JP7633655B2 - Capacitor and manufacturing method thereof - Google Patents

Description

The present invention relates to a capacitor in which lead terminals are connected to the anode foil and cathode foil of a capacitor element housed in a main case, and to a method for manufacturing the same.

A conventional capacitor has a cylindrical main case with an opening at one end, a capacitor element disposed within the main case, and a sealing body attached to the opening of the main case.

The capacitor element is made by winding a cathode foil and an anode foil with a separator between them, and a lead terminal is connected to each of the cathode foil and the anode foil. Each lead terminal includes a first member and a second member. The first member is disposed inside the main body case. The second member is connected to the first member and is led out to the outside of the main body case.

One end of the first member of the lead terminal is an elongated flat plate. The cathode foil or anode foil is connected to one surface of the flat plate. At this time, a separator is arranged facing the other surface of the flat plate. The other end of the first member is a columnar portion. The columnar portion is inserted into the through hole of the sealing body.

The flat plate portion is formed by crushing a part of a columnar member into a flat plate shape and then cutting off a part of it. The width of the flat plate portion is adjusted by cutting both ends of the flat plate portion.

JP 2017-168810 A

In the above conventional capacitor, when cutting the flat portion of the lead terminal, if the cutting blade cuts the flat portion in the thickness direction from the first surface side to the second surface side of the flat portion, a burr is formed on the second surface side. Therefore, when the first surface is connected to the cathode foil or anode foil, the burr can damage the separator, which can cause a short circuit between the cathode foil and the anode foil.

On the other hand, when the second surface of the flat plate is connected to the cathode foil or anode foil, the edges formed on both sides of the first surface by cutting the flat plate come into contact with the separator. For this reason, when the capacitor is used in a state where it is subjected to repeated vibrations, the edges may damage the separator, which may cause short circuits between the cathode foil and the anode foil.

In order to prevent the separator from being damaged by the edge of the flat plate portion, it is possible to process the edge portion on the first surface side of the flat plate portion. In other words, damage to the separator can be prevented by providing an edge removal portion in which the edge portion is removed by grinding or recessing the edge portion.

However, when an edge removal section is provided at the edge of the flat plate, work hardening occurs on both sides of the flat plate in the width direction perpendicular to the longitudinal direction. Because the pull-out terminal is formed by crushing a columnar member to form the flat plate, a sloped section is formed between the columnar section and the flat plate, where the periphery is sloped and the thickness gradually decreases. If the position of work hardening caused by processing the edge removal section is close to the position of work hardening caused by forming the sloped section, distortion will be large.

As a result, if a crack occurs at the tip of the inclined portion due to stress being applied to the lead-out terminal when the capacitor is subjected to vibration, the crack will progress toward the end face of the edge removal portion, causing a new problem in which the flat portion breaks.

Therefore, the capacitor of the present invention aims to prevent short circuits between the cathode foil and the anode foil, as well as to prevent damage to the lead-out terminal.

In order to achieve the above object, the present invention provides a capacitor comprising a capacitor element in which a pair of electrode foils consisting of a cathode foil and an anode foil are wound via a separator and a lead terminal is connected to each of the electrode foils, a cylindrical main body case having a closed surface on the upper surface thereof and housing the capacitor element, and a sealing body having a pair of through holes through which the lead terminals are inserted, the lead terminals being formed of a first member and a second member, the first member being a thin plate-like member having a columnar portion inserted into the through holes and a first surface and a second surface opposed in the thickness direction, the second surface being joined to the electrode foil. It has a flat plate portion and an inclined portion whose peripheral surface is inclined with respect to the axial direction of the columnar portion to connect the columnar portion and the flat plate portion, and an edge-removed portion in which the edges have been removed is provided at both ends of the width direction of the first surface of the flat plate portion and extends in the vertical direction, both side surfaces in the width direction of the flat plate portion are formed by cut surfaces, the upper end of the edge-removed portion reaches the end surface of the closed surface side of the flat plate portion and the lower end is disposed below the electrode foil and above the upper end of the inclined portion, and the second member is connected to the columnar portion and drawn out to the outside of the main body case to form a connection terminal portion when mounted.

The present invention is also characterized in that in the capacitor having the above configuration, the inclined portion has a first inclined portion and a second inclined portion formed on both sides of the flat portion, the tip of the first inclined portion on the flat portion side is disposed closer to the electrode foil than the tip of the second inclined portion on the flat portion side, and the lower end of the edge removal portion is disposed above the first inclined portion.

