JPS63110622A - Polarizing electrode - Google Patents

Abstract

(57) [Abstract] 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 polarizable electrodes used in electric double layer capacitors, batteries, or electrochromic displays.

PRIOR TECHNOLOGY This type of polarizable electrode includes one in which activated carbon powder is held together with a fluororesin binder on a current collecting metal (Japanese Patent Laid-Open No. 56-93216), and one in which a conductive material such as aluminum or nickel is used on one side of an activated carbon fiber cloth. There is one in which a layer is formed (Japanese Unexamined Patent Publication No. 83920/1983).

The former type, which uses activated carbon powder, contains impurities in the activated carbon and uses natural wood as a raw material, so there is large variation between lots, and the characteristics of capacitors using this are also inconsistent. Furthermore, activated carbon powder has a specific surface area of about 120Od19, and there is a limit to the double layer energy that can be stored per unit volume. The latter, which uses activated carbon fibers, has a specific surface area of 26°
/g, and has few impurities, making it suitable for electric double layer capacitors, but it is very expensive compared to activated carbon powder, and if it is not pressurized, it has a porosity of over 90%! 7 (occupies more than 60% even if pressurized), loss of space is large. As described above, since there are many spaces, there is little contact between the fibers and the book, and the contact resistance increases.

Problems to be Solved by the Invention In the case of a polarizable electrode having the above structure, the purity is low and the specific surface area is not large enough in the case of activated carbon, and the space contribution is low and high wi in the case of activated carbon fiber.

problem? Means for Solving The present invention solves all of the above problems by reducing the primary particle diameter to 1.
A polarizable electrode is constituted by activated carbon obtained by carbonizing and activating fine particulate phenol resin of ~20 μm and a binder.

Operation With the above configuration, it is possible to increase the density of polarizable electrodes, reduce resistance, and increase energy density, and to realize an electric double layer capacitor that is suitable for rapid charging and has high reliability. The particulate phenolic resin used here includes, for example, Perval (trade name) manufactured by Kanebo Co., Ltd. The activated carbon fine powder obtained by carbonizing and activating such a phenolic resin is a conventional activated carbon powder such as coconut shell charcoal (particle size 10 to 30
(approximately 0 μm), the particle size is small and uniform,
High density polarizable electrodes can be obtained. It also has extremely few impurities and has a specific surface area of ~2600 d/! j can be made more than twice as large as the conventional one. Next, as the binder, ordinary acrylic resin, polyethylene, or fluororesin may be used, but it is preferable to use the above-mentioned phenol resin after thermosetting because the bonding force is strengthened by the reactive methylol group.

Example The present invention will be explained in detail below.

(Example 1) Particulate phenolic resin 1 with a primary particle diameter of 1 to 20 μm
Activated carbon obtained by carbonization activation with water vapor in a nitrogen gas atmosphere at 1000°C and fine particulate phenol resin of 1 to 20 μm were mixed at a weight ratio of 8o:20, and this mixture was heated at 3) ton/cA. It was press-molded and heated at 300°C to form pellets with a thickness of 500 μm and an i diameter of 13 m1D.

A polarizable electrode was formed by forming a 100 μm aluminum layer as a current collector on one side of this by plasma spraying.

A flat capacitor shown in the figure was constructed using this pair of polarizable electrodes. 1 is a polarizable electrode, 2 is a current collector thereof, 3 is a separator made of a polypropylene porous membrane having a diameter of 16 mm, 4 is a case, 6 is a sealing plate, and 6 is a gasket. The electrolytic solution used was brobylene carbonate in which a total of 1 mol/β of tetraethylammonium borofluoride salt was dissolved.

After charging this capacitor with i 2.4 V, a constant current discharge was performed with a 1 m person, and a capacity of 2.2 F was obtained. Further, when 2-41f was constantly applied in an atmosphere of 70°C, the capacity reduction rate after 100 hours with respect to the initial capacity was 7%.

(Example 2) Particulate activated carbon, fluororesin, and i80 similar to Example 1
: After mixing at a weight ratio of 20, the mixture was pressed into pellets in the same manner as in Example 1, and a capacitor was produced using the same size and constituent materials. In this example, heating was not performed during pellet formation. This capacitor has a total length of 2.4”/1m after being charged.
A constant current discharge was performed to obtain a total capacity of 2.15 F. Also 7
When 2.4V'i was constantly applied in an atmosphere of 0'C,
The capacity reduction rate after 1000 hours with respect to the initial capacity is 8.
It was 3%.

(Example 3) A capacitor having the same configuration as in Example 1 was created using the same polarizable electrodes. In this example, a 10% by weight quick-brewing solution was used as the electrolyte. This capacitor 'i1.07
After charging, a constant current discharge of 1 mA was performed to obtain a capacity of 4.1 V. Also, under an atmosphere of 70'C, 1. When □1f was applied, the rate of decrease in the amount of melt after 1000 hours was 9% relative to the initial capacity.

(Example 4) Using the same electrode as in Example 1 as the positive polarizable electrode,
An electric double layer capacitor was created using, as a negative electrode, a non-polarizable electrode in which lithium was occluded in an alloy (Wood alloy) with a weight ratio of Sn and Cd of 85:15. 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 4.3F.

The polarizable electrode of the present invention can be widely used not only in electric double layer capacitors as described above but also in batteries, electrochromic displays, and the like.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a polarizable electrode that has a higher energy density than the conventional one, is uniform, and has high strength.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing an example of the structure of an electric double layer capacitor using the polarizable electrode of the present invention. 1... Polarizable electrode, 2... Current collector, 3
... Separator, 4 ... Case, 6.
... Sealing plate, 6... Gasket. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
--Polarization, piezoelectric 2--Ichito shield λ 3-m- and paregu? /4

Claims (2)

[Claims] (1) A polarizable electrode comprising activated carbon obtained by carbonizing and activating particulate phenolic resin having a primary particle diameter of 1 to 20 μm and a binder. (2) The polarizable electrode according to claim 1, wherein the binder is a phenolic resin.