JP2015079907A - Electrochemical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical device which can be made thinner, and which is low in capacitance and superior in resistance to bending.SOLUTION: An electrochemical device comprises: a device main body 10 arranged by laminating a pair of a first internal electrode and a second internal electrode together with a separator layer sandwiched therebetween; a package sheet 4 covering the device main body; a first lead terminal 18 led to outside the package sheet 4; and a second lead terminal 28 led to outside the package sheet 4. The first lead terminal 18 and the second lead terminal 28 are led from position opposite to each other to outside seal parts 40 and 42. In a position corresponding to the seal parts 40 and 42, the first lead terminal 18 and the second lead terminal 28 have thinner regions 60. In the regions 60, the first lead terminal 18 and the second lead terminal 28 are smaller in thickness than lead end portions thereof. At least a part of each thinner region 60 protrudes from peripheral edges 4d1 and 4d2 of the package sheet 4 outwardly; and the parts of the thinner regions 60 so protruding outwardly are also covered by the respective seal parts 40 and 42.

Description

  The present invention relates to an electrochemical device that is preferably used as an electric double layer capacitor (EDLC) or the like, and more particularly to an electrochemical device that can be thinned and has excellent bending resistance.

  Recently, the spread of IC cards equipped with IC chips is remarkable. In particular, there are IC cards that can exchange money, and they are used for various purposes such as employee ID cards and membership cards.

  With the increase in functionality, it has been studied to use a primary battery having a capacity as high as possible as a conventional storage battery for an IC card. However, with a primary battery, the card must be replaced when the storage capacity is exhausted. Therefore, development of an IC card using a rechargeable secondary battery is in progress.

  The characteristics of a secondary battery for an IC card are required to be thin below the card thickness, to be small enough to be embedded in the card, and to be flexible in response to bending. On the other hand, development of a system that does not have a power storage system inside an IC card and performs communication using electric power obtained by specific contact through a card reader is also progressing.

  However, since the power obtained by non-contact charging is very small, a highly functional product cannot obtain sufficient power. Therefore, there is a need for a secondary battery that has little charge loss, can be charged in a short time, and can be charged to the operating voltage of the circuit.

  In the conventional electrochemical device, since the storage capacity is large, a sufficient voltage cannot be sent by the card reader. Therefore, an EDLC having a low capacity and an appropriate resistance is required. In addition, the card needs to be flexible, and the conventional EDLC shape has a large thickness difference between the seal portion at the lead terminal take-out portion and the seal portion of the exterior body sheet alone, and is likely to break. It has a problem. Furthermore, if the aluminum current collector foil is made too thin in order to reduce the thickness of the EDLC, the current collector foil may be wrinkled when the EDLC is bent.

JP 2006-49670 A

  The present invention has been made in view of such a situation, and an object thereof is to provide an electrochemical device that has a low capacity, can be reduced in thickness, and has excellent bending resistance.

In order to achieve the above object, an electrochemical device according to the present invention comprises:
An element body in which a pair of first internal electrodes and second internal electrodes are stacked so as to sandwich the separator layer;
An exterior sheet covering the element body;
A first lead terminal electrically connected to the first internal electrode and drawn out of the exterior sheet;
A second lead terminal electrically connected to the second internal electrode and drawn out of the exterior sheet,
The outer periphery of the outer sheet is sealed with a seal so that the element body is immersed in the electrolyte solution,
The first lead terminal and the second lead terminal have substantially the same width as the width of the first internal electrode and the second internal electrode, respectively;
At the position corresponding to the seal portion, the first lead terminal and the second lead terminal have a thin region having a thickness smaller than the lead tip portion,
At least a part of the thin region protrudes outward from the peripheral edge of the exterior sheet, and the thin region protruding outward is also covered with the seal portion.

  In the present invention, the first lead terminal and the second lead terminal have a thin area that is thinner than the lead tip portion at a position corresponding to the seal portion. It is possible to effectively prevent the thickness of the portion from increasing suddenly. Therefore, it contributes to thinning of the device, suppresses an abrupt thickness change (step) of the seal portion, and improves bending resistance.

  Further, the present invention is not necessarily limited, but the lead terminal may come into contact with the exposed end of the metal sheet at the peripheral edge of the exterior sheet even when the metal is exposed at the end of the exterior sheet. There is also an additional effect that can reliably prevent a short circuit.

  Preferably, the first lead terminal and the second lead terminal are drawn out of the seal portion at positions opposite to each other along the longitudinal direction of the first internal electrode and the second internal electrode. . Therefore, compared to the structure in which the first lead terminal and the second lead terminal are drawn out on the same side, it is easy to reduce the electrode area per unit cell, and the electrochemical capacity is relatively low. A device can be realized, and the bending resistance is excellent.

Preferably, the first internal electrode has a first active layer in contact with the separator layer, and a first current collector layer in contact with the first active layer,
The second internal electrode has a second active layer in contact with the separator layer, and a second current collector layer in contact with the second active layer,
The first lead terminal is a part of the first current collector layer obtained by extending the first current collector layer;
The second lead terminal is a part of the second current collector layer obtained by extending the second current collector layer.

  Since the lead terminal is a part of the current collector layer, there is no need to connect the lead terminal and the current collector layer, and the manufacturing process can be shortened and the manufacturing cost can be reduced. It can be a chemical device.

