JP2019145755A - Electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical device capable of improving the life. SOLUTION: An element body 10 in which a pair of internal electrodes are laminated so as to sandwich a separator layer, an exterior sheet 4 covering the element body 10, and an exterior sheet of the exterior sheet so that the element body 10 is immersed in an electrolyte solution. The electrochemical device has seal portions 40 and 42 for sealing the peripheral edge portions and lead terminals 18 and 28 that are drawn out from the seal portions 40 and 42 of the exterior sheet 4. The exterior sheet 4 includes a metal sheet 4A. The maximum thickness of the resin forming the seal portion 40 at the position of the seal portion 40 from which the lead terminal 18 is pulled out is 40 to 140 μm, the thickness of the lead terminals 18 and 28 is 15 to 80 μm, and The thickness of the seal portion 40 from the surface to the metal sheet 4A is 10 μm or more. [Selection diagram] Fig. 2B

Description

  The present invention relates to an electrochemical device preferably used as an electric double layer capacitor (EDLC) or the like.

  For example, as shown in Patent Document 1 below, an ultra-thin electrochemical device is attracting attention in accordance with the use of an IC card or the like. The electrochemical device contains an electrolyte and is composed of a salt (ionic substance) and a solvent. When this electrolytic solution diffuses to the outside, the electrolytic solution is insufficient, and the life of the device may be reduced.

JP 2013-215637 A

  This invention is made | formed in view of such an actual condition, The objective is to provide the electrochemical device which can improve a lifetime.

In order to achieve the above object, an electrochemical device according to the present invention comprises:
An element body in which a pair of internal electrodes are laminated so as to sandwich the separator sheet;
An exterior sheet covering the element body;
A seal portion that seals a peripheral portion of the exterior sheet so that the element body is immersed in an electrolyte solution;
An electrochemical device having a lead terminal drawn out from the seal portion of the exterior sheet,
The exterior sheet includes a metal sheet;
The maximum thickness of the resin constituting the seal portion at the position where the lead terminal is pulled out is 40 to 140 μm,
The lead terminal has a thickness of 15 to 80 μm,
The maximum thickness of the resin constituting the seal portion is larger than the thickness of the lead terminal,
The thickness of the seal part from the surface of the lead terminal to the metal sheet is 10 μm or more at the position of the seal part from which the lead terminal is drawn.

  The inventors of the present invention can prolong the life of the device by maintaining a predetermined relationship between the maximum thickness of the resin that constitutes the seal portion where the terminal is led out and the thickness of the lead terminal. We have found what we can do and have completed the present invention. Each of the exterior sheets includes a metal sheet. Therefore, it is unlikely that the electrolytic solution permeates and diffuses through the exterior sheet itself, and the electrolytic solution is considered to diffuse outside through the seal portion.

  The thickness of the seal portion is particularly thick at the portion where the lead terminal is pulled out. In the electrochemical device of the present invention, the lifetime of the device can be extended by maintaining a predetermined relationship between the thickness of the seal portion where the terminal is pulled out and the thickness of the terminal. In addition, short circuit defects can be prevented.

  Preferably, the resin constituting the seal portion at the position where the lead terminal is drawn out is a polypropylene (PP) resin. By configuring the seal portion with polypropylene resin, the sealing performance is improved, and the ratio of the electrolyte solution diffusing outside through the seal portion can be reduced.

  Preferably, the sealing distance of the seal part along the lead-out direction of the lead terminal is 2 mm or more. By increasing the sealing distance in this way, the sealing performance is improved, and the proportion of the electrolytic solution that diffuses outside through the seal portion can be reduced.

  Preferably, the front end portion of the exterior sheet extends outward from the seal portion along the lead terminal drawing direction, and also serves as a support tab for holding the front end portion of the lead terminal. By providing the support tab, the lead terminal disposed thereon can be effectively reinforced and protected.

  Preferably, an insulating pedestal sheet is interposed between the lead terminal and the support tab. When the insulating pedestal sheet is provided, when the lead terminal and the external connection terminal are ACF (anisotropic conductive film) connection or ACP (anisotropic conductive paste) connection, the metal sheet of the exterior sheet and the lead terminal It is possible to effectively prevent a short circuit failure.

  Preferably, the current collector layer of the internal electrode is formed integrally and continuously with the lead terminal. With this configuration, it is easy to reduce the thickness of the lead terminal.

FIG. 1A is a perspective view of an electric double layer capacitor according to an embodiment of the present invention. FIG. 1B is a perspective view of an electric double layer capacitor according to another embodiment of the present invention. 2A is a schematic cross-sectional view taken along line IIA-IIA in FIG. 1A. 2B is an enlarged cross-sectional view of a main part of the seal portion shown in FIG. 2A. 2C is an enlarged cross-sectional view of a main part taken along line IIC-IIC in FIG. 1A. 2D is an enlarged cross-sectional view of a main part taken along line IID-IID in FIG. 1A. 3A is a cross-sectional view showing an example of a method for manufacturing the electric double layer capacitor shown in FIG. 2A. FIG. 3B is a perspective view showing a step subsequent to FIG. 3A. FIG. 4A is a schematic perspective view showing an example of a manufacturing method corresponding to FIG. 3A. FIG. 4B is a perspective view showing a step subsequent to FIG. 4A. FIG. 5 is a perspective view of an electric double layer capacitor according to another embodiment of the present invention. FIG. 6 is a cross-sectional view of a principal part taken along line VI-VI in FIG. FIG. 7 is a perspective view of an electric double layer capacitor according to still another embodiment of the present invention. FIG. 8 is a cross-sectional view of an essential part taken along line VIII-VIII in FIG. FIG. 9 is a perspective view of an electric double layer capacitor according to still another embodiment of the present invention. FIG. 10 is a graph showing a reliability test result of the electric double layer capacitor according to the example of the present invention. FIG. 11 is a graph showing a reliability test result of an electric double layer capacitor according to another example of the present invention. FIG. 12 is a graph showing a reliability test result of an electric double layer capacitor according to another example of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

First Embodiment As shown in FIG. 1A, an electric double layer capacitor (EDLC) 2 as an electrochemical device according to an embodiment of the present invention has an exterior sheet 4. The exterior sheet 4 has a top sheet 4a and a back sheet 4b formed by folding a single sheet at the peripheral edge 4c. Note that the top sheet 4a and the back sheet 4b are not folded back, and the exterior sheet 4 may be configured by laminating independent upper and lower sheets.

