JP2001068384A - Electric double layer capacitor, basic cell thereof, and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electric double layer capacitor of a structure wherein a pressure is applied by an encapsulating case to a capacitor element made of a basic cell alone or laminated to hold its structure and which can improve its stability with time in electrical characteristics. SOLUTION: A structure of the basic cell includes a porous separator 4, two cylindrical gaskets 3 and 3 sandwiching the separator therebetween as laminated therewith, polarizable electrodes 2 and 2 containing an electrolytic solution placed in the interior of the respective cylindrical gaskets, and lid- shaped collectors 1 and 1 for closing opening of the electrodes 2 and 2 opposed to the separator 4. A height of the electrodes 2 and 2 from the separator is set to be lower than the height of each gasket 3. Since a pressure applied to between the collectors 1 and 1 acts on the gaskets, a sealing ability between the collector 1 and the gasket 3 and between the gaskets can be improved, thus making it difficult to occur a dry-up phenomenon of the electrolytic solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor, a basic cell thereof, and a method of manufacturing the basic cell, and more particularly to a technique effective for preventing a dry-up phenomenon of an electrolyte solution contained in a polarizable electrode.

[0002]

2. Description of the Related Art An electric double-layer capacitor is a capacitor element formed by arranging a basic structure generally called a basic cell and exhibiting a charge accumulating action alone or electrically in series. FIG. 7 shows an example of a cross-sectional structure of the basic cell. With reference to FIG. 7, the basic cell shown in this figure comprises a non-electronically conductive and ion-permeable porous separator 4 and two polarizable electrodes 2 opposed to each other with the separator 4 interposed therebetween.
And two electrically insulating tubular gaskets 3 surrounding the polarizable electrode 2 and two conductive current collectors 1 closing the opening of the tubular gasket opposite to the separator.
1 expresses a charge storage effect. In order to use this basic cell as an electric double-layer capacitor for practical use, several basic cells must be stacked in series in order to increase the withstand voltage according to the purpose of use, or electrically connected to the outside. A lead-out structure (external lead terminal) or an exterior structure for holding and protecting the mechanical structure between the element and the external lead terminal is required, but from the viewpoint of the charge storage effect, The structure shown in FIG. 7 is fundamental.

The basic cell shown in FIG. 7 is obtained, for example, by the following materials and manufacturing steps. First, punch out a sheet of electrically insulating rubber in a ring shape,
A vertically open cylindrical gasket 3 is obtained. Next, at one open end of the gasket 3, a disk-shaped current collector 1 made by punching a sheet of conductive rubber is arranged.
And the current collector rubber 1 are bonded together using the adhesiveness of the rubber. By this step, a bottomed cylinder in which one opening of the cylindrical gasket is closed by the current collector 1 is formed. In addition, the current collector 1
Is not necessarily made of rubber, but may be a conductive plastic film. Further, the gasket 3 is not necessarily a cylinder, but may be a square tube.

Separately from the above steps, powdered activated carbon and an electrolyte solution such as dilute sulfuric acid are kneaded to prepare a paste-like polarizable electrode in advance. Then, the paste-like polarizable electrode 2 is filled into the gasket 3 whose bottom is closed with the conductive current collector 1 using a squeegee or the like to the height of the gasket. Two such bottomed cylindrical gaskets filled with the polarizable electrode 2 are prepared. Incidentally, the electrolyte solution is not necessarily an aqueous solution as described above, for example, an organic solvent such as propylene carbonate or γ-butyl lactone as a solute obtained by using a borofluoride or hexafluorophosphate of tetraethylammonium as a solute. And a non-aqueous solution type.

[0005] Next, the two gaskets filled with the polarizable electrodes are opposed to each other so that the opening surfaces face each other with the porous separator 4 interposed therebetween. The porous separator 4 is a film made of plastic or the like having very fine pores, and has non-electron conductivity and ion permeability.

