JP2011176141A - Electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a winding-type electrochemical device suppressing occurrence of failure while improving impedance characteristics. <P>SOLUTION: A belt-like electrode composing an anode electrode A includes a belt-like main metal foil A1 and a pair of active material layers AE1, AE2 respectively provided on both surfaces of the main metal foil A1. A belt-like electrode composing a cathode electrode K includes a belt-like main metal foil K2 and a pair of active material layers KE1, KE2 respectively provided on both surfaces of the main metal foil K2. A belt-like auxiliary metal foil T1 is provided on an upper surface of an exposed area of the main metal foil A1, and a belt-like auxiliary metal foil T2 is provided on an upper surface of an exposed area of the main metal foil K2. High-resistance layers TC1, TC2 made of insulating material such as polypropylene are provided on inner surfaces of the auxiliary metal foils T1, T2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrochemical device such as a battery or an electric double layer capacitor (EDLC).

  The technique regarding the electrochemical device (battery, EDLC) using the conventional winding electrode is disclosed by patent documents 1-11. Patent Document 1 discloses a technique related to a metal foil spacer, Patent Document 2 discloses a technique related to a resin spacer, Patent Document 3 discloses a technique related to application of an insulating tape, and Patent Document 4 discloses terminal attachment to a winding end surface. Patent Document 5 discloses a technique related to protective layer formation, Patent Document 6 discloses a technique related to metal band attachment, Patent Document 7 discloses a technique related to insulating spacer film attachment, and Patent Document 8 discloses A technique for separating the separator with a spacer is disclosed, Patent Document 9 discloses a technique using an insulating spacer layer, and Patent Document 10 and Patent Document 11 disclose a technique using a metal spacer band.

  In many wound-type electrochemical devices, a pair of strip electrodes and a pair of strip separators are alternately stacked. Activated carbon is applied to the upper and lower surfaces of one strip electrode with a binder resin. The stacked ones are wound around the core, and the ends in the width direction of the wound electrodes are directly welded and used directly as the extraction electrode. Here, the reason why the belt-like electrode is directly welded is that when an extra terminal is attached thereto, the impedance becomes high.

JP 2002-298922 A JP 2000-021436 A JP 2005-235414 A JP-A-2005-347608 JP 2007-095656 A JP 2007-335814 A JP 2008-193010 A JP 05-109435 A Japanese Patent Laid-Open No. 07-130389 Japanese Patent Laid-Open No. 11-135100 Japanese Patent Laid-Open No. 11-283606

  However, when the end in the width direction of the wound body is simply used as the extraction electrode, a gap is formed between the end portions in the width direction of the strip electrode. Due to the presence of this gap, there is a problem that the band-shaped electrode is deformed to deteriorate the impedance characteristics or vary. Therefore, it is conceivable to provide an auxiliary metal foil at the position of the gap between the strip electrodes to control the gap and suppress the impedance change, but despite using such a characteristic improvement technique, It was observed that the electrochemical device failed.

  This invention is made | formed in view of such a problem, and it aims at providing the winding type electrochemical device by which generation | occurrence | production of a failure is suppressed, improving an impedance characteristic.

  In order to solve the above-mentioned problems, the inventors of the present invention diligently studied the cause of failure of the electrochemical device. As a result, the constituent material of the active material layer diffuses into the electrolytic solution to become a conductive floating substance. It has been discovered that an auxiliary metal foil and a metal foil having a polarity different from that of the auxiliary metal foil are short-circuited by an object, resulting in a failure.

  Therefore, an electrochemical device according to the present invention includes a wound strip-shaped laminate and an enclosure that houses the laminate together with an electrolyte solution, and the strip-shaped laminate includes a pair of strip-shaped electrodes and the strip-shaped laminate. A pair of separators sandwiching one of the electrodes, and each of the strip-shaped electrodes is a strip-shaped electrochemical device having a strip-shaped main metal foil and an active material layer provided on the main metal foil. The positions of adjacent ones of the main metal foils are shifted along the width direction, and an exposed region where the active material layer is not formed is set in a region where they do not overlap, and this exposed region has a strip shape. The auxiliary metal foil is provided along the longitudinal direction of the main metal foil, and a high resistance layer having a higher resistivity than the auxiliary metal foil is provided on the inner surface of the auxiliary metal foil. It is characterized by that. The high resistance layer is preferably made of an insulating material such as a resin.

