JPH0266918A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To obtain satisfactory temperature characteristic, stable aging characteristic by opposing carbon electrodes composed by filling carbon black and slight binder in activated charcoal fiber cloth and solidifying it through a separator to form an element. CONSTITUTION:Carbon electrodes 1, 2 composed by filling carbon black and slight binder in activated charcoal fiber cloth and solidifying it are opposed through a separator 3, and its element is sealed in a metal case 6 to be used also as a current collector and a metal cover 5. Acetylene black, fine powder artificial graphite, ketjen black carbon black and, for example, polyflon dispersion, carbon-containing polyflon conductive enamel binder are filled in the electrode made of the cloth, and solidified to disperse the carbon black and the binder in the electrode thereby to raise conductivity between the fibers. The polyflon of second binder enhance the electrolyte solubility of the solidified electrode, the current collection of the electrode is largely improved, and aging characteristic is very stabilized.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electric double layer capacitor.

This electric double layer capacitor consists of a polarizable electrode and an electrocatalyst (liquid).
It has the characteristic of large electrolytic capacity using the electric double layer formed at the interface with
It is used as a backup during power outages.

2. Description of the Related Art This type of conventional electric double layer capacitor has a so-called disc-shaped (coin-shaped, button-shaped) structure as shown in Fig. 1, and electrolysis is carried out between carbon electrodes 1 and 2 made of activated carbon fiber cloth. A separator 3 impregnated with a liquid is interposed therebetween, and it is sealed by a metal case 6 that serves as a current collector and an exterior material, a metal lid 6, and a packing 4 that serves as an insulator and a sealing material. Furthermore, an aluminum layer is formed on the electrode made of activated carbon fiber cloth by plasma spraying or the like on the surface that contacts the metal case and the metal lid in order to improve current collection and enable welding. Further, the surface of the sealing body is usually coated with a thin layer of asphalt pitch to improve sealing performance.

Problems to be Solved by the Invention As stated above, the greatest use of electric double layer capacitors is as a backup for semiconductor memories during power outages. Therefore, in order to provide sufficient reliability for the application, it is necessary to ensure good temperature characteristics and stable aging characteristics.

The present invention is intended to solve these conventional problems, and provides an electric double layer capacitor having good temperature characteristics and stable aging characteristics.

Means for Solving the Problems To achieve this, the present invention comprises an element in which carbon electrodes made by filling and solidifying activated carbon fiber cloth with carbon black and some binder are placed facing each other with a separator interposed therebetween.

According to the structure of the present invention, an electrode made of activated carbon fiber cloth is filled with carbon black and some binder.
By solidifying, the carbon black and the binder are dispersed within the activated carbon fiber cloth electrode, increasing the conductivity between the activated carbon fibers, and the second binder, Polyflon, improves the electrolyte solubility of the solidified electrode. Increase. As a result, the current collecting ability of the electrode was greatly improved, the aging characteristics were extremely stable, and the lifespan of the electrode could be extended by about three times compared to conventional electrodes.

EXAMPLES Next, examples of the present invention will be described. First, an activated carbon fiber cloth was used as a polarizable electrode. 0 on one side of this.
An aluminum layer of about 0.05 mm is formed by plasma spraying. Its total thickness is 0.6 mm.

The basis weight of activated carbon fiber cloth alone is 125 f/rrl',
The specific surface area was 1860 m'/7, and the size was φ6. A metal case with an outer diameter of φ11, a corresponding metal lid, and a sealing body were prepared. The metal lid with negative potential is made of 5US304, the inner surface of the metal case with positive potential is made of aluminum, and the outer surface is made of 5U.
In S304, both are clad and integrated. The separator is a non-woven fabric made of polypropylene fiber with a thickness of 0.
．． It is a porous sheet with a length of 35 m and a basis weight of 6 oy/rrl.

The sealing body is a polypropylene resin molded product. The electrolytic solution consists of 1 mol of tetraethylammonium (tetrafluoroboret) in propylene carbonate, which is mixed with 3
μm is used.

The sealing agent is applied to the inner surface of the sealing body and the inner surface of the metal case.

Next, the sealed single cell has a withstand voltage of 3V, but in order to cope with the driving voltage of a semiconductor memory, two cells are laminated to make a 6.5V product.

The comparison between the inventive product and the conventional product is as follows: 1) Liquid stability when immersing activated carbon fiber cloth in aqueous solutions of these materials (part of the liquid composition floats), which is performed as part of the electrode filling and solidification process. Comparison, ■ Electrolyte solubility resistance, ■ High-temperature load test conducted as a reliability test...70"C, 6.6V
Electrical characteristics were performed after 3000 hours of application.

Table 1 shows the presence or absence of floating matter during the immersion treatment of the activated carbon fiber cloth under various conditions, the electrolytic solution resistance of the electrode, and the overall evaluation thereof.

Table 2 shows the initial characteristics (
Measurement temperature: 20'C), low-temperature characteristics (-26°C), and high-temperature load test (7o'C, s, aV applied) after 30oO hours.

The carbon blacks used were 5B (acetylene Pfuch), CB (finely powdered artificial graphite), and KB (Ketchen blank), and the first binders were CMC (carboxymethyl cellulose) and PV (polyvinyl alcohol).

Moreover, AQ (Aqua Duck) 1 and AQ2 are mixtures of the above materials.

The second binder is PDl (Polyflon dispersion), CPF (Polyflon conductive enamel with carbon).

Table 1 × The above symbols are Δ Same as conventional, ○ Better than conventional, ◎ Superior than conventional As mentioned above, addition of CPF is necessary to satisfy both floating matter generation and electrolyte solubility. There was found. This phenomenon was also found in other electrode treatment liquid compositions listed in Table 2. However, even if the generation of floating substances and the solubility in electrolyte are the same as those of conventional products, this does not mean that the product cannot be used.

Next, Table 2 lists the initial characteristics and high-temperature load characteristics of electric double layer capacitors prototyped using electrodes treated with various electrode treatment solutions. In this case, the type of electrode represents the amount attached to the original activated carbon fiber cloth after immersion in the treatment solution and drying. Furthermore, 1% CPF was added to all of these processing solutions.

(The following is a blank space) Effects of the Invention As described above, according to the present invention, a product using an electrode in which an activated carbon fiber cloth is filled with a carbon blank and a small amount of binder and solidified has advantages in terms of manufacturing method as well as initial characteristics, It is possible to maintain stable characteristics in low-temperature characteristics and reliability (high-temperature load test), and its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electric double layer capacitor. 1.2... Carbon electrode, 3... Separator,
4...Packskin, 5...Metal lid, 6...
...Metal case. Name of agent: Patent attorney Shigetaka Awano and 1 other person1
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Claims (1)

[Claims] Carbon electrodes made by filling and solidifying carbon black and some binder into activated carbon fiber cloth are placed facing each other with a separator in between to form an element, and the element is sealed with a metal case that also serves as a current collector and a metal lid. Electric double layer capacitor.