JPH05159974A - Electric double layer capacitor - Google Patents

Abstract

(57) [Summary] [Purpose] The withstand voltage is dramatically increased to about 5 volts. [Structure] A pair of polarizable electrodes 3p ... Arranged opposite to each other in an electrolytic solution C and a pair of conductive electrodes 2p ... Connected to the outer surface of each polarizable electrode 3p.
Is formed of an electrolyte impermeable carbon material M using non-graphitizable carbon such as high density isotropic carbon or glassy carbon.

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 provided with a pair of polarizable electrodes facing each other in an electrolytic solution and a pair of conductive electrodes connected to the outer surface of each polarizable electrode.

[0002]

2. Description of the Related Art Conventionally, as an electric double layer capacitor, an electric double layer capacitor disclosed in Japanese Patent Publication No. 25007 is known.

This type of electric double layer capacitor is provided with a pair of polarizable electrodes facing each other in an electrolytic solution and a pair of conductive electrodes connected to the outer surface of each polarizable electrode. A metal material such as stainless steel, aluminum or titanium is used as the conductive electrode.

[0004]

By the way, in this type of electric double layer capacitor, since it is necessary to prevent electrochemical alteration, there is a drawback that the withstand voltage cannot be set high. The voltage limit was about 3 volts.

That is, the electric double layer capacitor contains an electrolytic solution inside, and usually an aqueous electrolytic solution or an organic electrolytic solution is used as the electrolytic solution. The withstand voltage when an aqueous electrolytic solution is used is determined by the electrolysis potential of water, and this potential Ew
As shown in FIG. 5, it is about 1.7 V, which is much lower than that of the organic electrolyte. On the other hand, the withstand voltage when an organic electrolyte is used is determined by the dissolution potential Ed of the electrolyte with respect to the metal material used for the conductive electrode. For example, when the metal material is aluminum, the potential Ed is
It will be about 2.3 volts. Further, in the case of the electric double layer capacitor disclosed in the above publication, titanium is used as the conductive electrode to increase the withstand voltage, but even in this case, the withstand voltage that can be secured is about 2.9 volts.

As described above, the withstand voltage of the conventional electric double layer capacitor is limited to about 3 volts at most,
There was a drawback that the withstand voltage was not sufficient.

The present invention has solved the problems existing in such conventional techniques, and an object thereof is to provide an electric double layer capacitor capable of dramatically increasing the withstand voltage to about 5 volts.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to an electric battery comprising a pair of polarizable electrodes arranged in an electrolytic solution C so as to face each other, and a pair of conductive electrodes connected to the outer surface of each polarizable electrode. In constructing the multilayer capacitor 1, in particular, the conductive electrodes 2p, 2n are formed of an electrolyte impermeable carbon material M using non-graphitizable carbon such as high density isotropic carbon or glassy carbon. Is characterized by.

In this case, an electrode unit 5p formed by integrally forming the polarizable electrodes 3p and 3n on the conductive electrodes 2p and 2n,
5n can be used, and as the electrode unit 5p (same for the 5n side), the conductive electrode 2p molded from the electrolytic solution impermeable carbon material M has activated carbon such as activated carbon fiber containing at least a thermosetting resin. It can be obtained by stacking materials and thermocompression-molding them, and then carbonizing them. In addition, as the electrode unit 5p according to another embodiment, a conductive electrode 2p formed of an electrolyte impermeable carbon material M and a polarized side formed body 3pm formed of an activated carbon material containing at least a thermosetting resin, It can be obtained by carbonizing after bonding with the adhesive material B using a thermosetting resin. Furthermore, as the electrode unit 5p according to another embodiment, a conductive electrode 2p formed of an electrolytic solution impermeable carbon material M and an activated carbon material containing at least a thermosetting resin are formed and carbonized. The obtained polarizable electrode 3p can be obtained by sticking the adhesive material B using a thermosetting resin and then carbonizing the adhesive material B.

[0010]

In the electric double layer capacitor 1 according to the present invention, since the electrolytic solution impermeable carbon material M is used for the conductive electrodes 2p and 2n, its withstand voltage is a metal based on the organic electrolytic solution when a metal material is used. It does not depend on the melting potential Ed of the material. Therefore, as shown in FIG. 5, the withstand voltage depends on the decomposition potential Ec of the organic electrolytic solution or the anodic oxidation potential Em of the carbon material electrode, and these potentials Ec and Em are usually about 5 volts. Become.

Further, since the electrode units 5p and 5n in which the polarizable electrodes 3p and 3n are integrally formed on the conductive electrodes 2p and 2n can be used, they can be assembled without performing pressure treatment during assembly.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

The electric double layer capacitor 1 according to the present invention is
The electrode unit 5p shown in FIG. 1 is used. The electrode unit 5p is formed by integrally forming the polarizable electrode 3p on the conductive electrode 2p. Next, the manufacturing method thereof will be described with reference to the manufacturing process chart shown in FIG.

