JP2001244149A - Multilayer electric double-layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer electric double-layer capacitor which is low in internal resistance, high in electrostatic capacity and high in productivity. SOLUTION: A cell 14 for an electric double-layer capacitor is constituted into a structure, where an almost rectangle-shaped laminate formed by laminating a polarized electrode 3 on the surface on at least one side of the surfaces of a current-collecting body 2 is housed between two almost rectangle-shaped separators 5 and 5 and at the same time, a conductor 1 for forming terminals is provided on at least a part of the side parts of the body 2 and the conductor 1 is folded up where the conductor 1 pinches the end parts of the separators 5 and 5 to form the terminals 6 on the end parts of the separators 5 and 5 and a multilayer electric double-layer capacitor 20 is manufactured into a structure that the capacitor 20 is provided with a plurality of the cells 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric double layer capacitor formed by laminating a polarizable electrode, a current collector and a separator.

[0002]

2. Description of the Related Art Recently, an electric double layer capacitor capable of charging and discharging a large current has been receiving attention. An electric double layer capacitor is a capacitor that uses an electric double layer formed by the polarization of ions at the interface between the electrode and the electrolyte, and can charge a large capacitance compared to conventional capacitors, and can rapidly charge and discharge. Is possible and its application is expected.

In such an electric double layer capacitor,
A laminate in which polarizable electrodes are laminated on both sides of a substantially rectangular plate-shaped current collector as one unit of electrode pair forming a positive electrode or a negative electrode, and alternately laminated, and the electrode pair is insulated by a separator. There is known a multilayer electric double layer capacitor having a configuration in which the laminate is housed in a housing such as a gasket or sealed with a film such as an aluminum laminate.

This multilayer electric double-layer capacitor can produce a square electric double-layer capacitor with respect to the electric double-layer capacitor in a spiral type, and has a high mountability between electric double-layer capacitors or other members. And the internal resistance can be reduced.

In the above-mentioned multilayer electric double-layer capacitor, terminals protruding from a part of the side of the current collector are provided, and the terminals forming the positive electrode and the terminals forming the negative electrode are electrically connected to each other. There is known a method of connecting to an extraction electrode, connecting the electrode to an extraction electrode, and projecting the sealing member of the electric double layer capacitor to an external circuit.

[0006]

However, a plurality of cells for an electric double layer capacitor (hereinafter simply referred to as a cell) each including such a separator-polarizable electrode-current collector-polarizable electrode-separator as one unit are provided. In the laminated electric double layer capacitor, the position and the contact area between the members are easily changed during the manufacturing or use, and the contact state and the contact area between the members are changed by the position shift in the cell. Capacitance decreases due to misalignment between the polarizable electrodes, the internal resistance of the electric double layer capacitor increases due to misalignment between the polarizable electrode and the current collector, and in some cases, the polarizable electrode and the separator However, there is a possibility that the polarizable electrodes may come into contact with each other due to misalignment and short-circuit.

Therefore, for example, a laminate of a polarizable electrode and a current collector is housed in a bag-shaped separator such that the terminal portion provided on the current collector protrudes from the separator. There is known a method of preventing a short circuit due to contact between them.

However, even by such a method, it is not possible to prevent the displacement of the laminate of the current collector and the polarizable electrode, and since the separator is not fixed, the displacement may occur depending on the case. There is a risk that the polar electrodes may come into contact with each other, causing a short circuit, and furthermore, since the terminal portion is thin and formed so as to protrude from the separator, the strength and shape retention of the terminal portion are low, and Cracks and the like occur at the interface with the current collector, increasing the internal resistance value, and in some cases, disconnection may occur. Furthermore, the thickness difference between the current collector portion and the terminal portion of the cell is large,
This was one of the causes of displacement during stacking.

In Japanese Patent Application Laid-Open No. 10-74672, a thick metal plate for forming a terminal is provided on one side of the current collector, and unnecessary portions of the plate are cut off to reduce the thickness of the current collector. By manufacturing a thick terminal, and by approximating the thickness of the terminal to the thickness of the laminate of the current collector and the polarizable electrode, the strength and shape retention of the terminal can be increased, and the position at the time of stacking the cells can be improved. It is described that the displacement can be reduced.