  According to the present invention, since the auxiliary metal foil narrows the movable range in the radial direction in the exposed region of the main metal foil, it is possible to suppress the impedance change due to the displacement of the main metal foil. In addition, since a high resistance layer is formed on the inner side surface of the auxiliary metal foil, even if a suspended matter is interposed between the auxiliary metal foil and the active material layer facing the inner side surface, the high resistance layer is provided. The layer suppresses these short-circuits and thus suppresses the occurrence of electrochemical device failures.

  Moreover, it is preferable that the high resistance layer which has a resistivity higher than the said auxiliary metal foil does not exist on the opposing surface with respect to the said main metal foil of the said auxiliary metal foil. That is, a high resistance layer for preventing a short circuit is not originally required on the opposite surface, and if an unnecessary high resistance layer is provided here, there is a possibility that the introduction of the electrolyte into the active material layer may be hindered. Therefore, the high resistance layer is not provided.

  The high resistance layer is preferably made of a material that can be impregnated with an electrolytic solution. In this case, since the high resistance layer is impregnated with the electrolytic solution and swells, even if the electrolytic solution is reduced, it functions as an electrolytic solution holding member and can suppress a change in impedance.

  The active material layer preferably includes activated carbon and a binder resin, and the material of the high resistance layer is preferably the same as the material of the binder resin included in the active material layer. As the binder resin used for the active material layer, one that does not react with the electrolytic solution is selected, and there is little adverse effect on the device. Therefore, if the same material as the binder resin is selected as the material for the high resistance layer, adverse effects on the element can be suppressed. Specifically, the material of the high resistance layer is preferably made of polypropylene, polyethylene, polyimide, or polyamideimide, and these materials are easily available and do not react with a normal electrolyte solution. It is also chemically stable.

  According to the electrochemical device of the present invention, the occurrence of a failure is suppressed while improving the impedance characteristics.

It is a disassembled perspective view of the laminated body used for a winding type electrochemical device. It is a perspective view of the laminated body used for a wound-type electrochemical device. It is a perspective view of the laminated body wound around the core. It is a longitudinal cross-sectional view of the electrochemical device before the electrode plate used as a lid | cover is attached. It is a perspective view of the electrochemical device at the time of electrode plate attachment used as a lid. It is a longitudinal cross-sectional view of the electrochemical device after the electrode plate used as a lid | cover is attached. It is sectional drawing of the laminated body for demonstrating a laminated structure in detail.

  Hereinafter, the electrochemical device according to the embodiment will be described. The same reference numerals are used for the same elements, and redundant description is omitted.

  FIG. 1 is an exploded perspective view of a laminate used for a wound electrochemical device, and FIG. 2 is a perspective view of the laminate used for a wound electrochemical device. The electrochemical device is an electric double layer capacitor (EDLC), but this structure can also be applied to a normal battery.

  This laminated body is strip-shaped, and has a pair of strip-shaped electrodes (anode electrode A, cathode electrode K) and a pair of separators S1 and S2 sandwiching one of the strip-shaped electrodes (cathode electrode K in this figure). . In the following description, a three-dimensional orthogonal coordinate system is set, the width direction of the strip electrode is taken as the Z-axis direction, the thickness direction is taken as the X-axis direction, and the longitudinal direction perpendicular to both is taken as the Y-axis.

  The strip electrode constituting the anode electrode A has a strip-shaped main metal foil A1 and a pair of active material layers AE1 and AE2 provided on both surfaces of the main metal foil A1. The strip electrode constituting the cathode electrode K has a strip-shaped main metal foil K2 and a pair of active material layers KE1 and KE2 provided on both surfaces of the main metal foil K2. Adjacent ones of the strip-shaped main metal foils A1 and K2 are displaced along the width direction (Z-axis direction), and active material layers AE1, AE2, KE1, KE2 are formed in regions where they do not overlap. An unexposed area (indicated by dimension Z3 in FIG. 7) is set.

  In the anode electrode A, a strip-shaped auxiliary metal foil T1 is provided on the upper surface of the exposed region of the main metal foil A1 along the longitudinal direction (Y-axis) of the main metal foil A1. Similarly, in the cathode electrode K, a strip-shaped auxiliary metal foil T2 is provided on the upper surface of the exposed region of the main metal foil K2 along the longitudinal direction (Y axis) of the main metal foil K2. These auxiliary metal foil T1 and auxiliary metal foil T2 are separated along the Z-axis direction.