  In the present embodiment, the exterior sheet 4 has a rectangular shape in which the length L0 in the X-axis direction is longer than the length W0 in the Y-axis direction, but is not limited thereto, and is a square or other polygonal shape, Alternatively, it may be circular, elliptical, or other shapes. In this embodiment, the direction in which the topsheet 4a and the backsheet 4b of the exterior sheet 4 overlap is the thickness direction (Z-axis direction), and the directions perpendicular to each other are the X-axis and Y-axis.

  As shown in FIG. 2A, the element body 10 is built in the exterior sheet 4. The element body 10 constitutes an element of an electric double layer capacitor. In the present embodiment, a single capacitor element is accommodated in the exterior sheet 4.

  In the element 10, a pair of first internal electrodes 16 and second internal electrodes 26 are laminated so as to sandwich the separator sheet 11 infiltrated with the electrolyte solution. One of the first internal electrode 16 and the second internal electrode 26 is a positive electrode and the other is a negative electrode, but the configuration is the same. The first internal electrode 16 and the second internal electrode 26 have a first active layer 12 and a second active layer 22 that are laminated so as to be in contact with the opposite surfaces of the separator sheet 11, respectively. The first internal electrode 16 and the second internal electrode 26 include a first current collector layer 14 and a second current collector layer 24 that are stacked so as to be in contact with the active layers 12 and 22, respectively.

  The separator sheet 11 is configured to electrically insulate the internal electrodes 16 and 26 and to allow the electrolyte solution to permeate. For example, the separator sheet 11 includes an electrically insulating porous sheet. The electrically insulating porous sheet is at least selected from the group consisting of monolayers and laminates of films made of polyethylene, polypropylene or polyolefin, stretched films of the above-mentioned resin mixtures, or cellulose, polyester and polypropylene. Examples thereof include a fiber nonwoven fabric made of one kind of constituent material. The thickness of the separator sheet 11 is, for example, about 5 to 50 μm.

  The current collector layers 14 and 24 are not particularly limited as long as they are generally highly conductive materials, but metal materials having low electrical resistance are preferably used. For example, sheets of copper, aluminum, nickel, and the like are used. Used. The thickness of each of the current collector layers 14 and 24 is, for example, about 10 to 100 μm, preferably 80 μm or less, more preferably 60 μm or less, still more preferably 15 to 80 μm, and particularly preferably 15-60 μm. The width of the current collector layers 14 and 24 in the Y-axis direction is preferably 2 to 10 mm, and is preferably smaller than the width of the separator sheet 11 in the Y-axis direction. The current collector layers 14 and 24 are preferably disposed in the center of the separator sheet 11 in the Y-axis direction.

  The active layers 12 and 22 include an active material and a binder, and preferably include a conductive aid. The active layers 12 and 22 are formed by being laminated on the surfaces of the sheets constituting the current collector layers 14 and 24, respectively.

  Examples of the active material include porous bodies having various electron conductivity. For example, activated carbon, natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fiber (MCF), cokes, glassy carbon, organic compound firing And carbon materials such as body. The binder is not particularly limited as long as the above active material, preferably the conductive auxiliary agent, can be fixed to the sheet constituting the current collector layer, and various binders can be used. Examples of the binder include fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR) and water-soluble polymers (carboxymethylcellulose, polyvinyl alcohol, sodium polyacrylate, Dextrin, gluten, etc.) and the like.

  The conductive assistant is a material added to increase the electronic conductivity of the active layers 12 and 22. Examples of the conductive aid include carbon materials such as carbon black and acetylene black, fine metal powders such as copper, nickel, stainless steel, and iron, a mixture of carbon materials and fine metal powders, and conductive oxides such as ITO.

  The thickness of each of the active layers 12 and 22 is preferably about 1 to 100 μm, for example. The active layers 12 and 22 are formed on the surfaces of the current collector layers 14 and 24 on the surfaces of the current collector layers 14 and 24 so as to have an area equal to or smaller than that of the separator sheet 11. The active layers 12 and 22 can be produced by a known method.

  In the present embodiment, the “positive electrode” is an electrode that adsorbs anions in the electrolyte solution when a voltage is applied to the electric double layer capacitor, and the “negative electrode” is a voltage applied to the electric double layer capacitor. In this case, the electrode adsorbs cations in the electrolyte solution. In addition, when recharging after applying a voltage to the electric double layer capacitor once in a specific positive / negative direction, charging is usually performed in the same direction as the first and charged by applying a voltage in the opposite direction. There is little to do.

  The exterior sheet 4 is made of a material that does not allow the electrolyte solution to be described later to pass therethrough. Moreover, the outer peripheral parts of the exterior sheet 4 or the sealing tape 40a shown in FIG. 4A (hereinafter may include 42a) and heat seal are used. It is preferable that they are integrated. The sealing tape 40a is preferably a tape-like tape such as an adhesive tape from the viewpoint of workability. However, not only the tape but also a sealant resin that can be applied may be in any form as long as it can be melted and adhered by heat.

  The exterior sheet 4 is configured to seal the element body 10 and prevent air and moisture from entering the sheet 4. Specifically, the exterior sheet 4 may be a single layer sheet, but as shown in FIG. 2A, the exterior sheet 4 is a multilayer sheet in which the metal sheet 4A is laminated so as to be sandwiched between the inner layer 4B and the outer layer 4C. Is preferred.

  The metal sheet 4A is preferably made of, for example, Al, stainless steel or the like, and the inner layer 4B is made of an electrical insulating material, and is similar to a material such as polypropylene that hardly reacts with the electrolyte solution and can be heat sealed. It is preferable that it is comprised. The outer layer 4C is not particularly limited. For example, polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone (PES), polyethylene naphthalate (PEN), polyimide (PI), fluororesin, polyethylene (PE) It is preferably composed of polybutylene terephthalate (PBT) or the like. The thickness of the exterior sheet 4 is preferably 5 to 150 μm.