However, even in such a method, since the current collector, the polarizable electrode, and the separator are not adhered, it is impossible to prevent displacement between the respective layers.
Since the terminal has a shape protruding from the separator,
The terminal is susceptible to mechanical shock, and when processing the above-mentioned metal plate for forming a terminal, there is a risk that the metal plate may be damaged or deformed, or cracks may occur at the interface between the current collector and the terminal. Thus, the effect of reducing the internal resistance was not sufficient.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to prevent displacement of a current collector, a separator, and a polarizable electrode in a cell for an electric double layer capacitor, and to provide an electrostatic capacitance. It is an object of the present invention to provide a high-productivity multilayer electric double-layer capacitor capable of increasing internal resistance, reducing the internal resistance value, and easily stacking a plurality of the cells.

[0012]

In order to solve the above problems, the present inventors have studied the structure of a cell for an electric double layer capacitor, and found that a current collector and a polarizable electrode are housed between two separators. And, a terminal forming conductor is provided on the side of the current collector, and the terminal forming conductor is folded a plurality of times so as to sandwich the side of the separator to form a terminal. Since the displacement between the current collector, the polarizable electrode, and the separator is reduced, and the terminal is reinforced by the separator and a thick terminal can be formed, the strength and shape retention of the terminal can be improved. Capacitance and low internal resistance can be achieved simultaneously,
It has been found that a positional shift due to a partial thickness difference of cells at the time of cell stacking can be prevented, and productivity is improved.

That is, the electric double layer capacitor of the present invention accommodates a substantially rectangular laminate in which a polarizable electrode is laminated on at least one surface of a current collector between two substantially rectangular separators. A conductor for forming a terminal is provided on at least a part of the side of the current collector;
It is characterized by comprising a plurality of cells for an electric double layer capacitor in which the terminals are formed so as to sandwich the ends of the separators.

Here, the two separators are bag-shaped bodies, the folded portions of the terminal forming conductors are partially welded to each other, and the current collector and the polarizability of the electric double layer capacitor cell are determined. It is desirable that the thickness of the portion where the laminate with the electrode is housed is the same as the thickness of the portion where the terminal of the cell is formed.

In addition, the electric double layer capacitor cell forming a plurality of positive electrodes and the negative electrode on which the terminals forming the positive electrode and the negative electrode are formed is alternately laminated so that the terminals forming the positive electrode and the negative electrode do not contact with each other. Preferably, the terminals forming the positive electrode and the terminals forming the negative electrode are electrically connected to each other.

Further, a through hole is formed through the terminal and the separator of the plurality of electric double layer capacitor cells forming the positive electrode and the negative electrode, and two conductive rods forming the positive electrode and the negative electrode are formed in the through holes. Let each penetrate,
It is preferable that the electric double layer capacitor cells are stacked and fixed.

Also, the terminals forming the positive electrode and the negative electrode are as follows:
The cell 1 may be provided on the same side surface of the cell stack. In this case, the cell 1 for an electric double layer capacitor serving as the negative electrode
The terminals of the electric double layer capacitor cell serving as the positive electrode, which are disposed with a sheet interposed therebetween, are connected to the two separator sides of the electric double layer capacitor cell serving as the negative electrode. It is desirable that the parts are electrically connected via a conductor formed so as to sandwich the parts.

Further, a terminal forming the positive electrode and a terminal forming the negative electrode may be provided on opposite side surfaces of the cell stack.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a method for manufacturing an electric double layer capacitor according to the present invention is a cell for an electric double layer capacitor (hereinafter simply referred to as a cell) which is a part of the method.
1 and the schematic cross-sectional view of FIG. 2 showing the manufacturing process. First, a current collector 2 having a substantially rectangular terminal forming conductor (hereinafter simply referred to as a conductor) 1 provided on one side is prepared, and polarizable electrodes 3 and 3 are provided on both surfaces of the current collector 2. Laminate (see step (a)).

The polarizable electrode 3 is desirably a substantially rectangular plate, for example, a plate having a thickness of 0.1 to 3 mm, particularly 0.15 to 1 mm, contains activated carbon and has a high specific surface area. . Further, the polarizable electrode 3 is filled with an electrolytic solution described later.

