JPH0665206B2 - Electric double layer capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric double layer capacitor using activated carbon as a polarizable electrode.

2. Description of the Related Art Conventionally, the electrodes of electric double layer capacitors using this type of electrolytic solution are made by press-molding activated carbon particles or coating the current collector metal with a mixture with an appropriate binder. It was Also, when using activated carbon fibers, a method is known in which a sprayed layer of aluminum is formed on the activated carbon fibers, and an electrode case made of strong stainless steel as a case material and a sprayed layer of aluminum are spot-welded to form an electrode. The electrodes with the same capacitance were used for both the cathode and cathode.

Problems to be Solved by the Invention In such an electric double layer capacitor, deterioration in internal resistance and electrostatic capacitance change was observed when repeatedly charged and discharged at a withstand voltage.

This is because the reaction potential ratios on the anode side and the cathode side are different with respect to the reference voltage 0, as indicated by the VI characteristics in FIG.
When a withstand voltage is applied to this so that no reaction current flows and the characteristics can be applied stably, since the anode and cathode both have a single capacity with reference to 0 potential, the voltage rises with the same potential change, so the reaction current flows on the anode side. The characteristics deteriorate beyond the potential.

In this way, the potential range that can be actually used is 2 of the reaction potential of the anode.
The potential width is doubled and low, and the withstand voltage obtained from the VI characteristic cannot be effectively used.

The present invention solves such a problem, and an object thereof is to regulate the reaction current and improve the withstand voltage.

Means for Solving the Problems In order to solve the above problems, the present invention relates to the electrostatic capacity of each polarizable electrode of the anode and the cathode of the anode and the cathode with reference to 0 potential in the potential-current characteristics. It is adjusted to the ratio of the reciprocal of the ratio of the reaction potential.

Action The action of this technical means is as follows. As shown in FIG. 2, in order to effectively use the withstand voltage in the VI characteristic (potential-current characteristic), the reaction potentials on the anode side and the cathode side and the potentials of the anode and the cathode when voltage is applied are the same. By doing so, the withstand voltage obtained from the VI characteristic can be used without the reaction current flowing.

That is, the capacitance value of each electrode may be determined so that the anodes and the cathodes reach the same reaction potential during voltage application. When the capacitance on the anode side is 1, the capacitance on the cathode side is A / B.

Example As shown in FIG. 1, as a conductive electrode 3, a pair of polarizable electrodes 4 and 5 made of a phenolic activated carbon fiber cloth (thickness 0.5 mm, specific surface area 2,000 m ² / gr) was used as a conductive electrode 3. A 250 μm thick aluminum layer is formed by plasma spraying. This two-layer structure is punched out into a disk-shaped size with an anode and a cathode having a capacitance of 1: 0.6 to obtain an electrode body. This electrode body was impregnated with an electrolyte solution prepared by adding 10 wt% of tetraethylammonium tetrafluoroborate to propylene carbonate, and then superposed with a separator 6 interposed therebetween.
It is sandwiched by a pair of stainless steel cases 1 having a thickness of 70 μm and coated only on the side to be the anode, and packing 7 is arranged at the open end of the case 1 and sealing is performed by caulking.

Table 1 shows various characteristics of the electric double layer capacitor according to the present invention. Similarly, Table 1 shows the characteristics of a prototype of the anode and cathode with a capacity ratio of 1: 1 for comparison.

EFFECTS OF THE INVENTION As described above, according to the present invention, the reaction current can be regulated by adjusting the capacity of each electrode according to the ratio of the reaction potentials of the anode and the cathode, and a higher withstand voltage electric double layer capacitor can be easily obtained. Is something that can be done.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the electric double layer capacitor of the present invention, and FIG. 2 shows the capacity ratio of the anode and the cathode. FIG. 3 is a characteristic diagram showing the V-I characteristic of the device of FIG. 3 and FIG. 1 ... Case, 3 ... Conductive electrode, 4 ... Anode type polarizable electrode, 5 ... Cathode side polarizable electrode, 6 ... Separator.

Claims (1)

[Claims] 1. A pair of polarizable electrodes made of activated carbon fiber or activated carbon powder having a conductive electrode formed on one surface thereof are housed in a pair of metal cases, and a pair of polarizable electrodes is provided in each of the pair of metal cases. It is configured by electrically contacting the conductive electrodes, and the electrostatic capacity of each polarizable electrode of the anode and the cathode is the reciprocal of the ratio of the reaction potentials of the anode and the cathode with reference to 0 potential in the potential-current characteristics. An electric double layer capacitor characterized by matching the ratio.