JPH03283517A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To prevent leakage of electrolyte even though a part of a current collecting plate is damaged by bonding under fusion a protective plate consisting of a carbon sheet to the outside surface of the current collecting plate which corresponds to an electrode compact. CONSTITUTION:In thermo-fusion bonding of an electrode compact 1 and a current collecting plate 2, a carbon sheet 3 acting as a protective plate which has conductivity at opposite surfaces of the electrode compact 1 is disposed so that it sandwiches the current collecting plate 2. Being placed between upper and lower plates 11 and 12 of a thermo-presser, the carbon sheet is pressurized and heated and then is made to enter on one side of the current collecting plate and its fusion-bonding is performed. In this way, for example, even if a thin-walled part takes place in the thickness of the current collecting plate 2 because of the inferior surface-accuracy of the electrode compact 1, the place 2 hardly ever makes a hole. Further, if a pin hole and the like appear in the current collecting plate 2, they are protected by the carbon sheet 3 and leakage of electrolyte in a gasket 5 is thus prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric double layer capacitor which is intended to reinforce a current collector serving as an external terminal of the electric double layer capacitor to prevent an internal electrolyte from flowing out.

(Prior art) In recent years, electric double layer capacitors that utilize the electric double layer principle and have a large capacitance have been adopted as backup power sources for microcomputers, IC memories, etc., and have also been expanded to larger capacities for battery applications. Electric double layer capacitors with large capacitance that can be used in some parts of the world have also been developed.

As this type of electric double layer capacitor, an electrode body made of porous carbon particles is made by sintering a current collector made of a conductive substance with conductive particles mixed into the base material, as disclosed in Patent Application No. 232243 of 1999. The applicant has proposed that a part of the current collector be brought into contact with a porous electrode body.

(Problems to be Solved by the Invention) According to the proposal in the above-mentioned patent application, the contact between the current collector and the electrode body becomes close, and the internal resistance of the electric double layer capacitor is reduced.

However, as shown in Figure 4, if the surface precision of the electrode body is poor in the contact between the electrode body and the current collector, the thickness of the current collector at part A in the figure decreases, causing elongation and deformation, and holes. There is a risk of danger.

In addition, even if the mutual surfaces are kept parallel as shown in Figure 5, if foreign matter or pinholes occur in the current collector, a hole will occur in part B as described above, and the electrolyte inside There is a problem with leakage.

The present invention was made in view of such problems,
The purpose is to provide an electric double layer capacitor which attempts to prevent internal electrolyte from leaking even if a part of the current collector plate is damaged.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides an electrical secondary including a current collector plate that is fused to an electrode body impregnated with an electrolytic solution to collect electric charges. Provided is an electric double layer capacitor in which a conductive protection plate is disposed on the outer surface of the current collector plate, and the protection plate is thermally fused at the same time as the electrode body and the current collector plate are fused. .

(Function) In the present invention, since a protective plate made of a carbon sheet is fused to the outer surface of the current collector plate corresponding to the electrode body, leakage of the electrolyte can be prevented even if a part of the current collector plate is damaged.

(Example) Next, an example of the present invention will be described in detail using the drawings.

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

In the figure, 1 is an electrode body, which is made porous by sintering activated carbon powder with a predetermined particle size and a large surface area.
For example, it is made into a polarizable electrode by impregnating it with an electrolyte such as dilute sulfuric acid.

Reference numeral 2 denotes a current collector plate, which is formed into a flexible conductive sheet by kneading, for example, carbon and rubber-based materials, and one surface of which is in contact with the electrode body 1 by heat fusion. This is a device that collects electric charges.

3 is a conductive carbon sheet that serves as a protective plate, and when the electrode body 1 and the current collector plate 2 are thermally fused together, the carbon sheet is placed on the opposing surface of the electrode body 1 with the current collector plate 2 in between. 3 is placed between the upper plate 11 and lower plate 12 of the heat press machine as shown in Fig. 2, and pressurized and heated. It is penetrated and heat-sealed.

Reference numeral 4 in FIG. 1 denotes a separator, which is made of a microporous nonwoven fabric made of polypropylene or the like impregnated with an electrolytic solution, and serves to separate the pair of electrode bodies 1.1 containing the electrolytic solution.

5 is a gasket, which is cylindrical and made of a non-conductive synthetic resin material, and the above-mentioned separator 4 is placed in the middle part of the gasket.
The outer edge portion of the separator 4 is buried to house a pair of electrode bodies 1.1 separated by the separator 4.

Note that the electrode body 1 and the outer peripheral portion of the current collector plate 2 to which the carbon sheet 3 is fused are adhered to both end faces of the gasket 5, thereby sealing the electrode body 1 containing the electrolyte therein.

In this embodiment configured in this way, the carbon sheet 3 serving as a protection plate is fused to the outer surface of the current collector plate 2, so that, for example, if the surface precision of the electrode body 1 is poor, the current collector plate 2 may be damaged. Even if there is a thin part, it is difficult to form a hole, and the current collector plate 2
Even if there is a pinhole or the like in the gasket 5, it is protected by the carbon sheet 3 and the electrolytic solution inside the gasket 5 is prevented from leaking.

The present invention has been described above with reference to the above-mentioned embodiments. However, within the scope of the gist of the present invention, for example, instead of the carbon sheet fused to the current collector plate, a metal plate that is not easily eroded by the electrolytic solution may be used. Various modifications are possible and these modifications are not excluded from the scope of the invention.

(Effects of the Invention) As described above, according to the present invention, a carbon sheet is attached to the current collector plate that is fused to the electrode body containing the electrolytic solution, and the current collector plate is lined and protected. Even if there is a thin part on the current collector plate due to poor surface accuracy, or if there is a defect such as a pinhole, the effect of preventing defects such as holes forming and leaking of the internal electrolyte can be achieved. .

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the electric double layer capacitor according to the present invention, Fig. 2 is an explanatory view when placed in a heat press machine, Fig. 3 is a sectional view after fusion processing, and Fig. 4 and 5 are explanatory diagrams of the conventional state. l... Electrode body, 2... Current collector plate, 3... Carbon sheet, 4... Separator, 5... Gasket.

Claims (2)

[Claims] (1) In an electric double layer capacitor equipped with a current collector plate that is fused to an electrode body impregnated with an electrolytic solution and collects electric charges,
An electric double layer capacitor characterized in that a conductive protection plate is disposed on the outer surface of the current collector plate, and the protection plate is thermally fused at the same time as the electrode body and the current collector plate are fused. (2) The electric double layer capacitor according to claim (1), wherein the protective plate is a carbon sheet.