On the other hand, the conductor 1 and the current collector 2
It is desirable to be made of a metal foil of 50 μm thickness such as aluminum, tantalum, titanium, silver platinum, gold, etc. In particular, it is preferably made of a metal foil containing aluminum as a main component in terms of price, resistance value, workability, and durability. desirable.

The conductor 1 is formed integrally on one side of the current collector 2. Specifically, for example, the above-mentioned metal foil is cut into a shape in which the conductor 1 and the current collector 2 are combined to form an integral body. Alternatively, it can be formed by forming the conductor 1 and the current collector 2 as separate bodies and then joining these ends.

As shown in FIG. 3, the position of the current collector 2 where the conductor 1 is formed is as follows: (A) formed on one side of the current collector 2; 2 is formed to protrude to a part of the side part, in particular, to a width of not more than half the length of the side, (C) In addition to the configuration of (A) or (B), the conductor 1 A body 2 having a protruding portion 1a protruding outside of the top of the side on which the conductor 1 is formed is exemplified.

According to the configuration (A), the terminal 6 can be easily manufactured, and the strength and shape retention of the terminal 6 described later can be enhanced. When the cells 14b forming the negative electrode are alternately stacked, the terminals of the adjacent cells can be formed so as not to contact with each other. As a result, the terminal forming the positive electrode and the terminal forming the negative electrode can be formed on the same side surface of the stacked body. . Further, according to the configuration of (C), by folding the protruding portion toward the current collector surface side, the thickness of the terminal can be further increased, the strength of the terminal can be increased, and the thickness of the terminal forming portion of the cell can be reduced. The cells can be stably stacked by approximating the thickness of the current collector portion of the cells.

Next, a laminated body of the current collector 2 and the polarizable electrodes 3 and 3 is placed on a part of the conductor 1, specifically, such that a folded portion of the conductor 1 described later projects. It is stored in the separators 5, 5 (see step (b)). At this time, the width of the conductor 1 accommodated in the separator 5 is set to be equal to the width of the terminal 6, that is, the side of the laminate of the current collector 2 and the polarizable electrode 3 is separated by the height of the terminal 6. It is desirable to be disposed so as to be inside of the side of.

As the separator 5, specifically, electrolytic paper, polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyester nonwoven fabric, Teflon nonwoven fabric, kraft paper, Manila hemp sheet, glass fiber sheet, etc. can be used.
The thickness of the separator 5 is 0.01 to 0.1 mm, particularly 0.1 mm.
Desirably, it is 02 to 0.07 mm.

Here, the separators 5, 5 are open at least between the sides where the conductors 1 protrude, and in particular, the polarizable electrodes are preferably formed by contacting and fixing one side of the two separators 5, 5. It is desirable in order to prevent the displacement of 3 and, more specifically, one layered body for forming the separator 5 is folded at the center to form two sheets, and at least one side of the two separators 5 and 5 Adhered ones, and one in which two separators are made into a bag-like body are exemplified.

It is preferable that the separator 5 is fixed in contact between the side where the conductor 1 protrudes and the side opposite to the side where the conductor 1 protrudes. According to FIG. 1, the separators 5 and 5 have openings between sides where the conductor 1 protrudes, and the protrusions 1 a of the conductor 1 have openings and other separators 5 and 5 have openings. 5 is in the form of a bag fixed by contact, and according to such a configuration, it is possible to further prevent displacement between the current collector 2-the polarizable electrode 3-the separator 5.

Next, the portion of the conductor 1 protruding from the separator 5 is folded so as to hold one of the separators 5 (see step (c)), and then the folded portion is folded in the opposite direction to form the other separator 5. , And the separators 5 and 5 are sandwiched and overlapped and fixed, and the conductor 6 is bent twice or more to form the terminal 6 composed of at least four layers of the conductor 1 ( Step (d)). Note that the number of times of folding may be three or more, and the thickness of the terminal 6 can be controlled.

At this time, in order to make the thickness of the terminal 6 uniform, the side of the conductor 1 opposite to the side in contact with the current collector 2 is placed on the side of the laminate of the current collector 2 and the polarizable electrode 3. It is desirable to fold so as to match the side where 1 is formed, and
The fold folded at the end of the conductor 1 is the conductor 1 of the current collector 2
It is desirable that the adjustment be made so as to coincide with the side of the separator 5 located on the side of the formation side, in order to reduce the volume of the cell 14 and reduce the size of the multilayer electric double-layer capacitor 20 described later.

