JPH0434289B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a method for manufacturing electric double layer capacitors used in various electronic devices. Conventional technology An electric double layer capacitor has a characteristic of high capacitance by utilizing an electric double layer formed at the interface between a polarizable electrode and an electrolyte, and is mainly used for volatile semiconductor memories (e.g. RAM... ...Random access memory) is used for backup in the event of a power outage. As shown in FIG. 2, this type of conventional example consists of an electrode in which a carbon electrode body 1 made of graphite, carbon black, activated carbon, etc. and some binder is disposed on a current collector 2, and a carbon electrode body 1 is disposed on a current collector 2, and a It is composed of a separator 3 impregnated with an electrolytic solution. Furthermore, in order to obtain this electric double layer capacitor, first, as shown in FIG. 3, a lead 5 (inside aluminum, outside (consisting of tin-coated copper wire or iron-core tin-coated copper wire, etc.)
This is then wound together with a separator 6 to form an element 7. After that, as shown in FIG. 4, it is impregnated with an electrolytic solution, housed in an aluminum case 8, and sealed with a sealing material 9 to form a product. It is said that In addition, as shown in Figure 5, it has a structure called a disk shape (coin shape, button shape), and is made of materials such as graphite, activated carbon, carbon black, and some binder, or is made of aluminum or stainless steel net. A separator 11 impregnated with an electrolytic solution 10 is interposed between supported electrodes or carbon electrodes 9 made of carbon fiber, especially activated carbon fiber cloth, and a metal case 12 serving as a current collector and an exterior material, an upper lid 13 and It is sealed by a gasket 14 that serves as both insulation and sealing material. Furthermore, in the case of electrodes made of activated carbon fiber cloth, a metal case 1 is used to improve current collection.
2 and the metal lid 13, an aluminum layer is formed by plasma spraying or the like. Problems to be Solved by the Invention The main characteristics of the electric double layer capacitor configured as described above are capacitance, internal resistance, and leakage current.
Regarding the characteristics, when the present inventors measured these three characteristics, it was found that although there was no large difference in capacitance, there were large variations in internal resistance and leakage current. The present invention relates to a manufacturing method that reduces variations in internal resistance and leakage current. The inventors of the present invention first came up with the idea of aging by applying a voltage for a long time as an improvement measure. Furthermore, aging was performed at high temperatures, but these two methods failed to improve the properties. I also tried applying thermal shock, but still could not get good results. Therefore, the next method was the method of the present invention. Means for Solving the Problems In other words, the method for manufacturing an electric double layer capacitor of the present invention involves coating an element in which a separator and an electrolyte are interposed between carbon electrode bodies made of graphite, carbon black, activated carbon, etc. , the charge of a capacitor previously charged with a high voltage is applied between the electrodes a predetermined number of times. Effect As described above, when the manufacturing method of the present invention is adopted, the electrode material and current collector of the electric double layer capacitor,
We believe that this high-voltage energy acts as a heat shock on the separator and electrolyte, and works well to prevent the electrodes from scattering due to sparks, and vice versa, resulting in good results. . Embodiments Next, embodiments of the present invention will be described with reference to the drawings. The present invention is a method of providing an electrical shock to an electric double layer capacitor. This method uses another high-voltage capacitor and discharges the electric charge that has been previously charged into the capacitor into the electric double layer capacitor by switching a switch. The electrical wiring at that time is shown in Figure 1, where 15 is an electric double layer capacitor, 16 is an electric double layer capacitor,
1 is a high voltage application capacitor, 17 is a changeover switch, and 18 is a DC power supply. As shown in Tables 1 and 2, it was found that the manufacturing method of the present invention was significantly superior in the initial characteristics of the capacitor compared to conventional products. Next, a specific example will be explained. Example 1 (configuration shown in Figure 3) and Example 2
(The configuration shown in FIG. 5) will be described. First, the electric double layer capacitor of Example 1 (rated voltage is 2.0V, capacitance is 10F, case is φ12.5x35
We made 20 prototypes of cylindrical (mm cylindrical) pieces. In the experiment, we applied a DC voltage of 2.0V immediately after manufacturing this capacitor to perform aging, and the leakage current after 60 minutes was measured.
Then, internal resistance and capacitance were measured. Next, 10 of these 4.4 μF polyester film capacitors were charged from a 1000 V DC power supply, and the operation of discharging the charges was repeated 10 times by switching a switch. And after this operation again (also the remaining 10 pieces)
Characteristics were measured. The above results are listed in Table 1.

[Table] Next, 20 electric double layer capacitors of Example 2 (rated voltage: 3.0V, capacitance: 0.15F, case: φ11x1.7t) were fabricated. Immediately after manufacturing this capacitor, it was aged by applying a DC voltage of 3.0V, and the leakage current, internal resistance, and capacitance were measured after 60 minutes. Ten of these 4.4 μF polyester film capacitors were charged from a 200 V DC power supply, and the operation of discharging them by switching a switch was repeated 10 times. And after this operation again (and the remaining 10 pieces)
Characteristics were measured. The above results are listed in Table 2.

[Table] Especially in the case of large internal resistance or leakage current,
By increasing the number of times, increasing the voltage, or increasing the capacitance of the capacitor, I was able to get the value back to normal. As can be seen from Tables 1 and 2, by employing the manufacturing method of the present invention, most of the abnormal values of internal resistance and leakage current returned to normal values.
And the reason it didn't recover was clearly due to other factors. Another feature is that even if this method is applied to items that are close to normal or have normal values, the values do not improve much. By adding the operating process of the present invention as a step in the manufacturing method, most of the products that were conventionally considered defective can be recycled as good products, which has the effect of reducing manufacturing costs. This is a big deal, and it can be said to be a very effective method. By the way, the applied voltage of 1000V mentioned in the example
A capacitor with a capacitance of 4.4μF or 200V should be selected depending on the rating and capacitance of the electric double layer capacitor, and the inventors also
In the case of 1F electric double layer capacitor, 500V,
Discharge was performed using a 4.4μF capacitor. In particular, the method of keeping the capacitance constant and changing the charging voltage is the stored energy of the capacitor (1/
2CV ² ), this is an easy method. Further, in the above explanation, a case was explained in which a changeover switch was used, but a relay is advantageous when a large number of products are to be manufactured at once, and the use of a thyristor, which is a non-contact relay, is more effective. Effects of the Invention As described above, according to the method of manufacturing an electric double layer capacitor of the present invention, in terms of the internal resistance and leakage current characteristics of the electric double layer capacitor, what was conventionally considered to be a defective product can be regenerated as a good product. As a result, the yield can be improved, and its industrial value is great.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram for carrying out the method of manufacturing an electric double layer capacitor of the present invention, FIG. 2 is a sectional view showing the basic structure of the electric double layer capacitor, and FIG.
The figure is a perspective view showing the elements of one configuration of the same capacitor, FIG. 4 is a cross-sectional view showing the internal structure of the same capacitor with a part cut away, and FIG. 5 is the other electric double layer capacitor. FIG. 3 is a sectional view showing the configuration. 1... Carbon electrode body, 3... Separator, 15...
...Electric double layer capacitor, 16... High voltage application capacitor, 17... Changeover switch, 18...
DC power supply.

Claims (1)

[Claims] 1. After applying an exterior coating to an element consisting of a separator and an electrolyte interposed between carbon electrode bodies such as graphite, carbon black, and activated carbon, the electric charge of a capacitor that has been charged with a high voltage between the electrodes is set to a predetermined level. A method for manufacturing an electric double layer capacitor, which is characterized in that a voltage is applied repeatedly a number of times.