JPS61214418A - Manufacture of polarizing electrode body - 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 a polarizable electrode body used in small, thin, large-capacity electric double layer capacitors and electrochromic displays.

Conventional technology Representative examples of this type of polarizable electrode are listed below.

(1) It has a structure in which powdered activated carbon is kneaded with a fluororesin or the like and applied to a current collector made of a metal net or punched metal (Japanese Unexamined Patent Publication No. 54-90562).

(2) A current collector is provided by forming a sprayed metal layer on activated carbon fiber cloth by plasma spraying method (Japanese Patent Application Laid-open No. 5Ts=
e9714).

(3) A mixture of activated carbon fibers and a natural pipe as a binding medium is made into paper, and a current collector layer is formed on the paper using a thermal spraying method.

Problems to be Solved by the Invention First, in the configuration (1) above, the bonding strength between the current collector and the polarizable electrode body is weak, and especially when an electrolyte is injected into the polarizable electrode body, the activated carbon powder Desorption is observed, and as a result, internal resistance increases and reliability deteriorates. Furthermore, in order to strongly bond the activated carbon powders together, it is necessary to use a very large amount of binding medium, and the energy density decreases by the amount of binding medium used.

In the case of (2), which uses activated carbon fiber cloth, activated carbon fiber cloth obtained by directly carbonizing a phenolic resin is usually used. This material has electrical resistance of 1, mechanical strength, good activation yield, has a specific surface area more than twice that of powdered activated carbon, and has a high energy density because it does not use a binding medium. The current collector is also formed from a sprayed metal layer, and the adhesive strength between this and the activated carbon fiber cloth is strong, and the contact resistance is low, making it a good polarizable electrode body.

However, it does not fully satisfy the demands for smaller and thinner electronic components as electronic devices become lighter, thinner, and shorter. That is, in the case of, for example, an electric double layer capacitor using activated carbon fiber cloth, it is extremely difficult to reduce the thickness to less than 1B after sealing with a location song. The energy density of a double layer capacitor is proportional to the specific surface area of the activated carbon fiber, but as activation progresses, the specific surface area and pore volume of the activated carbon fiber cloth increase, but the strength of the fiber cloth decreases significantly. It becomes unbearable for actual use. In addition, in the manufacturing process of fiber cloth, activated carbon fibers are scattered when a circular shape or the like is punched out of the fiber cloth, causing dust pollution.

The one having the configuration (3) has a specific surface area of 20oOITI.
It is possible to use activated carbon fibers of t/no or more,
A very thin polarizable electrode body with a thickness of 100 μm or less can be obtained. However, when a natural pipe such as Manila hemp or kraft pulp is used, swelling occurs little by little after the electrolyte is injected, and the distance between the activated carbon fibers increases, which reduces the number of buses through which electrons can flow and increases internal resistance. In particular, natural pulp contains bound water, and when an organic electrolyte is used, its withstand voltage is affected by the water content and is reduced.

As described above, with the configuration of the conventional polarizable electrode body, it is difficult to configure an electronic component that has high energy density, high reliability, and is small and thin.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for producing a polarizable electrode body that can easily produce thin, high energy density, and highly reliable electronic components. There is.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a method of forming activated carbon fibers into a paper shape using a heat-fusible binding medium by a papermaking method, and then heat-pressing or heat-calendering the activated carbon fibers. The activated carbon fibers and the binding medium are thermally fused and the density is increased to obtain a thin, high energy density, and highly reliable polarizable electrode body.

Function The present invention can reduce the change over time of the polarizable electrode body by the above-described manufacturing method, and can achieve high reliability and high energy density.

Here, the binding medium marked with # is polyethylene, POIJ 7
'Lopylene, acrylic resin, nylon, polyester,
One or a combination of cupro resins can be used. Further, in the case of a polarizable electrode body used in an electric double layer capacitor using a non-aqueous electrolyte, the binding medium preferably has water repellency.

The activated carbon fibers constituting the polarizable electrode body are obtained by carbonizing and activating phenolic resin fibers, and have a specific surface area of B
1500 m2/Z by ET method, pore volume o,
It is preferable to have s cc/ 1 or more, and it is also good to mix carbon fiber, graphite powder, or carbon powder into the polarizable electrode body as a conductivity improver.

EXAMPLE Next, an example of the manufacturing process of a polarizable electrode body according to the present invention will be explained. Using tow-like phenolic novolac resin fibers as raw materials, aOO~1 using zinc chloride and water vapor.
Activate carbonization at 000°C.

The tow-like activated carbon fiber obtained in this way is 2oOo~
It has a specific surface area of 2500rrI2/y and is strong.

The fibers have a diameter of 10 μm 8 degrees. This material is cut into lengths of 2 to 4,111 m that pass through a paper machine, and pulverized. Water-repellent and heat-adhesive synthetic pulp made of polyethylene or polypropylene is used for the slurry, and wet-mixed using a mixer. Synthetic pulp is available in lengths of 2 to 4111M, and shorter lengths with more clarity. , and mix it considering the strength after paper making. Carbon fiber or graphite may be mixed as a conductivity improver.

The activated carbon fibers and nokurupu mixed as described above are made into paper using a paper machine. There are cylinder paper machines and short wire paper machines for paper making, and it is best to separate them so that it is easy to express the characteristics of the desired paper-like polarizable electrode body. The bonding medium and the activated carbon fibers are thermally fused by hot pressing or thermal calendering at a temperature of ~ aso'C.

