JPS60194514A - Method of producing polarized electrode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing polarizable activated carbon electrodes for use in capacitors, batteries, etc. The electric double layer capacitor and chemical battery used as a battery are small, high capacity, and high output.

Conventional Structures and Problems There are two typical examples of capacitors and batteries that use carbon fibers or activated carbon fibers as polarizable electrodes. That is, as shown in FIG. 1, it basically consists of a pair of polarizable electrodes 1 made of activated carbon fiber cloth, a metal collecting electrode 2 such as aluminum formed on one side of the polarizable electrode, and a separator 3. The polarizable electrode 1 is injected with an appropriate electrolyte. 4 and 6 are both correct.

There is a negative electrode case ''C, and 6 is an insulating gasket.

FIG. 2 shows a battery using a woven fabric 10i made of activated carbon fibers as a negative electrode, a porous nickel oxide plate 11 as a positive electrode, and a KOH aqueous solution as the electrolyte 12.

In the capacitor shown in Fig. 1, electric capacitance is accumulated in the electric double layer formed at the interface between the activated carbon polarizable electrode 1 and the electrolyte. Assuming that the dielectric constant is ε and the surface area of the activated carbon polarizable electrode is S, the electrode capacity and amount shown in equation 1 will be accumulated.

Also in the case of the battery shown in FIG. 2, since the integral value of oxidation rate reaction equation 2 on the negative electrode governs the output, the larger the surface area of the activated carbon polarizable electrode, the greater the output of the battery.

Km@C,K(m, )Cn+K+9...River...
(2) In this way, both capacitors and batteries that use activated carbon as a polarizable electrode require activated carbon with a larger specific surface area (surface area per weight) in order to increase the output capacity per volume and energy density. do.

Generally, when carbonizing and activating fibers to make activated carbon fibers, woven or nonwoven fabrics made of threads made by twisting multiple fibers are carbonized by keeping them in an inert gas atmosphere at high temperatures. An activating gas such as water vapor, carbon dioxide gas, or oxidizing hydrocarbon gas is brought into contact with the surface of the fiber to generate pores on the surface of the fiber. That is, the oxidation reaction of carbon shown in Formula 3 is allowed to proceed.

Cn+H2o-4Cn-1+CO+H2...(3) Activated carbon fibers with a large specific surface area are basically activated carbon fibers that have many pores. It must proceed uniformly and quickly over the surface. In other words, it is necessary to uniformly bring the activating gas such as water vapor into contact with the surface of the fibers.

By the way, FIG. 3 is an enlarged schematic diagram of a thread 21 made of a plurality of fibers 20. In general, the fiber 2o has a thickness of several micrometers to several tens of micrometers/lrn, and the thickness of the thread 21 made of the same fibers has a thickness of several hundred micrometers to several megameters. In other words, the thread is made up of several tens to hundreds of fibers twisted finely. FIG. 4 is an enlarged view of a woven fabric 22 woven in a plain weave using the above-mentioned thread 21.
The fibers 2o having a diameter of several tens of micrometers are gathered in a narrow area as shown in this figure.

By the way, as mentioned above, the rate of the activation reaction that forms the pores of activated carbon is determined by the contact reaction between the activation gas and the surface of the fibers. In the case of thin threads made by twisting fibers together with strong force, the fibers are in close contact with each other, and the activating gas easily comes into contact with the fibers on the outside of the thread, but it does not touch the fibers inside the thread. Difficult to approach.

As a result, it is difficult to obtain a yarn with a large pore surface area per unit yarn weight. On the other hand, in the case of thick yarn made by twisting fibers together with a relatively weak force, the fibers are in rough contact with each other, making it easy for the activating gas to penetrate into the inside of the yarn. The pore surface area becomes larger.

By the way, as mentioned above, in order to obtain a capacitor with a large capacity per unit volume, for example, it is necessary to have more activated carbon fibers with a large specific surface area in a small volume space. It is necessary to increase the weave density of the yarn by weaving it as shown in Figure 4. In this case, there is less chance of contact between the fiber surface and the activating gas, and only activated carbon fibers with a small specific table aIJ product can be obtained, resulting in a capacitance of a capacitor using the same.

OBJECTS OF THE INVENTION The object of the present invention is to obtain a polarizable electrode that effectively activates yarns with a high twist density or cloth with a high weave density and provides a high capacity capacitor or battery.

Structure of the Invention The present invention is characterized in that a woven fabric, nonwoven fabric, paper, felt, etc. made of fibers is previously subjected to swelling treatment, and then carbonized or carbonized activated.

According to the present invention, the fiber density per unit area of the raw material yarn or raw material fabric is high, and the activating gas does not contact the fiber surface sufficiently uniformly under normal conditions.

Woven fabrics are also treated with surfactants etc. in advance.
By making the yarn, cloth, etc. bulky, the activation gas can sufficiently penetrate into the fibers S inside the yarn or cloth in the subsequent carbonization activation reaction. As a result, a cloth made of fibers with a large specific surface area and a high weave density can be obtained, and the output capacity of capacitors and batteries using this fiber as a polarizable electrode will be extremely large.

In the present invention, the fibers are subjected to swelling treatment prior to activation so that the constituent fibers of the high fiber density yarn and cloth can more easily come into contact with the activation gas. be.