  Preferably, the thin region is formed by press molding corresponding portions of the first lead terminal and the second lead terminal. When the lead terminal is formed integrally with the current collector layer, the porous etching surface formed on the surface of the current collector layer is flattened by pressing by forming a thin region by press molding. . Therefore, when the flattened surface is covered with the seal portion, the sealing performance is improved, and the moisture resistance of the device is also improved.

  The thin region may be formed by forming a recess or a groove on the surface of the corresponding part of the first lead terminal and the second lead terminal.

  Preferably, a part of the seal portion is formed by heat sealing a sealing tape that sandwiches the first lead terminal and the second lead terminal between the peripheral portions of the exterior sheet. Is done. Preferably, the width of the seal portion corresponding to the length of the sealing tape is 1 mm or more. The wider the seal portion is, the more effective as a countermeasure against the electrolytic solution, and the bending resistance of the device is improved.

  Furthermore, in the present invention, at least a part of the thin region protrudes outward from the peripheral edge of the exterior sheet, and the thin region protruding outward is also covered with the seal portion. For this reason, the device thickness in the peripheral part of an exterior sheet can be minimized. In addition, even when the metal is exposed at the end of the exterior sheet, there is no possibility that the lead terminal comes into contact with the exposed end of the metal sheet at the peripheral edge of the exterior sheet, thereby reliably preventing a short circuit.

  Preferably, there is further provided a support sheet for preventing the first lead terminal and the second lead terminal pulled out from the seal portion from being bent. By comprising in this way, the bending of the 1st lead terminal and the 2nd lead terminal each pulled out from the 1st seal part and the 2nd seal part can be prevented effectively.

  Preferably, the support sheet is formed by extending a part of a peripheral edge portion of the exterior sheet positioned at the seal portion to the outside. By comprising in this way, formation of a support sheet becomes easy.

  Preferably, the protruding length of the support sheet is longer than the protruding lengths of the first lead terminal and the second lead terminal. By comprising in this way, the bending of the 1st lead terminal and 2nd lead terminal withdraw | derived from the 1st seal | sticker part can be prevented effectively.

1A is a perspective view of an electric double layer capacitor according to an embodiment of the present invention, and 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 FIG. 1A. FIG. 3 is a schematic perspective view showing an example of a manufacturing method of the electric double layer capacitor shown in FIG. FIG. 4A is a perspective view showing a continuation process of FIG. 4B is a schematic cross-sectional view taken along line IVB-IVB in FIG. 4A. 4C is an enlarged perspective view of a main part of FIG. 4A. FIG. 4D is an enlarged perspective view of a main part corresponding to FIG. 4C according to another embodiment of the present invention. FIG. 4E is an enlarged perspective view of a main part corresponding to FIG. 4C according to still another embodiment of the present invention. FIG. 5 is a perspective view showing a step subsequent to FIG. FIG. 6 is a perspective view showing a step subsequent to FIG. FIG. 7 is a perspective view of an electric double layer capacitor according to 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 schematic perspective view showing an example of a manufacturing method of the electric double layer capacitor shown in FIG. FIG. 10 is a perspective view showing a step subsequent to FIG.

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 front surface 4a and a back surface 4b formed by folding a single sheet 4 around the peripheral edge 4c.

  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 front surface 4a and the back surface 4b of the exterior sheet 4 overlap is the thickness direction (Z-axis direction), and the directions orthogonal to each other are the X-axis and Y-axis.

  As will be described later with reference to FIG. 2A, the exterior sheet 4 has a built-in element body 10. A pair of first lead terminals 18 and 28 drawn out from the element body 10 are drawn out of the exterior sheet 4.

  As shown in FIG. 1A, in the present embodiment, the interior of the rectangular exterior sheet 4 includes a first seal part 40, a second seal part 42, and a third seal part formed along the four sides of the exterior sheet 4. 44 and the fourth seal portion 46 are hermetically sealed.

  In this embodiment, a portion that seals the peripheral edge portion 4 d 1 of the exterior sheet 4 from which the lead terminal 18 is pulled out in the X-axis direction is referred to as a first seal portion 40. Further, a portion that seals the peripheral edge portion 4 d 2 of the exterior sheet 4 from which the lead terminal 28 is drawn out in the X-axis direction is referred to as a second seal portion 42. The first seal part 40 and the second seal part 42 are located on the opposite side of the exterior sheet 4 in the X-axis direction. Further, a portion that seals the peripheral edge portion 4c formed by folding the exterior sheet 4 is referred to as a third seal portion 44, and a portion that seals the side peripheral edge portion 4e of the exterior sheet 4 located on the opposite side in the Y-axis direction is the first seal portion 44. 4 seals.

