JPH0380520A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To reduce the internal resistance by providing pressure plates disposed at both ends of a capacity element for bringing into contact with current collecting electrodes only at corresponding parts to its paste electrode, a through hole formed in the center of each capacity element, and clamping means for coupling and clamping the plates through the hole. CONSTITUTION:An electric double layer capacitor 20 is composed by laminating a plurality of basic cells 30 for forming a disc-shaped flat surface, and all the cells 30 are formed in the centers with through holes 31. All the cells 30 have carbon paste polarizable electrode 33 separated into two layers by a separator 32 and sealed between a pair of current collecting electrodes 34, and annular gaskets 35, 36 for sealing the electrode 33 are provided on the inner periphery of the hole 31 side and the outer periphery of the electrode 34. The capacitors 30 are laminated by sequentially inserting a bolt 23 through a pressure plate 21, basic cells 30 of predetermined number and a pressure plate 21, engaging it with a nut 24 to be coupled, and clamping them. Thus, even if the cells are large in size, its internal resistance can be easily reduced by its small load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a large electric double layer capacitor that can reduce internal resistance and realize a stable capacitance value simply by applying a small load.

(Prior art) Vehicles equipped with an internal combustion engine, such as passenger cars, include a starter motor for starting the internal combustion engine, a generator that generates electricity using the rotational force between the internal combustion engines, and a generator that temporarily uses the generated power of the generator to generate electricity. A lead battery or the like is installed, which stores power and supplies power to the starter motor during startup or to other electrical equipment.

On the other hand, electric double layer type large capacity capacitors have been developed in recent years, and some are being used for battery applications, and there are proposals to use such large capacity capacitors for starting internal combustion engines in vehicles. Patent application filed in 1986 as a power supply device for
No. 329846 of the year.

FIG. 4 shows an electric double layer capacitor that is generally formed using paste electrodes. This is U.S. Patent No. 3
, 536,963, in which a current collector 1 of an electron conductor serving as a pair of current collecting electrodes, a carbon electrode 2 made of activated carbon particles, a non-conductive gasket 3, and an electron current collector 1 of an electron conductor serving as a pair of current collecting electrodes, a carbon electrode 2 made of activated carbon particles, a non-conductive gasket 3 and A single basic cell is constituted by a separator 4 to prevent movement of the cell.

The carbon electrode is manufactured as a concentrated slurry of activated carbon in powder or particulate form mixed with an electrolyte.

The electrolyte here performs three functions: as a promoter of ion conduction, as a source of ions, and as a binder for the carbon particles.

In order to use such an electric double layer capacitor as a power source for a vehicle, a large capacitance value of, for example, 100 to 150 F (Farad) is required. However, if we attempt to achieve the required capacity by increasing the number of cells integrated, the weight and volume will increase, making it unsuitable for loading onto a vehicle. Alternatively, in order to increase the capacity value per unit weight, it is necessary to increase the size of the basic cell itself.

Furthermore, when such an electric double layer capacitor is used as a power source for a vehicle, its internal resistance also becomes a problem. The internal resistance of an electric double layer capacitor is greatly affected by the contact resistance of the activated carbon that forms the polarizable electrodes, the contact resistance between the current collector electrode and the polarizable electrode, etc., so in order to reduce the internal resistance, requires applying pressure to the basic cell from above and below. In conventional electric double layer capacitors, the pressure applied there depends not only on the size of the electrodes but also on the size of the carbon material particles, the type of electrolyte used, etc., but is around 100 kg/cm2. pressure is required.

(Problems to be Solved by the Invention) In the structure of a typical electric double layer capacitor, a plurality of cells are pressurized by caulking in order to reduce the internal resistance. For example, a self-supporting capacitor described in Japanese Patent Application Laid-Open No. 56-2621 has a case structure shown in FIG. In other words, the outer case 5 includes the first
A second electrode plate 10 on which an electrode terminal 6 is provided standing up from a first electrode plate 7 and a second electrode terminal 9 stands up through an insulating plate 8.
are stacked and the required number of basic cells 12 to which pressure is applied by the reinforcing plate 11 is accommodated in the outer case 5, pressure is applied from above the electrode plate 7 on the two terminals 6.9 side, and the outer case 5 is stacked. The periphery is bent inward and caulked.

