JPH02294008A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To prevent the evaporation of an electrolyte and the penetration of moisture and maintain characteristics of an electric double layer capacitor at a stable state by holding lead terminals in such a way that the terminals are insulated electrically from a seating by means of a glass member. CONSTITUTION:A seating 16 is made of metals such as an iron and the like through which the peripheral part of the seating is joined with the opening end of a metallic case 15 by welding or soldering so that its seating may plug the opening of the metallic case 15. Two pieces of lead terminals 18 are installed in the seating 16 through a glass member 17 and these terminals are electrically insulated from the seating 16 through the glass member 17. Further, a lead plate 14 is connected to respective lead terminals 18. In such a case, even though an electric double layer capacitor uses an organic electrolyte having low water, its capacitor is not affected by external moisture at all. Then, it is superior in moisture resistance and may maintain stable characteristics for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a small-sized, large-capacity electric double layer capacitor.

Prior Art This type of electric double layer capacitor in the past
As shown in the figure, a polarizable electrode 1 is obtained by press-molding activated carbon powder or by forming a sprayed layer of aluminum on activated carbon fibers, and this polarizable electrode 1 is placed in metal cases 2 and 3 made of stainless steel, respectively. The two polarizable electrodes 1 were placed opposite to each other with an electrolyte and a separator 4 interposed therebetween, and the peripheral edges of the openings of both metal cases 2.3 were sealed with a gasket 5 interposed therebetween.

In addition, as another electric double layer capacitor, as shown in FIG. 11, the internal element 6 is constructed by winding a band-shaped polarizable electrode with an electrolyte and a separator interposed between them.
There is also a structure in which the internal element 6 is housed in a metal case 8 and the opening is sealed by inserting a sealing rubber 9 into the opening. Note that 7 is a lead wire connected to the polarizable electrode of the internal element 6.

The electrolytes used in these electric double layer capacitors include aqueous solutions using dilute sulfuric acid, and organic electrolytes using brobylene carbonate or γ-butyrolactone solutions of quaternary ammonium salts of perchloric acid compounds and borofluorides. There are two types: liquid type. The withstand voltage of a single cell is largely influenced by the decomposition voltage of the electrolyte, and in an aqueous system it is approximately I
, it is approximately 3V in an organic electrolyte system.

Although electric double layer capacitors have a large capacity on the order of farads compared to electrolytic capacitors, their withstand voltage is lower as mentioned above, so when used in 5 to 5.5 V lines for semiconductor memory backup etc. In order to use several capacitors connected in series, several capacitor Itt cells are connected in series and integrated. In this case, an aqueous solution system requires a minimum of six single cells connected in series, whereas an organic electrolyte system requires only two series connections, and the organic electrolyte system is much smaller than the aqueous solution system. It has the advantage of being able to be sized.

Problems to be Solved by the Invention In electronic devices that use semiconductor memory, which is the main use of electric double layer capacitors as backup power supplies,
In order to improve the reliability of semiconductors, emphasis has been placed on extending their lifespan in high-temperature, high-humidity environments, which were previously thought to be weak.

Although the aqueous solution system is more thermally constrained than the organic electrolyte system, it has the advantage that the influence of humidity can be ignored.

On the other hand, as mentioned above, electric double layer capacitors using an organic electrolyte can have a high withstand voltage of a single cell, so the product size can be reduced even when connected in series. A very small amount of water gradually enters the capacitor through the elastic resin gasket or sealing rubber used in the capacitor, and as a result of the water being decomposed, the capacitor's characteristics deteriorate rapidly.

Further, in sealing such an electric double layer capacitor, the solvent in the electrolyte, not only the organic electrolyte, diffuses through the gasket and evaporates.

In this case, the function as a capacitor is impaired and the capacitor cannot be put to practical use for a long period of time.

The object of the present invention is to solve these drawbacks, eliminate evaporation of electrolytic solution and intrusion of moisture, and maintain stable characteristics of an electric double layer capacitor.

Means for Solving the Problems To achieve this object, the present invention provides a metal case in which the peripheral edge of a metal pedestal is joined to the opening of the metal case that houses the single cell so as to close this opening. The inside is sealed, and the lead terminal connected to the electrode of the single cell is drawn out through the pedestal, and at least one lead terminal is held in the pedestal in an electrically insulated state by a glass member.

In the case of resins, rubbers, etc., if there is a difference in water concentration between two phases separated by these, the concentration gradient becomes a driving force: water diffuses and permeates from the phase with a higher degree of a to the phase with a lower degree of a, and enters. It is known to go.

