JPH01319921A - Capacitor having electric double layer - Google Patents

Abstract

PURPOSE:To suppress the increase in inner resistance and to obtain a capacitor characterized by a small leaking current by arranging any of titanium, tantalum, niobium or zirconium, e.g., a net shaped metal. CONSTITUTION:A laminated electrode is formed with a polarized electrode comprising active carbon fiber 3 or an active carbon powder sheet and an organic conductive plastic sheet 4 as a current collector. Any metal 2 of titanium, tantalum, niobium or zirconium is arranged on the side of the sheet 4. The shape of titanium, tantalum, niobium or zirconium is a net shape, an expanding metal, punching metal or a irregular body. In this way, the increase in inner resistance is suppressed, and a small capacitor characterized by a smell leaking current is obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a compact, large-capacity, wet-type electric 2 mJ! It relates to a capacitor, and relates to a carrier for a laminated electrode consisting of a polarizable electrode and a current collector, and at the same time, to a metal for taking leads for each positive pole.

[Summary of the invention]

The present invention provides an electric double layer capacitor in which an organic conductive plastic sheet is laminated in advance as a current collector for activated carbon fibers serving as polarizable electrodes, and the net, expanded metal, punched metal, or uneven body shape of the present invention is used. Titanium, tantalum, niobium, or zirconium is welded to the inner bottom of the positive electrode can, and the above-mentioned polarizable electrode is placed on top of it. By thermocompressing the polarizable electrodes after placing the electrodes in the test tube, an extreme increase in internal resistance at high temperatures and after storage at high temperatures can be suppressed in state B where a voltage of 2.4 V is applied (hereinafter abbreviated as applied state). , the leakage current is further reduced.

[Conventional technology]

Conventionally, an organic conductive plastic sheet, which is the current collector of the polarizable electrode used in this type of electric double layer capacitor, has a metal cathode can (hereinafter referred to as cathode can) that houses the sheet, with a metal cathode can (hereinafter abbreviated as cathode can) in which the inner bottom is kept at room temperature. It does not adhere at all even when pressurized, and although it adheres slightly even when pressurized at a temperature of 200 to 400° C., it has the disadvantage that it easily becomes Ill in the subsequent process. In order to eliminate these drawbacks, conventionally the positive electrode can is first punched out of stainless steel net or aluminum net in the shape of a disk, welded to the inner bottom of the can, and then a tri-electrode plastic sheet is placed on the positive electrode can. The conductive plastic sheet was heated in the same manner as when not in use, and then pressurized to form a conductive plastic sheet into a net.

[Problem to be solved by the invention]

However, although it has been found that the above-mentioned net etc. is sufficient for the purpose of supporting a polarizable electrode made of a laminate of activated carbon fibers and an organic conductive plastic sheet,
When an electric double layer capacitor is housed using these materials and an accelerated test is performed under applied conditions (high temperature or high temperature, high temperature),
The AC internal resistance increased several times more than before the accelerated test, and the leakage current also increased.

[Means and effects for solving the problem] In order to solve the above-mentioned problems, the present inventors used titanium, tantalum, or
By disposing a net-shaped metal such as either niobium or zirconium and welding it to the positive electrode can, a capacitor that suppresses a significant increase in internal resistance after an accelerated test in an applied state and has a small leakage current is manufactured. I was able to do that.

(Example) An example of the present invention will be described below.The first example is a capacitor of this example, which has an outer diameter of 9.5 m (height: 2°, 1.5 m), and a nominal capacity of 0.33F. (Farad) 0 In the figure, 1 is the positive electrode can, which is made of aluminum-stainless steel cladding material and has nickel plating on the stainless steel surface (
(hereinafter abbreviated as AI clad material), and 2 is welded with, for example, a titanium net of the present invention. Furthermore, a laminated activated carbon fiber 3 and an organic conductive plastic sheet 4, a gasket 5 which also serves as insulation, and a separator 6 are housed on the net. 7 is a negative electrode can that also serves as a negative electrode terminal, and is made of stainless steel plated with nickel.A nickel net 8 is welded to the negative electrode can.Activated carbon fibers 3 and organic conductive plastic sheet 4 are laminated on top of this in advance, and impregnated material is applied to it. It stores 9.

Fig. 2 shows the shape of the metal to be welded to the positive electrode can, which is a feature of the present invention.

[Comparative test]

In the above structure, the results of the embodiments of the main part of the present invention will be described below.