  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 a second electrode 26 are laminated so as to sandwich the separator layer 11 in which the electrolyte solution is soaked. 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. Each of the first internal electrode 16 and the second internal electrode 26 includes a first active layer 12 and a second active layer 22 that are stacked so as to be in contact with opposite surfaces of the separator layer 11. 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 layer 11 is configured to electrically insulate the internal electrodes 16 and 18 from each other and to allow the electrolyte solution to permeate. For example, the separator layer 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 layer 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 with low electrical resistance are preferably used, for example, sheets of copper, aluminum, nickel, etc. A foil or a plate is used. The thickness of each of the current collector layers 12 and 22 is preferably about 15 to 50 μm, for example.
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 electronic conductivities, such as natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fibers (MCF), cokes, glassy carbon, and organic compound fired bodies. The carbon material is mentioned. 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 200 μm, for example. The active layers 12 and 22 are formed on the surfaces of the current collector layers 12 and 24 on the surfaces of the current collector layers 12 and 24 so as to have an area equal to or smaller than that of the separate layer 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 preferably made of a material that does not allow permeation of an electrolyte solution, which will be described later, and is integrated with peripheral portions of the exterior sheet 4 or a sealing tape 40a shown in FIG. 5 by heat sealing. 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 sheet 4B and the outer sheet 4C. Is preferred.

  The metal sheet 4A is preferably made of, for example, stainless steel, and the inner sheet 4B is made of an electrical insulating material, and is similar to a partition wall sheet such as polypropylene that hardly reacts with the electrolyte solution and can be heat sealed. It is preferable that it is made of a material. The outer sheet 4C is not particularly limited, and is preferably composed of, for example, PET, PC, PES, PEN, PI, fluororesin, PE, polybutylene terephthalate (PBT), and the like. The thickness of the exterior sheet 4 is preferably 5 to 50 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 460, preferably 280 to 380 in Picker's hardness (Hv). From such a viewpoint, the metal sheet 4A of the exterior sheet 4 is made of stainless steel SUS (BA), SUS304 (1 / 2H), SUS304 (1 / 2H), SUS304H, SUS301BA, SUS301 (1 / 2H) defined by JIS. ), SUS201 (3 / 4H), and SUS304 (1 / 2H) is particularly preferable.

  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 lead terminal 18, 28 is formed by a sheet integrated with the conductive sheet constituting the current collectors 14, 24, and has the same thickness as the current collector layers 14, 24. 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, 28 can be different from the thickness of the current collector layers 14, 24.

  A space for sealing the element body 10 by the seal portions 40, 42, 44, and 46 sandwiched between the exterior sheets 4 is filled with an electrolyte solution (not shown), and part of the active layers 12, 22. The separator layer 11 is 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 ⁺ BF4 ⁻ ) and triethylmonomethylammonium tetrafluoroborate (TEMA ⁺ BF4 ⁻ ), ammonium salts, amine salts, and amidine salts. Is preferred. 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.

  As shown in FIG. 2A, the leading ends of the lead terminals 18 and 28 penetrate 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 have a sealing performance as compared with the third seal portion 43 and the fourth seal portion 44. The

  The widths in the Y-axis direction of the lead terminals 18 and 28 shown in FIGS. 3 and 4 may be the same or different. When these lead terminals 18 and 28 are integrally formed with the current collector layers 14 and 24, respectively, the width of the lead terminals 18 and 28 in the Y-axis direction is Y of the current collector layers 14 and 24. Although it is substantially the same as the axial width W1, it may be smaller or larger than the width W1 as long as an effect is produced. For example, the width of the lead terminal / the width W1 of the current collector layer is preferably 0.6 to 1.5.

  The Y-axis direction width W1 of the current collector layers 14 and 24 is preferably 2 to 10 mm, preferably smaller than the Y-axis direction width W3 of the separator layer 11, and W3-W1 is preferably 0.2 to 2 mm. The current collector layers 14 and 24 are preferably disposed at the center of the separator layer 11 in the Y-axis direction.

  Further, the width W0 in the Y-axis direction of the EDLC2 shown in FIG. 1A is preferably 10 to 50 mm when accommodated in the IC card, and the X-axis direction of the EDLC2 excluding the lead terminals 18 and 28. The length L0 is preferably 10 to 50 mm.

  In the present embodiment, as shown in FIG. 6 described later, the first seal portion 40 and the second seal portion 42 are configured such that the sealing tapes 40a and 42a and the peripheral portions 4d1 and 4d2 of the exterior sheet 4 are heat sealed. Are integrally formed by heating. At that time, the inner sheet 4B (see FIG. 2A) formed on the inner peripheral surface of the exterior sheet 4 is also integrated, and the sealing performance at the first seal part 40 and the second seal part 42 is improved.

  Moreover, in the 3rd seal | sticker part 44, the inner side sheet | seat 4B of the exterior sheet | seat 4 is fuse | melted and integrated by the folding | circulating periphery part 4c of the exterior sheet | seat 4, and the heat | fever at the time of heat sealing. In the fourth seal portion 46, the inner sheets 4B of the side peripheral edge portions 4e on the front surface 4a and the back surface 4b of the exterior sheet 4 are fused and integrated by heating during heat sealing.

  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 so as to be connected, respectively. The second seal portion 42 is formed continuously so as to connect the other end of the four seal portion 46. Therefore, the inside of the exterior sheet 4 is well sealed against the outside of the exterior sheet 4.

  As shown in FIG. 2B, in the present embodiment, the first lead terminal 18 (second lead terminal 28) is located at a position corresponding to the first seal portion 40 (second seal portion 42) than the lead tip portion. A thin region 60 having a small thickness is formed. The thin region 60 is formed by forming a recess or groove 62 on the front and back surfaces of the lead terminal 18 (28), for example, by press working. In addition, you may form the recessed part or the groove part 62 only in any one surface, without forming in both the front and back of the lead terminal 18 (28).

