JPH08115859A - Electrical double-layer capacitor - Google Patents

Abstract

PURPOSE: To provide an electrical double-layer capacitor which can be stably operated for a long time without sacrificing the characteristics of a capacitor. CONSTITUTION: In an initial state, the pressure in a container 1 is not high, a spherical body 8 is pressed against an inverse conical part 7 of a lower member 6 by the force of a spring 10, the gas inside the container 1 does not leak outside, and at the same time intrusion of the gas outside the container into the container l is prevented. Gas is generated in the container 1 due to the use of a capacitor. When the pressure inside the container 1 exceeds a specific pressure at a lapse of time, the spherical body 8 moves upward against the downward force of the spring 10 and a gap is generated between the inverse conical part 7 and the spherical body 8. The gas inside the container 1 passes through the gap and is unloaded outside the container, and the pressure in the container 1 decreases, thus preventing the container 1 from being deformed and exploded.

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 which can be stably operated for a long time.

[0002]

2. Description of the Related Art An electric double layer is a phenomenon discovered by Helmholtz in 1879. When a conductor electrode is inserted into an electrolytic solution, one molecule is arranged at the interface between the electrode and the electrolytic solution to form a thin layer. If this layer is used as an insulator, a parallel plate type capacitor is formed between the electrode and the electrolytic solution. In an actual capacitor, if two electrodes are inserted into an electrolytic solution and connected to a power source, the boundary surface between each electrode and the electrolytic solution becomes a capacitor, and a cell having two capacitors in series can be obtained.

[0003]

The electric double layer capacitors have been used for backup of integrated circuit memories, etc.
A small one with a small capacity has been put into practical use. However, recently, a large-capacity electric double layer capacitor of about 100 F to several 1000 F has been manufactured and used for power. When such a capacitor is used in the same manner as a secondary battery, the conditions under which it is used are very different from those of a small capacity capacitor, and a considerable amount of gas is generated inside the capacitor. Since the cell is hermetically sealed, the internal pressure of the cell rises and the cell may be deformed or burst if it is used for a long time.

Normally, the life of a secondary battery is 50 times the initial capacity.
Often judged by% down. When a large capacitor is used and used for power, and it is used in the same way as a secondary battery, its life is converted to the amount of energy storage, with a reduction of 20% to 50% of the initial value as a guideline. Want to. However, in reality, in a large electric double layer capacitor of 100 F or more, when the electrostatic capacity deteriorates by about 5 to 10%, the gas pressure in the cell rises, and the electric characteristics still make it usable. However, it becomes physically unusable.

As a measure against the above problem, a method of mixing an absorbent into the cell in order to absorb carbon dioxide gas generated inside the cell can be considered. However, this method requires mixing of a chemical substance used as an absorbent into the electrode material, etc., and therefore, in order to obtain a particularly remarkable effect, an electrode that is subtly created to increase withstand voltage and electrostatic capacity. And the characteristics of the electrolytic solution are changed, and the characteristics themselves of the capacitor are greatly deteriorated.

The present invention has been made in view of the above points, and an object thereof is to provide an electric double layer capacitor which can be stably operated for a long time without deteriorating the characteristics of the capacitor.

[0007]

To achieve this object, an electric double layer capacitor of the present invention is attached to a container of an electric double layer capacitor having an electrode and an electrolytic solution inside, and to a part of the container. And a valve means for preventing gas from flowing into the outside of the container and allowing gas generated inside the container to escape to the outside of the container.