Activated carbon fiber as a polarizable electrode (specific surface area 1500~2
000 rrr/g) and conductive polypropylene (volume resistance 0.5-1.0 Ω, cm) were passed between heated rollers (temperature 200-250° C.) and laminated thereon, and after standing to room temperature, punched out into a disk shape. The disk-shaped Jfl [electrode was inserted in advance into a positive electrode can made of AI clad material, which was made by welding the titanium net (100 mesh, thickness 0.12 mm) of the present invention with a resistance heating welder, and the net plate ( A positive electrode unit was prepared by pressing a metal rod onto the electrode from above while placing the electrode at a temperature of 200 to 250° C. for 2 to 5 minutes.

On the other hand, a nickel net was welded to a stainless steel negative electrode can with nickel plating on both sides using a resistance heating welder, and then a negative electrode unit was manufactured under the same conditions as the positive electrode unit described above. After vacuum drying these positive and negative electrode units at 100°C for 1 hour, they were dried in a dehumidifying room.
First, a polypropylene gasket was inserted into the positive electrode unit, and then a porous polypropylene separator was placed. On the other hand, an impregnating material made of a polypropylene nonwoven fabric was placed on the negative electrode unit, and a predetermined amount of a mixed solution of ethylene carbonate and butylene carbonate containing tetraethylammonium fluoride was added to the positive and negative electrode sides as an electrolytic solution, respectively. Five hundred button-shaped capacitors as shown in FIG. 1 were manufactured. In addition, similar to the titanium net in the example taken up here, 500 capacitors each using zirconium, tantalum, or niobium were fabricated as described above, and capacitors using conventional stainless steel net and aluminum net were fabricated. AC internal resistance was tested and the values before storage and after storage under applied conditions were compared. The results are shown in Table 1.

Table 1 Test Comparison Table A: Titanium B: Niobium C: Tantalum D: Zirconium It was possible to suppress a significant increase in the AC internal resistance of the high-temperature storage solution. The reason for this improvement is that R4 is a descendant of conventional capacitors after being stored at high temperatures or at high temperatures and high humidity.In the case of capacitors using stainless steel nets, the nets were severely corroded. a The conductive plastic sheet was peeled off from the net. Furthermore, a similar phenomenon was observed with aluminum net, although not with the stainless steel net. Furthermore, the leakage currents of the present invention and conventional capacitors after storage in the applied state were measured.

The measurement results are shown in FIG. In the figure, l is the present invention A, 2
and 3 are the leakage currents of conventional E and F, respectively. Note that the leakage currents of B, C, and D of the present invention were almost the same as A. Further, similar effects were obtained with expanded metal, punched metal, or uneven material.

The reason why the AC internal resistance after the accelerated test in the applied state was reduced and the leakage current was reduced as a result is thought to be due to the use of a metal net with less corrosion. Furthermore, although this may be due to the fact that both valve metals are used in the present invention, since aluminum is also a valve metal as a conventional example, it cannot be asserted that the present invention is effective solely for that reason. is currently under further investigation.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a small-sized, large-capacity electric double layer capacitor which has a smaller AC internal resistance and leakage current after an accelerated test while applying voltage than conventional capacitors.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the electric double layer capacitor of the present invention, and FIG. 2 (al to +d+ are plan views of the metal of the present invention;
FIG. 3 is a diagram showing a gradual decrease in leakage current. 1... Positive electrode can 2... Net, extracted band metal. Punched metal or uneven metal 3... Activated carbon fiber 4... Conductive plastic sheet 5... Gasket roller... Separator 7... 8° per negative electrode Nickel net 9... Impregnated material or more Applications People Seiko Electronic Components Co., Ltd.

Claims (3)

[Claims] (1) In a laminated electrode consisting of a polarizable electrode made of activated carbon fiber or activated carbon powder sheet and an organic conductive plastic sheet as the current collector, one metal of titanium, tantalum, niobium, or zirconium is placed on the plastic sheet side. An electric double layer capacitor characterized by: (2) Claim 1, characterized in that the shape of titanium, tantalum, niobium, and zirconium is a net, an expanded metal, a punched metal, or an uneven body.
Electric double layer capacitor described in section. (3) The electric double layer capacitor according to claims 1 and 2, which is made of titanium, tantalum, niobium, and zirconium and is welded to the inner bottom of the positive electrode can that also serves as the exterior.