JPS6059733B2 - carbon paste electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon paste electrode for an electric double layer capacitor using a carbon paste electrode.

An electric double layer capacitor using carbon paste electrodes has a cross-sectional structure as shown in FIG. 1, as seen in US Pat. No. 3,536,963.

In the figure, 1 is a conductive separator that is electronically conductive and impervious to ions, 2 is a carbon paste electrode made of activated carbon powder and an electrolyte solution, and 3 is an ion-permeable separator provided to prevent conduction between the electrodes. 4 is a porous separator that blocks electron conduction, and 4 is a non-conductive gasket provided to hold the carbon paste electrode and isolate it from the outside world. Conventionally, a two-component system in which activated carbon powder is mixed with an electrolyte solution has been used as the carbon paste electrode 2 serving as the electrode of this type of electric double layer capacitor (hereinafter referred to as basic cell). In the case of such two-component electrodes, when preparing a carbon paste electrode by mixing activated carbon powder and an electrolyte solution, it may be difficult to form a paste, or even if it becomes a paste, the activated carbon powder may deteriorate over time. This phenomenon occurred when the electrolyte solution separated.

Therefore, due to poor pasting properties, when carbon paste electrodes were printed using the Dr. Knaifue method, the carbon paste electrodes often scattered or the electrolyte solution leaked. Another drawback was that self-discharge characteristics were generally poor. An object of the present invention is to provide a carbon paste electrode that eliminates these drawbacks.

In addition to activated carbon powder and electrolyte solution, the carbon paste electrode of the present invention contains 0.05% of the amount of activated carbon powder as a third component.
It is characterized by adding and mixing ultrafine particulate anhydrous silica in an amount of ~W% by weight.

Here, ultrafine particulate silica refers to purified silicon tetrachloride with 10
It is manufactured by burning at high temperatures around 00°C, and has characteristics such as increasing solidity and thixotropy, preventing caking, and improving fluidity. Hereinafter, one embodiment of the present invention will be compared with a conventional example and will be described in detail with reference to FIG. 1, FIG. 2, and Table 1.

[Example] Specific surface area 1100d/9 (BET method),
Activated carbon powder 50y with a particle size of 325 mesh or less and 3% heel weight
2.59 (5% by weight) of ultrafine anhydrous silica was added to 170y of sulfuric acid and thoroughly mixed and stirred to prepare a carbon paste electrode.

The ultrafine anhydrous silica particles have a particle size of approximately 10 mm and a specific surface area of approximately 200 mm/Y. ．． High purity silica with a SlO2 content of 99.8% or more was used. Using the above carbon paste electrode, a non-conductive gasket with an outer diameter of 37 m and an inner diameter of 3 m has the same cross-sectional structure as shown in Figure 1.
0m1 thickness is approximately 1.5Tff! A basic cell of 1 t was obtained.

Eight of these basic cells were stacked in series to produce an electric double layer capacitor with an operating voltage of 5V.

The initial characteristics of the electric double layer capacitor manufactured by this method were as shown in a in Table 1. In addition, the initial characteristics of an electric double layer capacitor of the same shape manufactured by the method described above except that ultrafine particulate anhydrous silica is not added are as shown in b in Table 1. Ta. Furthermore, when we compared the self-discharge characteristics, we found the results shown in Figure 2. In Figure 2, a shows an electric double layer capacitor using a three-component carbon paste electrode with the addition of ultrafine anhydrous silica of the present invention, and b shows a conventional carbon paste electrode without the addition of ultrafine anhydrous silica. This is the self-discharge characteristic of an electric double layer capacitor using Here,
The self-discharge characteristic represents the change over time in the residual potential of the electric double layer capacitor after applying a voltage of 5V for 1 minute with a protective resistance of 0Ω as a charging condition.

As is clear from this example, compared to conventional electric double layer capacitors using paste electrodes without the addition of ultrafine anhydrous silica, the characteristics of the inventive capacitors are stable and C
It has a self-discharge time suitable for long-term hold applications such as MOSRAM. This demonstrated the effectiveness of the present invention.

In addition, by adding ultrafine anhydrous silica particles, appropriate fluidity can be added to the carbon paste electrode.
Separation of activated carbon powder and electrolyte solution did not occur, and workability in forming carbon paste electrodes was significantly improved.

In addition, ultrafine particulate anhydrous silica is added to 0.05 of the amount of activated carbon powder.
If less than 1% by weight is added, there will be no effect, and if more than 1% by weight is added, adverse effects such as an increase in internal resistance will occur, which is not preferable.

As described above, the present invention has a remarkable effect on improving various characteristics and workability of electric double layer capacitors, and has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electric double layer capacitor using a conventional paste electrode, and FIG. 2 is a characteristic diagram showing self-discharge of the electric double layer capacitor according to the present invention and the conventional electric double layer capacitor, respectively. 1... Conductive separator, 2... Carbon paste electrode, 3... Porous separator,
4...Non-conductive gasket.

Claims (1)

[Claims] 1. In a carbon paste electrode member for an electric double layer capacitor having activated carbon powder and an electrolyte as both poles, the carbon paste electrode component contains 0.05 to 10% by weight of ultrafine particulate anhydrous silica in the activated carbon powder and electrolyte solution. A carbon paste electrode for electric double layer capacitors characterized by an additive mixture.