According to the present invention, a single cell of an electric double layer capacitor using a conventional sealing material that gradually allows moisture to pass through is sealed in a metal case that does not allow moisture to pass through, and is placed in a place where electrical insulation is required. Since this also uses glass that does not allow moisture to pass through, even if it is an organic electrolyte-based electric double layer capacitor, it can completely eliminate the influence of moisture outside the capacitor.

EXAMPLE Hereinafter, an example of the present invention will be explained using the drawings of FIGS. 1 to 9.

(Example 1) A first example of the present invention is shown in FIGS. 1 to 3,
In the figure, 11 is a single cell of an electric double layer capacitor having a structure as shown in FIG.
Two of the illustrated devices are stacked and connected in series via a connecting cup l2. Further, an insulating sleeve 13 is placed over the outer peripheral surface of the series unit of the single cells l1. Furthermore, lead plates 14 are connected to both ends of the series unit of the single cells 11 by welding.

15 is a bottomed cylindrical metal case that houses the single cell II;
Reference numeral 6 denotes a pedestal made of metal such as iron, whose peripheral edge is joined by welding or soldering to the open end of the metal case 15 so as to close the opening of the metal case 15. A glass member 17 is mounted on the pedestal 16. Two lead terminals 18 are installed in between.

This lead terminal 18 is connected to the pedestal 16 by the glass member 17.
Electrically IP! A lead plate 14 is connected to each lead terminal 18.

Reference numeral 19 denotes an element fixing member that fixes the single cell 11 to the bottom of the metal case 15.

That is, in this embodiment, a plurality of single cells 11 are housed in a connected state in a metal case 15, and the opening of the metal case 15 is connected to a hardware using a pedestal 16, a glass member 17, and a lead terminal 18. It is sealed using a mekek seal structure. The electrodes are drawn out from the single cell 11 by connecting the lead plate 14 connected to the single cell 1l to the lead terminal 18.

Note that even if the structure is not such that all two lead terminals 18 are insulated from the pedestal 16 as in the above embodiment, only one lead terminal 18 is insulated by the glass member 17 as shown in FIG. The lead terminal 18 may be connected to the pedestal 16.

Furthermore, as shown in FIGS. 5 and 6, a lead terminal 20 having a structure in which the lead plate l4 and the lead terminal 18 are integrated is used, and the lead terminal 20 connected to the single cell 11 is directly inserted through the glass member 17. It may also be taken out by penetrating the pedestal l6.

In this case, as shown in FIG.
is attached via the glass member l7, and its metal ring 21
The lead terminal 20 is taken out, and the metal ring 2l and the lead terminal 20 are joined with solder 22.

Next, a specific example of the electric double layer capacitor in this embodiment will be explained.

An internal element formed by an activated carbon fiber cloth, a separator made of brobylene carbonate, and an organic electrolyte solution made by dissolving 1 mole of tetraethylammonium tetrafluoroborate in brobylene carbonate, a stainless steel metal case, a stainless steel metal lid, and the above-mentioned A single cell of an electric double layer capacitor is constructed by enclosing a metal lid and a gasket made of polypropylene which is installed between a metal case and a gold RM and is compressed and held by the metal lid, and the two single cells are electrically connected. Connect them in series, store them in an iron case, and connect them in series. A terminal plate whose negative and lead lead-out parts are insulated and sealed with electrically insulating lead-based glass is joined by welding at the contact point with the metal case to form a single cell 2.
The pieces were sealed.

The 5.5V rated electric double layer capacitor prepared as above and the conventional specification, that is, the case and terminal board for serializing the single cells, are used to connect the single cells housed inside and the outside air. A rated electric double layer capacitor is connected to a voltage of 5V in an atmosphere of 85℃ and 85% relative humidity.
A comparative test was conducted by applying The results are shown in Table 1.

(Margin below) As is clear from the results shown in Table 1, the product of the present invention has the following properties:
It is completely unaffected by the humidity of the outside air and has extremely stable characteristics even after 5,000 hours. In comparison, with the conventional product, water gradually entered through the gasket part, and
The properties rapidly deteriorate after 0 to 2000 hours.

(Embodiment 2) A second embodiment of the present invention is shown in FIGS. 7 and 8,
In this embodiment, three electric double layer capacitors shown in FIG. 11 are used as a single cell 23 and are connected in series and sealed in a metal case 15. 24 is single cell 2
This is the lead terminal pulled out from 3.

Next, a specific example of this embodiment will be explained.

A separator made of a mixture of Manila hemp fiber and glass fiber is sandwiched between two strip electrodes formed by coating activated carbon powder with an organic binder on an aluminum net, and these are wound, and tetraethylammonium perchlorate is applied to these. An internal element is constructed by impregnating 1 mol of organic electrolyte solution in γ-butyrolactone, and this element is housed in a cylindrical aluminum case with a bottom, and the opening has a hole for leading out leads from the internal element. At the same time as the encapsulating rubber is attached, the periphery of the rubber is pressurized and compressed by pressing the aluminum case to complete the encapsulation and obtain a single cell of an electric double layer capacitor.

