JPH0735379Y2 - Electric double layer capacitor - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to an electric double layer capacitor having a small contact resistance between a current collector and a polarizable electrode.

[Prior art]

The internal resistance of the electric double layer capacitor is mainly composed of the contact resistance between the activated carbon particles contained in the polarizable electrode and the contact resistance between the polarizable electrode and the current collector. If the internal resistance of the electric double layer capacitor is large, the quick charging and discharging performance will be impaired. Therefore, various efforts have been made to reduce the internal resistance. For example, in order to improve the contact between activated carbon particles and the contact between the current collector and the polarizable electrode, pressure is applied from the top and bottom of the electric double layer capacitor, or the contact area with the polarizable electrode is expanded, so For example, the surface of the body is made uneven. FIG. 3 shows such a conventional electric double layer capacitor. In FIG. 3, 1 is a current collector, 1-1 is an uneven surface of the current collector, 2 is a polarizable electrode, 3 is a separator, and 4 is a gasket. As the current collector 1, for example, conductive rubber is used. The surface of the side that contacts the polarizable electrode 2 is an uneven surface 1-1 in order to widen the contact area. The uneven surface 1-1 is formed, for example, by etching, polishing,
It is performed by press working or the like. The polarizable electrode 2 uses activated carbon particles as an electrolyte solution (eg, dilute sulfuric acid).
It is mixed with and made into a paste. Separator 3
Is for separating the two polarizable electrodes 2,
A porous plastic film is used. The gasket 4 is for insulating the polarizable electrode 2 from the surroundings, and for example, insulating rubber is used. The current collector 1 and the gasket 4 or the gaskets 4 are bonded together by an appropriate means such as vulcanization. The surface of the current collector 1 that is in contact with the polarizable electrode 2 has an uneven surface 1
Since it is set to -1, polarizable electrode 2
The contact area with and becomes large, and the contact between them becomes good.
When pressure is applied from the outside of the upper and lower current collectors 1, the contact resistance between the activated carbon particles of the polarizable electrode 2 and the contact resistance between the polarizable electrode 2 and the current collector 1 become small. Note that, as conventional documents relating to such electric double layer capacitors, there are, for example, JP-A-60-171716 and JP-A-61-287216.

[Problems to be solved by the device]

However, in the above-mentioned conventional electric double layer capacitor, it is said that the contact surface between the current collector 1 and the polarizable electrode 2 is increased by the uneven surface 1-1 and the contact resistance is made smaller than that in the case of the flat surface. However, it was not enough and needed a lot of pressure. Therefore, as a case of the electric double layer capacitor, a structure that generates a large pressing force is required, which is troublesome to manufacture and the cost is high. The present invention aims to solve such problems.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the electric double layer capacitor of the present invention, a carbon whisker reinforced plastic plate in which the plastic on the surface is subjected to melting treatment and carbon whiskers are projected is used as a current collector, and the surface where the carbon whiskers project is It was arranged to be in contact with the polarizable electrode.

The innumerable carbon whiskers protruding from the surface of the current collector act to greatly expand the contact area with the polarizable electrode. Therefore, the contact resistance between the current collector and the polarizable electrode becomes small, and the internal resistance of the electric double layer capacitor is greatly reduced.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an electric double layer capacitor according to an embodiment of the present invention. Reference numerals correspond to those in FIG. 3, and 5 is a carbon whisker. The structural feature of the present invention is that the current collector 1 is an FRP plate (reinforced plastic plate) reinforced with carbon whiskers 5. FIG. 2 shows a current collector 1 used in the present invention. One side of the FRP plate reinforced with carbon whiskers 5 is subjected to a treatment to dissolve only the plastic of the surface layer. Then, the carbon whiskers 5 included in the FRP plate for strengthening remain on that surface, and become infinitely protruding. The dissolution treatment can be performed using formic acid in the case of a FRP plate using nylon, for example. The carbon whisker 5 is bonded to the gasket 4 with the protruding surface facing the polarizable electrode 2. Adhesion is performed by vulcanization (temperature of about 150 to 160 ° C.) via an epoxy thermosetting adhesive, for example. When the current collector 1 has the above-described structure, the contact area with the polarizable electrode 2 is surprisingly increased as compared with the case of the uneven surface as in the conventional example, as illustrated below. Can be done. That is, the enlargement ratio of the surface area when the uneven surface is formed by polishing or etching as in the conventional case is about 10 to 20 times. However, in the present invention, for example, the surface area of carbon whisker ... 50m ² The specific gravity of carbon whisker 1.5g / cm ² The content of carbon whisker in the plastic 20vol
% When the dissolution depth is 100μ (0.1mm) and the surface area expansion ratio is calculated, the result is as follows.
However, A is the area of the plane before melting (unit m ² ). A × (0.1 × 10 ⁻³ ) × (1.5 × 100 ³ ) × 0.2 × 50 = 1500A That is, the surface area expansion rate is 1500 times. In addition, the plastic plate reinforced with carbon whiskers,
When manufactured by extrusion, the carbon whiskers are aligned in the extrusion direction. Therefore, if the direction is made perpendicular to the surface, the carbon whiskers can be projected vertically from the plastic plate, and the contact with the polarizable electrode can be further improved.

[Effect of device]

As described above, according to the electric double layer capacitor of the present invention, innumerable carbon whiskers are projected from the surface of the current collector, and the contact area with the polarizable electrode is greatly expanded.
The contact resistance between the current collector and the polarizable electrode is greatly reduced. Therefore, the magnitude of the pressure applied to reduce the contact resistance can be reduced. As a result, the case of the electric double layer capacitor does not need to have a structure that generates a large pressing force, which facilitates the manufacture and reduces the cost.

[Brief description of drawings]

FIG. 1 ... Electric double layer capacitor according to an embodiment of the present invention FIG. 2 ... Current collector used in the present invention FIG. 3 ... Conventional electric double layer capacitor. In the figure, 1 is a current collector, 1-1 is an uneven surface, 2 is a polarizable electrode, 3 is a separator, 4 is a gasket, and 5 is a carbon whisker.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akio Yoshida 8 Tsutana, Fujisawa, Kanagawa Prefecture Isuzu Motors Co., Ltd. Fujisawa factory (72) Inventor Hitoshi Koizumi 8th cabinet, Fujisawa, Kanagawa Prefecture Isuzu Motors Fujisawa factory (72) Inventor Mutsuo Nishimoto 8 Fujisawa City, Kanagawa Prefecture, Shelf Shelf, Isuzu Motors Co., Ltd. Fujisawa Plant (72) Inventor, Kazuko Takayama 3-25-1, Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa Isuzu Motors Co., Ltd. Kawasaki Plant (72) Inventor, Yoriaki Niida, No. 8 Tsutana, Fujisawa City, Kanagawa Prefecture, Isuzu Engineering Co., Ltd. (56) Reference: JP-A-2-153515 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A carbon whisker reinforced plastic plate having a carbon whisker protruding by melting a plastic on the surface is used as a current collector, and the surface on which the carbon whisker protrudes is arranged so as to come into contact with a polarizable electrode. Electric double layer capacitor characterized by.