The present invention is also characterized in that in the capacitor having the above configuration, the edge removal portion is formed by a recess recessed from the back surface of the flat plate portion toward the front surface.

The present invention is also characterized in that in the capacitor having the above configuration, the distance in the vertical direction between the lower end of the edge removal portion and the tip of the inclined portion on the flat portion side is 0.1 mm or more.

The present invention also relates to a method for manufacturing a capacitor comprising a capacitor element in which a pair of electrode foils consisting of a cathode foil and an anode foil are wound via a separator and a lead terminal is connected to each of the electrode foils, a cylindrical main body case having a closed surface on the upper surface and housing the capacitor element, and a sealing body having a pair of through holes through which the lead terminal is inserted, the lead terminal being formed of a first member and a second member, the first member having a columnar portion inserted into the through hole, a thin plate-like flat portion having a first surface and a second surface opposed in the thickness direction and the second surface being joined to the electrode foil, and an inclined portion having a peripheral surface inclined with respect to the axial direction of the columnar portion to connect the columnar portion and the flat portion. The second member is connected to the columnar portion and is pulled out to the outside of the main body case to form a connection terminal portion when mounted, and includes a process of cutting both ends of the flat plate portion in the width direction from the first surface side toward the second surface side to form the flat plate portion to a predetermined width, a process of forming edge-removed portions by removing the edges of both ends of the first surface of the flat plate portion in the width direction, and a process of attaching the flat plate portion to the electrode foil, and is characterized in that the edge-removed portions are provided extending in the vertical direction, both side surfaces of the flat plate portion in the width direction are formed by cut surfaces, the upper end of the edge-removed portion reaches the end surface of the flat plate portion on the closed surface side, and the lower end is disposed below the electrode foil and above the upper end of the inclined portion.

As described above, in the capacitor of the present invention, the upper end of the edge removal portion reaches the end face on the closed surface side of the flat portion and the lower end is positioned below the electrode foil and above the inclined portion, thereby preventing shorting between the cathode foil and the anode foil, preventing cracks at the boundary between the inclined portion and the flat portion, and preventing damage to the lead-out terminal.

1 is a cross-sectional view of a capacitor according to an embodiment of the present invention; FIG. 2 is a perspective view showing a portion of a capacitor element of a capacitor according to an embodiment of the present invention; FIG. 1 is a front view showing a lead-out terminal of a capacitor according to an embodiment of the present invention; FIG. 1 is a rear view showing a lead-out terminal of a capacitor according to an embodiment of the present invention; FIG. 1 is a side view showing a lead-out terminal of a capacitor according to an embodiment of the present invention; AA line cross-sectional view of FIG. Enlarged view of part C in FIG. FIG. 1 shows a method for forming an edge removal portion. FIG. 1 illustrates another method for forming an edge removal portion.

One embodiment of the present invention will now be described with reference to the accompanying drawings. Figure 1 shows a cross-sectional view of a capacitor 100. The capacitor 100 comprises a main case 1, a capacitor element 2, and a sealing body 8.

The main case 1 is made of a metal such as aluminum and is formed into a cylindrical shape with a lid. An opening 1a is provided on one end (lower end) of the main case 1, and the other end (upper end) is a closed surface 1b.

The capacitor element 2 is housed in the main body case 1. Figure 2 is a perspective view showing a portion of the capacitor element 2.

The capacitor element 2 has a cathode foil 3, an anode foil 4, a separator 5, and a lead terminal 6. The cathode foil 3, the anode foil 4, and the separator 5 each have a long, strip-like shape. As shown in FIG. 2, the cathode foil 3 and the anode foil 4 are wound with the separator 5 interposed therebetween. That is, a pair of electrode foils consisting of the cathode foil 3 and the anode foil 4 are wound with the separator 5 interposed therebetween. The cathode foil 3 and the anode foil 4 are each connected to a lead terminal 6 (see FIG. 1).

As is well known, the wound capacitor element 2 holds an electrolyte. The winding tape 7 is wrapped around the outermost circumference of the cylindrically wound capacitor element 2, but in Figure 2 it is shown in an unfolded state so that the state of each part can be easily understood.

As shown in FIG. 2, the width of the separator 5 (the dimension perpendicular to the longitudinal direction) is greater than the widths of the cathode foil 3 and anode foil 4 (the dimensions perpendicular to the longitudinal direction). This prevents short circuits between the cathode foil 3 and anode foil 4.