Thereafter, the upper and lower sides of the two gaskets opposed to each other are sandwiched between two highly rigid pressing plates (not shown) made of a reinforced plastic flat plate or an aluminum plate, and a force is applied between the pressing plates. Current collectors 1,
Heat while applying a uniform pressure between the two. This pressurization,
By heating, the space between the current collector 1 and the gasket 3 and between the upper and lower gaskets are vulcanized and joined, and the polarizable electrode 2 is sealed in the gasket.

[0007]

As described above, the basic cell of an electric double layer capacitor has a structure in which a polarizable electrode 2 containing an electrolyte solution is sealed therein, and constitutes a polarizable electrode. An electric double layer is formed at the solid / liquid contact interface between the activated carbon and the electrolyte solution. Therefore, in order for the capacitor to exhibit predetermined electrical characteristics and not to change over time, the electrolyte solution leaks and the ratio between the activated carbon and the electrolyte solution changes, or evaporation occurs. It must be ensured that it does not escape and change the density. That is, the sealing properties between the current collector 1 and the gasket 3 and the joint between the gasket and the gasket must be high.

[0008] One technique for improving the sealing property of each of the above joints is disclosed in Japanese Patent No. 2722021 (JP-A-4-302126) by the same assignee as the assignee of the present invention.
Is disclosed. FIG. 8 and FIG.
FIG. 2 is a diagram showing FIG. 1 and FIG. 2 of No. 2021 again (however, reference numerals and names of respective parts are omitted or changed for convenience of explanation). Referring to FIG. 8, the basic cell shown in FIG. 8 has a gasket 3 when pressure is applied from the current collector side to two gaskets filled with polarizable electrodes which are opposed to each other with a separator 4 interposed therebetween. , 3, a frame-shaped pressing plate 6 concentric with the gasket is sandwiched between the pressing plate 5 and the current collector 1 so that a large pressure is applied. In this case, since a sufficient pressure is applied to the gaskets 3 and 3, the bonding between the current collector 1 and the gasket 3 and between the gaskets is strengthened, and the sealing performance is improved.

Japanese Patent No. 2722021 also discloses FIG.
And vulcanizing and joining a gasket, a method of pressing a rubber plate 7 having an elasticity of Vickers hardness of 60 to 80 degrees between a pressing plate 5 and a current collector 1 to apply pressure. Is disclosed as an example. Also in this case, the degree of bonding between the current collector 1 and the gasket 3 and between the gaskets can be increased, and the sealing performance can be improved.

However, it has been found that even in the electric double-layer capacitor using the above-described basic cell having improved sealing properties, the electrical characteristics of the completed capacitor change with time. The change over time in the electrical characteristics is particularly remarkable when the device is placed in a high-temperature environment or when a high voltage is applied during actual use. The description is given below.

As described above, in a practical electric double layer capacitor, the basic cells shown in FIG. 7 are used alone or some of them are stacked in series to form a capacitor element. Structure and exterior structure are required. FIG. 10 shows an example of the structure of such a practical electric double layer capacitor. Referring to FIG. 10, the electric double-layer capacitor shown in FIG. 10 is a multilayer electric double-layer capacitor having six basic cells 10 stacked in series as a capacitor element. Are housed in a metal outer case 14 having a bottomed cylindrical shape. On the opening side of the exterior case of the element 11, a terminal plate 13B having a lead terminal cut and raised is provided so as to come into contact with the press contact plate 12B at a surface, and another terminal plate having a lead terminal similarly cut and raised. 13A is superimposed. The two lead terminal plates 13A and 13B are insulated from each other with an insulating case 15 made of plastic therebetween. Outer case 14
The edge of the opening of the lead terminal plate 13 is crimped inward.
A is pressed against the flat plate portion. After all, in the electric double layer capacitor shown in this figure, of the two current collectors (not shown) located on both upper and lower end surfaces of the element 11, the current collector on the upper side of the drawing is from the press contact plate 12 </ b> A to the bottom surface of the outer case 14. , The side surface and the caulking portion, and connected to the terminal plate 13A, while the current collector on the lower side of the paper surface is
This means that it is connected to the terminal plate 13B.

