium-containing composite oxides, aluminium is used instead of lithium. Potash metals (e.g., sodium, potassium, etc.), alkaline earth metals (e.g., calcium , strontium, barium, etc.), beryllium, or magnesium may also be used.

[0086] In addition, the positive electrode mixture layer 502 is not limited to being formed in direct contact with both sides of the positive electrode current collector 501. Between the positive electrode current collector 501 and the positive electrode mixture layer 502, 02 and to reduce the unevenness of the surface of the positive electrode current collector 501. a flattening layer for flattening the positive electrode current collector 501 or the positive electrode mixture layer 502; A functional layer such as a stress relief layer for relieving the stress may be formed using a conductive material such as a metal. stomach.

[0087] FIG. 5B shows a particulate positive electrode material capable of absorbing and releasing carrier ions as the positive electrode mixture layer 502. The positive electrode active material 503 is covered with the positive electrode active material 503. FIG. 5 is a plan view of a positive electrode mixture layer 502 in the case where the positive electrode mixture layer 502 is composed of graphene 504 packed in a portion of the positive electrode. The surfaces of the positive electrode active materials 503 are covered with different graphenes 504. In this case, the positive electrode active material 503 may be exposed.

[0088] Here, graphene, in the narrow sense, refers to horizontal layers of graphite, i.e., a material made of carbon. In other words, it is a carbon layer with one atomic layer of carbon atoms having π bonds. It is a sheet of elementary molecules. In particular, when the carbon layer is stacked in 2 to 100 layers. is sometimes called multi-layer graphene, but multi-layer graphene is also included in the graphene category here. In addition, graphene oxide refers to a compound in which the graphene is oxidized. When graphene oxide is reduced to form graphene, Not all of the oxygen that is released is released, and some of the oxygen remains in the graphene. When oxygen is contained, the ratio of oxygen is preferably 2 atomic % or more and 20 atomic % or less of the total. Preferably, it is 3 atomic % or more and 15 atomic % or less.

[0089] Here, when the graphene is a multi-layer graphene, the graphene is obtained by reducing graphene oxide. By having such a structure, the interlayer distance of the graphene is 0.34 nm or more and 0.5 nm or less, preferably 0.38 nm or more and 0.42 nm or less, more preferably 0.39 nm or more and 0.41 nm or less In ordinary graphite, the interlayer distance of single-layer graphene is 0.34 nm. Since the graphene used in the power storage device according to one embodiment of the present invention has a longer interlayer distance, This facilitates the movement of carrier ions between the graphene layers.

[0090] Graphene is chemically stable and has good electrical properties. The reason for this high molecular weight is that the six-membered rings made up of carbon atoms are continuous in the planar direction. Graphene has high electrical conductivity in the planar direction. Therefore, the graphene to be laminated has gaps in the direction parallel to the plane, and the inductive coupling is performed in the region. Although the movement of ions is possible, the movement of ions perpendicular to the graphene plane is difficult. It is difficult.

[0091] The particle size of the positive electrode active material 503 is preferably 20 nm or more and 100 nm or less. Since electrons move within 503, it is preferable that the particle size of the positive electrode active material 503 is smaller.

[0092] In addition, sufficient characteristics can be obtained even if the surface of the positive electrode active material 503 is not covered with a graphite layer. However, when graphene is used together with a positive electrode active material coated with a graphite layer, This is more preferable because the carriers hop between the positive electrode active materials and current flows.

[0093] Fig. 5(C) is a cross-sectional view of a part of the positive electrode mixture layer 502 in Fig. 5(B). The positive electrode active material 503 and the graphene 504 covering the positive electrode active material 503. The graphene 504 is In the cross-sectional view, the positive electrode active material is observed to have a line shape. The graphene is sandwiched between the graphene. In some cases, multiple positive electrode active materials are wrapped inside the graphene. In some cases, the positive electrode active material may be exposed.

[0094] The thickness of the positive electrode mixture layer 502 is selected from the range of 20 μm to 100 μm. In order to prevent cracks or peeling, the thickness of the positive electrode mixture layer 502 may be appropriately adjusted. preferable.

[0095] The positive electrode mixture layer 502 is made of acetylene bromide having a volume that is 0.1 to 10 times the volume of graphene. Carbon particles such as rack particles and carbon nanofibers with one-dimensional expansion are The conductive material may contain a conductive additive.