As shown in FIG. 1, the sealing body 8 seals the opening 1a. First, the sealing body 8 is attached to the opening 1a of the main case 1. In this state, the open end of the main case 1 is bent toward the underside of the sealing body 8. In addition, the outer surface of the part of the main case 1 that corresponds to the side of the sealing body 8 is drawn inward. In this way, the sealing body 8 is fixed to the opening 1a of the main case 1.

The drawer terminal 6 has a first member 9 and a second member 10. The first member 9 is made of, for example, aluminum. The second member 10 is made of, for example, CP wire with a copper layer provided on the outer surface of an iron wire. The second member 10 is fixed to the first member 9 by welding or the like.

A long and narrow flat portion 9a is provided on one end of the first member 9. The flat portion 9a is formed by pressing one end of a cylindrical member (e.g., cylindrical aluminum material). The flat portion 9a is thin. The cathode foil 3 or the anode foil 4 is mechanically and electrically fixed to the flat portion 9a by caulking.

A columnar portion 9b is provided on the other end side (sealing body 8 side) of the first member 9. The columnar portion 9b is a cylindrical member (e.g., cylindrical aluminum material) that is used in its original shape. As shown in FIG. 1, the columnar portion 9b is inserted (pressed) into the through hole 8a of the sealing body 8. This causes a portion of the lead-out terminal 6 to be pulled out to the outside of the main case 1.

A hole (not shown) is provided in the outer portion of the main body case 1 of the columnar portion 9b. One end of the second member 10 is inserted into this hole. In this state, the first member 9 and the second member 10 are mechanically and electrically fixed together by welding.

The other end of the second member 10 is bent at the bottom surface of the seat plate 11 that supports the main body case 1. This makes the other end of the second member 10 a connection terminal portion 10a. It is also possible to make the terminal portion without bending it.

Next, the first member 9 will be described in detail with reference to Figures 3 to 6.

Figure 3 is a front view showing the pull-out terminal 6. Figure 4 is a rear view showing the pull-out terminal 6. Figure 5 is a side view showing the pull-out terminal 6. In Figure 5, not only the pull-out terminal 6 is shown, but also part of the cathode foil 3. Figure 6 is a cross-sectional view taken along line A-A in Figure 3. Figure 7 is an enlarged view of part C in Figure 6. Note that Figures 3, 4, and 5 show the pull-out terminal 6 with part of the second member 10 omitted.

The direction of the arrow L is the up-down direction. The up-down direction L is the axial direction of the columnar portion 9b and the longitudinal direction of the flat plate portion 9a. The direction of the arrow W is the width direction perpendicular to the up-down direction L. This width direction W is parallel to the first surface 9g and the second surface 9h that face each other in the thickness direction of the flat plate portion 9a.

As described above, the flat portion 9a of the first member 9 is formed into a thin plate shape by press-molding a cylindrical member. An inclined portion is formed between the columnar portion 9b and the flat portion 9a of the first member 9. The inclined portion has a first inclined portion 9d and a second inclined portion 9e formed on both sides of the flat portion 9a. As shown in Figures 3, 4, and 5, the peripheral surfaces of each of the first inclined portion 9d and the second inclined portion 9e are inclined with respect to the up-down direction L and connect the columnar portion 9b and the flat portion 9a.

The tip 9j of the first inclined portion 9d on the flat portion 9a side and the tip 9p of the second inclined portion 9e on the flat portion 9a side are offset in the vertical direction L. That is, the tip 9j of the first inclined portion 9d on the flat portion 9a side is positioned closer to the electrode foil than the tip 9p of the second inclined portion 9e on the flat portion 9a side. This prevents stress from concentrating during vibration.

Here, a first inclined portion 9d having a tip 9j is provided on the first surface 9g side of the flat plate portion 9a, and a second inclined portion 9e having a tip 9p lower than the tip 9j is provided on the second surface 9h side of the flat plate portion 9a. The first inclined portion 9d may be provided on the second surface 9h side of the flat plate portion 9a, and the second inclined portion 9e may be provided on the first surface 9g side of the flat plate portion 9a. Note that the shapes of the first inclined portion 9d and the second inclined portion 9e may be shapes other than those shown in the figure.

As shown in Figs. 3 and 6, edge-removed portions 9f, which are portions where the edges have been removed, are formed on both ends of the first surface 9g of the flat plate portion 9a in the width direction W. The edge-removed portions 9f are formed along the side surfaces 9c.

