JPH05283287A - Electrode material and method of manufacturing electric double layer capacitor having the same - Google Patents

Abstract

(57) [Summary] [Purpose] Immediately and sufficiently impregnate a sheet electrode with an electrolytic solution. [Structure] Electrode powder is kneaded with activated carbon and carbon in a predetermined binder to form a sheet-like electrode material 1 with a conductive adhesive 3 attached to the bottom of a case 2, and the case 2 is filled with an organic electrolyte solution. A solvent is injected to generate an electrolytic solution in the electrode material 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode material and a method for manufacturing an electric double layer capacitor having the electrode material.

[0002]

2. Description of the Related Art For an electric double layer capacitor, for example, a sheet-like electrode is used which is obtained by kneading activated carbon powder, carbon and polytetrafluoroethylene (PTFE) as a binder and spreading the mixture to a predetermined thickness.

This sheet-shaped electrode is fixed to the bottom of the case through a conductive adhesive, and then an electrolytic solution is injected into the case so that the sheet-shaped electrode is impregnated with the electrolytic solution in the case. There is.

[0004]

However, since the surface of the sheet-shaped electrode is a smooth layer having a high density, and the electrolyte itself has a relatively high viscosity, impregnation into the electrode becomes insufficient. This tends to cause variations in internal resistance and other product characteristics.

For example, propylene carbonate as an organic solvent and tetraethylphosphonium tetrafluoroborate (Et ₄ PBF ₄ ) as an electrolyte in an amount of 1 mol / l.
In the case of the electrolytic solution added at the concentration of
Poise viscosity is shown.

Further, there is a drawback that the electrolytic solution spills out of the case due to vibration or the like applied in the transfer process after the electrolytic solution is injected.

Therefore, in order to effectively impregnate the sheet electrode with the electrolytic solution, the impregnation is performed in a vacuum device or the electrolytic solution is heated to, for example, 100 ° C. to reduce the viscosity. Vacuum impregnation requires expensive equipment, is not preferable in terms of cost, and is not good in productivity. Further, even if the electrolytic solution is heated, it is necessary to control the temperature of the electrolytic solution and the temperature of the electrolytic solution. Therefore, the problem cannot be solved.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances.
An electrode material used as a sheet-like electrode of an electric double layer capacitor, which is prepared by kneading a conductive powder such as carbon with a predetermined binder, and the electrode material contains an electrolyte powder that forms an electrolytic solution in advance. Especially.

Further, in the manufacturing method of the present invention, an electrode material is kneaded with a conductive powder such as activated carbon or carbon with a predetermined binder to form a sheet-like electrode material on the bottom of the case via a conductive adhesive. It is characterized in that it is attached, and then an organic solvent used as a solvent for the electrolytic solution is injected into the case, and the organic solvent is impregnated in the electrode material.

[0010]

Since the sheet-shaped electrode contains the electrolyte powder in advance, only the organic solvent used as the solvent of the electrolytic solution is injected in the impregnation step. Since this organic solvent has a relatively low viscosity (1.4 cpoise at 38 ° C. in the case of propylene carbonate), it has a good impregnation property for the sheet electrode, and the electrolyte powder is dissolved in the sheet electrode to dissolve the electrolyte solution. Is generated.

[0011]

Example First, PTFE was used as a binder with activated carbon powder, carbon black conductive powder and electrolyte powder.
After kneading together, this is spread to a predetermined thickness to obtain a sheet-shaped electrode material.

Examples of the electrolyte powder used include tetraethylphosphonium tetrafluoroborate, tetraalkylphosphonium salt, tetraalkylammonium salt, alkali metal salt and the like.

Then, for example, a circular sheet-shaped electrode is punched out from this electrode material. This sheet-like electrode is indicated by reference numeral 1 in FIG. 1, and the sheet-like electrode 1 is attached to the bottom of a case 2 having a shallow bottom via a conductive adhesive material 3.

After that, an organic solvent as a solvent for the electrolytic solution is injected into the case 2 by the dispenser nozzle 4, and the sheet-shaped electrode 1 is impregnated with the organic solvent to generate the electrolytic solution in the sheet-shaped electrode 1. To do.

As the organic solvent, for example, propylene carbonate, gamma butyrolactone, acetonitrile, dimethylformamide, etc. are used.

Although not shown in the drawing, also on the side of the cap that covers the case 2, a sheet-like electrode is attached to the bottom through a conductive adhesive, an organic solvent is injected, and the sheet-like electrode is impregnated. Done.