[0096] In the positive electrode active material 503, the volume expands due to the absorption of ions that become carriers. For this reason, the positive electrode mixture layer becomes brittle during charging and discharging, and part of the positive electrode mixture layer collapses. As a result, the reliability of the power storage device is reduced. Even if the volume increases or decreases, the surrounding area is covered with graphene, so graphene improves the dispersion and It is possible to prevent the positive electrode mixture layer from collapsing. Even if the volume of the positive electrode active material increases or decreases, the positive electrode active material has a function of maintaining the bond between the positive electrode active materials.

[0097] In addition, the graphene 504 is in contact with the plurality of positive electrode active material particles 503 and functions as a conductive additive. In addition, it has a function of retaining the positive electrode active material 503 capable of absorbing and releasing carrier ions. Therefore, there is no need to mix a binder into the positive electrode mixture layer, and the positive electrode per positive electrode mixture layer is The amount of active material can be increased, and the charge / discharge capacity of the power storage device can be increased.

[0098] Next, a method for producing the positive electrode mixture layer 502 will be described.

[0099] A slurry containing particulate positive electrode active material and graphene oxide is formed. Next, a positive electrode current collector 5 The slurry is applied to both sides of the substrate 01. After that, the substrate is heated in a reducing atmosphere to carry out a reduction treatment. The positive electrode active material is baked and oxygen contained in the graphene oxide is desorbed, and the graphene oxide is then heated. The oxygen in the graphene oxide is not released, and the gaps are formed in the graphene. A portion of the oxygen remains in the graphene.

[0100] Through the above steps, a positive electrode mixture layer 502 having a predetermined shape is formed on the positive electrode current collector 501. As a result, the conductivity of the positive electrode mixture layer is increased. Since graphene oxide contains oxygen, In polar solvents, the graphene oxide particles are negatively charged. As a result, the particles are dispersed among each other. The positive electrode active material contained in the slurry is less likely to aggregate, and the particle size of the positive electrode active material increases during firing. This facilitates the movement of electrons in the positive electrode active material, The electrical conductivity of the layer can be increased.

[0101] After forming a positive electrode mixture layer 502 on a positive electrode current collector 501, the layer is rolled using a roll press. A positive electrode 500 is fabricated.

[0102] (Negative electrode and its manufacturing method) Next, the negative electrode and a method for producing the same will be described with reference to FIG.

[0103] As shown in FIG. 6A, the negative electrode 510 includes a negative electrode current collector 511 and a negative electrode layer 512 on both sides of the negative electrode current collector 511. and a negative electrode mixture layer 512 provided thereon.

[0104] The negative electrode current collector 511 is made of a highly conductive material such as a metal. Examples of suitable materials include stainless steel, iron, aluminum, copper, nickel, and titanium. The negative electrode current collector 511 may be in the form of a foil, a plate (sheet), a mesh, a punch, or the like. Shapes such as solid metal and expanded metal can be appropriately used.

[0105] The negative electrode mixture layer 512 is provided on both sides of the negative electrode current collector 511. A negative electrode active material capable of absorbing and releasing ions, which act as carriers, is used.

[0106] As a negative electrode active material, it performs charge / discharge reactions by alloying and dealloying reactions with lithium metal. Alloy materials that can be used are also usable. For example, Al, Si, Ge, Sn, Pb, S Examples of the material include materials containing at least one of b, Bi, Ag, Zn, Cd, In, and Ga. These elements have a large capacity compared to carbon, and silicon in particular has a theoretical capacity of 4200m Ah / g, which is dramatically high. For this reason, it is preferable to use silicon as the negative electrode active material. Examples of alloy materials using such elements include SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni 3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, La Examples include Sn3, La3Co2Sn7, CoSb3, InSb, and SbSn.

[0107] In addition, titanium dioxide (TiO2) and lithium titanium oxide (Li4T i5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0108] 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 is preferable because it exhibits a large charge / discharge capacity (900 mAh / g).

[0109] 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. It is preferable that the positive electrode active material contains lithium ions. , by first removing the lithium ions, a complex nitride of lithium and a transition metal is used. It is possible.

[0110] When the negative electrode active material is silicon, amorphous silicon, microcrystalline silicon, The material can be silicon, polysilicon, or a combination of these. Generally, the crystallinity is high. Since the electrical conductivity of silicon is so high, it can be used in batteries as a highly conductive electrode. On the other hand, when silicon is amorphous, there are more carrier ions such as lithium than in crystalline silicon. Since the hydrogen can be absorbed, the discharge capacity can be increased.