In this embodiment, the proof stress of the exterior sheet 4 is 390-1275 N / mm < ² >, Preferably it is 785-980 N / mm < ² > in JISZ2241. The exterior sheet has a hardness of 230 to 480, preferably 280 to 380 in Picker's hardness (Hv) (JIS 2244). From such a viewpoint, the metal sheet 4A of the exterior sheet 4 is made of stainless steel SUS304 (BA), SUS304 (1 / 2H), SUS304 H, SUS301 BA, SUS301 (1 / 2H), SUS301 (3) defined by JIS. / 4H) is preferred.

  The lead terminals 18 and 28 are conductive members serving as current input / output terminals for the current collector layers 14 and 24, and have a rectangular plate shape. In the present embodiment, each of the lead terminals 18 and 28 is formed by a sheet integrated with a conductive sheet that constitutes the current collector layers 14 and 24, respectively, and has the same thickness as the current collector layers 14 and 24. There may be. However, the lead terminals 18 and 28 may be formed of a conductive member different from the current collector layers 14 and 24 and electrically connected to the current collector layers 14 and 24. In that case, the thickness of each lead terminal 18 and 28 can be different from the thickness of the current collector layers 14 and 24, for example, about 10 to 100 μm, preferably 60 μm or less, more preferably 20 to 60 μm. It is.

  As shown in FIG. 2A, the lead terminals 18 and 28 are pulled out along the support tabs 4f1 and 4f2 from the opposite sides of the element body 10 in the X-axis direction, and the inside of the element body 10 has a first seal portion. 40 and the second seal portion 42 are sealed. 4A and 4B, which will be described later, and the inner layer 4B of the exterior sheet 4 shown in FIG. 2A are heated by heat at the time of heat sealing. It is formed integrally. That is, as shown in FIG. 2D, a part of the inner layer (resin) 4B formed on the inner peripheral surface of the exterior sheet 4 is bonded together with the sealing tapes 40a and 42a in the Y-axis direction of the lead terminals 18 and 28. It adheres to both surface and becomes a heat welding part, and the sealing performance in the 1st seal part 40 and the 2nd seal part 42 is improved.

  Further, as shown in FIG. 1A, the third seal portion 44 from which the lead terminals 18 and 28 are not drawn is bent at the folded peripheral edge portion 4c of the exterior sheet 4 and heated by heat sealing to The inner layer 4B is fused and integrated. Similarly, in the fourth seal portion 46 from which the lead terminals 18 and 28 are not drawn, as shown in FIG. 2C, the inner layer 4B of the side peripheral edge portion 4e of the top sheet 4a and the back sheet 4b of the exterior sheet 4 is heat sealed. It is fused and integrated by heating at the time.

  As shown in FIG. 1A, at both ends in the Y-axis direction of the first seal portion 40, one end of the third seal portion 44 and the fourth seal portion 46 is continuously formed, respectively. The second seal portion 42 is continuously formed so as to connect the other ends of the third seal portion 44 and the fourth seal portion 46. Therefore, the inside of the exterior sheet 4 is well sealed against the outside of the exterior sheet 4.

  A space for sealing the element body 10 between the outer sheet 4 and the sealing portions 40, 42, 44, and 46 is filled with an electrolyte solution (not shown), and a part of the space is shown in FIG. 2A. The layers 12 and 22 and the separator sheet 11 are impregnated.

As the electrolyte solution, a solution in which an electrolyte is dissolved in an organic solvent is used. Examples of the electrolyte include quaternary ammonium salts such as tetraethylammonium tetrafluoroborate (TEA ⁺ BF ^{4 −} ) and triethylmonomethylammonium tetrafluoroborate (TEMA ⁺ BF ^{4 −} ), ammonium salts, amine salts, and amidine salts. Is preferably used. In addition, these electrolytes may be used individually by 1 type, and may use 2 or more types together.

  Moreover, a well-known solvent can be used as an organic solvent. Preferred examples of the organic solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethylformamide, sulfolane, acetonitrile, propionitrile, and methoxyacetonitrile. These may be used alone or in combination of two or more at any ratio. Preferably, propylene carbonate is preferable as the organic solvent (solvent).

  As shown in FIG. 2A, the tips of the lead terminals 18 and 28 pass through the first seal portion 40 and the second seal portion 42, respectively, and are drawn out of the first seal portion 40 and the second seal portion 42. The first seal portion 40 and the second seal portion 42 are portions from which the lead terminals 18 and 28 are drawn to the outside, and are particularly required to be sealed as compared with the third seal portion 44 and the fourth seal portion 46. The

  In the EDLC 2 of the present embodiment, the first lead terminal 18 and the second lead terminal 28 of the element body 10 are drawn out to the opposite side along the longitudinal (X-axis direction) direction of the EDLC 2. Therefore, the width of the EDLC 2 in the Y-axis direction can be reduced, the thicknesses of the first seal portion 40 and the second seal portion 42 can be minimized, and the overall thickness of the EDLC 2 can be reduced. . For this reason, size reduction and thickness reduction of EDLC2 are realizable.

  In the EDLC 2 of the present embodiment, for example, the first lead terminal 18 is a positive electrode and the second lead terminal 28 is a negative electrode, which is connected to the element body 10 immersed in an electrolyte solution. In EDLC, the withstand voltage of a single element is determined to be about 2.85 V at maximum, and the elements may be connected in series in order to improve the withstand voltage according to the application. Since the EDLC 2 of the present embodiment is extremely thin and has a sufficient withstand voltage, it can be suitably used as a battery for incorporation in a thin electronic component such as an IC card.

  In particular, in this embodiment, as shown in FIG. 2B, at the position of the seal portions 40, 42 from which the lead terminals 18, 28 are drawn, the seal portions 40, from the surface of the lead terminals 18, 28 to the metal sheet 4A on the surface side. When the first thickness of 42 is Z1, the second thickness of the seal portions 40 and 42 from the back surface of the lead terminals 18 and 28 to the metal sheet 4A on the back surface is Z2, and the thickness of the lead terminals 18 and 28 is Z3. In addition, the following relationship holds.