Here, when caulking the edge of the opening of the outer case 14 in the process of manufacturing the capacitor, the pressing plate 1
2A, capacitor element 11, press contact plate 12B, terminal plate 13
B, the insulating case 15, and the terminal plate 13A which are stacked in this order are inserted into the outer case, and then a force is applied to the flat portion of the terminal plate 13A with a jig (not shown) to cooperate with the bottom surface of the outer case 14. Pressure is applied to the element 11. Then, in the pressurized state, the open end of the outer case 14 is swaged and pressed against the terminal plate 13A. As a result, the pressure applied to the element 11 by the above-mentioned jigs and tools during the manufacturing process is maintained by the bottom surface and the swaged portion of the outer case even after completion. By keeping the element under pressure in this way, the contact resistance between the basic cells in the stacked element 11 and the element 11 and the pressure contact plates 12A, 1
2B or the contact resistance between the press contact plate and the terminal plates 13A, 13B can be reduced. Although the above description has been made with reference to a laminated electric double layer capacitor as an example, the same can be said for a capacitor having a single basic cell as a capacitor element.

By the way, in the electric double layer capacitor according to the above-mentioned Japanese Patent No. 2722021, a large pressure is applied to the gasket portion by using the method shown in FIG. . Therefore,
In the completed basic cell, the surface of the gasket 3 on the side of the current collector is lower than the surface of the internal polarizable electrode 2, or at most the same height. Therefore, FIG.
As shown in (1), even when the element 11 is housed in the outer case 14 and pressure is applied from the caulked portion, pressure is less likely to be applied to the gasket 3 in each basic cell. As a result, the pressure in the basic cell increases due to the generation of hydrogen gas due to the electrolysis of the electrolyte solution that occurs when a high voltage is applied during actual use, and the vaporization of the electrolyte solution when placed in a high-temperature environment. As the height increases, the gap between the current collector 1 and the gasket 3 (FIG. 7)
Or the degree of bonding between the gaskets (same as above) is reduced, and vaporized gas or hydrogen gas escapes from the interface between them, and in extreme cases, the electrolyte solution itself leaks out. Up occurs, and the electrical characteristics of the capacitor change with time.

Accordingly, the present invention provides an electric double-layer capacitor having a structure in which pressure is applied to and holds a capacitor element having a basic cell alone or in a stacked structure, thereby improving the stability over time of electric characteristics. It is the purpose.

[0015]

The basic cell of the electric double layer capacitor according to the present invention comprises a non-electronically conductive and ion-permeable porous separator, and a cylindrically-shaped electrically insulating laminate sandwiching the porous separator. Two gaskets, a polarizable electrode containing an electrolyte solution housed inside each cylindrical gasket, and a lid-shaped current collector for closing the opening of each cylindrical gasket on the side opposite to the separator. Wherein the height of each polarizable electrode from the porous separator is smaller than the height of each gasket.

The above-mentioned basic cell comprises a first step of closing one bottom of an electrically insulating, vertically open tubular gasket with a conductive current collector, and a current collector after completion of the first step. A second step of filling a paste-like polarizable electrode obtained by previously kneading powdered activated carbon and an electrolyte solution inside a bottomed cylinder made of a gasket and a gasket, and after the second step, Two bottomed cylindrical gaskets filled with polarizable electrodes inside are opposed to each other with a non-electroconductive and ion-permeable porous separator between the open ends facing each other,
And a third step of integrating by heating while applying pressure between the two current collectors, wherein in the second step, the polarizable electrode is It is manufactured by a manufacturing method characterized in that filling is performed below the height of the gasket.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a diagram illustrating a cross section of a completed state of a basic cell according to an embodiment of the present invention. FIG. 1B is a diagram showing a cross section of the basic cell during its manufacture. Referring to FIG. 1A, in the basic cell according to the present embodiment, the height of gasket 3 is greater than the height of polarizable electrode 2 when compared with the conventional basic cells shown in FIGS. The difference is that it is higher. The materials and manufacturing methods of each component (separator 4, polarizable electrode 2, gasket 3, current collector 1) are the same as those in the related art. Also, the method of manufacturing a basic cell using each of the above components is the same except for the points described later.