In this way, the strength and density of the polarizable electrode body can be increased, and it can be made extremely stable even with electrolytes that change little over time.

Finally, a conductive layer is formed on one side of the polarizable electrode body using a thermal spraying method using a metal such as aluminum, nickel, or stainless steel. The thickness of the conductor layer is preferably about 30 to 200 μm.

Next, a specific example will be described.

(Example 1) Through the above manufacturing process, a polarizable electrode having a composition of activated carbon fiber and binding medium in a weight ratio of 6Q:40, and having a conductive electrode made of aluminum with a thickness of 60 μm formed on one side of the polarized electrode. I got a body. The thickness of this thing is 300 μm 1 density 0.21
, fabric weight 62F/;ze. The binding medium used here is a synthetic polymer made of a mixture of polyethylene and polypropylene in a weight ratio of 50:50. In this example, the polarizable electrode body was heated to 20"C at a pressure of 2 tons/C- for 6 minutes.
Heat pressed at a temperature of

In FIG. 1, the polarizable electrode body is cut out into a circular shape with a diameter of 6n and combined with a polypropylene separator to construct an electric double layer capacitor as shown in FIG. 1.
3 is the above-mentioned polarizable electrode body, and the Sl is formed into a polarizable layer 2.
．． 4 is a separator 07, which is in spot contact with the upper and lower metal cases 6 and 6, and 8 is a gasket.

The electrolyte contains 1 mol/l of (C25,)4NBF6.
Propylene carbonate in which was dissolved was used.

A reliability test was conducted on this capacitor a by applying 2V under an atmosphere of 70'C(1)l. Figure 2 shows the rate of change in capacity during the reliability test. b is the characteristic of a comparative example capacitor constructed of a polarizable electrode body using kraft pulp as a binding medium. It can be seen that the reliability of the capacitor a of this example is much higher than that of the comparative example. The initial capacitance of the capacitor in this example is 0.03 F, and the impedance measured at 1 MZ is 24 Ω. When activated carbon fiber cloth is used as a polarizable electrode, it is possible to obtain a thin type with low impedance and small capacity. It is difficult to obtain a capacitor. 0 In the figure, C and d are the characteristics of the polarizable electrode body of a mixed with 10% by weight of carbon fiber and graphite powder, and these improve the conductivity of the polarizable electrode body. (Example 2) Using the same polarizable electrode body as in Example 1, a sheet-like electric double layer capacitor as shown in FIGS. 3 and 4 is shown.

9.11 is an aluminum conductive electrode 1 with a thickness of 20 μm.
Polarizable electrode body with 0.12, 13°14 has a thickness of 20
15 is a separator with a thickness of 2oA1m, and 16.17 is a lead. Reference numeral 18 and 19 denote an exterior film made of CQ modified polyethylene with a thickness of 100 μm, and the peripheral portions are heat-welded to each other to seal the contents.

The size of this capacitor is 30x50ff, thickness 6oo
μm, capacity 1. tsF Teashi, 2V applied 1 at 70°C
．． The capacity loss ratio after 000 hours was 7.8%.

(Example 3) Using the same polarizable electrode body as in Example 1, an electrochromic display device as shown in FIG. 5 was created. 20 is a display electrode using WO2, 21 is a glass plate serving as a base,
22 is a conductive transparent basket made of material N203. 2
3 is a polarizable electrode body, and 24 is In. Electrode consisting of 03, 2
6 is a glass plate. As the electrolytic solution filled between the electrodes 20 and 23, a propylene carbonate bath solution in which 1 mol/g of L I ClO4 was dissolved was used.

This device uses the following oxidation-reduction reaction to add carbon dioxide,
It is an erasable display. Since the capacitance of the polarizable electrode body is significantly larger than that using conventional carbon powder and is stable, it is possible to obtain a device with a long life.

LtxWO3 (1F): WOs (colorless) + xL
i+-)-2e Effects of the Invention As described above, according to the present invention, it is possible to obtain a polarizable electrode body that is thin, has low energy density, and provides a highly reliable electric double layer capacitor or electrochromic display device.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing an example of the structure of an electric 21-layer capacitor using the polarizable electrode body of the present invention, and Fig. 2 is a diagram showing the reliability of a double no-capacitor using various polarizable electrode bodies. , FIG. 3 is a plan view showing another example of the structure of the electric double layer capacitor, FIG. 4 is a cross-sectional view of the mounting portion thereof, and FIG. 6 is a cross-sectional view of the mounting portion of the electrochromic display device. Name of agent: Patent attorney Toshio Naka and one other person No.1
Arrogant reward ≦ real leaf a

Claims (4)

[Claims] (1) A polarizable electrode characterized in that activated carbon fibers and a heat-fusible binding medium are formed into paper by a paper-making method, and then heat-pressed or heat-calendered to heat-fuse the activated carbon fibers and the binding medium. How the body is manufactured. (2) The method for manufacturing a polarizable electrode body according to claim 1, wherein the binding medium has water repellency. (3) The method for producing a polarizable electrode body according to claim 1, wherein the binding medium is at least one selected from the group consisting of polyethylene, polypropylene, acrylic resin, nylon, polyester, and cupro resin. (4) The activated carbon fibers constituting the polarizable polarized body are obtained by carbonizing and activating phenolic resin fibers, and have a specific surface area of BET.
2. The method for producing a polarizable electrode body according to claim 1, wherein the polarizable electrode body has a pore volume of 1500 m^2/g and a pore volume of 0.5 cc/g or more.