[0111] In this embodiment, a conductive additive and a binder are added to the above-mentioned negative electrode active material, and the mixture is crushed, mixed, and fired. Alternatively, the negative electrode mixture layer 512 formed in this manner may be used.

[0112] As another example of a method for producing the negative electrode 510, the negative electrode 510 may be produced in the same manner as the positive electrode 500. In addition, graphene can be introduced into the negative electrode mixture layer 512. The negative electrode active material has a function of maintaining the bond between the negative electrode active materials even when the negative electrode active material expands and contracts. In addition, graphene also functions as a conductive additive.

[0113] When graphite is used as the negative electrode active material, for example, a fluorine-containing compound such as polyvinylidene fluoride is added to graphite powder. The vinylidene fluoride polymer is dissolved in NMP (N-methylpyrrolidone) and mixed as a binder. Next, the slurry is applied to one or both surfaces of the negative electrode current collector 511. When the coating process is performed on only one surface of the negative electrode current collector 511, A negative electrode mixture layer is formed on the other side in the same manner. Then, the resultant mixture is rolled to produce the negative electrode 510 .

[0114] On the other hand, when silicon is used as the negative electrode active material, the capacity expands by about four times due to the absorption of carrier ions. Therefore, simply forming a thin film on the negative electrode current collector 511 does not easily result in a negative electrode mixture layer This induces peeling. For this reason, silicon is used in the form of particles, whiskers, nanowires, or other thin films. It is necessary to use a shape that excludes the shape.

[0115] Examples of using particulate and whisker-shaped negative electrode active materials as the negative electrode active materials are shown in Figs. 6(A) to (D) ) will be used below for explanation.

[0116] 6A is a cross-sectional view of a negative electrode 510. The negative electrode is a negative electrode current collector 511 having a negative electrode mixture on both sides thereof. The negative electrode mixture layer 512 contains at least a negative electrode active material. In addition, the conductive material may contain a binder, a conductive additive, and graphene.

[0117] 6B is a plan view of a portion of the negative electrode mixture layer 512. The negative electrode mixture layer 512 is made of particles The negative electrode active material 513 is a shaped negative electrode active material 513. The negative electrode active material 513 is a shaped negative electrode active material 513. The negative electrode mixture layer 512 in plan view is made up of a plurality of graphenes 514 packed together. The surface of the negative electrode active material 513 is covered with different graphene 514. The negative electrode active material 513 may be exposed.

[0118] Fig. 6(C) is a cross-sectional view of a part of the negative electrode mixture layer 512 in Fig. 6(B). 513, and the graphite covering the negative electrode active material 513 in the plan view of the negative electrode mixture layer 512. In the cross-sectional view, the graphene 514 is observed to be linear. One graphene or a plurality of graphenes overlap with a plurality of negative electrode active material layers 513 or A single graphene or a plurality of graphenes contain a plurality of negative electrode active materials 513 therein. The graphene 514 has a bag shape and contains a plurality of negative electrode active materials therein. In addition, the graphene 514 may have an open portion, and the open portion may be used as a negative electrode active material. The material 513 may be exposed.

[0119] The thickness of the negative electrode mixture layer 512 is selected from the range of 20 μm to 100 μm.

[0120] The negative electrode mixture layer 512 contains acetylene at a volume that is 0.1 to 10 times the volume of graphene. Black particles and carbon particles with one-dimensional expansion (carbon nanofibers, etc.) It may include any known conductive additive and known binder such as polyvinylidene fluoride.

[0121] The negative electrode mixture layer 512 may be pre-doped with lithium. Alternatively, a lithium layer may be formed on the surface of the negative electrode mixture layer 512 by a sputtering method. Alternatively, lithium foil may be provided on the surface of the negative electrode mixture layer 512 to form a lithium ion battery. In particular, after assembling a lithium secondary battery, the positive electrode When graphene 504 is formed on the positive electrode mixture layer 502 of 500, It is preferable to pre-dope with lithium.