The three quasi-punched single cells are electrically connected in series so that they can withstand the application of 565V.

The leads pulled out from the single hill are joined by soldering to a terminal plate having a structure in which the lead-out part is insulated by a glass member and the innermost part through which the leads pass holds a solder-plated iron pipe, and the terminal plate is sealed.

The electric double layer capacitor with a rating of 5.5V prepared as described above is the same as the present invention up to the conventional structure of block type electric double layer capacitors, that is, three individual pieces are electrically connected in series. The exterior case that houses this device is made of resin, and the terminal board also uses a resin board, which was evaluated in comparison with a case that does not take care to isolate the internal elements from the outside air.

The test temperature was 85°C and 85% relative humidity. O
It was assumed that v was applied continuously. The test results are shown in Table 2.

(Margin below) As is clear from the results in Table 2, the product of the present invention is not affected by the humidity of the outside air at all and exhibits extremely stable characteristics even after 8000 hours. On the other hand, the conventional structure is affected by moisture in the outside air after about 2000 hours, and the deterioration of the characteristics begins to become noticeable.

(Example 3) FIG. 9 shows a third example of the present invention. In this example, the electric double layer capacitor shown in FIG. 10 is used as a single cell l1, and two are connected in series. They are stacked in the height direction and sealed in a bottomed cylindrical metal case 25 made of stainless steel. The opening of the metal case 25 is sealed by welding one lead terminal 18 and the peripheral edge of a pedestal 16 on which the other lead terminal 18 is implanted via a glass member 17. One lead terminal l8 held on the pedestal 16 via the glass member 17 is welded to a stainless steel terminal plate 26 connected to one electrode of the single cell 1l, and the other lead terminal l8, which is also connected to the pedestal 16, is welded to a stainless steel terminal plate 26 connected to one electrode of the single cell 1l. Lead terminal l8
is connected to the other electrode of the single cell l1 via the metal case 25 and a stainless steel buffer material 27 placed between the inner bottom surface of the metal case 25 and the other electrode of the single cell 11. Reference numeral 28 denotes an insulating container made of polypropylene, which is disposed between the metal case 25 and the single cell l1 and between the pedestal 16 and the terminal plate 26.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Even electric double layer capacitors that use a low-moisture organic electrolyte are completely unaffected by the humidity of the outside air.
An electric double layer capacitor with extremely excellent moisture resistance can be obtained.

Q) Rather than sealing individual capacitors with glass, each unit connected in series is sealed with glass, which requires less material and fewer man-hours, resulting in a significant reduction in sealing costs.

(3) Diffusion of the electrolytic solution solvent from the single cell can be suppressed, and stable characteristics can be maintained over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an electric double layer capacitor according to an embodiment of the present invention, FIG. 2 is a sectional view of the same, FIG. 3 is an exploded perspective view of the same, and FIG. FIG. 5 is a partially cutaway perspective view showing another embodiment of the present invention, FIG. 6 is a sectional view of the same, and FIG. 7 is a cross-sectional view of another embodiment of the present invention. A partially cutaway perspective view, FIG. 8 is the same sectional view, and FIG. 9 is the same. A partially cutaway perspective view showing another embodiment of the present invention, FIGS. 10 and 11 are electric double layer capacitors, respectively. FIG. 2 is a cross-sectional view and an exploded perspective view showing a single cell. 11.23...Single cell, 14...Lead plate, 15,25...Metal case, 16...
...Pedestal, 17...Glass member,. 18,2
0.24...Lead terminal, 26...Terminal board, 27...Buffer material. Name of agent: Patent attorney Shigetaka Awano and other names

Claims (3)

[Claims] (1) The periphery of a metal pedestal is joined to the opening of the metal case that houses the single cell so as to close the opening, thereby sealing the inside of the metal case, and the lead is connected to the electrode of the single cell. An electric double layer capacitor in which a terminal is drawn out through the pedestal and at least one lead terminal is held in an electrically insulated state by a glass member on the pedestal. (2) The electric double layer capacitor according to claim 1, wherein the single cell is constructed using an element impregnated with an organic electrode solution and having polarizable electrodes facing each other with a separator interposed therebetween. (3) The lead terminal connected to one electrode of the single cell is electrically insulated by a glass member and pulled out through the pedestal, and the other electrode of the single cell is inserted into the metal case. 2. The electric double layer capacitor according to claim 1, further comprising a lead terminal which is electrically connected to the base through a buffer material and which is connected to the other electrode of the single cell.