[0008]

In the present invention, when the pressure inside the container of the electric double layer capacitor becomes high, the gas inside the container is released to the outside by the valve means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an electric double layer capacitor according to an embodiment of the present invention, and 1 is a container (cell) of the electric double layer capacitor. Although not shown in detail in the inside of the container 1, electrodes, an electrolytic solution and the like necessary for the electric double layer capacitor are contained. The top plate 2 above the container 1 has an opening 3 formed therein, and a check valve 4 is attached so as to cover the opening 3. The check valve 4 has a lower member 6 having a hole 5 formed at the center thereof and communicating with the opening 3, a sphere 8 arranged in an inverted conical portion 7 provided at an opening portion above the hole 5, and a lower member. 6 and an upper member 9 which is integrated with the upper member 9, and a coil spring 10 which is arranged between the sphere 8 and the upper member 9. A hole 11 is also formed in the center of the lower member 9. In the above-described configuration, in the initial state, the pressure inside the container 1 is not high, the sphere 8 is pressed against the inverted conical portion 7 of the lower member 6 by the force of the spring 10, and the gas inside the container 1 does not leak to the outside. On the contrary, the gas outside the container is also prevented from entering the container 1.
When gas is generated inside the container 1 due to the use of the condenser and the pressure inside the container 1 becomes equal to or higher than a predetermined pressure over time, the spherical body 8 moves upward against the downward force of the spring 10 to form an inverted cone. A gap is created between the portion 7 and the sphere 8. The gas inside the container 1 is discharged to the outside of the container through this gap, the pressure inside the container 1 decreases, and the deformation and rupture of the container 1 are prevented. When the pressure inside the container 1 decreases, the sphere is pressed against the lower member 6 again by the spring 10, so that the inside of the container 1 is sealed.

As described above, in this embodiment, when the pressure in the container 1 rises, the sphere 8 rises to release the gas in the container 1 to lower the pressure, and the spring 10 and the sphere 8 allow the outside of the container 1 to be released. This prevents the above gas from entering the container 1. The force of the spring 10 is adjusted so that the sphere 8 is lifted when the pressure in the container 1 rises to about 5 to 6 atmospheres.

FIG. 2 shows another embodiment of the present invention,
The same parts as those in the embodiment of FIG. 1 are designated by the same reference numerals. In this embodiment, a rubber plug 15 is provided instead of the check valve 4 of the embodiment shown in FIG. The rubber plug 15 is attached so as to completely close the opening 3 portion of the top plate 2 of the container 1 of the electric double layer capacitor and keep the container 1 airtight.
If the pressure inside the container 1 rises, the rubber plug 1
The needle 17 of the syringe 16 is pierced through the needle 5 and the syringe 1
The cylinder 18 of No. 6 is pulled so that the gas inside the container 1 is released. Even with this configuration, the outside gas does not enter the container 1, and only the gas inside the container 1 can be discharged. The peripheral portion of the rubber plug 15 is formed thinner than the central portion, and when the gas pressure inside the container 1 becomes high, the rubber plug 15 portion swells as shown in FIG.
An increase in the pressure inside the container 1 can be detected from the outside.

FIG. 4 shows still another embodiment of the present invention. In this embodiment, a cup-shaped plug 20 is inserted into the opening 3 portion of the top plate 2 of the container 1 so as to completely close the opening 3. The cup-shaped plug 20 is made of polypropylene and has micro holes 21 at its bottom. Further, a highly viscous liquid 22 such as silicone oil is contained in the cup-shaped plug 20. The minute holes 21 are formed in a diameter such that the highly viscous liquid 22 does not pass through the holes. With this structure, the pressure inside the container 1 increases, and when the pressure exceeds a certain pressure, the container 1
The gas inside passes through the hole 21 at the bottom of the cup-shaped plug 20 and becomes bubbles in the liquid 22 and floats up. The pressure inside the container 1 is reduced by such an operation. Also,
Since the hole 21 is always closed with silicone oil, the atmosphere and water outside the container 1 do not flow back into the container 1. As the liquid 22, a liquid other than silicone oil can be used as long as it has a relatively high viscosity.