  In the present embodiment, the thickness t1 of each lead terminal 18, 28 is the same as the thickness of the current collector layers 14, 24, preferably 30-80 μm, and more preferably 40-50 μm. Moreover, each depth t2, t3 of the recessed part or the groove part 62 becomes like this. Preferably it is 5-20 micrometers, More preferably, it is 10-20 micrometers. The minimum thickness t4 of the thin region 60 is preferably 1/2 to 3/4 of the thickness t1 of the normal portion of each lead terminal 18, 28. In addition, the minimum thickness t4 of the thin region 60 is preferably 2/25 to 4/25 of the total thickness t5 of the seal portion 40 (42). With such a configuration, an appropriate resistance can be obtained, and the IC card can be charged efficiently.

  In the present embodiment, at least a part of the thin region 60 (the boundary portion 66 on the front end side with the normal thickness portion) is the peripheral portion 4d1 on the first seal portion side (the peripheral portion 4d2 on the second seal portion side) of the exterior sheet 4. Further, the thin region 60 protruding outward is covered with the seal portion 40 (42) including the distal end side boundary portion 66. The protrusion amount L2 along the X axis of the front end side boundary portion 66 with respect to the peripheral edge portion 4d1 on the first seal portion side (the peripheral edge portion 4d2 on the second seal portion side) in the exterior sheet 4 is preferably 0.2 to 1 mm. . Further, the protrusion amount L3 along the X axis of the seal portion 40 (42) with respect to the distal end side boundary portion 66 is preferably 0.1 to 0.5 mm. By providing these protrusion amounts L2 and L3, it is possible to prevent the bending strength of the lead terminal 18 (28) from being deteriorated even if the thin portion 60 is provided in the lead terminal 18 (28). There are advantages such as preventing a short circuit between (28) and the outer package 4b.

  The length L1 in the X-axis direction of the seal portion 40 (42) is preferably 2 to 4 mm. In addition, the X-axis direction length L4 of the thin region 60 from the front end side boundary portion 66 to the rear end side boundary portion 68 is shorter than the X-axis direction length L1 of the seal portion 40 (42). L4 is covered with the seal portion 40 (42). Further, the thickness t4 of the thin region 60 does not have to be constant over the entire length L4 of the thin region 60, and the thickness gradually changes from the minimum thickness portion toward the normal thickness portion, particularly near the boundary portions 66 and 68. It is preferable to be configured as described above.

  As shown in FIG. 4D, the thin region 60 may be formed by forming a plurality of grooves 62 on the front surface and / or the back surface of the lead terminal 18 (28). In the present embodiment, these grooves 62 extend along the Y-axis direction and are formed at predetermined intervals in the X-axis direction, but are not limited thereto. For example, as shown in FIG. 4E, in addition to a plurality of grooves 62 in the Y-axis direction, a plurality of grooves 64 extending in the X-axis direction may be formed to form the thin region 50. Alternatively, the thin region 60 may be formed by only the plurality of grooves 64 extending in the X-axis direction.

  Further, the thin region 60 may be formed by forming a groove intersecting the Y axis or the X axis at a predetermined angle (acute angle) on the front surface and / or the back surface of the lead terminal 18 (28). In any case, at least a part of the thin region 60 (the boundary portion 66 on the front end side with the normal thickness portion) is the peripheral portion 4d1 (the peripheral portion 4d2 on the second seal portion side) on the first seal portion side in the exterior sheet 4. Rather than outward in the X-axis direction. Further, the thin region 60 protruding outward is covered with a sealing tape 40a (42a) that constitutes the seal portion 40 (42) including the front end side boundary portion 66 and the rear end side boundary portion 68. Yes.

  The thin region 60 having the recesses or grooves described above is preferably formed by pressing, but may be formed by other processing methods. Further, the cross-sectional shape of the recess or groove formed in the thin region 60 is preferably a shape having no corners, and preferably has a gentle waveform.

  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 Y-axis direction width W0 of the EDLC 2 can be reduced, the thicknesses of the first seal part 40 and the second seal part 42 can be minimized, and the thickness t0 of the entire EDLC 2 can also be reduced. Can do. 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, and is connected to the element body 10 immersed in an electrolyte solution. In ELDC, 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.

Next, an example of a method for manufacturing the EDLC 2 of the present embodiment will be described with reference to FIGS.
As shown in FIGS. 3, 4A, and 4B, the element body 10 is first manufactured. In order to manufacture the element body 10, as shown in FIG. 3, the first internal electrode 16 and the second internal electrode 26 are disposed on the front surface and the back surface of the separator layer 11. Internal electrodes 16 and 26 are laminated on both sides of the separator layer 11 so that the active layers 12 and 22 are in contact with each other.

  Sealing tapes 40a and 42a are bonded to the lead terminals 18 and 28, respectively, so as to sandwich 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. It is. The width W2 of the tapes 40a and 42a in the Y-axis direction is preferably 0.5 to 3 mm longer than the width of the lead terminals 18 and 28 in the Y-axis direction. The width in the Y-axis direction of the tapes 40a and 42a corresponds to the width in the Y-axis direction of the first seal portion 40 and the second seal portion 42 of the EDLC2 shown in FIG. Is specified.