However, as the capacitor becomes larger, for example, when its surface area exceeds 100 cm+2, it becomes necessary to apply pressure of several tons or more, but with this type of crimping method, the force is also applied to the gasket part of the basic cell. Because of the additional structure, it is necessary to increase the rigidity of the reinforcing plate 11 and the outer case 5 by increasing their thickness, which limits the overall weight and material cost. Furthermore, it is necessary to prepare a pressurizing means and a special device for caulking, which poses a problem of complicating the process of applying appropriate pressure.

The present invention was made to solve the above problems, and
It is an object of the present invention to provide an electric double layer capacitor that can reduce internal resistance by easily pressurizing an electric double layer capacitive element and effectively utilizing the small force.

(Means for Solving the Problems) According to the present invention, an electric double layer capacitor including an electric double layer capacitive element formed by dividing a paste electrode between a pair of current collector electrodes via a gasket by a separator. a pressure plate disposed at both ends of the capacitive element and in contact with the current collector electrode only at the portion corresponding to the paste electrode;
An electrical device comprising: a through hole formed in the center of the capacitive element; and a fastening means that connects and tightens the pressure plates to each other through the through hole to pressurize the capacitive element. We can provide double layer capacitors.

(Function) In the double layer capacitor of the present invention, the pressure plates can be connected and tightened together through the through hole in the center of each capacitive element, and the pressure plates can be connected to the current collector electrodes corresponding to the paste electrodes. Pressure can be applied in a limited manner, and internal resistance can be reduced with a small load.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 3 shows changes in compressive displacement and resistance due to loads applied over the entire surface of current collector electrodes for an electric double layer capacitor having paste electrodes as shown in Figure 4. It is a line diagram.

Here, the basic cell to which the charge IHF is applied has a thickness of 3.5 mm and a surface area of its current collector electrode of 300 cm2.
(that is, a square shape with a length of 20 cm and a width of 15 cm), and 1
Experimental values are shown when five cells are stacked and a load F is applied. The amount of compressive displacement indicated by the thick line is the load F
increases linearly up to about 240 (1 kg), then bends and the rate of increase with respect to the load F decreases.

On the other hand, the resistance value shown by the broken line is F・30 when the load is further increased by about 800 kg from the bending point P of the above compressive displacement amount.
It becomes the minimum at 00 kg, and shows a stable value thereafter.

An important point to note here is that the experimental results shown in the graph of FIG. 3 were obtained when a load was also applied to the gasket portion of the basic cell.

In other words, a paste electrode made of a mixture of granular or fibrous activated carbon and a solvent such as sulfuric acid is enclosed in a gasket made of a non-conductive material such as hard, elastic waste material. Their elastic modulus is different. Therefore, the initial load F is received by the gasket, and the load on the paste electrode, which is porous and has a small bulk density, is substantially applied after the bending point P is exceeded. It is.

According to this experimental result, if the entire basic cell including the gasket is pressurized like a conventional electric double layer capacitor, a load of 3000 kg or more would be required.
If the structure is such that only the paste electrode is pressurized, it is estimated that a load of 800 kg will be enough.

FIG. 1 is a sectional view showing an electric double layer capacitor of the present invention, and FIG. 2 is an external perspective view showing an electric double layer capacitive element (basic cell) constituting the electric double layer capacitor of FIG. 1.

The electric double layer capacitor 20 is configured by stacking a plurality of circular planar basic cells 30, and each of these basic cells 30 has a through hole 31 formed in its center.

Each of these basic cells 30 has a structure in which a polarizable electrode 33 made of carbon paste separated into two layers by a separator 32 is enclosed between a pair of current collecting electrodes 34, and a ring-shaped electrode 33 seals the polarizable electrode 33. Gaskets 35 and 36 are provided on the inner circumference of the through hole 31 and on the outer circumference of the current collecting electrode 34. In other words, the configuration is different from that of the conventional electric double layer capacitive element shown in FIG. 4 in that a circular through hole 31 of a predetermined size is formed in the center of the gasket 35 that seals the polarizable electrode 33. different.

