JPH0610979B2 - Method for producing activated carbon for polarizable electrodes - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing fibrous activated carbon for polarizable electrodes used in electric double layer capacitors, batteries and the like.

2. Description of the Related Art Capacitors and batteries using activated carbon fibers as polarizable electrodes are already known. On the surface of the activated carbon electrode, the formation reaction of the electric double layer due to the adsorption and desorption of positive and negative ions mainly occurs in both the capacitor and the battery, and the accumulation of the charge in this portion becomes one electrode reaction.

By the way, as a polarizable electrode using such an activated carbon fiber as its constituent material, conventionally, a raw material fiber is woven into a cloth shape and carbonized and activated as it is, and the activated carbon fiber cloth is used as it is as a polarizable electrode. Mainly used is a configuration in which filamentary fibers are activated by carbonization, which are cut, mixed with an appropriate binder and made into paper to be used as a paper-like or felt-like polarizable electrode. Of these two configurations,
The one using activated carbon fiber cloth is very easy to manufacture because it can be used as an electrode as it is. On the other hand, using long filament fibers as a starting material,
Paper and those using felt-like polarizable electrodes are made through several processes such as carbonization activation of raw material fibers, cutting, and papermaking, and the production is slightly more complicated than that using rods,
For example, it is possible to increase the amount of activated carbon filled per volume by increasing the density of the paper by pressurizing.

Conventionally, the carbonization activation of the long filament fibers has been carried out using a batch type furnace as shown in FIG. That is, the furnace chamber portion 20, the heating portion 21, the heat insulating portion 2
2. A method in which long filament fibers 24 are placed in a furnace composed of a control unit 23 and activated gas from an activated gas supply device 25 is caused to act on the long filament fibers 24.

The problem to be solved by the invention is that when the carbonization activation is carried out by the batch method as described above, it takes time to raise and lower the temperature of the furnace, and the energy associated therewith also becomes large, resulting in high productivity and cost. You will be at a disadvantage. The characteristics of the obtained activated carbon fiber (specific surface area,
There is room for improvement in terms of the pore size distribution) and the characteristics of the electric double layer capacitor using this as a component of the polarizable electrode. That is, (1) increase the chances of contact reaction between the activated gas and the activated fiber, (2) remove the decomposition gas of the raw material fiber generated during carbonization activation to the outside of the system as quickly as possible, thereby increasing the high specific surface area. It is possible to obtain the activated carbon fiber of

The present invention provides a method for obtaining an activated carbon fiber which provides a polarizable electrode having a particularly high capacity, using such a long filament raw material fiber as a starting material.

Means for Solving the Problems The present invention has openings in an upper part and a lower part, and supplies an activating gas from at least an opening different from the above in a lower part of a furnace chamber,
From the upper opening to the lower opening of the furnace that made the atmosphere inside the furnace controllable, or from the lower opening to the upper opening,
The present invention is characterized in that a roving or tow-shaped substance made of long filament-like fibers is continuously moved to activate and carbonize the long filament-like fibers.

Effects According to the present invention, long filament-like activated carbon fibers having a high specific surface area and an effective pore distribution are continuously obtained. Therefore, by chopping it into a high-density paper, a polarizable electrode having a higher capacity and a smaller size than the activated carbon cloth can be obtained.

Compared with the case where cloth is used as a raw material, long filament fiber roving-like or tow-like one is one raw material fiber.
Compared to a woven fabric in which books are bundled at a low density and fibers are spun and strongly woven, there are many opportunities for contact between the activated gas and the activated fibers, and the carbonization decomposition generated gas is also a continuous furnace of the present invention. Then it is promptly removed from the system. Therefore, a high capacity activated carbon fiber can be obtained.

Example FIG. 1 shows the configuration of the electric furnace used in the example. Reference numeral 1 denotes a furnace chamber body, which has an upper opening 2 and a lower opening 3. Four
Is a heater for heating the main body, and 5 is a heat insulating layer. 6
Is a storage box communicating with the lower opening 3, 7 is an activating gas generator that supplies activating gas from the supply port 8 into the main body 1, and 9 is a raw material fiber.

The raw material fiber 9 is charged from the upper opening 2 of the furnace, and the steam from the activation gas generator 7 is introduced from the activation gas supply port 8 to the furnace chamber body 1 by using nitrogen as a carrier gas to continuously activate the raw material fiber. Do. The activated carbonized long filament fiber 10 is obtained in the lower storage box 6. The steam supply during continuous activation is an amount corresponding to 4 to 8 cc in terms of water with respect to 1 g of long filament fiber.

Next, specific examples of the present invention will be described.

