JPH0744129B2 - Method for manufacturing electric double layer capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an electric double layer capacitor having a flat coin shape, and more specifically to impregnating a sheet electrode thereof with an electrolytic solution. Is.

[Conventional example] An electric double layer capacitor includes a dish-shaped case body and a cap that covers the case body. First, in manufacturing, the case body and each bottom of the cap are electrically conductive with an adhesive. Sheet electrodes are attached respectively.
Next, an electrolytic solution is injected into the case body and the cap to impregnate the sheet-shaped electrode with the same solution, and a separator is arranged between the electrodes. After that, a gasket is arranged on the inner circumference of the case body, a cap is put on the case body, and the periphery thereof is caulked to form a coin cell of a predetermined capacity.

[Problems to be Solved by the Invention]

By the way, the above-mentioned sheet-like electrode is made of, for example, a sheet obtained by kneading activated carbon, carbon, and polytetrafluoroethylene (PTFE) as a binder, and rolling the kneaded sheet into a predetermined thickness in a circular shape. On the other hand, as the electrolytic solution, for example, propylene carbonate is used as the solvent and tetraethylphosphonium fluoroborate (TEP) is used as the electrolyte. The characteristics of the electric double layer capacitor depend on the impregnated amount of the electrolytic solution into the sheet electrode.

That is, as the electrolyte solution (ion concentration) impregnated into the sheet-shaped electrode increases, the product life becomes longer and the defect rate (ESR defect) decreases. However, since the electrolytic solution is viscous and has been conventionally injected at room temperature, the impregnation property for the sheet-like electrode is poor, and many of the results have been found to be defective as a result of the product test. In addition, since the electrolytic solution is not immediately impregnated, there is a drawback that the case body and the cap may be spilled when transported to a subsequent step such as caulking.

[Means for Solving the Problems]

In order to solve the above-mentioned conventional problems, in the present invention, the electrolytic solution heated to a predetermined temperature higher than room temperature is injected into the case body and the cap.

[Action]

Since the viscosity of the electrolytic solution is lowered by heating, the electrolytic solution is quickly impregnated into the sheet electrode.

For example, the relationship between the kinematic viscosity and the liquid temperature of propylene carbonate, which is the solvent of the electrolytic solution, is shown in FIG.
It can be seen that the higher the liquid temperature, the lower the kinematic viscosity.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 illustrates a cross section of an electric double layer capacitor having a coin shape, and the manufacturing process of the capacitor will be briefly described based on this.

That is, the capacitor includes a metal case body 10 formed in a dish shape, and a cap 20 that covers the case body 10.
It has and. Sheet-shaped electrodes 12 and 12 are attached to the respective bottoms thereof via conductive adhesives 11 and 11. As in the conventional case, the sheet-shaped electrode 12 is formed by, for example, kneading activated carbon, carbon, and PTFE, and punching it into a predetermined shape (for example, a circle) from a sheet rolled to a predetermined thickness. The surface 12a of the electrode 12 is provided with a scratch 13 that destroys the surface smoothing layer. The scratches 13 are formed, for example, by pressing a die having a large number of needle-like projections (both not shown) against the base material sheet of the electrode 12. After that, an electrolytic solution is injected into the case body 10 and the cap 20, the sheet-shaped electrodes 12 and 12 are impregnated with the same solution, and the gasket 16 and the separator 17 are put into the case body 10,
The case body 10 is covered with a cap 20 and the periphery thereof is caulked. In addition, each of these work is a flow work,
The case body 10 and the cap 20 are conveyed to the next step on a belt conveyor or a turntable.

As described above, the coin-shaped electric double layer capacitor is manufactured.In the present invention, when the electrolytic solution is injected into the case body 10 and the cap 20, the electrolytic solution is heated to reduce its viscosity. I am trying to lower it. FIG. 2 shows a state in which the electrolytic solution is injected into the case main body 10 by the nozzle 15 as a liquid injection means. In this example, the nozzle 15 is provided with an electric heater 14 for heating the electrolytic solution. ing. Since the decomposition temperature of the electrolytic solution used in this example is about 160 ° C, the heating temperature is selected in the range from room temperature to the thermal decomposition temperature of the electrolytic solution, here in the range of 40 ° C to 150 ° C. . Similarly, the heated electrolytic solution is also injected into the cap 20.