[0122] In addition, the negative electrode active material 513 may expand in volume due to the absorption of carrier ions. For this reason, the negative electrode mixture layer becomes brittle during charging and discharging, and part of the negative electrode mixture layer collapses. This reduces the reliability of the lithium secondary battery (e.g., cycle characteristics, etc.). In the negative electrode of the lithium secondary battery according to one embodiment of the present invention, the negative electrode active material 513 is surrounded by graphite. Even if the volume of the negative electrode active material 513 increases or decreases due to charging and discharging, the graphene 514 covers the negative electrode active material 513. The negative electrode active material 513 can be prevented from being pulverized and the negative electrode mixture layer 512 can be prevented from being destroyed by the negative electrode active material 513. That is, the graphene 514 contained in the negative electrode of the lithium secondary battery according to one embodiment of the present invention Even if the volume of the negative electrode active material 513 expands and contracts with charging and discharging, how does the negative electrode active material 513 Therefore, the use of the negative electrode 510 improves the durability of the electric storage element. It is possible to improve the performance.

[0123] In other words, there is no need to use a binder when forming the negative electrode mixture layer 512, and the negative electrode mixture layer 512 can be formed by a constant weight (constant In the negative electrode mixture layer (volume), the amount of the negative electrode active material can be increased. The charge / discharge capacity per electrode weight (electrode volume) can be increased.

[0124] The graphene 514 has conductivity and is in contact with the plurality of negative electrode active material particles 513. In other words, when the negative electrode mixture layer 512 is formed, the conductive additive is added. It is not necessary to use a negative electrode active material, and the amount of the negative electrode active material is increased in a negative electrode mixture layer of a constant weight (constant volume). Therefore, it is possible to increase the charge / discharge capacity per electrode weight (electrode volume). It is possible.

[0125] In addition, the graphene 514 provides an efficient and sufficient conductive path (carrier Since a conductive path for ions is formed, the conductivity of the negative electrode mixture layer 512 and the negative electrode 510 are Therefore, the electric storage element having the negative electrode 510 has a capacity of the negative electrode active material 513. Since the battery can be used as efficiently as its theoretical capacity, the charge / discharge capacity can be increased sufficiently. can.

[0126] In addition, graphene 514 also functions as a negative electrode active material capable of absorbing and releasing carrier ions. Therefore, the charge / discharge capacity of the negative electrode 510 can be improved.

[0127] Next, a method for producing the negative electrode mixture layer 512 shown in FIGS. 6(B) and 6(C) will be described.

[0128] A slurry containing particles of the negative electrode active material 513 and graphene oxide is formed. Specifically, The particulate negative electrode active material 513 and a dispersion containing graphene oxide are mixed to form a slurry. Form.

[0129] Next, the above slurry is applied onto the negative electrode current collector 511. Next, vacuum drying is performed for a certain period of time. The solvent is removed from the slurry applied onto the negative electrode current collector 511 by using a roll press. The material is rolled using a rolling machine.

[0130] After that, the graphene oxide was electrochemically reduced using electrical energy and then heat-treated. Graphene 514 is produced by thermal reduction of graphene oxide. Then, a negative electrode mixture layer 512 can be formed on both sides of the negative electrode current collector 511, and a negative electrode 510 can be manufactured. can be done.

[0131] Next, the structure of the negative electrode shown in FIG. 6(D) will be described.

[0132] FIG. 6(D) is a cross-sectional view of a negative electrode in which a negative electrode mixture layer 517 is formed on a negative electrode current collector 511. The negative electrode mixture layer 517 is made of a negative electrode active material 515 having an uneven surface and a negative electrode active material 515 having an uneven surface. The graphene 516 covers the

[0133] The uneven negative electrode active material 515 has a common portion 515a and a protrusion 51 protruding from the common portion 515a. The protrusions 515b are cylindrical, prismatic, conical, pyramidal, or other acicular. The top of the protrusion may be curved. 5 uses a negative electrode active material capable of absorbing and releasing carrier ions (typically lithium ions). The common portion 515a and the protruding portion 515b are formed using the same material. Alternatively, the common portion 515a and the protruding portion 515b may be made of different materials. stomach.

[0134] In the negative electrode shown in FIG. 6D, when silicon is used as the negative electrode active material 515, graphene 5 Since the negative electrode active material 515 is covered with the negative electrode active material 515, the negative electrode active material 515 is not easily charged or discharged. Therefore, even if the volume increases or decreases, the negative electrode active material 515 is prevented from being pulverized and the negative electrode mixture layer 517 is prevented from collapsing. It is possible.

