JPH011219A - Manufacturing method of polarizable electrodes - 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 the Invention The present invention relates to a method for manufacturing polarizable electrodes for use in electric double layer capacitors, batteries, or electrochromic displays.

BACKGROUND ART A conventional technique will be explained using an electric double layer capacitor as an example. As a paper-like polarizable electrode, Japanese Patent Application Laid-Open No. 159-932
There is one shown in Publication No. 16. In this device, a conductive layer 2 made of aluminum, nickel, etc. is formed on one side of a paper-like polarizable electrode 1 made of activated carbon fibers and a binder, and these are placed facing each other with a separator 3 in between, and are placed in a metal case 6 along with an electrolyte. and a sealing plate 6 and a gasket 4 that insulates both.

Furthermore, those using activated carbon fiber cloth for polarizable electrodes have a large specific surface area of 2,500rd/g, and have few impurities, making them suitable for electric double layer capacitors, but they are very expensive compared to activated carbon powder, and voids can occur unless pressure is applied. The loss of space is large, as the ratio occupies more than 90% (occupies more than 60% even when pressurized).

As described above, since there are many spaces, there is little contact between the fibers and the book, and the contact resistance increases.

Furthermore, there is a polarizable electrode in which activated carbon powder is bonded with a fluororesin and held on a current collector.

Problems to be Solved by the Invention When a polarizable electrode having the above structure is in paper form, the content of binder is increased in order to increase the strength, and therefore the resistance value becomes large and the impedance also becomes high. In addition, the purity is low and the operating voltage cannot be increased. Furthermore, activated carbon fiber cloth has low space efficiency and is expensive. Even when activated carbon powder is used, the binder content increases and the resistance value increases.

The present invention aims to solve the above problems and provide a low resistance and uniformly polarizable electrode.

Means for Solving the Problems In order to solve the above problems, the present invention involves kneading activated carbon powder or activated carbon fibers with phenolic resin, forming a cylindrical molded body by extrusion molding, and then curing the phenolic resin. This is a method for producing a polarizable electrode, which is formed by cutting a molded body made of activated carbon powder or activated carbon fiber and carbon into disk shapes through a carbonization or activation process.

Function The above configuration simplifies the manufacturing process of the polarizable electrode, increases activated carbon density, reduces resistance, and increases capacitance density, and makes it possible to realize a highly reliable polarizable electrode.

Example The present invention will be explained in detail below.

(Example 1) Pulverized activated carbon fiber (phenolic) Tresol type phenolic resin with a specific surface area of 200,077 g was mixed at a weight ratio of 80:20, added with some water, and molded using an extrusion molding machine to a diameter of 6 mm. , 2- were continuously extruded into a cylindrical shape. This material was cured at 100° C. for 1 hour and then heated to 90° C. at a temperature increase rate of 40° C./hr in a nitrogen gas atmosphere to carbonize the phenol resin as a binder. Note that the temperature was maintained at 900°C for 6 hours.

The above molded body has a length of 500 ff1ffl + a diameter of 6M.
It is.

The carbonization yield was 92%. The molded body of activated carbon fiber and carbon thus obtained was 0.7. Cut to a thickness of
Furthermore, an aluminum layer of 200 μm in thickness was formed on one side of the cut product using a plasma spraying method.

The coin-shaped capacitor shown in the figure was constructed using the polarizable electrodes thus created. A polypropylene porous membrane with a diameter of 10 mm was used as the separator. After the polarizable electrodes were faced to each other through this separator, a 1 mol/l propylene carbonate organic electrolyte with tetraethylammonium borofluoride salt (Et4NBF4) as an electrolyte was injected into a sealed casing to create a coin-shaped capacitor. did. After charging this capacitor with 2.4V, 1
A constant current discharge was performed at mA to obtain a capacity of 0.26 F and an impedance of 16 Ω. When 2.4 μm was constantly applied in an atmosphere of 70° C., the capacity reduction rate after 1000 hours was 9% with respect to the initial capacity. The characteristics of conventional capacitors using activated carbon fiber cloth and vaporized activated carbon fiber as polarizable electrodes are that the capacitance is 0.2 F and 0.21 F, respectively.
Impedance (IKHz) is 21Ω and 23Ω respectively
Met.