  When the width W2 in the Y-axis direction of the tapes 40a and 42a shown in FIG. 4A is too narrow, the sealing performance in the first seal part 40 and the second seal part 42 shown in FIG. 1 (A) may not be sufficient. If the width is too wide, the Y-axis direction width W0 of the EDLC 2 becomes larger than necessary. The width in the X-axis direction of the tapes 40a and 42a corresponds to the length L1 in the X-axis direction of the first seal portion 40 and the second seal portion 42 shown in FIG. The thicknesses of the tapes 40a and 42a are preferably the same, and can be represented as ((t5−t4) / 2) + α using, for example, the thickness symbol shown in FIG. 2B. In addition, (alpha) shows the amount of thermocompression bonding deformation at the time of forming the seal parts 40 and 42, Preferably it is 0.3-0.7 mm.

  Next, as shown in FIG. 5, the exterior sheet 4 is folded at the peripheral edge 4c so as to cover the entire element body 10, and the element body 10 is covered with the front surface 4a and the back surface 4b of the sheet. The exterior sheet 4 is formed long in advance in the Y-axis direction. The width of the exterior sheet 4 in the X-axis direction is such that the periphery 4d1 on the first seal portion side of the exterior sheet 4 overlaps with the tape 40a, and the periphery 4d2 on the second seal portion side of the exterior sheet 4 overlaps with the tape 42a. Have been adjusted so that.

  Next, as shown in FIG. 6, the exterior sheet 4 that covers the entire element body 10 is set in a jig (not shown), the folded peripheral edge 4 c of the exterior sheet 4 is heated under pressure, and the third seal A portion 44 is formed. Next, the peripheral edge 4d1 on the first seal part side and the peripheral edge 4d2 on the second seal part side of the exterior sheet are pressurized and heated to form the first seal part 40 and the second seal part 42.

  At that time, the sealing tape 40a and the inner sheet 4B (see FIG. 2A) formed on the inner peripheral surface of the exterior sheet 4 are also integrated, and the sealing performance at the first seal portion 40 is improved. Similarly, the sealing tape 42a and the inner sheet 4B (see FIG. 2A) formed on the inner peripheral surface of the exterior sheet 4 are also integrated, and the sealing performance at the second seal portion 42 is improved.

  Next, as shown in FIG. 6, an electrolyte solution is injected from the opening 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 similar to the above. Formed by heat sealing. 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 manufacturing method of the present embodiment, the first sealing portion 40 is heat-sealed by sealing the sealing tape 40a sandwiching the first lead terminal 18 between the peripheral portion 4d1 on the first sealing portion side of the exterior sheet 4. Is formed. Similarly, in the second seal portion 42, the sealing tape 42 a that sandwiches the second lead terminal 28 is sandwiched between the peripheral portion 4 d 2 on the second seal portion side of the exterior sheet 4 and heat-sealed. It is formed.

  By heat-sealing, the sealing tape 40a and the peripheral edge portion 4d1 of the exterior sheet 4 are integrated by heat, and the inside of the exterior sheet 4 is favorably sealed at the lead terminal 18 take-out portion. In addition, the thickness of the first seal portion 40 can be reduced to a minimum while maintaining good sealing. Similarly, by heat sealing, the sealing tape 42a and the peripheral edge portion 4d2 of the exterior sheet 4 are integrated by heat, and the inside of the exterior sheet 4 is well sealed at the lead terminal 28 take-out portion. In addition, the thickness of the second seal portion 42 can be reduced to the minimum while maintaining good sealing.

  In the EDLC 2 of the present embodiment, as shown in FIG. 2A, the first lead terminal 18 and the second lead terminal 28 are opposite to each other along the longitudinal direction of the first internal electrode 16 and the second internal electrode 26. At the position, it is pulled out of the seal portions 40 and 42. Therefore, compared with the structure in which the first lead terminal 18 and the second lead terminal 28 are drawn out to the same side, it is easy to reduce the electrode area per unit cell, and the capacity is relatively low. EDLC2 can be realized. A low capacity EDLC 2 of preferably 0.1 to 50 mF, particularly 1 to 10 mF, can be realized.

  In the present embodiment, the first lead terminal 18 and the second lead terminal 28 at the positions corresponding to the seal portions 40 and 42 have a thin region 60 (see FIGS. 2B and 4C to 4C to 4C) that is thinner than the lead tip portion. 4E), it is possible to effectively prevent a sudden increase in the thickness of the seal portions 40 and 42 at the position where the lead terminals 18 and 28 are taken out. Therefore, it contributes to thinning of the device, suppresses an abrupt thickness change (step) of the seal portion, and improves bending resistance.

  Furthermore, in this embodiment, at least a part of the thin region 60 protrudes outward from the peripheral edge portion 4d1 (4d2) of the exterior sheet 4, and the thin region 60 protruding outward is also the seal portion 40 (42). Covered. For this reason, device thickness t0 in the peripheral part of the exterior sheet | seat 4 can be made into the required minimum (preferably 1 mm or less, More preferably, 0.8 mm or less). Further, as shown in FIG. 2A, even if the exterior sheet 4 is composed of a resin-coated metal sheet 4A, the lead terminal 18 (28) is exposed to the metal sheet at the peripheral edge 4d1 (4d2) of the exterior sheet 4. There is no risk of contact with the ends, and short circuit prevention can be reliably achieved.