  That is, the first thickness Z1 and the second thickness Z2 are each 10 μm or more, preferably 15 to 60 μm, more preferably 15 μm or more and 30 μm or less. The first thickness Z1 and the second thickness Z2 are substantially the same in this embodiment, but are not necessarily the same. For example, the first thickness Z1 is configured with a thickness corresponding to the sealing tape 40a and the inner layer 4B shown in FIG. 3A, and the second thickness Z2 is configured with a thickness corresponding to the inner layer 4B shown in FIG. 3A, and vice versa. But you can.

  Moreover, in this embodiment, the thickness Z3 of the lead terminals 18 and 28 is 15-80 micrometers, Preferably it is 15-60 micrometers, More preferably, it is 15-40 micrometers. By reducing the thickness Z3, the entire device can be reduced. However, in order to maintain the strength of the lead terminal, the thickness Z3 of the lead terminal is preferably 20 μm or more, more preferably 30 μm or more.

  In the present embodiment, as shown in FIG. 2D, the maximum thickness Z5 of the resin constituting the seal portions 40 and 42 at the position where the lead terminals 18 and 28 are pulled out is preferably 40 to 140 μm, more preferably 50 to 120 μm. The resin constituting the seal portions 40 and 42 at the position where the lead terminals 18 and 28 are pulled out is the resin constituting the sealing tape 40a shown in FIG. 3A and the resin constituting the inner layer 4B of the exterior sheet 4. Composed.

  The maximum thickness Z5 of the resin constituting the seal portions 40, 42 at the position where the lead terminals 18, 28 are pulled out is larger than the thickness Z3 of the lead terminals 18, 28, and the first thickness Z1 and the second thickness Z2 are: Each is determined to be 10 μm or more.

  In the present embodiment, the thicknesses Z1 and Z2 of the seal portions 40 and 42 where the terminals 18 and 28 are led out, the thickness Z3 of the terminals, and the maximum thickness of the resin constituting the seal portion are maintained in a predetermined relationship. As a result, the life of the EDLC 2 can be extended. The top sheet 4a and the back sheet 4b each include a metal sheet 4A. Therefore, it is unlikely that the electrolytic solution permeates and diffuses through the top sheet 4 a and the back sheet 4 b itself, and the electrolytic solution is thought to diffuse outside through the seal portions 40 and 42.

  The thickness of the seal portion is particularly thick at the portion where the lead terminals 18 and 28 are pulled out. In the present embodiment, the thicknesses Z1 and Z2 of the seal portions 40 and 42 where the terminals 18 and 28 are drawn, the thickness Z3 of the terminals, and the maximum thickness of the resin constituting the seal portion are in the predetermined relationship described above. By keeping it, the life of the EDLC 2 can be extended. In addition, short circuit defects can be prevented.

  As shown in FIG. 2C, the thickness Z4 of the seal portion 46 from the metal sheet 4A on the front surface side to the metal sheet 4A on the back surface side at the position of the seal portion 46 where the lead terminal is not pulled out (same for the seal portion 44), Preferably it is 50 micrometers or less, More preferably, it is 40 micrometers or less. With this configuration, it is possible to suppress the diffusion of the electrolytic solution from the seal portion 46 from which the lead terminal is not pulled out, and the life of the EDLC 2 can be further improved. The thickness of the seal portion 46 is preferably 10 μm or more from the viewpoint of improving the seal performance.

  Moreover, in this embodiment, resin which comprises the seal parts 40 and 42 in the position where the lead terminals 18 and 28 are pulled out includes the resin constituting the sealing tape 40a shown in FIG. 3A and the inner layer 4B of the exterior sheet 4. It is comprised with resin to comprise, Preferably, it is a polypropylene (PP) resin. By configuring the seal portion with polypropylene resin, the sealing performance is improved, and the ratio of the electrolyte solution diffusing outside through the seal portion can be reduced.

  The resin constituting the seal portions 40 and 42 at the positions where the lead terminals 18 and 28 are pulled out may be a resin other than polypropylene, for example, polyethylene (PE), ionomer resin, acid-modified polyolefin, polymethylpentene. Etc. are exemplified.

  In this embodiment, as shown in FIG. 2A, the sealing distance X1 of the seal portion 40 or 42 along the lead-out direction of the lead terminal 18 or 28 is preferably 2 mm or more, and more preferably 2.5 to 4 mm. is there. By increasing the sealing distance in this way, the sealing performance is improved, and the proportion of the electrolytic solution that diffuses outside through the seal portion can be reduced. The sealing distance X1 of the seal portion 40 or 42 is the length of the seal portion 40 or 42 in the X-axis direction along the lead-out direction of the lead terminal 18 or 28, and the resin constituting the seal portion 40 or 42. Is the length in the X-axis direction in which the lead terminal 18 or 28 is covered. Further, the sealing distance X1 of the seal portion 40 or 42 corresponds to the length in the X-axis direction in which the heat-sealing jig 50 shown in FIG.

  In the present embodiment, as shown in FIG. 2B, the front end portions 4d3 and 4d4 of the back sheet 4b are equal to or more than the front end portions of the lead terminals 18 and 28 along the lead-out direction (X-axis direction) of the lead terminals 18 and 28. It is located outside and also serves as support tabs 4f1 and 4f2. The front end portion of the surface sheet 4 a is positioned inside the front end portions of the lead terminals 18 and 28 along the lead-out direction of the lead terminals 18 and 28. By providing the support tabs 4f1 and 4f2, the lead terminals 18 and 28 disposed thereon can be effectively protected.

  As shown in FIG. 2B, an insulating base sheet 60 is preferably interposed between the lead terminals 18 and 28 and the support tabs 4f1 and 4f2. The insulating pedestal sheet 60 may be composed of a single layer, but may be composed of two or three or more layers. In any case, the insulating pedestal sheet 60 is not particularly limited as long as it is an insulating material such as a plastic film or synthetic paper. However, a predetermined thickness is maintained even by applied heat and pressure applied, resulting in insulation. Any material can be used as long as it is maintained.