FIG. 5 shows another embodiment of the present invention used in one experiment, but this embodiment also uses a check valve as in FIG. Reference numeral 1 denotes an electric double layer capacitor container, which is an AL type (2.5V, 10F) electric double layer capacitor manufactured by Matsushita Electronic Components Co., Ltd.
An opening 3 having a diameter of 2 mm is formed in a top plate 2 on the upper side of the container 1 (on the side opposite to the terminals), and a packing 25 in which a rubber plate is laminated on a polypropylene sheet is provided to close the opening 3. An L-shaped pressing metal fitting 26 is fixed on the top plate 2 close to the opening 3. Packing 25 and press fitting 2
6 and a coil spring 28 with a washer 27 interposed therebetween.
Is arranged. Further, for one experiment, a rubber balloon 29 was attached to the upper part of the condenser container 1.

With the above structure, when the pressure inside the container 1 reaches 2 atm, the packing 25 is lifted upward against the force of the spring 28, and the spring 28 is adjusted so that the gas inside the container 1 leaks to the outside. 37-4 in this condenser
When the voltage of 3 V was continuously applied at 0 ° C., the packing 25 was lifted after 70 hours, the gas inside the container 1 started to leak to the outside, and the balloon 29 was inflated by the leaked gas to the outside. When the electrostatic capacitance of the capacitor was measured in this state, there was almost no change in 10 F, and the DC internal resistance was increased to about 4 times the original value (0.11 Ω). However, it operated as a capacitor without any problem, and when it was once discharged to zero V and left as it was for 12 hours, the internal resistance recovered to 1.8 times the original value after 24 hours. From this result, it is not necessary to make the container of the capacitor an excessively pressure resistant container by providing a means for venting the internal gas in the electric double layer capacitor for power, and it will take a long time until it cannot be used due to the deterioration of the performance as a capacitor. It proved possible to use.

[0015]

As described in detail above, according to the present invention, when the pressure inside the container of the electric double layer capacitor becomes high,
Since the gas inside the container is made to escape to the outside, it is possible to operate stably for a long time without impairing the characteristics of the capacitor. That is, since there is no risk of the container being deformed or ruptured by the gas generated inside the capacitor container, it can be used for a long time. For example, the operation of accommodating a decrease in electrostatic capacity of about 10% caused deformation of the container that could not be used, but according to the present invention, a capacitor may be used up to a capacity decrease of about 50% in some cases. It will be possible. For example, the cycle life of a silver-zinc secondary battery used for solar car racing is about several times. When the electric double layer capacitor is used in a similar manner and charged to a high voltage that can be used only 5 times, by attaching the valve according to the present invention,
You can use it more than 10 times.

[Brief description of drawings]

FIG. 1 is a diagram showing an electric double layer capacitor which is an embodiment of the present invention using a check valve.

FIG. 2 is a diagram showing an electric double layer capacitor which is an embodiment of the present invention using a rubber plug.

FIG. 3 is a diagram showing an electric double layer capacitor which is an embodiment of the present invention using a rubber plug.

FIG. 4 is a diagram showing an electric double layer capacitor which is an embodiment of the present invention using a cup-shaped plug.

FIG. 5 is a diagram showing an electric double layer capacitor which is one example of the present invention used in one experiment.

[Explanation of symbols]

 1 Container 2 Top Plate 3 Opening 4 Check Valve 5 Hole 6 Lower Member 7 Reverse Cone Part 8 Sphere 9 Upper Member 10 Spring 11 Hole

Claims (4)

[Claims] 1. A container of an electric double layer capacitor having an electrode and an electrolytic solution inside, and a part of the container,
An electric double layer capacitor having valve means for preventing gas from flowing out of the container and allowing gas generated inside the container to escape to the outside of the container. 2. The electric double layer capacitor according to claim 1, wherein the valve means is a check valve. 3. The electric double layer capacitor according to claim 1, wherein the valve means is a rubber plug, and hollow fine needles are inserted through the rubber plug to take out gas inside the container to the outside of the container. 4. The valve means is a cup-shaped member in which a hole is formed in a part and a liquid is put inside, and the gas inside the container is released to the outside through the hole of the cup and the liquid. The electric double layer capacitor according to claim 1, configured as described above.