(Example 2) Activated carbon powder with a specific surface area of g5oyyf/17 and phenol resin were mixed in the same ratio as in Example 1, and after extrusion molding in the same manner, a polarizable electrode was formed into the capacitor shown in the figure (same as in Example 1). ), the capacitance was 0.22 F and the impedance was 18 Ω.

(Example 3) The same extrusion molded body as in Example 1 was heated up to 300'c by 8
0℃/hr, 30℃/hr up to 1000℃
The temperature was raised in a nitrogen stream. A fin-type capacitor similar to that in Example 1 was produced using the polarizable electrode produced under these conditions, and the following characteristics were obtained. Capacity 0.20F, impedance 17Ω.

(Example 4) Pulverized activated carbon fibers with a specific surface area of 1000 m/9 (
The mixture was mixed with a resol-type phenolic resin in the weight ratio shown in Table 1, added with some water, and continuously extruded into a cylinder having a diameter of 8.2 cm using an extrusion molding machine. These materials were cured at 100° C. for 1 hour, and then carbonized and activated for 3 minutes in a nitrogen gas and water vapor atmosphere. The molded body has a length of approximately somms and a diameter of emm. Carbonization, activation yield, and characteristics of capacitors produced under the conditions shown below are also added to the same table. A molded body of activated carbon fibers and activated carbon is 0.
It was cut to a thickness of 7 fences, and an aluminum layer of 200 μm was formed on one side of the cut piece using plasma spraying.

Using polarizable electrodes created in this way? The coin-shaped canopy shown in the figure was constructed. The separator has
A polypropylene porous membrane with a diameter of 1 oInI11 was used. After making the polarizable electrodes face each other through the separator, the borofluoride salt of tetraethylammonium (Et4
NBF4) was injected as a 1 mol/l propylene carbonate organic electrolyte solution as i solute, then sealed in a casing.
I made a coin type capacitor. This capacitor 2.
After charging at 4 V and discharging at a constant current of 1 mA, the capacity, impedance, and 2.4 V were constantly applied in an atmosphere of 70° C., and the capacity reduction rate after 1000 hours with respect to the initial capacity was obtained.

The characteristics of conventional capacitors using activated carbon fiber cloth and paper-like activated carbon fiber as polarizable electrodes are that the capacitance is 0.2, respectively.
F, 0.21 F, and the impedance (I K
Hz) is 21Ω each.

It was 23Ω.

(Example 6) Example 4 as a positive polarizable electrode. An electric double layer capacitor was prepared by using the same electrode as in Table 3, and surrounding it with a non-polarizable electrode in which lithium was occluded in an alloy (wood alloy) with an Sn to - ratio of 85:15 as a negative electrode. In this embodiment, other constituent materials are the same as in the first embodiment. This capacitor exhibited a voltage of 3V and a capacitance of 0.41F.

The polarizable electrode of the present invention is an electric double electrode as described above.

It can be widely used not only in layered capacitors but also in battery electronic comic displays and the like.

Effects of the Invention As described above, according to the present invention, a polarizable electrode with higher energy density, lower resistance, and uniformity can be obtained easily and with good productivity than before.

[Brief explanation of the drawing]

The figure is a cross-sectional configuration diagram of an example of an electric double layer capacitor having a structure common to the present invention and a conventional example. 1... Polarizable wire, 2... Current collector, 3
・・・・・・Seno (retar, 4・・・gasket, 6・・・sealing plate, 6・・・case. Name of agent: Patent attorney Toshio Nakao and 1 other person) given name!
・-Sharing electrode 2-@ Electric body' 3- Separate lake 4- Gasket 5- 4t opening 6- Case

Claims (1)

[Claims] After kneading activated carbon powder or activated carbon fiber and phenol resin and forming a cylindrical molded body by extrusion molding method,
A method for producing a polarizable electrode, which comprises curing a phenol resin, further carbonizing or activating it to obtain a molded body made of activated carbon powder or activated carbon fibers, and carbon, and cutting the molded body into disk shapes.