  In order to use the insulating pedestal sheet 60 industrially, polyethylene (PE), polypropylene (PP) and the like are inexpensive and easy to handle, but preferably have heat resistance. Polyethylene terephthalate (PET), polymethyl methacryl (PMMA), polyvinyl alcohol (PVA), polycarbonate, polyimide, polyamide, polybutylene terephthalate, etc. may be used. Further, even with PE and PP, stretched polyethylene (OPE) and stretched polypropylene (OPP) are stretched in the vertical and horizontal directions during production and have excellent crystal orientation, and are used as sealing materials. CPP (Extruded, Casting PP) This is preferable because the heat resistance is improved. The insulating pedestal sheet 60 may be a thermosetting resin such as polyurethane or epoxy resin. Or the film which consists of these composite materials may be sufficient.

  In the present embodiment, the insulating pedestal sheet 60 is preferably composed of, for example, a resin film having a three-layer structure, and a high-melting point resin such as PET having excellent heat resistance is disposed at the center in the laminating direction, and its surface It is preferable that a low melting point resin such as PP is laminated on the back surface. The high melting point resin such as PET does not melt even when ACF (Anisotropic Conductive Film) connection or ACP (Anisotropic Conductive Paste) connection, which will be described later, maintains the thickness, and PP melts to the back sheet. It is heat-sealed to the inner layer 4B of 4b or the back surface of the lead terminal 18 or 28.

  The insulating pedestal sheet 60 is joined and integrated with the inner layer 4B of the support tabs 4f1 and 4f2 formed at the front end in the X-axis direction of the back sheet 4b by heat fusion or adhesion. The thickness Z6 from the surface of the insulating pedestal sheet 60 (the back surface of the lead terminal 18 or 28) to the metal sheet 4A of the back surface sheet 4b is equal to or greater than the second thickness Z2 of the seal portion 40 or 42 described above. It is preferable. The reason is to facilitate ACF (Anisotropic Conductive Film) connection or ACP (Anisotropic Conductive Paste) connection in the subsequent process and to provide insulation between the terminals after connection.

  In the present embodiment, the insulating pedestal sheet 60 is provided between the lead terminals 18 and 28 and the support tabs 4f1 and 4f2, so that the lead terminals 18 and 28 and the external connection terminals (not shown) can be connected to an ACF (different from each other). When connecting (conductive film) or ACP (anisotropic conductive paste), it is possible to effectively prevent a short circuit failure between the metal sheet 4A of the exterior sheet 4 and the lead terminals 18 and 28.

  Next, an example of the manufacturing method of EDLC2 of this embodiment is demonstrated using FIG. 4A-FIG. 5B.

  As shown in FIGS. 3A and 4A, first, the element body 10 is manufactured. In order to manufacture the element body 10, one electrode 16 is prepared, and a tape 40 a is attached to a boundary portion between the electrode 16 and the lead terminal 18. Further, the other electrode 26 is prepared, and a tape 42 a is attached to the boundary portion between the electrode 26 and the lead terminal 28. Then, the separator 11 is disposed between the electrode 16 and the electrode 18.

  The lead terminals 18 and 28 are respectively provided with sealing tapes 40a and 42a on one side surface or both sides of the terminals 18 and 28 at the X-axis direction positions to be the first seal portion 40 and the second seal portion 42 described above. Glued. The widths of the tapes 40a and 42a in the Y-axis direction are longer than the widths of the lead terminals 18 and 28 in the Y-axis direction.

  Next, the exterior sheet 4 is folded back at the peripheral edge 4 c so as to cover the entire element body 10, and the element body 10 is covered with the top sheet 4 a and the back sheet 4 b of the sheet 4. The exterior sheet 4 is formed long in advance in the Y-axis direction. The width in the X-axis direction of the topsheet 4a of the exterior sheet 4 is adjusted so that the tip portions 4d1 and 4d2 of the topsheet 4a in the X-axis direction are positioned inside the tapes 40a and 42a in the X-axis direction, respectively. In addition, the top sheet 4a and the back sheet 4b may not be folded back, and the exterior sheet 4 may be configured by bonding independent upper and lower sheets.

  Next, as shown in FIGS. 3B and 4B, in order to form the first seal portion 40 and the second seal portion 42, the tapes 40a and 42a are sandwiched between the top sheet 4a and the back sheet 4b. The sheets 4a and 4b are heated and pressed by the heat fusion jig 50 from the outside in the Z-axis direction. At that time, the sealing tapes 40a and 42a are in close contact with and integrated with the inner layer 4B of the exterior sheet 4 as an adhesive resin that flows by pressurization and heating, and become the seal portions 40 and 42 after solidification. When the tapes 40a and 42a are fused, it is preferable that the resin constituting the tapes 40a and 42a protrudes and covers the exposed surface of the metal sheet 4A located at the tip portions 4d1 and 4d2 in the X-axis direction of the topsheet 4a. This is to prevent short-circuit defects.

  Before and after that, the folded peripheral edge portion 4 c of the exterior sheet 4 is pressurized and heated to form the third seal portion 44. Next, an electrolyte solution is injected from the open end 52 of the exterior sheet 4 where the fourth seal portion 46 is not formed, and then the last fourth seal portion 46 is repaired to form the third seal portion 44. It is formed by heat sealing using a jig similar to the tool. Thereafter, the exterior sheet 4 is cut along the cutting line 54 outside the fourth seal portion 46, and the excess exterior sheet 4 'is removed, whereby the EDLC 2 of the present embodiment is obtained.

  In the present embodiment, the first seal portion 40 is formed by sealing the sealing tape 40 a adhered to the first lead terminal 18 with the inner layer 4 </ b> B of the exterior sheet 4 (heat pressing). Similarly, the second seal portion 42 is formed by thermally sealing (thermocompression bonding) the sealing tape 42 a adhered to the second lead terminal 28 with the inner layer 4 </ b> B of the exterior sheet 4.

  In the present embodiment, for example, the maximum thickness of the EDLC 2 can be 1 mm or less, preferably 0.9 mm or less, and more preferably 0.5 mm or less.

  Note that the insulating pedestal sheet 60 shown in FIGS. 3A and 3B may be bonded to a predetermined position of the exterior sheet 4 before the element body 10 is sealed inside the exterior sheet 4, or the lead It may be provided between the terminals 18 and 28 and the support tabs 4f1 and 4f2.