When the basic cell has a structure as shown in FIG. 1A, when the basic cell is casing as a capacitor element in the outer case 14 (see FIG. 10), the bottom surface of the case and the caulked portion on the opening side are formed. The pressure applied to the element 11 is applied to the gasket 3. Therefore, even if the pressure inside the basic cell increases due to being placed in a high-temperature environment after the casing or being applied with a high voltage during actual use as an electric double-layer capacitor, the current collector 1 and the gasket 3 are not connected to each other. The degree of bonding between the gaskets or between the gaskets does not decrease, and the sealing performance does not decrease. That is, the stability over time of the electrical characteristics of the electric double layer capacitor is improved as compared with the conventional electric double layer capacitor.

The present inventors have prepared an electric double layer capacitor by the method described below and investigated the magnitude of the change over time in the electric characteristics in order to confirm the above-mentioned effects. FIG.
Referring to (b), first, a gasket 3 is obtained by punching out an insulating butyl rubber sheet having a thickness of 0.1 mm into a cylindrical shape. Gasket inner diameter is 30mmφ, outer diameter is 40mmφ
It is. On the other hand, a conductive butyl rubber sheet obtained by dispersing carbon in the same butyl rubber and imparting conductivity thereto has a diameter of 40.
The disk-shaped current collector 1 is formed by punching into a diameter of mmφ. The thickness of the current collector is 0.1 mm. Thereafter, the current collector 1 and the gasket 3 are arranged so as to be concentric, and are bonded by utilizing the adhesiveness of rubber. Thereby, a bottomed cylindrical gasket in which one opening is closed by the current collector 1 is obtained.

Next, a paste-like activated carbon electrode previously obtained by kneading dilute sulfuric acid and powdered activated carbon is filled in a bottomed cylinder composed of the current collector 1 and the gasket 3 described above. I do. At this time, as shown in FIG. 1B, the height of the activated carbon electrode 2 in the gasket is set lower than the height of the gasket 2. This is a difference from the conventional method for manufacturing a basic cell. In the present embodiment, several types of basic cells (described later) in which the ratio of the height of the activated carbon electrode to the height of the gasket was changed were prepared.

Next, two gaskets filled with the above-mentioned activated carbon electrode are prepared, concentrically opposed to each other with the porous separator 4 interposed therebetween, and bonded with rubber adhesiveness.
The separator 4 is a disk having a diameter of 33 mmφ and obtained from a 0.05 mm thick polypropylene sheet.

Thereafter, the upper and lower gaskets 3 and 3 bonded together with a separator interposed therebetween are sandwiched from above and below by an elastic rubber plate 7 and a reinforced plastic pressing plate 5 thereon. A pressure of 7 kg / cm ² is applied. In this manner, the paste-like polarizable electrode 2 sinks into the separator 4 due to the elasticity of the rubber plate 7, and the height of the polarizable electrode 2 from the separator is higher than that of the gasket 3 as shown in FIG. Lower than the height of After that, by heating at a temperature of 125 ° C. for 5 hours while applying pressure in the above state, vulcanization and joining are performed between the current collector 1 and the gasket and between the gasket and the gasket. 1 (a)
Was obtained. The rubber plate 7 having a Vickers hardness in the range of 60 to 80 degrees was suitable. As the rubber material, butyl rubber, silicon rubber, fluorine rubber, or the like can be used.

Further, the basic cell obtained as described above is used alone as a capacitor element, and the element 11 having the structure shown in FIG.
Was applied so that a pressure of 50 kg / cm ² was applied thereto, thereby completing the electric double layer capacitor according to the present embodiment.