[0135] In addition, the surface of the negative electrode mixture layer comes into contact with the electrolyte that constitutes the electricity storage device, and The negative electrode active material reacts with the electrolyte to form a coating on the surface of the negative electrode. However, it is believed that the coating is necessary to soften and stabilize the When the thickness is increased, carrier ions are less likely to be absorbed by the negative electrode, and the carrier ions between the electrode and the electrolyte are However, there are problems such as a decrease in on-conductivity and consumption of the electrolyte.

[0136] By covering the surface of the negative electrode active material 515 with graphene 516, the thickness of the coating can be increased. It is possible to suppress the decrease in charge / discharge capacity.

[0137] As another structure of the uneven negative electrode active material 515, the negative electrode current collector 511 may be provided with a negative electrode current collector 51 The bumps formed as part of 1 are covered with a thin film of anode active material to form an uneven surface. In this case, the negative electrode active material may be a part of the negative electrode current collector 511. The protrusions function as the core of the thin film of the negative electrode active material, which increases the strength of the negative electrode active material. This is especially true in the case of silicon, which is a negative electrode active material that expands and contracts significantly due to the absorption and desorption of carrier ions. This is useful in cases where

[0138] Next, a method for producing the negative electrode mixture layer 517 shown in FIG. 6(D) will be described.

[0139] A bumpy negative electrode active material 515 is applied to a negative electrode current collector 5 by a printing method, an inkjet method, a CVD method, or the like. Alternatively, a film-like negative electrode may be formed on both sides of the substrate 11 by coating, sputtering, vapor deposition, or the like. After the negative electrode active material is provided, it is selectively removed, and the uneven negative electrode active material 515 is placed on the negative electrode current collector 51. 1. Install on both sides of the top.

[0140] Next, a dispersion liquid containing graphene oxide is applied onto the uneven surface of the negative electrode active material 515. As a method for applying the dispersion liquid containing laphene, the above-mentioned methods may be appropriately used.

[0141] Next, after removing the solvent from the dispersion liquid containing graphene oxide, the graphene oxide is electrochemically decomposed by using electrical energy. Graphene 516 can be produced by chemically reducing graphene oxide. Energy may be used to thermally reduce the graphene oxide to produce graphene 516. .

[0142] In this way, by producing graphene using a dispersion liquid containing graphene oxide, it is possible to obtain a rough The surface of the negative electrode active material 515 can be covered with the graphene 516 having a uniform thickness.

[0143] In addition, the negative electrode is produced by the LPCVD method using silane, silane chloride, silane fluoride, etc. as raw material gas. On the current collector 511, a concave-convex negative electrode active material 515 (hereinafter, silicon It is possible to provide a gap between the wire and the base.

[0144] The silicon whiskers may have an amorphous structure. By using the agent layer 517, the material is resistant to volume changes caused by the absorption and release of carrier ions (for example, For example, the silicon whisker can reduce the stress caused by volume expansion by repeatedly charging and discharging the battery. The pulverization of the sintered body and the collapse of the negative electrode mixture layer 517 can be prevented, and the cycle characteristics are further improved. An electrical device can be fabricated.

[0145] Alternatively, the silicon whiskers may be crystalline in structure, in which case the electrical conductivity and carrier ions are The crystalline structure, which has excellent crystallinity and excellent electron mobility, is in contact with the current collector over a wide area. The conductivity of the entire electrode can be further improved, enabling faster charging and discharging. A power storage device with further improved capacitance can be manufactured.

[0146] Alternatively, the silicon whisker has a core, which is a region having crystallinity, and is provided to cover the core, and an outer shell which is an amorphous region.

[0147] The amorphous structure of the outer shell is resistant to volume changes caused by the absorption and release of carrier ions (e.g. It has the characteristic of relieving the stress caused by volume expansion. It also has the core crystallinity. The structure has excellent electrical conductivity and carrier ion mobility, and is fast at absorbing carrier ions. The characteristic of the suction is that the concentration and release rate per unit mass are fast. By using silicon whiskers having the above structure as the negative electrode mixture layer 517, high-speed charging and discharging is possible. As a result, a power storage device with improved charge / discharge capacity and cycle characteristics can be manufactured.

[0148] (Electricity storage element and its manufacturing method) The belt-shaped positive electrode 500 and negative electrode 510 manufactured as described above are cut to a predetermined size. A plurality of each is prepared, and the positive electrode 500 is connected to the positive electrode tab, and the negative electrode 510 is connected to the negative electrode tab. Specifically, the connection between the electrode and the tab is a connection between a current collector of the electrode and the tab. The positive and negative tabs are electrically connected and the physical structure is fixed. The fixing to the tube can be performed by ultrasonic welding, for example.