Here, the number of times of folding may be three or more, and if necessary, the protruding portion 1a protruding outside the top of the side on which the current collector 2 of the conductor 1 is formed.
The projecting portion 7 of the conductor 1 such as a portion where
The fold 8 of the conductor 1 located on the surface may be folded as a fold between them. According to FIG. 1, the third folding is performed in a direction orthogonal to the first and second folding directions.

As a result, the thickness of the terminal 6 can be increased.
The strength of the terminal 6 can be increased to further prevent the displacement of the polarizable electrode 3, and the thickness of the terminal 6 forming portion of the cell 14 can be reduced by the thickness of the laminate of the current collector 2 and the polarizable electrode 3 in the cell 14. By approximating the thickness to desirably the same, the cells can be stably stacked, and partial stress concentration does not occur in the terminal 6 of the cell 14. An increase in the internal resistance at the interface between the current collector 6 and the current collector 2 can be prevented (see step (e)).

Also, before conducting the protruding portion 7 of the conductor 1 or the last folding when folding the conductor 1 three times or more, the conductor 1 protruding portion 7 such as a portion projecting from the side of the separator 5 is ultrasonically or laser-welded. The strength and rigidity of the conductor 1 protruding portion 7 and the terminal 6 can be increased by welding using a known welding method such as that described above.

Further, if desired, the terminal 6 may be a part of the side of the separator 5, in particular, a width equal to or less than half of the side, that is, of the adjacent cell 14 in the stacked body of the cell 14 having the terminal stacked on the same side. In the case where the terminals 6 are formed so as not to be in contact with each other, a region where the terminals 6 of the separator 5 are not in contact with the terminals 6, particularly a portion which is line-symmetric with respect to the center of the side of the separator 5, is provided. The conductors 10 sandwiching the separators 5 are formed.

The conductor 10 is desirably a clip made of a metal foil or a metal plate containing at least one selected from the group consisting of aluminum, tantalum, titanium, iron, cobalt, nickel, copper, silver, platinum and gold. Thereby, the displacement between the current collector 2 and the polarizable electrode 3 can be further reduced, and in the cell 14 laminate in which the terminals 6 forming the positive electrode and the negative electrode are formed on the same side surface, the adjacent cells with one cell interposed therebetween Conductor 1 is connected between terminals 14 and 14
The terminals 6 and 6 can be electrically connected by bringing them into contact with 0, respectively. Note that the thickness of the conductor 10 forming portion of the cell 14 is desirably the same as the thickness of the terminal 6 forming portion.

Further, if necessary, a through-hole 12 penetrating the terminal 6 and the separator 5 and a through-hole 12 penetrating the conductor 10 and the separator 5 are formed to form a cell for an electric double layer capacitor (hereinafter simply referred to as a cell). (Abbreviated) 14 can be manufactured (see FIG. 1F).

Then, the cell 14 is replaced with the adjacent cell 14.
A plurality of layers are stacked so that the terminals 6 and 6 do not contact each other, and two sets of terminals that electrically connect the terminals 6 and 6 of every other cell 14 are respectively connected to a positive terminal group and a positive terminal group. A terminal group for the negative electrode is provided, and leads 15 are respectively connected to a part of the terminal group.

Further, after the laminate of the cells 14 is housed in a sealing material 16 such as an aluminum laminate so that the leads 15 protrude outside, an electrolytic solution is poured into the polarizable electrode 3 and the separator 5 of the cells 14. The multilayer electric double layer capacitor 20 of the present invention can be manufactured by injecting and sealing the laminate of the cells 14 with the lead 15 interposed therebetween.

The electrolyte may be an aqueous solution such as sulfuric acid or nitric acid, or an organic solvent such as propylene carbonate, γ-butyrolactone, N, N-dimethylformamide, ethylene carbonate, sulfolane or 3-methylsulfolane, and a quaternary ammonium salt. An organic solution in which an electrolyte such as a quaternary sulfonium salt or a quaternary phosphonium salt is combined can be used.