The edge removal portion 9f is recessed (concave) from the first surface 9g side to the second surface 9h side of the flat plate portion 9a. The cross-sectional shape of the edge removal portion 9f is not limited to that shown in FIG. 6 and may be other shapes.

As shown in FIG. 5, in the vertical direction L of the flat plate portion 9a, the upper end 9n of the edge removal portion 9f reaches the end face 9m on the closed surface 1a side of the flat plate portion 9a. The edge removal portion 9f may also be formed on the entire end of the end face 9m. The lower end 9i of the edge removal portion 9f is located below the cathode foil 3 and above the upper ends of the first and second inclined portions 9d and 9e.

Furthermore, the lower end 9i of the edge removal portion 9f is disposed above the tip 9j of the first inclined portion 9d. In other words, the lower end 9i of the edge removal portion 9f is disposed between the tip 9j and the lower end 3a of the cathode foil 3 (the range indicated by the arrow S in FIG. 5).

The upper end 9n of the edge removal portion 9f reaches the end surface 9m of the flat plate portion 9a on the closed surface 1a side, and the lower end 9i is located below the electrode foil, so that the edges of both ends of the flat plate portion 9a in the width direction W do not come into contact with the separator 5. Therefore, even if the capacitor 100 is repeatedly subjected to vibration, damage to the separator 5 due to the edges of the flat plate portion 9a is prevented, and short circuits between the cathode foil 3 and the anode foil 4 can be prevented.

In particular, when the thickness of the separator 5 is 40 μm or less for the purpose of increasing the capacity of the capacitor 100, it can be very effective in preventing short circuits.

In addition, since the lower end 9i of the edge removal portion 9f is arranged above the upper ends of the first and second inclined portions 9d and 9e, the edge removal portion 9f is not formed on the sides of the first and second inclined portions 9d and 9e. Therefore, distortion due to the formation of the edge removal portion 9f does not occur on the sides of the first and second inclined portions 9d and 9e. Furthermore, there is no area where work hardening due to the formation of the edge removal portion 9f occurs between the lower end 9i of the edge removal portion 9f and the upper ends of the first and second inclined portions 9d and 9e. Therefore, when vibration is repeatedly applied to the capacitor 100, the stress concentrated at the boundary between the first and second inclined portions 9d and 9e and the flat portion 9a is dispersed and spread over a wide area on both sides of the flat portion 9a. This prevents cracks at the boundary between the first and second inclined portions 9d and 9e and the flat portion 9a, and prevents damage to the lead-out terminal 6.

Damage to the pull-out terminal 6 due to vibration is likely to occur when the height H (the length from the top end of the main body case 1 to the bottom end of the pull-out terminal 6, see Figure 1) is large relative to the diameter D (the diameter of the main body case 1, see Figure 1) of the capacitor 100. For this reason, it is highly effective in preventing damage to the pull-out terminal 6 in the case of a capacitor 100 whose height H is equal to or greater than the diameter D.

In the vertical direction L, the distance between the bottom end 9i of the edge removal portion and the tip 9j of the first inclined portion 9d (the length indicated by the arrow T in FIG. 5) is preferably 0.1 mm or more, and is preferably at least half the distance between the tip 9j of the first inclined portion 9d and the bottom end 3a of the cathode foil 3 (the length indicated by the arrow S in FIG. 5). The length indicated by the arrow S is preferably 0.2 to 1 mm; if it is longer than 1 mm, the vibration resistance will be weakened, and if it is less than 0.2 mm, the inclined portion and the foil will be more likely to come into contact with each other, which will easily cause a short circuit.

Note that while FIG. 5 shows the case where the cathode foil 3 is connected to the flat plate portion 9a, the same applies when the anode foil 4 is connected to the flat plate portion 9a.

The first member 9 is formed by a pressing process, a cutting process, and an edge removal process. As described above, the pressing process presses one end of a cylindrical member (e.g., a cylindrical aluminum material) to form a thin plate-like flat portion 9a. At this time, the flat portion has a larger width than the columnar portion 9b formed by the original cylindrical member.

At the same time, a first inclined portion 9d and a second inclined portion 9e are formed between the columnar portion 9b and the flat portion 9a of the first member 9.