[0149] Next, a continuous wire is inserted between the multiple positive electrodes 500 and the multiple negative electrodes 510 bound by the tabs. A single separator or multiple separators are placed between the positive and negative electrodes. The separator uses an insulating porous body, but has a low coefficient of sliding friction between the surfaces of the positive and negative electrodes. The material is preferably a non-sticky insulating material, such as polypropylene or polytetrafluoroethylene. is preferred.

[0150] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0151] (Embodiment 5) A power storage device according to one embodiment of the present invention can be used as a power source for various electrical devices. Here, electrical equipment refers to all industrial products that contain parts that are acted upon by electrical power. The scope of application is not limited to consumer electronics such as home appliances, but also covers a wide range of applications, including commercial, industrial, and military use. This falls within the category of.

[0152] Examples of electrical devices using a power storage device according to one embodiment of the present invention include displays such as televisions and monitors. display device, lighting device, desktop or notebook personal computer, Word Processors, recording media such as DVDs (Digital Versatile Discs) Image playback devices that play back still or moving images stored in the , tape recorders, headphone stereos, stereos, table clocks, wall clocks, cordless Telephone handsets, transceivers, portable radios, mobile phones, car phones, portable game consoles, toys, Calculators, mobile information terminals, electronic organizers, electronic books, electronic translators, voice input devices, video cameras, Digital still cameras, electric shavers, microwave ovens and other high-frequency heating devices, electric rice cookers, Washing machines, vacuum cleaners, water heaters, electric fans, hair dryers, air conditioners, humidifiers, dehumidifiers Air conditioning equipment such as humidifiers, dishwashers, dish dryers, clothes dryers, futon dryers, electric refrigerators, Electric freezers, electric refrigerators and freezers, freezers for DNA storage, flashlights, electric tools, smoke detectors, In addition, emergency lights, traffic lights, conveyor belts, elevators, and other medical equipment are also included. Beta, escalators, industrial robots, power storage systems, power leveling and smart grids In addition, the electric power from the electric storage device is used for industrial equipment such as a power storage device for a lid. The moving body propelled by an electric motor is also included in the category of electrical equipment. For example, electric vehicles (EVs) and hybrid vehicles that combine an internal combustion engine and an electric motor ( HEV, Plug-in Hybrid Vehicle (PHEV), and converting these tires and wheels into tracks Tracked vehicles, motorized bicycles including electrically assisted bicycles, motorcycles, electric wheelchairs, Cargo carts, small or large ships, submarines, helicopters, aircraft, rockets, and artificial satellites Examples include space probes, planetary rovers, and spacecraft.

[0153] In addition, the above-mentioned electrical equipment is provided with a main power source for covering almost all of the power consumption, and Alternatively, the electrical equipment may be powered by the main power source or a commercial power source. An uninterruptible power supply that can supply power to electrical equipment when the power supply from the source is interrupted. The power storage device according to one embodiment of the present invention can be used as a power source. Electrical equipment is supplied with power from the main power source or commercial power source in parallel with the power supply to the electrical equipment. The power storage device of one embodiment of the present invention is used as an auxiliary power source for supplying power to the can be done.

[0154] FIG. 7 shows a specific configuration of the above-mentioned electric device. In FIG. 7, a display device 8000 is 8 is an example of an electric device using a power storage device 8004 according to one embodiment of the present invention. 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker The power storage device 8004 according to one embodiment of the present invention includes a core unit 8003 and a power storage device 8004. The display device 8000 is provided inside a housing 8001. The display device 8000 is supplied with power from a commercial power source. The power can be supplied to the power supply device 8002, or the power stored in the power storage device 8004 can be used. Therefore, even when power cannot be supplied from a commercial power source due to a power outage or the like, The display device 8000 can be used by using the power storage device 8004 as an uninterruptible power supply. It becomes Noh.

[0155] The display unit 8002 may be a liquid crystal display device, an emitting device having light emitting elements such as organic EL elements in each pixel, or the like. Device, electrophoretic display device, DMD (Digital Micromirror Devi ce), PDP (Plasma Display Panel), FED (Field A semiconductor display device such as a 3D Emission Display can be used.