  The widths of the separators S1 and S2 are equal and the widths of the active material layers AE1, AE2, KE1, and KE2 are also equal, but the width of the separator is slightly wider than the width of the active material layer. A single thickness of the auxiliary metal foils T1, T2 is thicker than a single thickness of the active material layers AE1, AE2, KE1, KE2. The above relationship is maintained even after the laminate is wound. However, after the winding, the auxiliary metal foils T1 and T2 are electrode plates L1 serving as lids provided at both ends in the width direction (Z-axis direction). , L2 respectively (see FIG. 6). The auxiliary metal foils T1 and T2 are welded to the electrode plates L1 and L2 together with the main metal foils A1 and K2, respectively, and in particular, laser welding (see FIG. 6).

  High resistance layers (insulating layers) TC1 and TC2 are provided on the inner side surfaces (XY plane) of the auxiliary metal foils T1 and T2, respectively. The high resistance layers TC1, TC2 have a higher resistivity than the auxiliary metal foils T1, T2. Since the high resistance layers TC1 and TC2 are formed on the inner side surfaces of the auxiliary metal foils T1 and T2, the auxiliary metal foils T1 and T2 and the active material layers KE1 and KE2 or the main metal foil facing the inner side surface are provided. Even if a suspended matter is present between K2 and K2, the high resistance layers TC1 and TC2 suppress these short-circuits, and thus suppress the occurrence of failure in the electrochemical device.

  Moreover, on the opposing surface (auxiliary metal foil exposure surface prescribed | regulated by the dimension Z5 of FIG. 7) with respect to main metal foil A1, K1 of auxiliary metal foil T1, T2, higher resistivity than auxiliary metal foil T1, T2 is provided. There is no high resistance layer. That is, a high resistance layer for preventing a short circuit is not originally required on the opposite surface, and if an unnecessary high resistance layer is provided here, there is a possibility that the introduction of the electrolyte into the active material layer may be hindered. Therefore, the high resistance layer is not provided.

  The high resistance layers TC1 and TC2 are made of a material that can be impregnated with an electrolytic solution. In this case, since the high resistance layers TC1 and TC2 are impregnated with the electrolytic solution and swell, even if the electrolytic solution is reduced, it functions as an electrolytic solution holding member and can suppress an impedance change. In addition, the resistance value between the anode electrode A and the cathode electrode K in this portion is almost maintained through the separator, and no short circuit occurs.

  The active material layers AE1, AE2, KE1, and KE2 include activated carbon and a binder resin, and the high resistance layers TC1 and TC2 are made of the binder resin included in the active material layers AE1, AE2, KE1, and KE2. It is the same as the material. Since the binder resin used for the active material layers AE1, AE2, KE1, and KE2 is selected so as not to react with the electrolytic solution, there is little adverse effect on the element. Therefore, if the same material as the binder resin is selected as the material for the high resistance layer, adverse effects on the element can be suppressed.

  In addition, what is necessary is just to use a well-known thing as a material of above-mentioned separator S1, S2, active material layer AE1, AE2, KE1, KE2, metal foil A1, K2, and high resistance layer TC1, TC2. Examples of these materials are shown below, but the present invention is not limited to these materials.

  Separator S1, S2 consists of a nonwoven fabric or a porous film containing polyolefin resin of 10% or more of weight ratio, for example. The polarizable electrode and the separator can be bonded together by applying pressure to the pair of polarizable electrodes in a temperature environment equal to or higher than the softening point temperature of the polyolefin resin. A cellulose nonwoven fabric or an aramid fiber nonwoven fabric can also be used as the separator.

  The active material layers AE1, AE2, KE1, and KE2 are polarizable electrodes. This polarizable electrode is made of a porous material, and is manufactured by mixing activated carbon with a binder resin. Examples of the binder resin include fluorine-containing polymer compounds such as polytetrafluoroethylene, and rubber-based polymer compounds such as styrene butadiene rubber. If necessary, carbon black, carbon nanotubes, fine particles of graphite, or fine fibers can be blended as a conductive aid. At the time of manufacture, these materials are emitted from the nozzle and applied to both sides of the main metal foil.

