JP2002141251A - Method for manufacturing electric double layer capacitor - Google Patents

Abstract

(57) [Problem] To provide an electric double layer capacitor which is less deteriorated by repeated charge and discharge. SOLUTION: In a method for manufacturing an electric double layer capacitor, a positive electrode and a negative electrode are housed in an outer container facing each other via a separator, filled with an electrolytic solution, and charged and discharged at least once. A method for manufacturing an electric double layer capacitor in which a part is replaced and then sealed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor, and more particularly, to an electric double layer capacitor having a long cycle life and capable of exhibiting stable performance for a long time.

[0002]

2. Description of the Related Art An electric double layer capacitor utilizes the capacitance of an electric double layer formed at an interface between an electrode and an electrolytic solution, and has an extremely large capacitance per volume as compared with other capacitors. It is characterized by being large. The electric double layer capacitor has a feature that it has a longer cycle life than a battery because it does not involve a chemical reaction, and has been used as a backup power source for a memory taking advantage of such a feature. In addition, the rate of charge and discharge is limited by the time constant, but can be increased compared to batteries,
It also has the feature that large current charge and discharge is possible.
Therefore, development as an electric vehicle power storage means or an electric power storage means has been promoted.

On the other hand, since the electric double layer capacitor utilizes the capacitance of the electric double layer formed at the interface between the electrode and the electrolyte, the rated voltage of one electric double layer capacitor is It is limited by the electrolysis voltage, and is about 1 V for an aqueous electrolyte, and about 3 V even when a non-aqueous electrolyte is used.

Therefore, for power storage, it is necessary to connect a large number of electric double layer capacitors in series and to make the voltage at least such that the power converter can operate efficiently. It becomes essential. In a system using such a large number of electric double layer capacitors, it is extremely important to improve the reliability of each electric double layer capacitor.

There are various factors that reduce the reliability of the electric double layer capacitor. Among them, the characteristics are greatly reduced due to the carbon material used as the electrode. The carbon material for an electric double layer capacitor is obtained by carbonizing a carbonaceous raw material and then treating the pores with a desired size and surface area. Exists. Moreover, it is difficult to remove these organic compounds adsorbed on the active pores by a relatively gentle treatment operation that does not change the properties of the carbon material.

The organic compound remaining in the carbon material may be dissolved in the electrolyte while operating as an electric double layer capacitor, or may prevent the electrolyte from reaching the pores of the carbon material electrode. This has been one of the factors that deteriorate the electric characteristics of the electric double layer capacitor. In addition, in an electric double layer capacitor using a non-aqueous electrolytic solution, the incorporation of moisture degrades the electrolytic solution and lowers the rated voltage by lowering the electrolysis voltage. Therefore,
At the time of assembling the electric double layer capacitor, various measures have been taken to reduce the moisture mixed from the used material as much as possible, but it was extremely difficult to completely eliminate the introduced moisture.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an electric double layer capacitor using a non-aqueous electrolytic solution using a carbonaceous material. To remove water and the like introduced from
It is an object of the present invention to provide an electric double-layer capacitor that maintains electrical characteristics for a long time and has excellent cycle characteristics.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an electric double layer capacitor, in which a positive electrode and a negative electrode are housed in an outer container facing each other via a separator, filled with an electrolytic solution, and at least once. The problem can be solved by a method for manufacturing an electric double layer capacitor, which is solved by a method for manufacturing an electric double layer capacitor in which at least a part of an electrolytic solution is exchanged after charging and discharging and then sealed. In the method for manufacturing an electric double layer capacitor, the positive electrode and the negative electrode are housed in an outer container facing each other with a separator interposed therebetween. This is a method for producing an electric double layer capacitor in which after at least one charge / discharge is carried out while flowing through the battery, the flow of the electrolytic solution is stopped and then sealed. Further, in the above-mentioned method for manufacturing an electric double layer capacitor, at least one charge / discharge after filling the electrolyte is performed at a temperature higher than the maximum usable temperature.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an aging process for an electric double layer capacitor, in which an organic substance or the like introduced by adsorbing on a carbon material or moisture introduced together with various materials at the time of assembling the electric double layer capacitor is used. It has been found that an electric double layer capacitor having stable electric characteristics over a long period of time can be obtained by removing it from the electrolytic solution.

The present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a manufacturing process of the electric double layer capacitor of the present invention. The outer container 2 of the electric double layer capacitor 1 in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, and a capacitor element in which a current collector is connected to a conductive connection tab is covered with a flexible outer material and sealed, The liquid inflow pipe 3 and the electrolyte outflow pipe 4 are connected to each other, and the electrolyte flows in from the electrolyte supply storage tank 5 through the electrolyte inflow pipe 3, and is returned to the electrolyte storage tank 6 through the electrolyte outflow pipe 4 while being returned to the positive electrode terminal. After a charging power supply 9 is connected to the negative electrode terminal 7 and the negative electrode terminal 8 and charging / discharging is performed at least once, the flow of the electrolytic solution in the electric double layer capacitor is stopped, and the electric double layer capacitor is sealed to manufacture an electric double layer capacitor.