In this embodiment, the polarizable electrode 2 has a lower structure than the gasket 3 as shown in FIG.
Height of the polarizable electrode 2 above the porous separator 1 (hereinafter referred to as
Electrode referred to as the height h _D) of the pair gasket 3 height (same, to create a gasket referred to as height h _G) ratio four different electric double layer capacitor (see Examples 1-4. Table 1) A high-temperature load test was performed to investigate the magnitude of changes in the capacitance C and the equivalent series resistance ESR over time. Also,
For comparison, according to the conventional manufacturing method shown in FIG. 8, the polarizable electrode has a higher structure than the gasket, and two types of electric electrodes having different electrode height to gasket height ratios (h _D / h _G ). Multilayer capacitors (Comparative Examples 1 and 2; same) were prepared and subjected to a high-temperature load test together with the examples. In the high-temperature load test, the applied voltage to the basic cell = 0.8 V, the temperature = 85
The operation was performed at 500C for up to 500 hours.

[0025]

[Table 1]

FIG. 2 shows the relationship between the test time and the change in the equivalent series resistance in Example 4 and Comparative Examples 1 and 2. FIG. 3 shows the relationship between the test time and the change in capacitance.
Note that in FIGS. 2 and 3, the ordinate represents a value defined as follows. In the case of FIG. 2, the equivalent series resistance value ESR _t after the test / the initial value ESR ₀ of the equivalent series resistance In the case of FIG. 3, the capacitance value C _t after the test / the initial value C _{0 of the} capacitance Referring to FIG. Equivalent series resistance ESR of capacitor
Shows a tendency to increase over time in any of the samples. This tendency is a phenomenon generally observed in electric double layer capacitors, but the amount of increase in ESR increases as the ratio of electrode height to gasket height increases. In particular, h
_{When D} / h _G = 1.2 (Comparative Example 2), the increase in ESR after 500 hours has become remarkable. On the other hand, referring to FIG. 3, the capacitance C of any of the samples tends to decrease over time. This tendency is also a phenomenon generally observed in the electric double layer capacitor, but the amount of reduction of C increases as the ratio of the electrode height to the gasket height increases. In particular, when h _D / h _G = 1.2 (Comparative Example 2), 2
After about 50 hours, the decrease of C becomes remarkable. From the above, it can be said that the smaller the ratio of the electrode height to the gasket height is, the higher the stability over time of the electrical characteristics of the electric double layer capacitor is.

Next, FIG. 4 shows the relationship between the ratio of the electrode height to the gasket height and the change in the equivalent series resistance after 500 hours of the high-temperature load test. FIG. 5 shows the relationship between the ratio of the electrode height to the gasket height and the change in capacitance after 500 hours of the high-temperature load test. Note that in FIGS. 4 and 5, the vertical axes respectively indicate values defined by the following equations. In the case of FIG. 4, the equivalent series resistance value ESR ₅₀₀ after ₅₀₀ hours / the initial value ESR ₀ of the equivalent series resistance In the case of FIG. 3, the capacitance value C ₅₀₀ after ₅₀₀ hours / the initial value C _{0 of the} capacitance FIG. equivalent series resistance after 500 hours, although up to h _D / h _G = 0.6~0.9 is substantially constant, exceeds h _D / h _G = 0.9, the h _D / h _G It shows a tendency to increase with increase. On the other hand, referring to FIG. 5, the capacitance after 500 hours elapses is h _D / h _G = 0.
It is almost constant from 6 to 0.8, but beyond this, h _D
/ H _G tends to decrease with increase. In particular, h
The change after _D / h _G = 0.9 is remarkable.

From the results of the high-temperature load test described above and shown in FIGS. 2 to 5, the temporal stability of the electric characteristics of the electric double-layer capacitor is smaller when the ratio of the electrode height to the gasket height of the basic cell is smaller. Indicates a high tendency. That is, the electric double layer capacitor of the present invention having an electrode height to gasket height ratio of less than 1.0 is better than the conventional electric double layer capacitor having an electrode height to gasket height ratio of ≧ 1.0. Can be said to have excellent stability over time in electrical characteristics. In particular, in the range of h _D / h _G = 0.6 to 0.9, it is not an exaggeration to say that the change over time in the electrical characteristics is zero.