  The main metal foils A1 and K2 are current collectors, and aluminum foil or copper foil whose surface is roughened by etching can be used. As an electrode manufacturing method, there are innumerable methods such as adding a conductive additive and a binder to activated carbon to form a sheet and adhering it to the collector, and a method of applying activated carbon to a collector in a slurry.

  Specifically, the material of the high resistance layers TC1 and TC2 is preferably made of polypropylene, polyethylene, polyimide, or polyamideimide. These materials are easily available, do not react with ordinary electrolytes, and are chemically stable. In addition, these materials can become binder resin and can be impregnated with electrolyte solution. As a material of the high resistance layers TC1 and TC2, a material used for the separator can be employed.

  FIG. 3 is a perspective view of the laminate wound around the winding core.

  The laminated body shown in FIGS. 1 and 2 is wound around a core B having an outer surface having a cylindrical surface, and the electrochemical device body 10 is formed from these. The central axis of the winding core B is the Z axis, and the laminate is wound around the Z axis. As the distance from the axial center increases, anode electrodes A and cathode electrodes K are alternately stacked, and separators S1 and S2 are interposed therebetween. Auxiliary metal foils T1 and T2 are located at the ends in the Z-axis direction. At the positive end of the Z-axis, the auxiliary metal foil T1 is disposed adjacent to the radial direction in the XZ plane. At the negative end of the Z-axis, the auxiliary metal foil T2 is disposed adjacent to the radial direction in the XZ plane. In the drawing, the thicknesses of the auxiliary metal foils T1 and T2 are smaller than the distance of the gap between the main metal foils opposed at the end portions, but they may be equal.

  FIG. 4 is a vertical cross-sectional view (XZ cross-sectional view) of the electrochemical device before attachment of the electrode plate serving as a lid.

  The electrochemical device body 10 is inserted into the cylindrical body H so that the respective axes coincide with each other, and both end openings of the cylindrical body H are sealed with electrode plates L1 and L2 which are lids. An adhesive can also be used for this sealing. A surrounding body is constituted by the cylindrical body H and the electrode plates L1 and L2. The shape of the cylindrical body H may be a cylindrical shape as well as a rectangular cylindrical shape. Further, the outer surface shape of the core B can be a rectangular tube surface. As a material for the core B and the cylinder H, various materials can be used as long as they can prevent a short circuit between the anode electrode and the cathode electrode. For example, an insulator can be used. The structure of the core B or the cylinder H may be a structure in which a metal cylinder is joined to both ends of the insulator cylinder.

  FIG. 5 is a perspective view of the electrochemical device when the electrode plate serving as a lid is attached, and FIG. 6 is a longitudinal sectional view (XZ sectional view) of the electrochemical device after the electrode plate serving as a lid is attached.

  This electrochemical device includes a wound belt-like laminated body and an enclosure that houses the laminated body together with the electrolytic solution LQ. As described above, the enclosure includes the cylinder H and the electrode plates L1 and L2. In order to electrically connect the electrode plates L1 and L2 and the auxiliary metal foils T1 and T2, respectively, the electrode plates L1 and L2 are irradiated with the laser beam LB from the outside, the irradiation positions are melted, and the positions are respectively located inside these. The auxiliary metal foils T1 and T2 to be joined to the electrode plates L1 and L2. A concave portion D is formed at the irradiation position of the laser beam LB. The plurality of recesses are formed radially in the XY plane. Note that, instead of the laser beam LB, a current is applied to the electrode plates L1 and L2 at a high voltage, so that the current supply portions are melted. Similarly, the auxiliary metal foils T1 and T2 and the electrode plates L1 respectively located inside these portions. , L2 can also be joined. Note that an electrolytic solution LQ is sealed inside the enclosure.

  As the electrolytic solution LQ, an aqueous solution type and an organic type are known. Examples of the solvent for the organic electrolyte include propylene carbonate and acetonitrile, and examples of the solute include ammonium salt, amine salt, and amidine salt.

  FIG. 7 is a cross-sectional view of a laminated body for explaining the laminated structure in detail.

  Explaining the dimensions in the Z-axis direction, the dimension Z1 is the width of the main metal foils A1, K2, the dimension Z2 is the width of the active material layers AE1, AE2, KE1, KE2, and the dimension Z3 is the width of the exposed region (Z1-Z2). The dimension Z4 indicates the distance that the separator protrudes from the active material layer in the Z direction, the dimension Z5 indicates the width of the auxiliary metal foils T1 and T2, and the dimension Z6 indicates the width of the separators S1 and S2.