Next, in the cutting process, both sides of the flat portion in the width direction W are cut to adjust the dimension of the flat portion 9a in the width direction W. This cutting is performed by pressing a cutting blade in the thickness direction from the first surface 9g side to the second surface 9h side of the flat portion 9a. As a result, the side surface 9c of the flat portion 9a is formed. The side surface 9c is the cut surface created by the cutting. At this time, as shown in FIG. 7, a burr 9k is formed on the second surface 9h. As described above, the second surface 9h of the flat portion 9a is fixed to the cathode foil 3 or the anode foil 4 by caulking, so that damage to the separator 5 by the burr 9k is prevented.

Next, in the edge removal process, the edges of both ends of the first surface 9g of the flat plate portion 9a are removed to form the edge-removed portions 9f. The edge removal process is carried out by pressing both ends of the first surface 9g of the flat plate portion 9a or by cutting along the longitudinal direction (L).

The cutting process and the edge removal process may be performed simultaneously. For example, as shown in FIG. 8, a convex portion 20a is provided on the inside (the center side of the flat plate portion 9a) of a pair of blades 20 that cut the side surface of the flat plate portion 9a. By cutting the flat plate portion 9a from the first surface 9g side to the second surface 9h side using such blades 20, the side surface 9c of the flat plate portion 9a and the edge removal portion 9f are formed simultaneously.

The pressing process, cutting process and edge removal process may also be performed simultaneously. For example, as shown in FIG. 9, a recess 21a is provided in a part of a die 21 used in press molding. The recess 21a extends in the longitudinal direction (L) of the flat plate portion 9a. The width of the die 21 is set to correspond to the distance between both side surfaces 9c in the width direction W of the flat plate portion 9a. A cylindrical member (e.g., cylindrical aluminum material) is pressed with this die 21, and a blade 20 for forming the side surface 9c is lowered along the die 21 to cut it. This forms a thin plate-like flat plate portion 9a, and simultaneously forms the side surface 9c of the flat plate portion 9a and the edge removal portion 9f.

According to this embodiment, the second surface 9h of the flat plate portion 9a is connected to the electrode foil (anode foil 3 and cathode foil 4), so even if burrs are formed on the second surface 9h side due to the cut surfaces on both sides of the flat plate portion 9a, damage to the separator 5 arranged on the first surface 9g side by the burrs is prevented. In addition, an edge removal portion 9f is provided on the first surface 9g side, and the lower end 9i of the edge removal portion 9f is arranged below the electrode foil, so that the edges of both ends in the width direction of the flat plate portion 9a do not contact the separator 5. Therefore, even if vibrations are repeatedly applied to the capacitor 100, damage to the separator 5 by the edges of the flat plate portion 9a can be prevented, and short circuits between the cathode foil 3 and the anode foil 4 can be prevented.

In addition, since the lower end 9i of the edge removal portion 9f is arranged above the first and second inclined portions 9d and 9e, the edge removal portion 9f is not formed on the side of the first and second inclined portions 9d and 9e. Therefore, distortion due to the formation of the edge removal portion 9f does not occur on the side of the first and second inclined portions 9d and 9e. Furthermore, there is no area between the lower end of the edge removal portion 9f and the upper ends of the first and second inclined portions 9d and 9e where work hardening due to the formation of the edge removal portion 9f occurs. Therefore, when vibration is repeatedly applied to the capacitor 100, the stress concentrated at the boundary between the first and second inclined portions 9d and 9e and the flat portion 9a is dispersed and spread over a wide area on both sides of the flat portion 9a. This prevents cracks at the boundary between the first and second inclined portions 9d and 9e and the flat portion 9a, and prevents damage to the lead-out terminal 6.

In addition, the tip of the first inclined portion 9d formed on one surface of the flat plate portion 9a is disposed closer to the electrode foil 9e than the second inclined portion formed on the other surface, and the lower end of the edge removal portion 9f is disposed higher than the upper end of the first inclined portion 9d, thereby reliably preventing cracks at the boundaries between the flat plate portion 9a and the first and second inclined portions 9d, 9e.

In addition, since the edge removal portion 9f is formed by a recess recessed from the first surface 9g of the flat plate portion 9a toward the second surface 9h, the edge removal portion 9f can be easily formed, and the side surface of the flat plate portion 9a and the edge removal portion 9f can be formed simultaneously.

In addition, the distance between the bottom end of the edge removal portion 9f and the tips of the first and second inclined portions 9d, 9e on the flat portion 9a side in the vertical direction is 0.1 mm or more, so cracks at the boundaries between the first and second inclined portions 9d, 9e and the flat portion 9a can be reliably prevented.

