JPH06132163A - Electric double-layer capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To provide an electric double-layer capacitor such that the inner resistance is reduce and the energy density is increased. CONSTITUTION:This is an electric double-layer capacitor using a polarizable electrode 11 consisting of the composite material between activated carbon material and carbon material and a collector 12 consisting of electrolyte impermeable carbon material, and the collector 12 combines an external lead electrode and one part of an container, and further a metallic layer 15 is made on the collector 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor for accumulating electric energy in an electric double layer at the interface between activated carbon and an electrolytic solution and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional electric double layer capacitor will be described in detail below with reference to FIG. The outer circumference of the separator 32 made of a polyethylene porous film is heat-sealed to the inner circumference of the central portion of the cylindrical polyethylene sealing material 31, and the sealing material 3
1 is filled with a paste-like polarizable electrode 33 made of sulfuric acid (not shown) as an electrolytic solution and activated carbon, and the openings at both ends of the sealing material 31 are heat-melted by a current collector 34 made of a conductive rubber. It is attached and sealed, the polyethylene sealing material 36 is arranged in the central portion of the outer periphery of the sealing material 31, and the stainless steel containers 35 also serving as external extraction electrodes are arranged on both sides thereof to form an electric double layer capacitor. Was.

[0003]

The above-mentioned conventional electric double layer capacitor has the following problems. (1) Since the volume resistivity of the conductive rubber used for the current collector 34 is 10,000 times or more that of the metal, the internal resistance of the electric double layer capacitor was high. (2) Since the contact resistance between the current collector 34 and the stainless steel device 35 as the external extraction electrode is large, the internal resistance of the electric double layer capacitor was high. (3) Since the contact resistance between the current collector 34 and the paste-like polarizable electrode 33 is large, the internal resistance of the electric double layer capacitor was high. (4) The container 35 that also serves as an external extraction electrode is required outside the current collector 34, and the volumetric efficiency of the electric double layer capacitor is poor and the energy density is low.

As described above, the internal resistance is high and the energy density is low, so that it cannot be used for a large current charging / discharging application. The present invention solves the problems of the conventional electric double layer capacitors described above, and an object of the present invention is to provide an electric double layer capacitor that can be used for high-current charging / discharging applications and a manufacturing method thereof.

[0005]

In order to achieve the above object, the present invention provides an electric double layer capacitor in which a current collector is formed of an electrolyte impermeable carbon material, and the current collector serves as an external extraction electrode. The container also serves as a part, and a metal layer is formed on the current collector that also serves as the external extraction electrode and a part of the container.

As a method of manufacturing an electric double layer capacitor, a step of forming a polarizable electrode made of a composite material of an activated carbon material and a carbon material on an electrolytic solution impermeable carbon material, and also serving as the external extraction electrode. The method has a step of forming a metal layer on the current collector.

[0007]

With the above construction, the present invention has the following actions. (1) Since the current collector is a carbon material, the volume specific resistance of the current collector is reduced, and the internal resistance of the electric double layer capacitor is reduced. (2) Since the metal layer is present on the current collector that also serves as the external extraction electrode, the volume resistivity of the current collector is reduced,
Lower the internal resistance of the electric double layer capacitor. (3) Since the current collector also serves as the external extraction electrode, the contact resistance between the current collector and the external extraction electrode is reduced, and the internal resistance of the electric double layer capacitor is reduced. (4) Since the current collector also serves as the external extraction electrode, the external extraction electrode, which is conventionally required separately from the current collector, can be omitted, so that the volume efficiency is improved and the energy density of the electric double layer capacitor is improved. Will increase. (5) Since the current collector is the electrolyte impermeable carbon material, the current collector can be used as a part of the container, and the container that also serves as the external extraction electrode can be omitted, so that the volume efficiency is improved. However, the energy density of the electric double layer capacitor increases.

[0008]

EXAMPLES Example 1 Phenolic resin-based activated carbon (specific surface area 1500 m ² / g) and phenol resin dispersed or dissolved in methanol in a composite material obtained by dispersing and pressing glassy carbon in phenol resin. After dipping, carbonization treatment is applied to form a polarizable electrode composed of a phenolic resin-based activated carbon (specific surface area 1500 m ² / g) and a carbonaceous material using phenolic resin as a raw material. As shown in FIG. The electrode 11 is formed on the inside of a substantially U-shaped current collector 12 which is an electrolyte impermeable carbon material made of a composite material of glassy carbon and a carbon material using phenol resin as a raw material. Next, a pair of the polarizable electrodes 1
1 are arranged so as to face each other with a separator 13 made of polypropylene nonwoven fabric interposed therebetween. In this state, 30
After being impregnated with sulfuric acid (not shown) in a weight percentage, a current collector 1 having a U-shape
A polyethylene sealing material 14 is heat-sealed between the two protruding pieces to seal them. Finally, a copper layer 15 is formed on the outer periphery of the current collector 12 by electrolytic plating to complete the electric double layer capacitor.