As described above, the terminal 6 and the conductor 1
For the cell 14 in which the through holes 12 and 12 are formed in 0,
Each of the through holes 12 of the cell 14 is connected to the conductive rod 1
After penetrating and laminating the cells 8, the ends of the conductive rods 18 are deformed or screwed to caulk the cells 14, thereby further preventing displacement of the laminated body of the cells 14.

Further, when stacking the cells 14 having the terminals 6 formed on the entire sides of the current collector 2, the terminals 6 of the positive electrode cells 14 a and the terminals 6 of the negative electrode cells 14 b are stacked so as to face each other. In addition, the conductor protruding portions 7 are stacked in a state where they protrude, and the conductor protruding portions 7 are brought into contact with the terminals 6 of the next cell 14 via the outer peripheral portion of the adjacent cell 14. The terminals 6 can be electrically connected to each other.

Although the cell 14 shown in FIGS. 1 and 2 has the polarizable electrodes 3 and 3 laminated on both sides of the current collector 2, the present invention is not limited to this. 14
For the cell located at the lamination end of the laminate, the polarizer electrode 3 may be formed on one surface of the current collector 2.

(Structure of Electric Double Layer Capacitor) FIG.
1 is a schematic cross-sectional view illustrating an example of a multilayer electric double-layer capacitor of the present invention obtained by the above-described method. FIG.
According to the above, the multilayer electric double layer capacitor 20 is connected to the cell 1
4 are stacked, and the stacked body of the cells 14 is housed and sealed in the sealing material 16. In addition, cell 1
Reference numeral 4 denotes a cell forming a positive electrode (hereinafter, simply referred to as a positive electrode cell) 1
4a and a cell forming a negative electrode (hereinafter simply referred to as a negative electrode cell)
14b are alternately stacked.

The cell 14 has a substantially rectangular current collector 2 in which the substantially rectangular polarizable electrodes 3 and 3 are laminated on both sides.
Are housed in two separators 5, and one side of the separator 5 has a conductor 1 connected to two sides of the current collector.
Is folded a plurality of times or more, and the conductor 1 has at least four or more layers, and a terminal 6 having two sides of the separator 5 interposed therebetween is formed.

Here, according to FIG. 4, on the side of the separator 5 opposite to the side on which the terminal 6 is formed, the two separators 5, 5 are fixed to each other by gluing or folding back, so that it is desirable. Is fixed between the sides of the separators 5 and 5 other than the side where the terminals 6 are formed.

According to FIG. 4, the terminal 6 of the positive electrode cell 14a is formed only on a part of the side of the separator 5, and is in contact with the terminal (not shown) of the adjacent negative electrode cell 14b. It is formed not to be. Further, according to FIG. 4, between the terminals 6 facing each other with one negative electrode cell 14b interposed therebetween, a conductor 10 provided to sandwich the separators 5, 5 of the negative electrode cell 14b is electrically connected. It is connected.

According to FIG. 4, a lead 15 connected to the terminal 6 or a part of the conductor 10 of the positive electrode cell 14a is disposed substantially parallel to the cell 14 at substantially the center of the cell 14 laminate. 15 protrudes outside the sealing material 16. Although not shown, the lead 15 is similarly formed in the negative electrode cell 14b. Then, the electric double layer capacitor 20 can be connected to an external circuit (not shown) by connecting the two leads 15 projecting outside the sealing material 16 to the terminals (not shown) of the external circuit as extraction electrodes. it can.

Further, according to FIG. 4, a through hole 12 penetrating each of the terminal 6 and the conductor 10 is formed, and a conductive rod 18 made of metal such as rivets or bolts is provided in the through hole 12. Have been. This facilitates positioning when the cells 14 are stacked, prevents misalignment between the cells 14, 14, ensures connection between the plurality of terminals 6 and the conductor 10, and reduces the internal resistance value. Can be reduced.

Although not shown, the above-described conductor 10, lead 15, through hole 12, and conductive rod 18 are also formed on the negative electrode cell side, and are electrically connected in the same manner as the positive electrode cell.

