JPH03116708A - Electric double-layer capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a large capacitance electric double layer capacitor using the electric double layer principle.

(Prior Art) In recent years, large-capacity capacitors using the electric double layer principle have been developed as backup power supplies for semiconductor memories in electronic devices, and are widely used by being incorporated into microcomputers, IC memories, and the like.

FIG. 3 is a cross-sectional view showing an example of a conventional capacitor, in which 20 is a current collector plate made of conductive rubber, 40 is a gasket made of non-conductive rubber, and 10 is a polarizable electrode made of activated carbon. A paste-like electrode impregnated with dilute sulfuric acid is housed in a space of a gasket 40 divided into upper and lower halves by a separator 30.

In order to make a large capacitor with a large capacitance from such a paste-like electrode, it is necessary to apply pressure to lower the internal resistance of the electrode and reduce the contact resistance with the current collector plate. It has the disadvantage that it becomes uneven and cracks occur, making the electrical characteristics unstable.

For this reason, as a high-capacity capacitor using sintered material for the electrode, it is difficult to use an electrolyte containing carbon with a large specific surface area.
JP-A-49-8753 discloses a proposal in which a polarizable electrode made of a sintered material mainly composed of inert metal powder is arranged with a separator interposed therebetween, and the electrode is sealed in an outer can containing an electrolyte. ing.

In addition, various other proposals have been made to generate electrodes for electric double layer capacitors by sintering, but most of them involve mixing activated carbon with graphite powder, mixing this with metal powder and a binder, and firing the mixture. It is being said.

(Problems to be Solved by the Invention) In the electric double layer capacitor as described above, manufacturing an electrode body by mixing a binder with activated carbon requires a mixing and stirring process with the activated carbon and a coating process on the current collecting electrode. There are many steps such as a drying step, a pressurizing/heating step, and a binder removal step, and furthermore, the binder must be removed after sintering, making the electrode production time-consuming and takes several hours. Furthermore, if the binder is incompletely removed, problems arise such as the manufactured capacitor not being able to exhibit its full performance.

The present invention was made in view of such problems,
The purpose is to use sintering molding for both the electrode body and current collector plate.
The object of the present invention is to simplify the manufacturing process and provide an excellent electric double layer capacitor having a large capacitance.

(Means for Solving the Problems) According to the present invention, in an electric double layer capacitor having an electrode body made of activated carbon immersed in an electrolytic solution and a current collector plate in electrical contact with the electrode body, the The electrode body is made of a sintered body of activated carbon fine particles, and an electric double layer capacitor is provided in which regions in which the activated carbon fine particles have different sintered densities are provided.

(Function) In the present invention, an electrode body that is immersed in an electrolytic solution and has an electric charge is formed by sintering highly porous activated carbon fine particles, and a current collector plate that collects the electric charge is a part of the electrode body. Since the part is sintered with a fine particle density, low internal resistance is obtained, and the contact between the electrode body and the part that becomes the current collector plate is close, so the electrical resistance between them is low, and the electrode Having a high-density portion as a current collector inside the body increases mechanical strength.

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

FIG. 1(a) is a sectional view of an electrode body and its current collector plate showing an embodiment of the present invention, and FIG. 1(b) is a sectional view of an example in which the current collector plate is provided in the center of the electrode body. It is.

In these drawings, 1 is an electrode body, which is formed into a plate shape by sintering activated carbon fine particles into a porous form using high-temperature plasma, and is made into a polarizable electrode by immersing it in a predetermined electrolyte solution. It is.

2A is a current collector plate that is placed on one side of the electrode body and is made by sintering activated carbon fine particles to a high density using high-temperature plasma.The density is dense and the internal resistance is low. is fired to have low contact resistance, and its physical strength as an electrode body is also strengthened.

In addition, in FIG. 1(b), a current collector plate 2B similar to the above-mentioned current collector plate 2A is sandwiched and placed in the center part of the electrode body by plasma sintering. Since the electrode 2B has a high density, its internal resistance and contact resistance with the electrode body 1.1 adjacent to both side surfaces are configured to be low values.

FIG. 2 is a cross-sectional view of the composite body of the electrode body and current collector plate shown in FIGS. 1(a) and (b) arranged in series in a predetermined selected order and housed in a case. Since the withstand voltage is low, the withstand voltage is increased by connecting them in series.

In the figure, a separator 3 is made of, for example, a microporous polypropylene thin film, and separates adjacent electrode bodies 1.1 immersed in a predetermined electrolyte.As shown in the figure, a case 4 made of an insulating material is used. The entire periphery of the separator 3 is sandwiched between the electrode body 1 and the current collector plate 2A or 2B to separate each composite body.

Note that the illustrated X portion near the top of the current collector plate 2A adjacent to the terminal portion 4A of the case 4, and the illustrated 7 portion of the current collector plate 2B that contacts the inner circumferential surface of the case 4 are thermally welded or bonded. It is bonded with an adhesive to prevent electrolyte from leaking.

In this embodiment configured in this way, the polarizable electrode immersed in the electrolyte has a large surface area because the activated carbon is porous and sintered, and the electric charge stored in this electrode is transferred to the electrode body 1. By being guided to the terminal portion 4A through the low contact resistance with the current collector plate 2A or 2B and the low internal resistance of the high-density current collector plate 2A or 2B, a large capacity capacitor with low internal resistance can be obtained as a capacitor. It turns out.

In addition, since each electrode body 1 is attached with a highly densely sintered current collector plate 2A or 2B, even when manufacturing a large electrode body 1, an electrode body that is strong against external forces can be obtained. become.

Although the present invention has been described above with reference to the above embodiments, various modifications can be made within the scope of the gist of the present invention, and these modifications are not excluded from the scope of the present invention.

(Effects of the Invention) According to the present invention, an electrode body that becomes a polarizable electrode immersed in an electrolytic solution and a current collector plate that collects the electric charge of the polarizable electrode are formed by plasma sintering of activated carbon particles. The electrode body part is sintered to have a coarse density structure to increase the surface area, and the current collector plate part is sintered to a high density structure, which reduces the internal resistance of the electrode body and reduces the contact between the electrode body and the electrode body. In addition to reducing the contact resistance with the current collector plate, the manufacturing process is simplified as no binder or other mixtures are used, preventing performance deterioration due to the effects of binder and other residues, and reducing internal resistance. This has the effect of providing a capacitor with low cost and excellent performance.

In addition, according to the present invention, since both the electrode body and the current collector plate are sintered, it is possible to obtain a product with careful quality control such as the accuracy of each dimension and the amount of activated carbon filled. This has the effect of eliminating the need for additional pressure means.

Furthermore, in the present invention, each electrode body is attached with a highly densely sintered current collector plate, so even if the electrode body is formed into a large size to obtain a large capacity capacitor, a strong electrode body can be obtained. There are benefits to be gained.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are cross-sectional views of an electrode body and a current collector plate in an example of the present invention, FIG. 2 is a cross-sectional view of a composite body according to this example housed in a case, and FIG. FIG. 2 is a sectional view showing a conventional example. ...Electrode body, 2A. B... Current collector plate, 3... Separator, 4... Case.

Claims (1)

[Claims] In an electric double layer capacitor having an electrode body made of activated carbon immersed in an electrolytic solution and a current collecting plate in electrical contact with the electrode body, the electrode body is made of a sintered body of activated carbon fine particles, and the electrode body is made of a sintered body of activated carbon fine particles. An electric double layer capacitor characterized by having regions in which activated carbon fine particles have different sintered densities.