In this embodiment, the edge removal portion 9f is provided only on the first surface 9g side of the flat plate portion 9a, but the edge removal portion 9f may also be provided on the second surface 9h side of the flat plate portion 9a. This removes burrs 9k, making the product safer.

This invention is used in capacitors that are used in various electronic devices.

REFERENCE SIGNS LIST 1 Main case 2 Capacitor element 3 Cathode foil 4 Anode foil 5 Separator 6 Lead terminal 7 Winding tape 8 Sealing body 8a Through hole 9 First member 9a Flat plate portion 9b Columnar portion 9c Side surface (cut portion)
9d: first inclined portion; 9e: second inclined portion; 9f: edge removed portion; 10: second member; 10a: connection terminal portion; 100: capacitor

Claims (4)

A capacitor including a capacitor element in which a pair of electrode foils, each consisting of a cathode foil and an anode foil, are wound with a separator therebetween and lead terminals are connected to the electrode foils, a cylindrical main case having a closed surface on an upper surface thereof and housing the capacitor element, and a sealing body having a pair of through holes for inserting the lead terminals therethrough and sealing a lower surface of the main case, wherein the lead terminals are formed from a first member and a second member,
the first member has a columnar portion inserted into the through hole, a thin plate-like flat portion having a first surface and a second surface opposed in a thickness direction, the second surface being joined to the electrode foil, and an inclined portion whose peripheral surface is inclined with respect to an axial direction of the columnar portion to connect the columnar portion and the flat portion, and edge-removed portions in which edges have been removed are provided extending in a vertical direction at both ends in a width direction of the first surface of the flat portion, both side surfaces in the width direction of the flat portion are formed by cut surfaces, an upper end of the edge-removed portion reaches an end face on the closed surface side of the flat portion, and a lower end is disposed below the electrode foil and above the upper end of the inclined portion,
the second member is connected to the columnar portion and is extended to the outside of the main body case to form a connection terminal portion when mounted ;
A capacitor characterized in that the inclined portion has a first inclined portion and a second inclined portion formed on both sides of the flat portion, the tip of the first inclined portion on the flat portion side is positioned closer to the electrode foil than the tip of the second inclined portion on the flat portion side, and the lower end of the edge removal portion is positioned higher than the upper end of the first inclined portion . 2. The capacitor according to claim 1 , wherein the edge removal portion is formed by a recess recessed from the first surface of the flat plate portion toward the second surface. 3. The capacitor according to claim 1 , wherein the distance between a lower end of the edge removed portion and a tip end of the inclined portion on the flat portion side in the vertical direction is 0.1 mm or more. A method for manufacturing a capacitor comprising: a capacitor element in which a pair of electrode foils, each consisting of a cathode foil and an anode foil, is wound with a separator therebetween and lead terminals are connected to the electrode foils; a cylindrical main case having a closed surface on an upper surface thereof and housing the capacitor element; and a sealing body having a pair of through holes for inserting the lead terminals therethrough and sealing a lower surface of the main case,
the lead-out terminal is formed of a first member and a second member,
the first member has a columnar portion inserted into the through hole, a thin plate-like flat portion having a first surface and a second surface opposed to each other in a thickness direction, the second surface being joined to the electrode foil, and an inclined portion having a peripheral surface inclined with respect to an axial direction of the columnar portion to connect the columnar portion and the flat portion,
the second member is connected to the columnar portion and is extended to the outside of the main body case to form a connection terminal portion when mounted;
cutting both ends of the flat portion in the width direction from the first surface side toward the second surface side to form the flat portion to a predetermined width; forming edge-removed portions by removing edges of both ends of the flat portion in the width direction on the first surface; and attaching the flat portion to the electrode foil,
the edge removal portion is provided extending in a vertical direction, both side surfaces in a width direction of the flat plate portion are formed by cut surfaces, an upper end of the edge removal portion reaches an end face of the flat plate portion on the closed surface side, and a lower end of the edge removal portion is disposed below the electrode foil and above an upper end of the inclined portion ,
a first inclined portion and a second inclined portion formed on both sides of the flat portion, the tip of the first inclined portion on the flat portion side is positioned closer to the electrode foil than the tip of the second inclined portion on the flat portion side, and the lower end of the edge removal portion is positioned higher than the upper end of the first inclined portion .

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