  Explaining the dimensions in the X-axis direction, the dimension X1 is the thickness of the main metal foils A1, K2, the dimension X2 is the thickness of the active material layers AE1, AE2, KE1, KE2, and the dimension X3 is the thickness of the separators S1, S2. The dimension X4 is the thickness of the auxiliary metal foils T1 and T2.

The preferred range of each dimension is as follows.
10 ≦ Z1 ≦ 1000mm
5mm ≦ Z2 ≦ 995mm
2mm ≦ Z3 ≦ 50mm
1mm ≦ Z4 ≦ 10mm
1mm ≦ Z5 ≦ 49mm
7mm ≦ Z6 ≦ 997mm

10 μm ≦ X1 ≦ 200 μm
10 μm ≦ X2 ≦ 500 μm
10 μm ≦ X3 ≦ 50 μm
10 μm ≦ X4 ≦ 500 μm

  Regarding the above-mentioned range, the range of Z1 indicates a realistic width of the electrode foil. The range of Z2 indicates the width (electrode width) of the active material layer that can be actually applied. Since the region defined by Z3 does not affect the device function, it is preferable that the region is small from the viewpoint of miniaturization. After the strip electrode is wound, both ends in the width direction are cut perpendicularly to the Z axis to cut the cut surface. It can be flat and the width can be set arbitrarily. However, since there is a risk of damaging the active material layer that functions effectively below the lower limit value during welding, the upper limit value is preferably greater than or equal to the upper limit value. It is preferable that

  Z4 defines the amount of protrusion of the separator, and this range does not affect the electrical characteristics and has a margin that prevents the separated metal foil from contacting. Since Z6 is the width of the separator, it was set as a value obtained by adding 2 mm to Z2.

  Moreover, Z5 prescribes | regulates the width | variety of auxiliary metal foil T1, T2, and was set to the width Z3-1mm of an exposure area | region.

  The range of X1 is a realistic thickness range of the main metal foil that is a current collector. A thicker one is preferable from the viewpoint of low resistance and high strength, but the degree of integration per unit volume Becomes so low that a large amount of charge cannot be accumulated. In order to prevent damage due to relatively low resistance, a thickness equal to or greater than the lower limit value is suitable, and the thickness that can sufficiently maintain strength with low resistance without greatly degrading the integration degree is a value equal to or less than the above upper limit value. is there.

  The range of X2 defines the realistic thickness range of the active material layer, and since the contact resistance of the electrode activated carbon particles is reduced, there is an advantage that the lower the internal resistance in the thickness direction, the lower the above upper limit value. However, if it is too thin, the function as the active material layer is not sufficient, so that it is preferably not less than the above lower limit value.

  The range of X3 is a realistic thickness range of the separator, and since the thinner one has the advantage that the internal resistance in the thickness direction becomes smaller, it is preferably not more than the above upper limit value. Is not sufficient, and the active material layer separated by the separator is effectively short-circuited.

  The range of X4 is equal to or less than the total thickness of the layers positioned between adjacent main metal foils, and in this case is equal to or less than 1250 μm. Therefore, from this viewpoint, X4 is preferably 500 μm or less, and the thickness thereof is preferably the same as that of the main metal foil from the viewpoint of reducing internal stress. Therefore, X4 is preferably 10 μm or more and 500 μm or less, which is the lower limit value of the thickness X1 of the main metal foil.

  According to the electrochemical device described above, the auxiliary metal foils T1 and T2 narrow the movable range in the radial direction (X-axis direction in FIG. 7) in the exposed regions of the main metal foils A1 and K2, and thus the main metal foils A1 and K2 The impedance change due to the positional deviation in the X-axis direction can be suppressed. Since the auxiliary metal foils T1, T2 have a thickness X4, the auxiliary metal foils T1,. The contact area between the side surface (XY plane) of T2 and the above-described electrode plate can be increased, and the contact resistance can be decreased. Thus, when the contact resistance is reduced, the internal resistance of the element can be suppressed and the output is improved. Further, heat can be radiated through the contact part. Therefore, this electrochemical device is superior in impedance characteristics and heat dissipation characteristics. The thickness X4 is preferably as large as possible from the above viewpoint.