[0156] In addition, display devices are used for TV broadcast reception, personal computers, advertising displays, etc. In particular, the power storage device according to one embodiment of the present invention is thin. By utilizing the fact that the material has flexibility, it can be used for a thin, curved information display device. can be applied.

[0157] In FIG. 7, a stationary lighting device 8100 includes a power storage device 810 according to one embodiment of the present invention. 8101, a light source 8102, and a housing 8101. 7, the power storage device 8103 is disposed inside the housing 8101. 8, the light source 8102 is provided inside a ceiling 8104. However, the power storage device 8103 may be provided inside the housing 8101. When the device 8100 is thin and has a curved surface, It is best to use the lighting device 8100 with a power supply that is also powered by a commercial power source. In addition, the power stored in the power storage device 8103 can also be used. Even when power cannot be supplied from a commercial power source, the power storage device 8103 according to one embodiment of the present invention can be used. By using this as an uninterruptible power supply, the lighting device 8100 can be used.

[0158] In addition, FIG. 7 illustrates a lighting device 8100 that is installed on a ceiling 8104. However, in the power storage device of one embodiment of the present invention, in addition to the ceiling 8104, for example, the side wall 8105, the floor 81 06, Window 8107, etc., can be used for a stationary lighting device installed, or a tabletop type The present invention can also be used in lighting devices.

[0159] In addition, the light source 8102 may be an artificial light source that artificially obtains light using electricity. Specifically, incandescent lamps, fluorescent lamps and other discharge lamps, light emitting diodes (LEDs) and organic electroluminescence (EL) elements The element is an example of the artificial light source.

[0160] In FIG. 7, an air conditioner having an indoor unit 8200 and an outdoor unit 8204 is 8 is an example of an electric device using a power storage device 8203 according to one embodiment of the present invention. The electronic device 200 includes a housing 8201, an air outlet 8202, a power storage device 8203, and the like. In the illustrated example, the power storage device 8203 is provided in the indoor unit 8200. 203 may be provided in the outdoor unit 8204. Alternatively, the indoor unit 8200 and the outdoor unit 8 A power storage device 8203 may be provided in both the power supply 204 and the power supply 205. The power supply can be received from a power source, or the power stored in the power storage device 8203 can be used. In particular, both the indoor unit 8200 and the outdoor unit 8204 may include a power storage device 8203. If a power supply is provided, this equipment will continue to operate even when power is not available from the commercial power source due to a power outage or other reason. The power storage device 8203 according to one embodiment of the present invention can be used as an uninterruptible power supply, It will be possible to use Yona.

[0161] In addition, Figure 7 shows an example of a separate type air conditioner consisting of an indoor unit and an outdoor unit. However, it is an integrated air conditioner that has both the indoor and outdoor functions in a single housing. The power storage device according to one embodiment of the present invention can be used in the load balancer.

[0162] In FIG. 7, an electric refrigerator-freezer 8300 uses a power storage device 8304 according to one embodiment of the present invention. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator 7, the power storage device 8304 and the like. The electric refrigerator-freezer 8300 is a commercial refrigerator-freezer. It can receive power from a power source, or can use the power stored in the power storage device 8304. Therefore, even when power cannot be supplied from commercial power sources due to a power outage, By using the power storage device 8304 of one embodiment of the present invention as an uninterruptible power supply, 8,300 storehouses will be available for use.

[0163] Among the above-mentioned electrical appliances, high-frequency heating devices such as microwave ovens, electric rice cookers, etc. The equipment requires high power for a short period of time. Therefore, the equipment supplements the power that cannot be supplied by commercial power sources. By using a power storage device according to one embodiment of the present invention as an auxiliary power source for It can prevent the commercial power breaker from tripping during use.

[0164] In addition, during periods when electrical equipment is not being used, especially during periods when the total amount of power that can be supplied by the commercial power supplier is low, During times when the proportion of electricity actually used (called the electricity usage rate) is low, By storing power in the device, it is possible to prevent high power usage outside of the above time periods. For example, in the case of the electric refrigerator-freezer 8300, when the temperature is low, the refrigerator compartment door 830 2. During the night when the freezer door 8303 is not opened or closed, electricity is stored in the power storage device 8304. Then, as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. By using the power storage device 8304 as an auxiliary power source during the daytime, the daytime power usage rate can be kept low.

[0165] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0166] (Embodiment 6) In this embodiment, a power storage device according to one embodiment of the present invention is applied to an electrical device having a curved surface. An example will be described with reference to FIG.