Second Embodiment As shown in FIG. 1B, the EDLC 2a of the present embodiment is the same as the EDLC 2 of the first embodiment except that the support tabs 4f1 and 4f2 shown in FIG. 1A are not provided. In the drawings, common members are denoted by common reference numerals, and description of common portions is omitted.

  In the present embodiment, the top sheet 4a and the back sheet 4b have substantially the same length in the X-axis direction, and may be formed by folding the same exterior sheet 4 or separate sheets. It may be configured.

Third Embodiment As shown in FIGS. 5 and 6, in the EDLC 2 b of the present embodiment, two element bodies 10 a and 10 b are built in the exterior sheet 4 side by side in the Y-axis direction. The other parts are the same as those in the first embodiment, and therefore, in the drawings, common members are denoted by common reference numerals, and in the following description, description of common parts is omitted, and different parts are described in detail.

  In the present embodiment, the exterior sheet 4 includes a top sheet 4a1 and a back sheet 4b1, and has a size approximately twice as large in the Y-axis direction as compared to the exterior sheet 4 illustrated in FIG. 1A. As shown in FIG. 6, two element bodies 10 a and 10 b are built in the exterior sheet 4, and each of the element bodies 10 a and 10 b has the same structure as the element body 10 of the first embodiment. have.

  In the present embodiment, the second lead terminals 28 and 28 of the element bodies 10a and 10b are formed separately, but the first lead terminals 18a of the element bodies 10a and 10b are integrally formed with the connecting portion 18b. And they are continuous with each other. That is, as shown in FIG. 5, the element bodies 10a and 10b are connected in series via the first lead terminal 18a and the connecting portion 18b.

  A third seal portion 44a is formed along the X-axis direction at the center of the exterior sheet 4 in the Y-axis direction, and the flow of the electrolyte solution is blocked between the element bodies 10a and 10b. Yes. The space in which the element main body 10a is accommodated is sealed by the first seal portion 40, the second seal portion 42, the third seal portion 44a, and the fourth seal portion 46a that are continuously formed on the exterior sheet 4, and the electrolyte solution is Stored. Similarly, the space in which the element body 10b is accommodated is sealed by the first seal portion 40, the second seal portion 42, the third seal portion 44a, and the fourth seal portion 46b that are continuously formed on the exterior sheet 4. The electrolyte solution is stored.

  In this embodiment, the lead terminals drawn to the same side in the X-axis direction are connected in series or in parallel with connecting pieces or the like, so that the battery capacity can be increased or the withstand voltage can be increased. Also in this embodiment, since the support tabs 4f1 and 4f2 as shown in FIG. 1A are provided, it is possible to effectively prevent the lead terminals 28 and 18a and the connecting portion 18b from being bent.

  In this embodiment, as shown in FIG. 2B, in each of the seal portions 40 and 42, the thicknesses (Z1, Z2) of the seal portions 40, 42 where the terminals 18, 28 are led out, and the terminal thickness Z3, By maintaining the maximum thickness Z5 of the resin constituting the seal portions 40 and 42 in a predetermined relationship, the life of the EDLC 2 can be extended. Other structures and operational effects of this embodiment are the same as those of the above-described embodiment.

Fourth Embodiment As shown in FIGS. 7 and 8, in the EDLC 2c of the present embodiment, the leading end portions 4d1 and 4d2 of the surface sheet 4a of the exterior sheet 4 are leads at positions where the respective lead terminals 18 and 28 are pulled out. The terminals 18 and 28 are opened outward in a direction away from the lead terminals 18 and 28 along the X-axis which is a drawing direction of the terminals 18 and 28. Other than that, EDLC2c of this embodiment is the same as EDLC2 of 1st Embodiment. In the drawings, common members are denoted by common reference numerals, and description of common portions is omitted.

  As shown in FIG. 8, in this embodiment, even if the tip of the metal sheet 4A is exposed at the tip portions 4d1 and 4d2 of the surface sheet 4a, the lead terminals 18 and 28 and the exposed tip 4Aa of the metal sheet 4A The tip clearance distance Z7 can be increased. Therefore, a short circuit failure between the lead terminals 18 and 28 and the exposed tip 4Aa of the metal sheet 4A can be effectively prevented. The front end portions 4d1 and 4d2 of the surface sheet 4a are positioned on the inner side in the X-axis direction from the front end portions of the lead terminals 18 and 28 along the lead-out direction of the lead terminals 18 and 28. For this reason, the operation | work which connects the lead terminals 18 and 28 with an external circuit is also easy.

  That is, in the present embodiment, it is compared with the minimum gap distance Z0 (corresponding to Z1 or Z2 in the first embodiment) between the lead terminals 18 and 28 and the metal sheet 4A at the position corresponding to the seal portions 40 and 42. Thus, the tip clearance distance Z7 between the lead terminals 18 and 28 protruding outward in the X-axis direction from the seal portion 40 and the exposed tip 4Aa of the metal sheet 4A is large. With this configuration, it is possible to effectively prevent a short circuit failure.

  In the present embodiment, the opening angle θ of the leading end portions 4d1 and 4d2 of the exterior sheet 4 with respect to the lead terminals 18 and 28 is preferably 5 degrees or more and 70 degrees or less, and more preferably 5 to 60 degrees. With such a configuration, it is possible to more effectively prevent a short circuit failure, suppress a crack, and improve the repeated bending resistance of the EDLC 2c.

  In the present embodiment, at the positions where the lead terminals 18 and 28 are pulled out, the leading end portions 4d1 and 4d2 of the surface sheet 4a are along the lead-out direction of the lead terminals 18 and 28 as shown in FIG. The length L1 of the opening portions 4d11 and 4d22 that are open outward in the direction away from the distance is preferably 100 μm or more and 2000 μm or less. With this configuration, it is possible to effectively prevent a short circuit failure.

  The open portions 4d11 and 4d22 are a distance larger than the minimum gap distance Z0 between the lead terminals 18 and 28 and the metal sheet 4A at the position corresponding to the seal portions 40 and 42, and the metal sheet 4A is in the Z-axis direction. It is a front-end | tip part of the surface sheet 4a (exterior sheet | seat 4) which leaves | separates. The open portions 4d11, 4d22 may be linear or curved in the cross section shown in FIG.