  In the present embodiment, the first lead terminal 18 is formed continuously and integrally with the first current collector layer 14, and the second lead terminal 28 is formed continuously and integrally with the second current collector layer 24. Is formed. By integrally molding these, the operation of connecting the lead terminal 18 (28) and the current collector layer 14 (28) becomes unnecessary, and the manufacturing process can be shortened and the manufacturing cost can be reduced.

  Furthermore, in this embodiment, since the thin region 60 is formed by press-molding the corresponding portions of the first lead terminal 18 and the second lead terminal 28, it is integrally formed with the current collector layer 14 (24). The porous etching surface formed on the surface of the lead terminal 18 (28) is flattened by pressing. Therefore, when the flattened surface is covered with the seal portion 40 (42), the sealing performance is improved, and the moisture resistance of the device is also improved.

  Further, by forming the thin region 60 in the first lead terminal 18 and the second lead terminal 28, the resistance of the terminals 18 and 28 is adjusted, and the resistance of the EDLC 2 itself is controlled to 1 to 10Ω (preferably 4 to 10Ω). It is also possible to use the EDLC 2 for IC card applications.

  Moreover, in this embodiment, the Y-axis direction width | variety of the seal part 40 or 42 corresponding to the length of the Y-axis direction of sealing tape 40a, 42a is 1 mm or more. The wider the seal portion is, the more effective as a countermeasure against the electrolytic solution, and the bending resistance of the device is improved. However, since the width of the device increases as the width of the seal portion increases, the width of the seal portion 40 or 42 is preferably 3 mm or less.

In the present embodiment, the reason why the capacitance and resistance of the EDLC 2 are preferable in the above range will be described below.
An electromagnetic wave including a control signal for starting communication is transmitted from the reader / writer antenna to the RF, and an electromotive force is generated in the RF circuit by receiving the electromagnetic wave, and the control unit IC in the RF card is activated. Assume that electronic paper is displayed. In addition, the driving voltage of a general control IC is considered to be about 1.8 V to 3.8 V, the current consumption is about 150 μA, the operating voltage of the electronic paper is 2.0 V to 3.6 V, and the current consumption is 0.2 mA. . Considering such general information, it is considered that the general power consumption when the information is taken in from the IC, processed by the microcomputer, and displayed once on the E-INK is about 2 mAs. For example, when the power consumption of 2 mAs is driven with a voltage difference of 2 V at the maximum and 0.2 V at the minimum, the required capacity is 1 mF to 10 mF from the formula of C (V1−V2) = It and C = It / (V1−V2). It is led to be.

  Also, since the RF transmission frequency is a 13.56 MHz sine wave, when a diode is used for rectification, a reverse current flows due to the capacitance component inside the diode. As a countermeasure, the EDLC can be improved by connecting an internal DC resistance of 1 to 10Ω in series, and the series internal resistance of the EDLC plays the role.

Second Embodiment As shown in FIG. 1B, the EDLC 2a of the present embodiment includes a first lead terminal 18 drawn from the first seal portion 40 and a second lead terminal drawn from the second seal portion 42. Further, support sheets 4f1 and 4f2 are provided to prevent 28 from being bent. 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 first embodiment described above, as shown in FIG. 2A, the position in the X-axis direction is the same on the front surface 4 a and the back surface 4 b of the exterior sheet 4 at the peripheral edge portion 4 d 1 on the first seal portion side of the exterior sheet 4. . On the other hand, in this embodiment, as shown in FIG. 1B, the support sheet 4f1 has the peripheral edge 4d3 of the exterior sheet 4 located on the back surface 4b of the exterior sheet 4 located on the first seal part 40. It is formed to extend outward in the X-axis direction. The length of the peripheral edge portion 4d3 of the exterior sheet 4 protruding outward in the X-axis direction with respect to the first seal portion 40 is longer than the length of the first lead terminal 18 protruding outward in the X-axis direction. .

  Similarly, the support sheet 4f2 is formed by extending the peripheral edge portion 4d4 of the exterior sheet 4 positioned on the front surface 4a or the back surface 4b of the exterior sheet 4 positioned at the second seal portion 42 to the outside in the X-axis direction. . The length of the peripheral edge portion 4d4 of the exterior sheet 4 that protrudes outward in the X-axis direction with respect to the second seal portion 42 is longer than the length of the second lead terminal 28 that protrudes outward in the X-axis direction. .

  With this configuration, the support sheets 4f1 and 4f2 can be easily formed. Moreover, by configuring in this way, it is possible to effectively prevent the first lead terminal 18 drawn from the first seal portion 40 and the second lead terminal drawn from the second seal portion 42 from being bent. Further, by making the protruding length of the peripheral edge 4d3 or 4d4 of the exterior sheet 4 longer than the protruding length of the lead terminal 18 or 28, the lead terminal 18 or 28 is connected to the peripheral edge 4d3 or There is no risk of contact with the exposed end of the metal sheet (metal sheet 2A in FIG. 2) at 4d4, and short circuit prevention can be reliably achieved.

