JPH06236829A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To allow the carbon particles of electrode material to penetrate into the interior of the meshes of a metal porous body of three dimensional reticular structure which is formed by conducting electroplating on foamed resin which is used as a current collecting body and the foamed resin is used for the metal porous body, having three-dimensional structure, which is formed by burning off the foamed resin by heat treatment. CONSTITUTION:A conduction treatment is performed on urethane foam by carbon coating and the like, and nickel or nickel-chrome is electroplated thereon, for example. Then, the foamed resin is burnt out, and a porous metal body, having three-dimensional reticular structure, is obtained. A cellumet, having porosity rate of 98% and the density of 0.18gr/sq cm, is used as a current collecting body 2. Also, activated carbon of surface area of 1700sqmm/g and carbon powder are mixed at the ratio of 5:5, paste-like material is obtained by adding a binder, and it is used as an electrode material 3. The current collecting body 2 is coated with the electrode material 3 uniformly, dried up, rolled out, and a carbon electrode 1 of uniform thickness is obtained. A read terminal is attached to the carbon electrode 1, an electrolyte is impregnated, and current collecting efficiency is greatly improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electric double layer capacitor, and more particularly to a carbon electrode thereof.

[0002]

2. Description of the Related Art For example, in the case of forming a capacitor element by winding a pair of carbon electrodes while sandwiching a separator paper, a current collector is attached to the carbon electrodes for the purpose of mechanical support.

Generally, an expanded metal net or an etched metal plate is used for the current collector, and a carbon electrode is applied to the current collector through a predetermined binder.

[0004]

The purpose of using the current collector as described above is to improve the contact with carbon both electrically and mechanically, but it is still not sufficient. This is because, particularly when the carbon electrode is wound, a strain is generated between the carbon electrode and the current collector, which has an adverse electrical effect.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and its characteristic feature is that a carbon electrode is formed by coating an electrode material containing carbon as a main material on a current collector. In the electric double layer capacitor having the above-mentioned, a porous metal body having a three-dimensional network structure in which a foamed resin is electroplated and burned off by heat treatment is used as the current collector.

Examples of the metal porous body include simple metals or alloys of nickel, chromium, copper or the like having a porosity of 50 to 99%. The density of the porous metal is 0.1 g
It is preferably r / cubic cm or more.

[0007]

This porous metal body has a three-dimensional mesh structure, and the carbon particles of the electrode penetrate into the mesh, so that good current collecting efficiency can be obtained.

[0008]

EXAMPLE FIG. 1 shows a carbon electrode 1 used in this electric double layer capacitor. Same carbon electrode 1
Is composed of a current collector 2 coated with an electrode material 3 containing carbon as a main material. In this case, the current collector 2 is a porous metal body having a three-dimensional mesh structure.

This porous metal is subjected to a conductive treatment, for example, with a urethane-based foamed resin by carbon coating or the like, followed by electroplating with, for example, nickel or nickel-chromium plating, and then subjected to a burning treatment to obtain the foamed resin. It is obtained by burning out. As a commercially available product, Celmet (trade name) manufactured by Sumitomo Electric Industries, Ltd.
There is.

Example 1 As a current collector, a porosity of 98
%, A density of 0.18 gr / cubic cm was used. Also, the surface area of the electrode material is 1700 mm 2 / g
The activated carbon and the carbon powder were mixed at a ratio of 5: 5, and a binder was further added to prepare a paste. Then, an electrode material was evenly applied to this current collector, and 10
Drying was performed at 0 ° C. for 10 hours. Then, in order to make the thickness uniform, it was rolled to a thickness of 150 to 200 μm with a rolling roller. After attaching the lead terminal to the carbon electrode thus obtained, the pair was wound with a separator paper sandwiched between them to impregnate the electrolytic solution. Then, the electric double layer capacitor having a diameter of 8 mm, a shaft length of 20 mm and a rating of 2.4 V 0.47 F was assembled by housing in a metal case and sealing. When the characteristics of this were measured, the capacitance was 0.641 F, the equivalent series resistance (ESR) at 1 kHz was 430 mΩ, and the maximum discharge current was 2 A.

<Comparative Example 1> An aluminum foil subjected to etching treatment was used as a current collector, and the same electrode material as in Example 1 was applied thereto. Thereafter, an electric double layer capacitor having the same shape and the same rating was assembled in the same manner as in Example 1 above.
And when the characteristic was measured, the capacitance was 0.5.
Equivalent series resistance (ESR) at 20F, 1kHz is 780
mΩ, the maximum discharge current was 300 mA.

These measured values are shown in Table 1. According to the present invention, the current collection efficiency is improved, the internal resistance is lowered, and a larger current can be discharged.

[0013]

[Table 1]

Although the above-described embodiment is directed to a wound type electric double layer capacitor, the present invention is not limited to this and is also applicable to a coin (or button) type electric double layer capacitor. To be done.

[0015]

As described above, according to the present invention, in the electric double layer capacitor having the carbon electrode formed by coating the current collector with the electrode material containing carbon as the main material, As a metal porous body having a three-dimensional mesh structure in which the foam resin is electroplated and burned off by heat treatment as the material, the carbon particles of the electrode material enter the inside of the mesh. A dramatic improvement in electrical efficiency can be achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a carbon electrode used in an electric double layer capacitor.

[Explanation of symbols]

 1 Carbon electrode 2 Current collector 3 Electrode material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinao Kobayashi 2-2-1 Tsujido Shinmachi, Fujisawa City, Kanagawa Elner Co., Ltd.

Claims (1)

[Claims] 1. An electric double layer capacitor having a carbon electrode formed by coating an electrode material having carbon as a main material on a current collector, wherein the current collector is electroplated on a foamed resin to form the foamed resin. An electric double layer capacitor comprising a porous metal body having a three-dimensional network structure burned down by heat treatment.