  The length L1 of the opening portions 4d11 and 4d22 is the length along the surface of the sheet 4a. In the case of a curve, the length L1 is the length when the straight portion is stretched. When the opening portions 4d11 and 4d22 are curved, the opening angle θ is determined by the leading end portions 4d1 and 4d2 of the sheet 4a having the leading end clearance distance Z7 and the starting point positions of the opening portions 4d11 and 4d22 having the minimum clearance distance Z0. Can be defined as an angle between the virtual straight line and the lead-out direction of the lead terminals 18 and 28.

  In the present embodiment, the minimum gap distance Z0 is preferably 15 μm or more and 60 μm or less, more preferably 15 μm or more and 30 μm or less. With this configuration, the device can be thinned while the inside of the device is secured. In addition, the life can be improved.

  Further, the tip clearance distance Z7 is preferably 24 μm or more and 1748 μm or less, more preferably 24 μm or more and 485 μm or less. With this configuration, it is possible to effectively prevent a short circuit failure.

  In particular, in the EDLC 2c according to the present embodiment, it is not necessary to control the amount of protrusion of the seal portions 40 and 42 from the front end portions 4d1 and 4d2 of the topsheet 4a during manufacture. Therefore, it is easy to manufacture the EDLC 2c according to this embodiment. Note that the seal portions 40 and 42 may protrude somewhat from the front end portions 4d1 and 4d2 of the topsheet 4a.

  The means for forming the opening portions 4d11 and 4d22 at the front end portions 4d1 and 4d2 of the surface sheet 4a constituting the exterior sheet 4 is not limited to the method using the opening portion forming jig. For example, after forming the seal portions 40 and 42 by a normal method, the front end portions 4d1 and 4d2 of the exterior sheet 4 may be processed so as to open outward.

  In the present embodiment, a part of the adhesive resin constituting the seal portions 40 and 42 is at least one of the gaps between the front end portions 4d1 and 4d2 of the surface sheet 4a and the lead terminals 18 and 28 shown in FIG. You may spread to fill the part. Alternatively, an adhesive or resin different from the adhesive resin constituting the seal portions 40 and 42 is at least a part of the gap between the front end portions 4d1 and 4d2 of the surface sheet 4a and the lead terminals 18 and 28 shown in FIG. May be filled.

  Also in this embodiment, as shown in FIG. 2B, in each of the seal portions 40 and 42, the thicknesses (Z1, Z2) of the seal portions 40, 42 where the terminals 18, 28 are led out, and the terminal thickness Z3 By maintaining the maximum thickness Z5 of the resin constituting the seal portions 40 and 42 in a predetermined relationship, the life of the EDLC 2 can be extended. Other structures and operational effects of this embodiment are the same as those of the above-described embodiment.

Fifth Embodiment In the EDLC of the above-described embodiment, the first lead terminal 18 and the second lead terminal 28 of the element body 10 are pulled out to the opposite side along the longitudinal (X-axis direction) direction of the EDLCs 2 and 2a to 2c. However, as shown in FIG. 9, in the EDLC 2d of the present embodiment, all of the first to third lead terminals 18, 28, 38 are drawn out to only one side in the X-axis direction. The third lead terminal 38 is drawn as a single terminal in FIG. 9, but actually, two terminals are stacked and drawn. Further, the two terminals constituting the third lead terminal 38 may be arranged so as to be displaced in the Y-axis direction.

  In the exterior sheet 4 of the EDLC 2d of the present embodiment, a single sheet 4 is bent at the second seal portion 42 to form a top sheet 4a2 and a back sheet 4b2. In the present embodiment, the first seal portion 40 is a portion that seals the peripheral portion of the exterior sheet 4 from which the lead terminals 18, 28, and 38 are pulled out in the X-axis direction. Further, the sheet folding portion opposite to the peripheral edge portion of the exterior sheet 4 from which the lead terminals 18, 28, and 38 are drawn out in the X-axis direction becomes the second seal portion 42. Furthermore, let the part which has sealed the both-side peripheral part of the exterior sheet | seat 4 located in the mutually opposite side of a Y-axis direction be the 3rd seal part 44 and the 4th seal part 46. FIG.

  In the present embodiment, the single or plural sealing tapes 40a for forming the first seal portion 40 are partially heat-sealed to the inner surface of the exterior sheet 4 in the same manner as in the above-described embodiment. After that, the first seal portion 40 is formed. Since other configurations and operational effects of the present embodiment are the same as those of the first to fourth embodiments, common members are denoted by common reference numerals in the drawings, and description of common portions is omitted.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, the sealing tapes 40a and 42a shown in FIG. 4A and the like are not limited to a single layer resin tape, and may be a multilayer structure resin tape. For example, a tape having a three-layer structure in which a high melting point resin (for example, PP) layer is provided at the center in the stacking direction and a low melting point resin (for example, PP) layer is provided on both sides thereof may be used. By using the tapes 40a and 42a having such a configuration, the sealing performance at the seal portions 40 and 42 is further improved, and even if burrs are generated on the lead terminals 18 and 28, the burrs are formed on the high melting point resin layer. This prevents punching. Therefore, it is possible to prevent a short circuit failure at the seal portions 40 and 42 and to effectively prevent breakage of the lead terminal at the time of thermocompression bonding.

  In addition, the laminate type electrochemical device to which the present invention is applied is not limited to EDLC but can be applied to lithium batteries, lithium ion capacitors, and the like. In addition, the specific shape and structure of the electrochemical device are not limited to the illustrated example.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
A sample of EDLC2 shown in FIG. 1A was produced. The material of the metal sheet 4A in the exterior sheet 4 in the EDLC 2 was SUS304. The thickness Z3 of the lead terminals 18 and 28 shown in FIG. 2B is 30 μm, the thickness Z1 (same for Z2) of the seal portions 40 and 42 is 10 μm, and the maximum resin thickness Z5 shown in FIG. 2D is 50 μm. It was. The manufacturing error of the thickness Z3 is within ± 2 μm, the manufacturing error of the thickness Z1 (the same applies to Z2) is ± 2 μm or less, and the manufacturing error of the thickness Z5 is ± 5 μm or less. Moreover, the thickness Z4 of the seal portion 46 shown in FIG. 2C was 30 μm.