Example 1 Long filament of phenolic resin fiber (diameter 20 μ
The raw material fibers in the form of rovings that had a spring m) were activated by carbonization using the electric furnace shown in FIG. Cut the resulting activated carbon fiber into chopped pieces with a length of 1 to 3 mm, and
It was wet-mixed with a natural pulp of mm in a weight ratio of 60:40, paper-made and dried. The basis weight of the obtained paper is 100 g /
m ² and thickness are 200 μm. An aluminum current collector layer was formed on one surface of the activated carbon paper by a plasma spraying method, and the aluminum current collector layer was punched into a circle having a diameter of 10 mm. The pair of polarizable electrodes thus obtained were opposed to each other with a separator interposed therebetween to form a flat electric double layer capacitor as shown in FIG.

In FIG. 2, 11 and 12 are polarizable electrodes, 13 and 14 are collector layers thereof, 15 is a separator, 16 is a gasket ring, 17 is a metal case, and 18 is a metal lid. As the electrolytic solution, a solution prepared by dissolving 30% by weight of tetraethylammonium perchlorate in propylene carbonate was used.

Example 2 A weight ratio of the activated carbon fiber of the example and the natural pulp is 60:40.
Were mixed at a ratio of 100 g / m ² to produce a paper having a basis weight of 150 g / m ² , and then pressure calendered to a thickness of 200 μm. Using this activated carbon paper, a capacitor was prototyped in the same manner as in Example 1.

Example 3 A long filament-like activated carbon fiber was prepared in the same manner as in Example 1, cut into lengths of 1 to 3 cm and interlocked with each other to give a felt having a basis weight of 100 g / m ² and a thickness of 250 μm, and one side thereof. An aluminum current collector layer was formed by plasma spraying, and a capacitor was produced as a trial by the same method as in Example 1 below.

Example 4 An aluminum layer was formed on one surface of the activated carbon paper obtained in Example 1 by a plasma spraying method and cut into a size of 3 cm × 5 cm. These two electrodes were made to face each other with their activated carbon paper sides via a separator, and an aluminum foil having a thickness of 0.02 mm was arranged along the aluminum layer and spirally wound to form a cylindrical capacitor. The electrolytic solution is Example 1
Is the same as.

Example 5 An aluminum layer was formed on one surface of the activated carbon paper obtained in Example 1 by a plasma spraying method, and this was punched into a circle having a diameter of 10 mm. This polarizable electrode is used as a positive electrode and as a negative electrode,
An electrochemical device having a structure as shown in FIG. 2 was assembled using a Sn-Pb alloy doped with lithium. The electrolyte used was a solution of lithium perchlorate in propylene carbonate.

Example 6 Sn—P doped with lithium as used in Example 5 instead of activated carbon paper for the negative electrode using the same material as the positive electrode of Example 4
It was assembled by winding in a spiral shape using b alloy foil. The same electrolytic solution as in Example 5 was used.

Comparative Example 1 A capacitor similar to that of Example 1 was experimentally manufactured using the activated carbon fiber obtained in the batch furnace.

Comparative Example 2 An activated carbon fiber cloth was chopped to manufacture a capacitor similar to that of Example 1.

Comparative Example 3 A capacitor as shown in FIG. 1 was manufactured using a polarizable electrode obtained by punching an activated carbon fiber cloth having a basis weight of 100 g / m ² into a circular shape having a diameter of 10 mm.

As a characteristic of the above capacitor, the capacitance C at 25 ° C.
₂₅ , 1-C when the capacity at -25 ° C is C- ₂₅
The impedance at _-25 / C ₂₅ and 1KHz shown in the following table.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to continuously obtain activated carbon fibers that provide a high-capacity polarizable electrode from long filament fibers.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a furnace used in an embodiment of the present invention,
FIG. 1 is a vertical sectional view showing an example of a capacitor, and FIG. 3 is a schematic vertical sectional view of a conventional furnace. 1 ... furnace chamber main body, 2, 3 ... opening, 4 ... heater, 6
…… Storing room, 8 …… Gas supply port.

Continuation of the front page (51) Int.Cl. ⁵ Identification number In-house reference number FI Technology display location H01M 4/04 Z (72) Inventor Ichiro Tanahashi 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56 ) Reference JP 53-31820 (JP, A) JP 51-121739 (JP, A) JP 60-25166 (JP, A) JP 60-28170 (JP, A) JP 54-1815 (JP, B2) Japanese Patent Publication Sho 53-47420 (JP, B2)

Claims (1)

[Claims] Claims: 1. An upper opening and a lower opening, and a storage box communicating with the lower opening, and from at least another opening at the lower part of the furnace chamber, 4 g in terms of water for 1 g of long filament fiber. Roving made of long filament fiber from the upper opening to the lower opening or from the lower opening to the upper opening of the furnace that can supply the steam gas of ~ 6cc to control the atmosphere inside the furnace. Alternatively, a method for producing activated carbon for a polarizable electrode, which comprises continuously moving a tow-shaped substance to activate carbonize the long filament fibers.