The change in capacitance and the equivalent series resistance (ERS) of two laminated products of the present invention thus obtained and two laminated products of the conventional product were tested under a high temperature load condition of 70 ° C. The changes are shown in the following table.

The pass / fail criteria for this test are the capacitance change rate within ± 30%, ESR1
Within 20 Ω, the conventional product has a larger variation range in both the rate of change in capacitance and the ESR than the product of the present invention, and the average value thereof is also larger. It is speculated that the deterioration of the characteristics of the conventional product is due to the fact that the sheet-shaped electrode was not sufficiently impregnated with the electrolytic solution.

In the above embodiment, the nozzle 15 is provided with the electric heater 14 to heat the electrolytic solution.However, the electrolytic solution may be heated to a predetermined temperature in an electrolytic solution storage tank (not shown). May heat the case body and the cap side.

In the above-mentioned examples, a solution of tetraethylphosphonium dissolved in propylene carbonate was used as the electrolytic solution, but in addition to this, butylene carbonate, γ-butyrolactone, acetonitrile, dimethylformamide, 1,2-dimethoxyethane, sulfolane, and nitromethane were used as the solvent. Then
The same effect can be obtained by using an electrolyte solution containing perchloric acid, hexafluorophosphoric acid, tetrafluoroboric acid, perfluoroalkylsulfonic acid, or another metal salt, a tetraalkylammonium salt, or a tetraalkylphosphonium salt as the electrolyte. .

〔The invention's effect〕

As described above, according to the present invention, it is possible to quickly impregnate the sheet electrode with the electrolyte. Therefore, there is almost no ESR defect or characteristic (especially life characteristic) defect due to insufficient electrolyte. Further, since there is no leakage of the electrolytic solution from the case body and the cap during the transfer between steps, the working speed of the automatic assembly machine can be increased, and the productivity can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the finally assembled electric double layer capacitor according to the present invention, and FIG. 2 is a sectional view showing a state of injecting an electrolytic solution into a case body for explaining the present invention, FIG. 3 is a kinematic viscosity characteristic diagram with respect to the liquid temperature of the electrolytic solution. In the figure, 10 is a case body, 11 is a conductive adhesive, 12 is a sheet-like electrode, 12a is its surface, 13 is a scratch, 14 is an electric heater, 1
5 is a nozzle, 16 is a gasket, 17 is a separator, and 20 is a cap.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenichi Ichisugi 2-2-1 Tsujido Shinmachi, Fujisawa-shi, Kanagawa Elner Co., Ltd. (72) Inventor Kiyoshi Takahashi 2-2-1 Tsujido Shinmachi, Fujisawa-shi, Kanagawa Elner Co., Ltd. (56) Reference JP-A-64-9610 (JP, A)

Claims (5)

[Claims] 1. A case main body formed in the shape of a dish, and a cap for covering the case main body. Sheet-shaped electrodes are attached to the bottoms of the case main body, and an electrolyte solution is injected into the case main body and the cap from a liquid injection means. And then impregnate the sheet-shaped electrode with the same liquid, with a separator interposed between the sheet-shaped electrodes, and placing a gasket on the inner circumference of the case body, and then covering the case body with the cap. A method of manufacturing an electric double layer capacitor, the method of manufacturing an electric double layer capacitor having a crimped peripheral edge, comprising injecting an electrolytic solution heated to a predetermined temperature higher than room temperature into the case body and the cap. 2. The method for manufacturing an electric double layer capacitor according to claim 1, wherein the liquid injection means is provided with a heating device. 3. The method for manufacturing an electric double layer capacitor according to claim 2, wherein the heating device is an electric heater. 4. The method of manufacturing an electric double layer capacitor according to claim 1, wherein the case body and the cap itself are also heated. 5. The method for producing an electric double layer capacitor according to claim 1, wherein the heating temperature of the electrolytic solution is in the range from room temperature to the thermal decomposition temperature of the electrolytic solution.