FIG. 6 shows the relationship between the initial value of the equivalent series resistance and the ratio of the electrode height to the gasket height. Referring to FIG. 6, the initial value of the equivalent series resistance tends to increase as the ratio value decreases in a region where the ratio of the electrode height to the gasket height is small, and h _D / h _G = 1.2. ~ 0.
8 is almost constant, whereas h _D / h _G is equal to 0.
If it is smaller than 8, it will increase rapidly.

From the above, the ratio of the height of the electrode to the height of the gasket is 0.8 or more in consideration of the improvement of the temporal stability of the electrical characteristics and the deterioration of the initial characteristics, particularly the equivalent series resistance.
It can be said that it is preferable to set the value to less than 0.

In the present invention, the members constituting the basic cell are not limited to those of the embodiment. For example, the current collector 1 and the gasket 3 are not limited to butyl rubber, but other rubbers such as ethylene propylene diene rubber,
Alternatively, plastics such as polypropylene and polyvinyl chloride can be used. In addition, the polarizable electrode 2
In addition to those obtained by kneading powdered activated carbon and an electrolyte solution to form a paste, those obtained by kneading powdered activated carbon and a resin to form a sheet, and impregnating the electrolyte solution, or fibrous After kneading the activated carbon and the resin to form a sheet, and then similarly impregnating with an electrolyte solution, it can be used. The electrolyte solution is not an aqueous solution,
For example, a non-aqueous electrolyte solution such as one obtained by using a borofluoride or hexafluorophosphate of tetraethylammonium as a solute in an organic solvent such as propylene carbonate or γ-butyllactone may be used. When an aqueous electrolyte is used, the equivalent series resistance can be reduced as compared with the case where a non-aqueous electrolyte is used. As the separator, a sheet-like material made of polypropylene, polyethylene, glass fiber, or the like can be used.
The above-mentioned materials are those conventionally used in the production of electric double layer capacitors, and are not special at all.

In the electric double layer capacitor housed in the case shown in FIG.
Press-connecting plates 12A, provided between the terminal plates 13A and 13B,
Since 12B is for uniformly applying pressure to the element, it is not particularly necessary if the rigidity of the terminal plates 13A and 13B is high.

[0033]

As described above, according to the present invention, in the basic cell of the electric double layer capacitor, the height of the polarizable electrode from the porous separator is made lower than the height of the gasket so that the current collectors at both end faces are provided. When a uniform pressure is applied between the gaskets, the pressure is applied to the gasket portion.

Thus, according to the present invention, when each of the basic cells is housed in an outer case in a structure in which a pressure is applied between the current collectors at both ends of the element, the basic cells are individually or laminated to form a capacitor element. Since it is possible to always apply pressure from the outer case to the gasket part,
The sealability between the current collector and the gasket and between the gasket and the gasket can be improved, and the temporal stability of the electrical characteristics of the capacitor can be improved.

[Brief description of the drawings]

FIG. 1A is a diagram showing a cross section of a basic cell of an electric double layer capacitor according to the present invention after completion. (B) is a diagram showing a cross section during the manufacturing.

FIG. 2 shows how the equivalent series resistance changes with time when an electric double layer capacitor is subjected to a high-temperature load test by comparing an electric double layer capacitor according to the present invention with an electric double layer capacitor according to a conventional technique. FIG.

FIG. 3 shows how the capacitance changes over time when the electric double-layer capacitor is subjected to a high-temperature load test by comparing the electric double-layer capacitor according to the present invention with the electric double-layer capacitor according to the related art. FIG.

FIG. 4 is a diagram showing the relationship between the magnitude of the change in equivalent series resistance after subjecting the electric double-layer capacitor to a high-temperature load test, and the relationship between the height of the polarizable electrode and the height of the gasket.

FIG. 5 is a diagram showing the relationship between the magnitude of change in capacitance after subjecting an electric double-layer capacitor to a high-temperature load test, and the relationship between the height of a polarizable electrode and the height of a gasket.