First, a thin plate-shaped conductive electrode 2p is formed from an electrolyte impermeable carbon material M (step 11). As the electrolytic solution impermeable carbon material M, for example, high density isotropic carbon or glassy carbon belonging to non-graphitizable carbon made of thermosetting resin such as cellulose, furfuryl alcohol resin, phenol aldehyde resin, etc. Is available.

Also, activated carbon fibers (or activated carbon fibers and other materials such as rayon, polyacrylonitrile,
A material such as a mixture of fibers or pulp made from pitch or the like) is impregnated with a thermosetting resin such as a phenolic resin (step 12),
Activated carbon fiber containing a thermosetting resin obtained from this,
The conductive electrode 2p obtained in step 11 is overlaid and thermocompression-molded (step 13). As a result, as shown in FIG. 2, the activated carbon fiber containing the thermosetting resin was formed into a thin plate-shaped molded body 3 pm.
And is smaller than the conductive electrode 2p. Therefore, the polarization side molded body 3pm is integrally overlapped on the conductive electrode 2p, and the two-layered intermediate molded body 4pf in which the peripheral edge portion of the conductive electrode 2p projects outward by a predetermined width from the polarization side molded body 3pm is formed. obtain.

The intermediate compact 4p obtained in step 13
For f, carbonization treatment is performed by heating at a temperature that does not deteriorate the electrode function. As a result, the thermosetting resin in the activated carbon fiber is carbonized and a so-called C / C composite is formed, and this portion becomes the polarizable electrode 3p (step 14).

Therefore, the polarizable electrode 3p is added to the conductive electrode 2p.
An electrode unit 5p integrally formed with is obtained (step 15).
Since the electrode unit 5p is manufactured in this way, the contact resistance (internal resistance) between the conductive electrode 2p and the polarizable electrode 3p is reduced. On the other hand, a pair of the obtained electrode units 5p is prepared and the electric double layer capacitor 1 according to the present invention is assembled (step 16).

In FIG. 1, 5p and 5n are the electrode units thus obtained, which are on the anode side and the cathode side, respectively. In the electrode units 5p and 5n, the polarizable electrodes 3p and 3n are opposed to each other and arranged in parallel, and a plurality of insulating bridges 7 are interposed therebetween. The insulating bridges 7 ... Have a function to insulate the electrode units 5p and 5n by slightly positioning them.
Therefore, it is desirable that the contact area of each electrode unit 5p, 5n with respect to the polarizable electrodes 3p, 3n be as small as possible from the viewpoint of reducing the internal resistance.

On the other hand, reference numeral 8 denotes a casing, which is composed of a side plate portion 8k formed of an insulating material and end plate portions 8p and 8n formed of a conductive material which cover both ends of the side plate portion 8k.
The conductive electrodes 2p, 2n in each of the electrode units 5p, 5n described above are fitted and assembled in the cutout portions 9p, 9n formed at one end and the other end of the inner peripheral surface of the side plate portion 8k, respectively, and at the same time, the side plate portion. Both ends of 8k are end plates 8p, 8n
To close it. As a result, each electrode unit 5p, 5
n is positioned and supported by the casing 8. In addition, at the same time as this assembly, each electrode unit 5p
The organic electrolytic solution C is injected between 5 and 5n. Therefore, the side plate portion 8k and the end plate portions 8p and 8n are wholly sealed, and the outer surfaces of the conductive electrodes 2p and 2n contact the inner surfaces of the end plate portions 8p and 8n formed of a conductive material, respectively. The plate portions 8p and 8n serve as electrode terminal surfaces connected to an external circuit. As described above, the electric double layer capacitor 1 according to the present invention is obtained.

Since the electrode units 5p and 5n are regulated by the casing 8, the insulating bridges 7 ... May be omitted. When the insulating bridges 7 ... Are not used, the inclusions between the polarizable electrodes 3p and 3n can be eliminated at all except the organic electrolytic solution C. FIG. 4 shows the principle configuration of the electric double layer capacitor 1, in which the organic electrolytic solution C also penetrates into the polarizable electrodes 3p and 3n.

Next, a modified embodiment of the present invention will be described with reference to FIG.
And FIG. 7 will be described.

FIG. 6 shows another manufacturing method of the electrode unit 5p, and the manufacturing method thereof will be described below with reference to the manufacturing process chart of FIG.

First, in the same manner as in the above embodiment, the thin plate-shaped conductive electrode 2p is molded from the electrolytic solution impermeable carbon material M (step 21).

On the other hand, activated carbon fibers (or activated carbon fibers and other materials such as rayon, polyacrylonitrile,
A thin plate-shaped polarization for obtaining a polarizable electrode 3p (C / C composite) by impregnating a thermosetting resin such as a phenolic resin into a mixture of fibers and pulp made from pitch or the like) and thermocompression bonding. The side molded body 3pm is molded (step 2)
2).