  30 samples of the same were prepared and stored in an environment of 85 ° C., and the reliability (life) was compared from the impedance change. As for reliability, the time when the sample is stored is set to 0 hour, the impedance of the sample from that time is continuously measured, the average of the impedance is obtained for 30 samples, and the graphed results are shown in FIG.

  In addition, reliability is evaluated from the graphed results, and the results are shown in Table 1. In FIG. 10 and Table 1, Real 1 shows the data of Example 1. In Table 1, the reliability test results indicate that NG does not satisfy the reliability standard, G satisfies the reliability standard, and VG shows a result even better than G. The reliability criterion was determined as G and VG when the increase rate of impedance was 2.67 times or less after 1250 hours from the start of storage of the sample and not exceeding 20 ohms.

  In addition, Table 1 shows the results of examining whether or not there is a short circuit between the metal sheet of the exterior sheet and the lead terminal for the same 30 samples. In Table 1, the number of shorts indicates the number of samples in which a short circuit was observed among 30 samples.

Examples 2-6 and Comparative Examples 1-2
As shown in Table 1, a sample of EDLC2 was manufactured in the same manner as in Example 1 except that the maximum resin thickness Z5 shown in FIG. 2D and the thickness Z1 (Z2) of the seal portions 40 and 42 were changed. The same evaluation as in Example 1 was performed. The results are shown in FIG. In FIG. 10 and Table 1, Examples 2 to 6 show data of Examples 2 to 6, and ratios 1 and 2 show data of Comparative Examples 1 and 2.

Examples 10-16 and Comparative Examples 3-4
As shown in Table 2, except that the thickness Z3 of the lead terminals 18 and 28 shown in FIG. 2B, the maximum resin thickness Z5 shown in FIG. 2D, and the thickness Z1 (Z2) of the seal portions 40 and 42 were changed. A sample of EDLC2 was produced in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The results are shown in FIG. In FIG. 11 and Table 2, real 10 to real 16 show data of Examples 10 to 16, and ratio 3 and ratio 4 show data of Comparative Example 3 and Comparative Example 4. However, in FIG. 11, the data of the comparative example 3 shown in Table 2 are not illustrated.

Examples 20-22 and Comparative Examples 5-6
As shown in Table 3, except that the thickness Z3 of the lead terminals 18 and 28 shown in FIG. 2B, the maximum resin thickness Z5 shown in FIG. 2D, and the thickness Z1 (Z2) of the seal portions 40 and 42 were changed. A sample of EDLC2 was produced in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The results are shown in FIG. In FIG. 12 and Table 3, real 20 to real 22 show the data of Example 20 to Example 22, and ratio 5 and ratio 6 show the data of Comparative Example 5 and Comparative Example 6.

As shown in Evaluation Tables 1 to 3 and FIGS. 10 to 12, the resin maximum thickness Z5 is 40 to 140 μm, the lead terminal thickness Z3 is 15 to 80 μm, and the resin maximum thickness Z5 is the thickness of the lead terminal Z3. It was confirmed that when the seal portion thickness Z1 (Z2) was 10 μm or more, the reliability test result was good and the number of short circuits (the number of short circuits) was small. In particular, when the maximum resin thickness Z5 is preferably 50 to 140 [mu] m, more preferably 50 to 100 [mu] m, it has been confirmed that there are few short circuits and the reliability is improved.

2, 2a, 2b, 2c, 2d ... Electric double layer capacitor (EDLC)
4 ... exterior sheet 4a, 4a1 ... top sheet 4b, 4b1 ... back sheet 4c ... folding edge 4d1-4d4 ... tip 4d11, 4d22 ... open part 4e ... side edge 4f1, 4f2 ... support tab 4A ... metal sheet 4Aa ... Exposed tip 4B ... Inner layer 4C ... Outer layer 10 ... Element body 11 ... Separator sheet 12 ... First active layer 14 ... First current collector layer 16 ... First internal electrode 18 ... First lead terminal 22 ... Second active layer 24 ... Second current collector layer 26 ... Second internal electrode 28 ... Second lead terminal 40 ... First seal portion 42 ... Second seal portion 44 ... Third seal portion 46 ... Fourth seal portion 50 ... Thermal fusion treatment Ingredient 60 ... Insulation base sheet

Claims (7)

An element body in which a pair of internal electrodes are laminated so as to sandwich the separator sheet;
An exterior sheet covering the element body;
A seal portion that seals a peripheral portion of the exterior sheet so that the element body is immersed in an electrolyte solution;
An electrochemical device having a lead terminal drawn out from the seal portion of the exterior sheet,
The exterior sheet includes a metal sheet;
The maximum thickness of the resin constituting the seal portion at the position where the lead terminal is pulled out is 40 to 140 μm,
The lead terminal has a thickness of 15 to 80 μm,
The maximum thickness of the resin constituting the seal portion is larger than the thickness of the lead terminal,
An electrochemical device characterized in that, at the position of the seal portion from which the lead terminal is drawn, the thickness of the seal portion from the surface of the lead terminal to the metal sheet is 10 μm or more.   The electrochemical device according to claim 1, wherein a resin constituting the seal portion at a position where the lead terminal is pulled out is a polypropylene resin.   The electrochemical device according to claim 1, wherein the solvent of the electrolyte solution is a carbonate-based solvent.   The electrochemical device according to any one of claims 1 to 3, wherein a sealing distance of the seal portion along the lead-out direction of the lead terminal is 2 mm or more.   The front end of the exterior sheet extends outside the seal portion along the lead-out direction of the lead terminal, and also serves as a support tab that holds the front end of the lead terminal. The electrochemical device according to any one of the above.   The electrochemical device according to claim 5, wherein an insulating pedestal sheet is interposed between the lead terminal and the support tab.   The electrochemical device according to claim 1, wherein the current collector layer of the internal electrode is formed integrally and continuously with the lead terminal.

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