  In the present embodiment, the terminal strength can be increased by fixing the first lead terminal 18 and the second lead terminal 28 to the support sheet 4f1 or 4f2, for example, with a heat seal layer. By fixing to the exterior sheet 4f1 or 4f2, it is difficult for terminal displacement to occur, and various terminal connections such as ACF connection are facilitated.

Third Embodiment As shown in FIG. 7, in the EDLC 2 b of this 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, as shown in FIG. 7, the exterior sheet 4 includes a top sheet 4 a 1 and a back sheet 4 b 1, and is approximately twice in the Y-axis direction as compared to the exterior sheet 4 illustrated in FIG. Have a size of As shown in FIG. 8, two element bodies 10a and 10b are built in the exterior sheet 4, and the separator layer 11 is shared by the two element bodies 10a and 10b. The element bodies 10a and 10b have the same structure as the element body 10 of the first embodiment, respectively, except that the separator layer 11 is shared. However, in this embodiment, a single separator layer 11 may be used for each of the element bodies 10a and 10b without necessarily using a single separator layer 11.

  A third seal portion 44a is formed along the X-axis direction at the axial central portion of the exterior sheet 4, and the flow of the electrolyte solution is blocked between the element main bodies 10a and 10b. . 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.

  Next, an example of the manufacturing method of EDLC2 of this embodiment is demonstrated using FIGS. 9-10.

  As shown in FIG. 9, first, two element bodies 10a and 10b are formed side by side in the Y-axis direction on a single separator layer 11 that is wide in the Y-axis direction. Two element bodies 10a and 10b may be formed using two separator layers 11. The manufacturing method of the element bodies 10a and 10b is the same as in the case of the first embodiment.

  Sealing tapes 40a and 42a are bonded to the lead terminals 18 and 28 in the element bodies 10a and 10b so as to sandwich the terminals 18 and 28, respectively, in the same manner as in the above-described embodiment.

  Next, the top sheet 4a and the back sheet 4b constituting the exterior sheet 4 are combined so as to cover the entire element bodies 10a and 10b, and the element bodies 10a and 10b are covered with these. The exterior sheet 4 is formed long in advance in the Y-axis direction. The width of the exterior sheet 4 in the X-axis direction is such that the periphery 4d1 on the first seal portion side of the exterior sheet 4 overlaps with the tape 40a, and the periphery 4d2 on the second seal portion side of the exterior sheet 4 overlaps with the tape 42a. Have been adjusted so that.

  Next, as shown in FIG. 10, the exterior sheet 4 that covers the entire element body 10 is set in a jig (not shown), and the center portion of the exterior sheet 4 in the Y-axis direction extends along the X-axis direction. The third seal portion 44a is formed by pressurizing and heating. Next, the peripheral edge 4d1 on the first seal part side of the exterior sheet and the peripheral edge 4d2 on the second seal part side are heated under pressure to form the first seal part 40 and the second seal part 42.

  Next, an electrolyte solution is injected from the open end 52 of the exterior sheet 4 where the fourth seal portions 46a and 46b are not formed, and then the last fourth seal portions 46a and 46b are heat sealed as described above. To form. Thereafter, the exterior sheet 4 is cut along the cutting line 54 outside the fourth seal portions 46a and 46b, and the excess exterior sheet 4 ′ is removed, whereby the EDLC 2 of the present embodiment shown in FIG. 7 is obtained. .

  In the embodiment described above, the lead terminals 18, 18 or 28, 28 having the same polarity are drawn from the same side of the exterior sheet 4 in the X axis direction, but the lead terminals 18, 28 or 28, 18 having different polarities are drawn out. May be pulled out. 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, support sheets 4f1 and 4f2 as shown in FIG. 1B may be provided.

  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, in the above-described embodiment, the lead terminals 18 and 28 are formed integrally with the current collector layers 14 and 24, respectively, and are part of the current collector layers 14 and 24 extending the current collector layers 14 and 24, respectively. However, in the present invention, these may be formed separately.

  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 battery capacitors, and the like.

  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. The dimensional relationships shown in FIGS. 1, 2A, 2B, and 4A were as follows. That is, t0 = 0.45mm, t1 = 0.04mm, t2 = 0.01mm, t3 = 0.01mm, t4 = 0.02mm, L0 = 20mm, L1 = 3mm, L2 = 0.5mm, L3 = 0. 1 mm, L4 = 2.5 mm, W0 = 10 mm, W1 = 3 mm, W2 = 5 mm, W3 = 4 mm. Moreover, the capacity | capacitance of EDLC was 1-10 mF, and resistance was 1-10 ohms.

  20 samples were prepared for each sample, and the short-circuit probability, peel strength (yield after tensile test), and generation of wrinkles (yield after bending test) were evaluated under the following conditions. These evaluations were performed as follows.

  The short-circuit probability was determined by measuring both positive and negative terminals with a tester for 20 samples, and determining that the resistance was 1 MΩ or less as a short, and determining the ratio. As shown in Table 1, the short-circuit probability was 0%.