At this time, since the current collector 12 is impermeable to the electrolytic solution, it also serves as a container of the electric double layer capacitor and an external extraction electrode. It should be noted that phenolic resin-based activated carbon was used as the activated carbon material of the examples, phenolic resin was used as the raw material of the carbon material, and glassy carbon and phenolic resin as the raw materials of the electrolytic solution-impermeable carbon material Using a composite material, dipping and pressing a polarizable electrode on an electrolyte impermeable carbon material, using 30 wt% sulfuric acid as an electrolyte, using a polypropylene non-woven fabric as a separator,
The fact that the current collectors are sealed by heat fusion of polyethylene is an example, and the present invention is not limited to these. (Example 2) A pitch-based activated carbon (specific surface area 1500 m ² / g) and a phenol resin are subjected to a carbonization treatment after printing to form a polarizable electrode composed of a pitch-based activated carbon (specific surface area 1500 m ² / g) and a carbon material using a phenol resin as a raw material, as shown in FIG. As described above, the polarizable electrode 21 is formed on the inside of the current collector 22 of the electrolyte impermeable carbon material, which is made of a carbon material made of a phenol resin as a raw material and a graphite plate and has a substantially U shape. Next, the pair of polarizable electrodes 22 are opposed to each other with a separator 23 made of a polypropylene porous film interposed therebetween. Polarizable electrode 2 in this state
1 was impregnated with a 30 wt% potassium hydroxide aqueous solution (not shown), and then heat-sealed between the protruding pieces of the current collector 22 by using a part of the separator 23 made of the polypropylene porous film. To do. Next, a nickel layer 24 is formed on the outer periphery of the current collector 22 by electrolytic plating.

At this time, since the current collector 22 is impermeable to the electrolytic solution, it also serves as a container of the electric double layer capacitor and an external extraction electrode. The separator 23 also serves as a sealing material.

Pitch-based activated carbon was used as the activated carbon material, phenolic resin-based carbon material was used as the carbon material, and phenolic resin-based carbon material and graphite were used as the electrolyte impermeable carbon material. A composite material consisting of a plate was used, a polarizable electrode was formed by printing on an electrolyte impermeable carbon material, and a 30 wt% potassium hydroxide aqueous solution was used as the electrolyte.
The use of a polypropylene porous film as the separator, the heat-sealing between the current collectors with the separator, and the like are examples, and the present invention is not limited thereto.

Table 1 shows the internal resistance and energy density of the electric double layer capacitor according to the above embodiment. As a comparative example, the case of the above-mentioned conventional electric double layer capacitor is shown. The electric double layer capacitors are compared with each other in a withstand voltage of 0.9 V and an electrostatic capacity of 1 F, and the internal resistance is shown as an impedance value at 120 Hz.

[0013]

[Table 1]

[0014]

As is apparent from the above description of the embodiments, according to the present invention, an electric double layer capacitor having a low internal resistance, a high energy density and a high current charge / discharge capacity can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric double layer capacitor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an electric double layer capacitor according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional electric double layer capacitor.

[Explanation of symbols]

 11 Polarizing Electrode 12 Current Collector 13 Separator 14 Sealing Material 15 Copper Layer (Metal Layer)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Yoshida 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. An electric double layer capacitor comprising a polarizable electrode made of a composite material of an activated carbon material and a carbon material, a current collector, an external extraction electrode, a separator, an electrolytic solution, and a sealing material. An electric double layer capacitor in which the current collector is made of an electrolyte impermeable carbon material and also serves as an external extraction electrode. 2. The current collector constitutes a part of the container.
The electric double layer capacitor described. 3. The electric double layer capacitor according to claim 1, wherein a metal layer is formed on the current collector that also serves as an external extraction electrode. 4. A polarizable electrode made of a composite material of activated carbon material and carbon material is dipped on an electrolyte impermeable carbon material,
A method for manufacturing an electric double layer capacitor, which is formed by at least one of printing and pressing. 5. The method of manufacturing an electric double layer capacitor according to claim 4, further comprising the step of forming a metal layer on a current collector that also serves as an external extraction electrode.