Then, the cap is put on the case 2. At that time, a separator is arranged between the sheet-like electrodes, and although not shown, a gasket is inserted in advance in the case 2, and by caulking the opening edge of the case 2, the gasket is inserted through the gasket. The periphery of the cap and the case 2 is caulked in an airtight manner.

In this way, a coin-shaped electric double layer capacitor is obtained. Next, a concrete example and a conventional example as a comparative example will be described.

Example 1 Activated carbon powder, carbon black, tetraethylphosphonium tetrafluoroborate as an electrolyte and PTFE powder as a binder were mixed in a weight ratio of 6: 1: 2: 1, and kneaded with ethanol. A sheet-shaped electrode material was obtained by wet-kneading as a solvent and extruding while stretching, and then drying at 100 ° C. for 6 hours.
A sheet electrode having a thickness of 0.5 mm and a thickness of 0.5 mm was obtained.

Next, this sheet electrode was attached to the bottom of the case via a conductive adhesive, and 100 mg of propylene carbonate as an organic solvent was injected into the case.
The sheet electrode was impregnated.

Further, a sheet-shaped electrode punched from the same electrode material was attached to the cap side via a conductive adhesive, and the same amount of propylene carbonate was injected to impregnate the sheet-shaped electrode.

Then, a separator was interposed between both sheet-like electrodes, a cap was put on the case through a gasket inserted in the case, and the peripheral edge of the opening was caulked.

The coin-shaped electric double layer capacitor thus obtained was laminated with two cells to give a rating of 5.5.
V1F electric double layer capacitors, 100 prototypes of which were measured for capacitance and internal resistance,
The average values were 1.020 (F) and 10.0 (Ω), respectively.

Comparative Example 1 Activated carbon powder, carbon black and PTFE powder as a binder were added in a ratio of 8: 1: 1.
And mixed in the same manner as in Example 1 to obtain an electrode material.

An electrolyte solution was prepared by adding tetraethylphosphonium tetrafluoroborate (electrolyte) to propylene carbonate (organic solvent) at a concentration of 1 mol / l.

Then, the sheet-like electrode was attached to the bottom of the case via a conductive adhesive, and 250 mg of the electrolytic solution was injected into the case to impregnate the sheet-like electrode.

Further, a sheet-shaped electrode punched from the same electrode material was attached to the cap side via a conductive adhesive, and the same amount of the electrolytic solution was injected to impregnate the sheet-shaped electrode.

Then, a separator was interposed between both sheet-like electrodes, a cap was put on the case through a gasket inserted in the case, and the periphery of the opening was caulked.

The coin-shaped electric double layer capacitor thus obtained was laminated with two cells to give a rating of 5.5.
When the electrostatic capacity and the internal resistance of 100 V1F electric double layer capacitors were measured, the average values were 0.850 (F) and 12.0 (Ω), respectively.

For reference, the results of comparison between Example 1 and Comparative Example 1 are shown in Table 1.

[0031]

[Table 1] As described above, according to the present invention, both the capacitance and the internal resistance are superior to those of the conventional example, and it can be seen that the organic solvent is sufficiently impregnated in the sheet electrode.

In addition to the above, according to the present invention, it is not necessary to prepare an electrolyte solution in advance, and even if the solution spills out of the case during the transfer process, it is only an organic solvent, so that there is no electrolyte loss. It also contributes to cost reduction.

[0033]

As described above, according to the present invention,
By using a sheet-shaped electrode in which electrolyte powder is kneaded and by impregnating the sheet-shaped electrode with only a relatively low-viscosity organic solvent in the impregnation step of the electrolytic solution, it is possible to use a device such as a vacuum device or a heating device. Impregnation into the sheet-like electrode is carried out promptly without the need, and an electric double layer capacitor having good electrical characteristics with high productivity can be obtained.

[Brief description of drawings]

FIG. 1 relates to an example of the present invention and is a schematic diagram showing a liquid impregnation process for a sheet electrode.

[Explanation of symbols]

 1 sheet electrode 2 case 3 conductive adhesive 4 dispenser nozzle

Claims (2)

[Claims] 1. An electrode material which is obtained by kneading a conductive powder such as activated carbon or carbon with a predetermined binder and is used as a sheet-like electrode of an electric double layer capacitor, in which an electrolyte powder forming an electrolytic solution is contained in advance. An electrode material characterized by being. 2. An electrode material which is formed into a sheet by kneading an electrolyte powder with a conductive powder such as activated carbon or carbon with a predetermined binder is attached to the bottom of the case via a conductive adhesive, and then in the same case. A method for producing an electric double layer capacitor, comprising injecting an organic solvent used as a solvent for an electrolytic solution and impregnating the organic solvent in the electrode material.