(1) Method of treatment with a surfactant Depending on the type of fiber to be treated, such as cationic, a/ionic, nonionic, amphoteric, nonaqueous, or aqueous, use a surfactant to make the contact between fibers rougher. This is a method for making the contact between the fibers and the activating gas more uniform. Polyhydric alcohols and higher alcohols such as ethylene glycol may also be present.

(2) Method of treatment under high temperature and high humidity This is a method in which threads or cloth made of fibers are sufficiently wetted with steam at a high temperature and high humidity such as 85° C. and 190% RH.

(3) Method of processing under high temperature, high humidity, and pressure A method of processing yarn or cloth made of fibers in a pressure vessel such as an autoclave in the coexistence of water vapor under high temperature and high pressure such as 120°C and 11.5 atmospheres. It is. Due to the pressurized steam, the contact between the fibers becomes rougher.

(4) Freezing method This is a method in which fibers are impregnated with water, once frozen, and then the ice is thawed. Since the density of water reaches its maximum at 4°C, frozen ice expands in volume and expands the gaps between fibers.
Even after this is melted, rough contact between the fibers is maintained.

The above four types of treatments may be followed by drying treatment.

Description of Examples Example 1 Phenol resin fiber (manufactured by Nippon Kynol Co., Ltd., thickness 1
The following 8 types of treatments were applied to a group of cloths (weighing 200gΔy?) knitted in a satin weave using yarn (number 20) composed of 0μm).

(A) The above fabric was immersed in a mixed solution of 2 eswt% of nonionic surfactant (glycerin monostearate) and 76 wt% of higher alcohol.

(B) Hold the cloth for 2 hours in a constant temperature bath at 85°C and 190% R).

(q) Put the above cloth into the upper space of an autoclave with water in the bottom, seal it, and keep it at 120°C for 2 hours.

p) Sufficiently soak the cloth with water and keep it in a -2o0 freezer for 1 hour. Next, take it out of the freezer and leave it at room temperature to gradually melt the ice.

(a) to (d) Two or more (A) - (D) after processing 8
Dry at 5°C for 1 hour.

These 8 types of cloth were made into an inert atmosphere with nitrogen gas9
The material is maintained in an electric furnace at 60° C., and carbonization activation treatment is performed by sending water vapor using nitrogen gas as a carrier to obtain an activated carbon cloth.

Subsequently, an aluminum metal layer (thickness: 200 μm) was formed on one side of the obtained activated carbon cloth by plasma spraying, and the cloth was punched out into a disk shape with a diameter of 12M1. This electrode, separator, gasket ring, and case are constructed as shown in FIG. 1 to obtain a coin-shaped capacitor. As the electrolytic solution, a solution of tetraethylammonium verchlorate dissolved in fluorobylene carbonate was used. The characteristics of the capacitor thus obtained are shown in Table 1. The same table also shows the characteristics of a capacitor using the same fibers but carbonized without any of the above treatments. Furthermore, in the same table,
The cumulative BET surface area of a disk-like cloth with a diameter of 12 words is also shown.

Example 2 Cloths A and a used in Example 1 and the conventional untreated product were cut into square shapes of 50 MX 50 M after carbonization activation treatment.

This was used as the negative electrode, a sintered porous nickel oxide electrode was used as the positive electrode, and a 20% by weight aqueous solution of KOH was used as the electrolyte.
The battery shown in the figure was constructed. FIG. 6 shows the discharge characteristics of these three types of batteries.

Effects of the Invention As described above, according to the manufacturing method of the present invention, even in yarns and fabrics with high twist density and high weave density, the activation gas sufficiently penetrates into the constituent fibers in the center, so that the activation can be improved. It is completely and uniformly distributed over the entire surface, and compared to conventional activation methods, a much larger capacity and output can be obtained per unit cloth area. Furthermore, by using this method, it is possible to uniformly activate even fabrics with a fairly high weave density, making it possible to obtain smaller capacitors and batteries with larger capacities.

[Brief explanation of drawings]

Figure 1 is a longitudinal sectional view of a capacitor using activated carbon fibers as polarizable electrodes, Figure 2 is a longitudinal sectional view of a battery, Figure 3 is a diagram showing the relationship between fibers and threads, and Figure 4 is a diagram showing the relationship between fibers and threads. FIG. 5 is a schematic diagram showing the relationship between yarn and cloth, and FIG. 5 is a diagram showing the characteristics of a battery using an activated carbon fiber polarizable electrode. Name of agent: Patent attorney Toshio Nakao and one other name
1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A method for producing a polarizable electrode, which is characterized by subjecting a woven or nonwoven fabric made of fibers, paper, or felt to a swelling treatment in advance, and then carbonizing or activating carbonization. (2) The method for producing a polarizable electrode according to claim 1, wherein the swelling treatment is performed using a surfactant. (3) The method for producing a polarizable electrode according to claim 1, wherein the Mi swelling treatment is performed in a high temperature and high humidity atmosphere. (4) The method for producing a polarizable electrode according to claim 3, wherein the swelling treatment is carried out under a pressurized atmosphere. (5) The swelling treatment impregnates water, freezes it, and then melts it again. A method for producing a polarizable electrode according to claim 1, which comprises treating.