The electrolyte stored in the returned electrolyte storage tank 6 is subjected to filtration, distillation, adsorption treatment with an adsorbent, etc. in the regeneration step 10 to perform electrolysis by initial charging and discharging of the electric double layer capacitor from the returned electrolyte. It can be reused by removing the substances mixed in.

Further, instead of the above-described method of continuously flowing the electrolytic solution, a predetermined amount of the electrolytic solution is injected from the electrolytic solution inflow pipe, and then the flow of the electrolytic solution is stopped to stop the discharge. After charging, the operation of removing the electrolytic solution by suction and then adding a new electrolytic solution may be performed at least once.

These operations may be carried out at room temperature. However, by raising the temperature to about the maximum operating temperature of the electric double layer capacitor, the electric double layer capacitor can be used while the electric double layer capacitor is being used. Substances expected to migrate into the electrolyte can be more completely removed.
Specifically, the electric double layer capacitor and the
It can be performed in a state heated to about ° C.

The electric double layer capacitor of the present invention can be applied to an electric double layer capacitor using either an aqueous electrolytic solution or a non-aqueous electrolytic solution. A greater effect can be obtained by applying the present invention to an electric double layer capacitor using a non-aqueous electrolyte in which the electrical characteristics are significantly reduced.

Further, the electric double layer capacitor of the present invention comprises:
The outer container can be applied to both a metal can and a container using a flexible outer material. However, when a flexible outer material is used, the flexible outer material and the electrolytic solution are used. The inflow pipe and the electrolyte outflow pipe are made integrally, and the sealing is removed except for the electrolyte inflow pipe and the electrolyte outflow pipe.The electrolyte is discharged after the initial charge / discharge and the new electrolyte is injected. The electric double layer capacitor can be manufactured by closing the liquid inlet tube and the electrolyte outlet tube.

[0016]

The present invention will be described below with reference to examples and comparative examples. Example 1 82 mg of activated carbon having an average pore diameter of 1.6 nm as measured by the BET method, 9 mg of carbon black, and 9 g of polytetrafluoroethylene powder were mixed and compacted into a disc having a diameter of 20 mm, and this was vacuum desiccatored. 1.33 of which
The pressure was reduced to Pa (10 ^-2 Torr) and dried at 110 ° C for 4 hours to obtain a polarizable electrode.

The obtained polarizable electrode is laminated with a glass fiber separator interposed therebetween, and sealed with a flexible outer material except for an electrolyte injection pipe and an electrolyte discharge pipe. After charging a 1.0 M tetraethylammonium tetrafluorate propylene carbonate solution from a tube, charging at 70 ° C. with a constant current of 5 mA to 2.5 V, holding for 15 minutes, and discharging and discharging at a constant current of 5 mA. After performing once, after discharging the electrolyte from the electrolyte discharge pipe, the electrolyte is again injected from the electrolyte injection pipe, and then the electrolyte injection pipe and the electrolyte discharge pipe are closed to close the electric double layer. A capacitor was manufactured.

With respect to the obtained electric double layer capacitor,
After charging to 2.5 V at a constant current of 5 mA, the battery was held for 15 minutes, and a charge / discharge cycle of discharging at a constant current of 5 mA was repeated to measure the capacitance. Table 1 shows the discharge capacity with respect to the charge / discharge test time.

Comparative Example 1 A charge / discharge test was performed in the same manner as in Example 1 except that an electrolytic solution was first injected, and then sealed as it was to produce an electric double layer capacitor. The results are shown in Table 1. .

[0020]

Table 1 Test time 0 25 50 100 250 500 750 Example 1 (F) 1360 1300 1290 1288 1286 1285 1283 Comparative example 1 (F) 1375 1207 1198 1192 1195 1195 1192

[0021]

According to the electric double layer capacitor of the present invention,
During the initial charge and discharge, undesirable substances contained in the electrode material and the like can be removed by transferring them into the electrolytic solution, so that in repeated charge and discharge over a long period of time, there is little deterioration in electrical characteristics and high reliability An electric double layer capacitor can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a manufacturing process of an electric double layer capacitor of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric double layer capacitor, 2 ... Outer container, 3 ... Electrolyte inflow pipe, 4 ... Electrolyte outflow pipe, 5 ... Electrolyte supply storage tank, 6 ...
Return electrolyte storage tank, 7 ... Positive electrode terminal, 8 ... Negative electrode terminal, 9 ... Charging power supply, 10 ... Regeneration process

Claims (2)

[Claims] In a method for manufacturing an electric double layer capacitor, a positive electrode and a negative electrode are housed in an outer container facing each other via a separator, filled with an electrolytic solution, and charged and discharged at least once. A method for manufacturing an electric double layer capacitor, comprising sealing at least a part of the electric double layer capacitor. 2. The method for manufacturing an electric double layer capacitor, wherein the positive electrode and the negative electrode are housed in an outer container facing each other with a separator interposed therebetween, and an electrolyte inflow pipe and an electrolyte outflow pipe are attached to the outer vessel. A method for manufacturing an electric double layer capacitor, comprising: performing at least one charge / discharge while flowing through the inside of the electric double layer capacitor;