[0167] FIG. 8A shows an example of a mobile phone. A mobile phone 8500 is provided in a housing 8501. In addition to the built-in display unit 8502, operation buttons 8503, external connection port 8504, The mobile phone 8500 is equipped with a speaker 8505, a microphone 8506, and the like. The power storage device of one embodiment of the present invention is mounted on the vehicle.

[0168] In the mobile phone 8500 shown in FIG. 8A, information is displayed by touching a display portion 8502 with a finger or the like. You can also make calls, enter text, and do any other operations. An operation can be performed by touching the display portion 8502 with a finger or the like.

[0169] In addition, by operating the operation button 8503, the power can be turned on and off, and the display unit 8502 can be displayed. For example, you can change the type of image displayed from the main menu to the email composition screen. You can switch to the screen.

[0170] Here, the flexible power storage device of one embodiment of the present invention is incorporated in the mobile phone 8500. In FIG. 8(A), the mobile phone 8500 is arranged so as to be convex upward in the horizontal direction. Therefore, the power storage device of one embodiment of the present invention is curved in a bow shape. In this way, the curved shape is Moreover, the mobile phone can be made thin.

[0171] FIG. 8B shows an example of a wristband-type display device. The electronic device includes a housing 8601, a display unit 8602, an operation button 8603, and a transmitting / receiving device 8604. The power storage device of one embodiment of the present invention is mounted inside the portable display device 8600. do.

[0172] The portable display device 8600 can receive a video signal by a transmitting / receiving device 8604. Video can be displayed on the display unit 8602. Audio signals can also be sent to other receiving devices. It is also possible.

[0173] In addition, the operation button 8603 can be used to turn the power on and off and to switch the image to be displayed. , or adjust the volume of the audio.

[0174] Here, the flexible power storage device of one embodiment of the present invention is incorporated in the portable display device 8600. In FIG. 8B, the portable display device 8600 is convex upward in the vertical direction. Therefore, the power storage device of one embodiment of the present invention is a portable display device 860. Therefore, the curved surface is Moreover, it is possible to provide a thin portable display device.

[0175] Note that the electric device is not particularly limited to the above-described electric devices as long as the power storage device of one embodiment of the present invention is included. Needless to say, this is not possible.

[0176] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Explanation of symbols]

[0177] 100 Energy storage element 101 Positive electrode 102 Separator 103 Negative electrode 104 Positive electrode tab 105 Negative electrode tab 200 Energy storage element 201 Positive electrode 202 Separator 203 Negative electrode 204 Positive electrode tab 205 Negative electrode tab 400 Energy storage device 401 Exterior body 401a Insulating synthetic resin film 401b Metal thin film 401c Insulating film 402 Positive electrode tab 402a Positive tab 402b Negative tab 403 Positive electrode tab 404 Energy storage element 405 Electrolyte 406 Support plate 407 Wiring 500 positive electrode 501 Positive electrode current collector 502 Positive electrode mixture layer 503 Cathode active material 504 Graphene 510 negative electrode 511 Negative electrode current collector 512 Negative electrode mixture layer 513 Negative electrode active material 514 Graphene 515 Negative electrode active material 515a Common area 515b Convex 516 Graphene 517 Negative electrode mixture layer 8000 display device 8001 Case 8002 Display section 8003 Speaker section 8004 Electricity storage device 8100 Lighting equipment 8101 Case 8102 Light source 8103 Energy storage devices 8104 Ceiling 8105 Side wall 8106 Bed 8107 Window 8200 indoor unit 8201 Case 8202 Ventilator 8203 Energy storage devices 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Case 8302 Refrigerator door 8303 Freezer door 8304 Energy storage devices 8500 Mobile Phone 8501 Case 8502 Display section 8503 Operation button 8504 External connection port 8505 Speaker 8506 Microphone 8600 Portable display device 8601 Case 8602 Display section 8603 Operation button 8604 Transmitting and Receiving Equipment

Claims

[Claim 1] A plurality of flexible sheet-like positive electrodes, each having one end fixed to a positive electrode tab; a plurality of flexible sheet-like negative electrodes, each having one end fixed to a negative electrode tab; A storage element having a plurality of flexible sheet-like separators, The positive electrodes and the negative electrodes are alternately stacked with one of the plurality of separators interposed therebetween, The power storage device includes a power storage element that is enclosed in a flexible exterior body.

Images