  Further, the single thickness X4 of the auxiliary metal foils T1 and T2 is less than or equal to the gap distance L (= 4 × X2 + 2 × X3 + X1) between the opposing main metal foils A1 (or K2) in the exposed region (region of dimension Z3). is there. In this case, the auxiliary metal foils T1 and T2 do not spread the distance L between the main metal foils A1 and K2 at the end in the width direction (Z-axis direction), and the increase in the radial dimension is suppressed. can do. Of course, the single thickness X4 of the auxiliary metal foils T1 and T2 may coincide with the distance L of the gap, and in this case, the radial movement in the exposed region of the main metal foils A1 and K2 is reliably suppressed. In addition, each main metal foil A1 (or K2) can be electrically connected to improve strength and electrical stability.

  The material of the auxiliary metal foils T1, T2 is preferably the same as the material of the main metal foils A1, K2. For example, both are made of aluminum or copper. In this case, both materials can be easily welded, and since there is no potential difference between the materials at the time of contact, there is an advantage that characteristics are stabilized. The auxiliary metal foils T1 and T2 and the main metal foils A1 and K2 are electrically connected and preferably welded (welded), but this welding is sequentially performed while winding the laminate. It is preferable. This is because stress is hardly generated between them.

  Also, the auxiliary metal foil T1. When T2 is continuously or intermittently welded to the main metal foils A1 and K2 along the longitudinal direction of the main metal foils A1 and K2 (which becomes the circumferential direction after winding), these are strengthened. Can be fixed to.

  In the above description, the auxiliary metal foil is provided on one side of the main metal foil, but it may be provided on both sides. The thickness when the auxiliary metal foil is provided on both sides is ½ of the thickness when the auxiliary metal foil is provided on one side. When the thickness X4 of the auxiliary metal foil is smaller than the thickness X2 of the active material layer (electrode layer), the deformation of the end portion of the belt-like electrode becomes remarkably large. In addition, a fixed pressure is applied to the thickness direction at the time of manufacture of a laminated body.

  When the thickness X4 is smaller than the distance L (= 4 × X2 + 2 × X3 + X1), a slight gap is formed between the auxiliary metal foils T1 and T2 and the main electrodes A1 and K2, and therefore in the Z-axis direction. Accordingly, a penetration gap for the electrolyte introduced along the line is ensured, and the electrolyte sufficiently penetrates into the inside, variation in impedance is suppressed, and impedance characteristics are improved.

  The thickness in the Z-axis direction of the high resistance layers TC1 and TC2 is preferably 10 μm to 200 μm from the viewpoint of no peen holes and ensuring flexibility, and the electrolyte introduced from the outside along the Z-axis direction In order to introduce the active material layer into the active material layer, it is preferable that the high resistance layers TC1 and TC2 do not contact the side surfaces of the separators S1 and S2 and have a slight gap.

  A ... anode electrode, A1, K2 ... main metal foil, AE1, AE2, KE1, KE2 ... active material layer, K ... cathode electrode, T1, T2 ... auxiliary metal foil, TC1, TC2: High resistance layer.

Claims (5)

A wound strip-shaped laminate, and an enclosure that houses the laminate together with an electrolyte solution, the strip-shaped laminate having a pair of strip electrodes and a pair of separators sandwiching one of the strip electrodes. Each of the strip-shaped electrodes is a wound-type electrochemical device having a strip-shaped main metal foil and an active material layer provided on the main metal foil.
The positions of the adjacent strips of the main metal foil are shifted in the width direction, and an exposed region in which the active material layer is not formed is set in a region where these do not overlap, A strip-shaped auxiliary metal foil is provided along the longitudinal direction of the main metal foil,
On the inner surface of the auxiliary metal foil, a high resistance layer having a higher resistivity than the auxiliary metal foil is provided,
An electrochemical device characterized by that. On the opposite surface of the auxiliary metal foil to the main metal foil, there is no high resistance layer having a high resistivity of the auxiliary metal foil,
The electrochemical device according to claim 1. The high resistance layer is made of a material that can be impregnated with an electrolyte solution.
The electrochemical device according to claim 1. The active material layer contains activated carbon and a binder resin,
The material of the high resistance layer is the same as the material of the binder resin contained in the active material layer.
The electrochemical device according to claim 1 or 3 characterized by things. 5. The electrochemical device according to claim 1, 3 or 4, wherein the material of the high resistance layer is made of polypropylene, polyethylene, polyimide, or polyamideimide.

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