Next, the conductive electrode 2p obtained in step 21 and the polarization side molded body 3pm obtained in step 22 are attached by the adhesive material B using a thermosetting resin such as phenol resin.
As a result, the intermediate molded body 4 is substantially the same as the intermediate molded body 4pf in which the conductive electrode 2p and the polarization side molded body 3p are bonded together.
Obtain ps (step 23: see FIG. 2).

The intermediate compact 4p obtained in step 23
s is carbonized by heating at a temperature that does not deteriorate the electrode function. As a result, both the thermosetting resin in the activated carbon fiber and the adhesive material B are carbonized, so-called C / C.
By forming the composite, this portion becomes the polarizable electrode 3p. Therefore, the same electrode unit 5p as that in the above-described embodiment is obtained in which the polarizable electrode 3p is integrally formed with the conductive electrode 2p (steps 24 and 25).

In another modified embodiment, step 22
By performing the same carbonization treatment as in step 24 on the polarized side molded body 3pm obtained in step 3, a polarizable electrode 3p was manufactured before sticking, and the polarizable electrode 3p obtained from this and step 21 were obtained. The conductive electrode 2p may be attached with the adhesive material B. In this case, it is necessary to carbonize the adhesive material B again after pasting, but there is an advantage that the conditions of each carbonizing treatment can be set to be optimum.

On the other hand, FIG. 7 shows another structure of the electric double layer capacitor 1 according to the present invention. The electric double layer capacitor 1 shown in the figure is provided with two electric double layer capacitor elements 1x and 1y inside a casing 8. in this case,
Structurally, it is the same as the structure in which two electric double layer capacitors shown in FIG. 1 are connected in series, except that the conductive electrode 2c arranged in the center is also used for each capacitor element 1x and 1y.
Therefore, such a structure can be similarly implemented even when three or more electric double layer capacitor elements 1x ... Are used.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, materials, etc. can be arbitrarily changed without departing from the scope of the present invention.

[0030]

As described above, according to the present invention, an electric double layer capacitor comprising a pair of polarizable electrodes opposed to each other in an electrolytic solution and a pair of conductive electrodes connected to the outer surface of each polarizable electrode. In particular, since the conductive electrode is an electrolyte impermeable carbon material using non-graphitizable carbon such as high-density isotropic carbon or glassy carbon, the withstand voltage is set to the decomposition potential of the organic electrolyte. Alternatively, there is a remarkable effect that the anodic oxidation potential of the carbon material electrode can be dramatically increased to about 5 V.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electric double layer capacitor according to the present invention,

FIG. 2 is a perspective view of an electrode unit used in the electric double layer capacitor,

FIG. 3 is a manufacturing process diagram of the electrode unit,

FIG. 4 is a principle configuration diagram of the electric double layer capacitor,

FIG. 5 is an operation explanatory view of the electric double layer capacitor,

FIG. 6 is a manufacturing process diagram according to a modified embodiment of the electrode unit;

FIG. 7 is a vertical sectional view according to a modified embodiment of the electric double layer capacitor,

[Explanation of symbols]

 1 Electric Double Layer Capacitor 2p ... Conductive Electrode 3p ... Polarizing Electrode 3pm Polarized Side Molded Body 5p ... Electrode Unit B Adhesive Material M Electrolyte Impermeable Carbon Material C Electrolyte (Organic Electrolyte)

Claims (6)

[Claims] 1. An electric double layer capacitor comprising a pair of polarizable electrodes facing each other in an electrolytic solution, and a pair of conductive electrodes connected to the outer surface of each polarizable electrode. An electric double layer capacitor formed of a liquid impermeable carbon material. 2. The electric double layer capacitor according to claim 1, wherein the electrolyte impermeable carbon material is non-graphitizable carbon such as high density isotropic carbon or glassy carbon. 3. The electric double layer capacitor according to claim 1, wherein an electrode unit in which a polarizable electrode is integrally formed with a conductive electrode is used. 4. The electrode unit is formed by stacking an activated carbon material such as activated carbon fiber containing at least a thermosetting resin on a conductive electrode formed of an electrolytic solution impermeable carbon material and thermocompression-molding the carbonized material. The electric double layer capacitor according to claim 3, wherein the electric double layer capacitor is obtained. 5. The electrode unit is formed by thermosetting a conductive electrode formed of an electrolyte impermeable carbon material and a polarized side formed body formed of an activated carbon material such as activated carbon fiber containing at least a thermosetting resin. The electric double layer capacitor according to claim 3, wherein the electric double layer capacitor is obtained by laminating with a laminating material using a conductive resin and then carbonizing. 6. The electrode unit is formed of a conductive electrode formed of an electrolyte impermeable carbon material and an activated carbon material such as activated carbon fiber containing at least a thermosetting resin,
5. The electric electrode according to claim 3, wherein the polarizable electrode obtained by the carbonization treatment is adhered to the adhesive material using a thermosetting resin, and then the adhesive material is carbonized. Multilayer capacitor.