  Regarding the seal strength, 10 samples were allowed to stand for 100 hours in an environment of 60 ° C. and 90%, and the case where there was no seal peeling due to gas generation was judged to be good, and the ratio was determined. As shown in Table 1, the non-defective rate of the seal strength was 100%, which was confirmed to be good.

  For generation of wrinkles, 20 samples were prepared, 20 were subjected to a bending test under the following conditions, and wrinkles were visually evaluated. When wrinkles were observed visually, it was judged as defective and the proportion of samples in which no wrinkles were observed was determined. The results are shown in Table 1. As shown in Table 1, the non-defective product rate at which no wrinkle breakage was observed was 100%, which was confirmed to be good.

  The conditions for the bending test were as follows. That is, two PET films having a card size of 80 mm × 50 mm were stacked, and each sample was sandwiched between the centers. The sandwiched card was bent 250 times up to a height of 2 cm in the 80 mm direction, and then bent downward 250 times. Next, it was bent 250 times up to a height of 1 cm in the 50 mm direction. Then it was bent down 250 times. The test method was performed in accordance with JIS X 6305.

Examples 2-4
Samples were prepared and evaluated in the same manner as in Example 1 except that t1, t2 + t3, t5-t4, (t5-t4) / t4 were changed. The results are shown in Table 1. As shown in Table 1, it was confirmed that the same effect as in Example 1 was obtained.

Comparative Example 1
Samples were prepared and evaluated in the same manner as in Example 1 except that t2 = 0 mm, t3 = 0 mm, t4 = t1 = 40 μm, t5 = 196 μm, and the thin region 60 was not formed. In Comparative Example 1, the percentage of non-defective products with creases was 66%, and creases were observed.

Comparative Example 2
Samples were prepared and evaluated in the same manner as in Example 1 except that t2 = 0 mm, t3 = 0 mm, t4 = t1 = 60 μm, t5 = 196 μm, and the thin region 60 was not formed. In Comparative Example 1, the non-defective product rate of wrinkling was 33%, and wrinkling was observed.

2, 2a, 2b ... electric double layer capacitor 4 ... exterior sheet 4a ... front surface 4a1 ... top sheet 4b ... back surface 4b1 ... back sheet 4c ... folded peripheral edge 4d1 ... first seal part side peripheral part 4d2 ... second seal part side 4e, 4e1, 4e2 ... side periphery 4f ... support sheet 10 ... element body 11 ... separator layer 12 ... first active layer 14 ... first current collector layer 16 ... first internal electrode 18 ... first lead terminal 22 ... 2nd active layer 24 ... 2nd collector layer 26 ... 2nd internal electrode 28 ... 2nd lead terminal 40 ... 1st seal part 42 ... 2nd seal part 44 ... 3rd seal part 46 ... 4th seal part 60 ... Thin region 62 ... Recess or groove 66 ... Front end side boundary 68 ... Rear end side boundary

Claims (9)

An element body in which a pair of first internal electrodes and second internal electrodes are stacked so as to sandwich the separator layer;
An exterior sheet covering the element body;
A first lead terminal electrically connected to the first internal electrode and drawn out of the exterior sheet;
A second lead terminal electrically connected to the second internal electrode and drawn out of the exterior sheet,
The outer periphery of the outer sheet is sealed with a seal so that the element body is immersed in the electrolyte solution,
The first lead terminal and the second lead terminal have substantially the same width as the width of the first internal electrode and the second internal electrode, respectively;
At the position corresponding to the seal portion, the first lead terminal and the second lead terminal have a thin region having a thickness smaller than the lead tip portion,
An electrochemical device, wherein at least a part of the thin region protrudes outward from a peripheral edge of the exterior sheet, and the thin region protruding outward is also covered by the seal portion.   The first lead terminal and the second lead terminal are pulled out to the outside of the seal portion at positions opposite to each other along the longitudinal direction of the first internal electrode and the second internal electrode. The described electrochemical device. The first internal electrode has a first active layer in contact with the separator layer, and a first current collector layer in contact with the first active layer,
The second internal electrode has a second active layer in contact with the separator layer, and a second current collector layer in contact with the second active layer,
The first lead terminal is a part of the first current collector layer obtained by extending the first current collector layer;
The electrochemical device according to claim 1 or 2, wherein the second lead terminal is a part of the second current collector layer obtained by extending the second current collector layer.   The electrochemical device according to any one of claims 1 to 3, wherein the thin region is formed by press molding corresponding portions of the first lead terminal and the second lead terminal.   The electrochemical device according to any one of claims 1 to 4, wherein the thin region is formed by forming a recess or a groove on a surface of a corresponding portion of the first lead terminal and the second lead terminal.   A part of the sealing portion is formed by sealing a sealing tape that sandwiches the first lead terminal and the second lead terminal between the peripheral portions of the exterior sheet and heat-sealing. Item 6. The electrochemical device according to any one of Items 1 to 5.   The electrochemical device according to any one of claims 1 to 6, further comprising a support sheet that prevents the first lead terminal and the second lead terminal drawn out from the seal portion from bending.   The electrochemical device according to claim 7, wherein the support sheet is formed by extending a part of a peripheral edge portion of the exterior sheet positioned at the seal portion to the outside.   The electrochemical device according to claim 7 or 8, wherein a protruding length of the support sheet is longer than a protruding length of the first lead terminal and the second lead terminal.

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