Reference numeral 21 denotes pressure plates that are located on the upper and lower surfaces of the stacked basic cells and also serve as bipolar plates of the capacitor. The pressure plate 21 is made of a highly rigid metal such as stainless steel, has a circular shape that is large enough to press only the polarizable electrode 33 of the basic cell 30 as a fixed plate of the basic cell, and has a circular through hole 31.
The center thereof is raised correspondingly to the current collector electrode 34 of the basic cell 30 . A hole corresponding to the through hole 31 is formed in the raised central part of the pressure plate 21, and these pressure plates 21 are connected to each other to form a base-tr rule 3.
0, a bolt 23 is inserted into the through hole 31 of this basic cell 30 with an insulating collar 22° 25 interposed, and the tip of this bolt 23 is pressed against the other pressure plate 21 by a nut 24. ing.

The electric double layer capacitor 20 having the above structure is stacked by inserting the bolt 23 through the pressure plate 21, a predetermined number of basic cells 30, and the pressure plate 21 in this order, screwing the nut 24 to connect them, and tightening them. The basic cell 30 can be easily pressurized.

Moreover, since the pressure plate 21 applies pressure only to the polarizable electrode 33 without applying any load to the gasket part of the basic cell 30, the internal resistance of the capacitor can be reduced with a small load, and the capacitor can be stabilized. The state can be maintained.

Note that even with the caulking method shown in FIG. 5, the same effect can be achieved by configuring the reinforcing plate 11 to contact the current collector electrode only at the portion corresponding to the paste electrode. It is.

The present invention has been described above in some detail with respect to its most preferred embodiment, but the description of the preferred embodiment M may include variations in the detailed structure and contrary to the spirit of the present invention as described in the claims. It is clear that various modifications or combinations thereof may be made.

(Effects of the Invention) As explained above, according to the present invention, even if the basic cell becomes large, pressure can be applied by the pressure plate that contacts the current collector electrode only at the portion corresponding to the paste electrode. ,
The internal resistance can be easily reduced by applying a small load, and by tightening the central part, the degree of adhesion between the collector electrodes of basic cells becomes uniform when multiple layers are stacked, and the contact resistance of the capacitor as a whole is also reduced. We can provide electric double layer capacitors that can be made low-cost.

Therefore, when using an electric double layer capacitor for a power source for a vehicle, a capacitance value required can be easily obtained.

4. PtJJIL explanation of drawings Figure 1 is a sectional view showing one embodiment of the present invention, Figure 2 is a cross-sectional view showing an embodiment of the present invention.
Figure 1 is an external perspective view showing the electric double layer capacitive element constituting the electric double layer capacitor, and Figure 3 is a diagram showing the change in compressive displacement and resistance value due to the load applied to the electric double layer capacitor. , FIG. 4 is a partial sectional view showing an example of an electric double layer capacitor formed using a conventional paste electrode, and FIG. 5 is a sectional view showing a pressurizing structure of a conventional capacitor.

20... Electric double layer capacitor, 21... Pressure plate,
23... Bolt, 24... Nut, 30... Electric double layer capacitive element (basic cell), 31... Through hole.

Claims (2)

[Claims] (1) In an electric double layer capacitor including an electric double layer capacitive element formed by a paste electrode sealed between a pair of current collector electrodes via a gasket and divided by a separator,
Pressure plates disposed at both ends of the capacitive element and in contact with the current collector electrode only at the corresponding parts to the paste electrodes; a through hole formed in the center of the capacitive element; and a through hole formed in the center of the capacitive element; and a fastening means that connects and tightens the capacitive elements to each other and pressurizes the capacitive element. (2) In the electric double layer capacitor in which a plurality of electric double layer capacitance elements are laminated, the fastening means is configured to apply pressure from a pressure plate serving as one current collector electrode of the laminated capacitor elements to a pressure plate serving as the other current collector electrode. The electric double layer capacitor according to claim 1, comprising a bolt that reaches the pressure plate and a nut that is screwed onto the bolt.