FIG. 6 is a diagram showing an initial value of an equivalent series resistance of an electric double layer capacitor and a relationship between a height of a polarizable electrode and a height of a gasket.

FIG. 7 is a diagram showing a structure of an example of a basic cell of an electric double layer capacitor.

FIG. 8 is a diagram for explaining a method of manufacturing a basic cell according to a conventional technique.

FIG. 9 is a view for explaining another example of a method of manufacturing a basic cell according to a conventional technique.

FIG. 10 is a diagram showing a casing structure of the electric double layer capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current collector 2 Polarized electrode 3 Gasket 4 Separator 5 Press plate 6 Press plate 7 Rubber plate 10 Basic cell 11 Capacitor element 12A, 12B Pressure contact plate 13A, 13B Terminal plate 14 Outer case 15 Insulation case

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Kazuya Mimura 5-7-1 Shiba, Minato-ku, Tokyo F-term within NEC Corporation 5E082 AB09 BC40 LL21 MM22 MM24 PP09 PP10

Claims (8)

[Claims] 1. A non-electronically conductive and ion-permeable porous separator, two cylindrical gaskets which are stacked with the porous separator interposed therebetween, and housed inside each cylindrical gasket. In a basic cell of an electric double layer capacitor comprising a polarized electrode containing an electrolyte solution and a lid-shaped current collector closing an opening of the cylindrical gasket on the side opposite to the separator, 3. The basic cell of an electric double layer capacitor, wherein the height of the polarizable electrode from the porous separator is lower than the height of each gasket. 2. The electric power according to claim 1, wherein a ratio of a height of the polarizable electrode from the porous separator to a height of the gasket is 0.8 or more and less than 1.0. Basic cell for double-layer capacitors. 3. The basic cell of an electric double layer capacitor according to claim 1, wherein said polarizable electrode is a paste-like material obtained by kneading an activated carbon powder and an electrolyte solution. 4. The basic cell according to claim 3, wherein the electrolyte solution is water-soluble. 5. A capacitor element in which the basic cells according to claim 1 are stacked singly or plurally so as to be electrically connected in series, and a high rigidity in surface contact with current collectors at both ends of the capacitor element. And a bottomed cylindrical metal case that houses the capacitor element including the electrode plate such that one of the electrode plates is in close contact with the bottom, and the opening side of the metal case. An electric double layer capacitor having a structure in which a predetermined pressure is applied to the capacitor element via the two electrode plates by holding the edge of the capacitor element inward and pressing the other electrode plate of the capacitor element to the other electrode plate. 6. A first step of closing one bottom of an electrically insulating, vertically open tubular gasket with a conductive current collector; and the current collector and the gasket after completion of the first step. A second step of filling a paste-like polarizable electrode obtained by previously kneading powdered activated carbon and an electrolyte solution into the inside of a bottomed cylinder having the following characteristics: Two bottomed cylindrical gaskets filled with electrodes are opposed to each other, opposed to each other with a non-electron conductive and ion permeable porous separator between their open ends, and between the two current collectors. In the method for manufacturing a basic cell of an electric double layer capacitor, comprising: a polarizable electrode, a gasket, and a third step of joining the gaskets to each other by heating while applying pressure, wherein in the second step, the polarizable electrode is Fill below the gasket height A method for manufacturing a basic cell of an electric double layer capacitor, comprising: 7. In the third step, an elastic member is disposed in two bottomed cylinders filled with the polarizable electrode and opposed to each other with a porous separator interposed therebetween so as to be in contact with each current collector. 7. The method for manufacturing a basic cell of an electric double layer capacitor according to claim 6, wherein pressure is applied via a highly rigid member disposed so as to be in contact with a body and the elastic body. 8. A plate body made of any one of butyl rubber, silicon rubber, and fluorine rubber and having an elasticity of Vickers hardness of 60 degrees or more and 80 degrees or less is used as the elastic body. 8. The method for manufacturing a basic cell of an electric double capacitor according to item 7.