The cell 14 located at the end of the layered structure of the cell 14 shown in FIG. 4 has the same configuration as the cells inside the cell 14 layered structure, but the present invention is not limited to this. Regarding the cell 14 at the end, the polarizable electrode 3 is formed on one surface of the current collector 2, and the cell 14 at the end may be such that the current collector is in direct contact with the separator at the lamination end. Good.

[0051]

As described above in detail, according to the multilayer electric double layer capacitor of the present invention, the current collector and the polarizable electrode are accommodated between the two separators, and the side of the current collector is provided. In the part, while providing a terminal forming conductor partially projecting from the opening of the separator, and forming a terminal by folding the terminal forming conductor a plurality of times so as to sandwich the side of the separator, Since the sides of the two separators can be sandwiched between the terminals and overlapped and fixed, the displacement between the current collector, the polarizable electrode and the separator in the cell can be reduced, and the terminals can be connected to the sides of the separator. Part, and a thick terminal can be formed.
It is possible to simultaneously achieve high capacitance and low internal resistance, which can enhance shape retention, and prevent displacement due to a partial thickness difference of cells at the time of stacking cells, thereby improving productivity.

[Brief description of the drawings]

FIG. 1 is a schematic plan view for explaining some steps of an example of a method for manufacturing an electric double layer capacitor of the present invention.

FIG. 2 is a schematic sectional view of FIG.

FIG. 3 is a schematic diagram for explaining an example of forming a conductor and a current collector in an example of a method for manufacturing an electric double layer capacitor of the present invention.

FIG. 4 is a schematic sectional view of an example of the electric double layer capacitor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor for terminal formation 1a Protruding part 2 Current collector 3 Polarized electrode 5 Separator 6 Terminal 7 Conductor protruding part 8 Folding part 10 Conductor 12 Through hole 14 Electric double layer capacitor cell 15 Lead 16 Sealing material 18 Conductivity Rod 20 Laminated electric double layer capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Shimadzu 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kyocera Research Institute

Claims (9)

[Claims] 1. A current collector comprising a substantially rectangular laminated body in which a polarizable electrode is laminated on at least one surface of a current collector between two substantially rectangular separators; A cell for an electric double layer capacitor is provided in which a terminal forming conductor is provided in part, and the terminal is formed by folding the terminal forming conductive layer so as to sandwich the ends of the two separators. A multilayer electric double-layer capacitor comprising a plurality of components. 2. A multilayer electric double layer capacitor according to claim 1, wherein said two separators are bag-shaped bodies. 3. The multilayer electric double layer capacitor according to claim 1, wherein the folded portions of the terminal forming conductor are partially welded to each other. 4. A thickness of a portion of the electric double layer capacitor cell in which a laminate of a current collector and a polarizable electrode is housed is the same as a thickness of a portion of the cell where the terminal is formed. The multilayer electric double-layer capacitor according to any one of claims 1 to 3, wherein 5. The electric double layer capacitor cell forming a plurality of positive electrodes and the negative electrode having the terminals forming the positive electrode and the negative electrode are alternately stacked so that the terminals forming the positive electrode and the negative electrode do not contact with each other. The multilayer electric double-layer capacitor according to any one of claims 1 to 4, wherein the terminals forming the positive electrode and the terminals forming the negative electrode are electrically connected to each other. 6. A through hole penetrating through said terminal and separator of a plurality of cells for an electric double layer capacitor forming a positive electrode and a negative electrode, and two conductive rods forming a positive electrode and a negative electrode are formed in said through hole. 6. The multilayer electric double-layer capacitor according to claim 5, wherein the electric double-layer capacitor cells are stacked and fixed so as to penetrate through the respective cells. 7. The multilayer electric double layer capacitor according to claim 5, wherein the terminals forming the positive electrode and the negative electrode are provided on the same side surface of the cell stack. 8. The electric double layer capacitor cell as a negative electrode, wherein terminals of the electric double layer capacitor cell as a positive electrode disposed with one electric double layer capacitor cell as a negative electrode interposed therebetween. 8. The two separator sides are electrically connected to each other via a conductor formed so as to sandwich the two separator sides. The multilayer electric double layer capacitor as described in the above. 9. The multilayer electric double layer capacitor according to claim 5, wherein the terminal forming the positive electrode and the terminal forming the negative electrode are provided on opposite side surfaces of the cell stack.