JPH06302473A - Manufacture of coin-shaped electric double layer capacitor - Google Patents

Abstract

PURPOSE:To increase an electrostatic capacity by increasing the filling amount of an active carbon electrode, to be housed, without increasing the outside shape of a case for a coin-shaped electric double-layer capacitor. CONSTITUTION:A metal ring i4 is fixed to, and installed on, in advance by a spot welding operation or the like, the inside bottom face of a metal case 10, in a flat container shape, which constitutes a current collector part for a coin-shaped electric double layer capacitor, and a pellet-shaped active carbon electrode 16 which has been preliminarily molded and which is composed of a mixture of an active carbon powder and a bonding agent is arranged at the inside of the ring 14. Then, the active carbon electrode 16 is pressurized, and the inside bottom face of the case 10 is brought into close contact with the inner circumference of the ring 14. A ring which is similar to the ring 14 is fixed to, and installed on, a cover which corresponds to the case 10, and an active carbon electrode pellet which has been preliminarily molded in the same manner is molded inside a can.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a coin type electric double layer capacitor.

[0002]

2. Description of the Related Art A coin type electric double layer capacitor stores positive and negative electric charges taken in through a case and a cover during charging in a polarizable electrode and gradually discharges the electric charge through the case and the cover during discharging. It takes less time to charge, and can be used in the same usage mode as a kind of secondary battery.

As a method of arranging the activated carbon electrode constituting the polarizable electrode on the case and the cover, for example, as shown in FIG. 5, a collector such as expanded metal is previously formed on the inner bottom surface of the flat container-shaped metal case 1. 3 is spot-welded, and the powdery activated carbon electrode 2 is press-molded with a die 4
There is a method of molding.

The molding die 4 includes a lower die 4a for mounting the case 1, a die 4b surrounding the current collector 3 on the inner bottom surface of the case 1, and a punch 4c that moves up and down inside the die 4b.
Consists of. First, the case 1 is set in the lower die 4a, and with the die 4b positioned inside the case 1, the powdered activated carbon electrode 2 is charged into the cavity formed inside the die 4b, and then the punch 4c is placed. When lowered, the activated carbon electrode 2 is pressure-molded, and the activated carbon electrode 2 bites into and is fixed to the uneven surface of the current collector 3. The same molding method is adopted on the side of the cover 5 shown in FIG.

After the activated carbon electrode 2 is thus loaded, the electrolytic solution is injected, the case 1 and the cover 5 are opposed to each other with the separator 6 sandwiched therebetween, and the sealing gasket 7 is provided around the periphery.
As shown in FIG. 6, the cover 5 is caulked to the case 1 to seal the inside, so that the case 1 and the cover 5 serve as a positive electrode and a negative electrode current collector, and a coin-shaped electric battery having a polarizable electrode inside. The double layer capacitor is completed.

According to the above-mentioned molding method, the activated carbon electrode 2 bites into the current collector 3 so that the case 1 and the cover 5 are formed.
It is possible to manufacture a coin-type electric double-layer capacitor having electrical connectivity of the activated carbon electrode with respect to, a small internal resistance, and a small variation in performance.

[0007]

However, the coin type electric double layer capacitor assembled by this method has a drawback that the capacitance is smaller than the outer diameter of the case.

That is, as shown in FIG. 6, the cover 5 has a structure in which it is fixed to the inside of the case 1 through a sealing gasket 7, and the loading amount of the activated carbon electrode 2 on the side of the cover 5 having an inner diameter smaller than that of the case 1. It is necessary to set the same loading amount on the case 1 side based on
Since the installation margin of the die 4b with respect to is determined according to the wall thickness D of the die 4b, the diameter of the molded activated carbon electrode 2 is equal to
Is much smaller than the inner diameter of.

Further, since the diameter of the activated carbon electrode 2 on the case 1 side is also determined in accordance with the diameter of the activated carbon electrode 2 provided on the cover 5 side, a considerable gap is generated at the inner peripheral edge of the case 1, and the outer diameter of the case 1 is increased. It had a small electrostatic capacity.

The present invention is to solve the above problems, and an object thereof is to increase the filling amount of the activated carbon electrode molded in the case and the cover, thereby improving the electrostatic capacity. It is to provide a method for manufacturing a multilayer capacitor.

[0011]

In order to achieve the above-mentioned object, a method of manufacturing a coin type electric double layer capacitor according to the present invention comprises a flat container-shaped metal case and a cover constituting a positive and negative electrode current collector. By pre-fixing a metal ring on the inner bottom surface, disposing a pellet-shaped activated carbon electrode made of a mixture of preformed activated carbon powder and a binder inside the ring, and then pressing the activated carbon electrode. It is characterized in that the molding is performed in a state of being in close contact with the inner bottom surfaces of the case and the cover and the inner circumference of the ring.

Here, it is preferable that the metal rings fixed to the case and the cover are formed to have different diameters.

[0013]

According to the method of the present invention having the above-described structure, a metal ring is preliminarily fixed to the inner bottom surface of a flat container-shaped metal case and a cover forming the positive and negative electrode current collectors. Place a pellet-shaped activated carbon electrode consisting of a mixture of preformed activated carbon powder and a binder, and then pressurize the activated carbon electrode, so that the ring is thick enough to withstand the preformed pressing pressure. The outer diameters of the positive electrode and the negative electrode can be set according to the maximum inner diameter of the cover.

Further, the activated carbon electrode is formed by press forming into a shape approximately equal to the inner diameter and height of the ring, and at the same time, electrical connection to the case and the cover is secured.

Further, when the ring fixed to the metal case and the ring fixed to the cover are formed to have the same diameter, a strong pressing force is applied from above and below the cell composed of the case and the cover. Is added, the upper edge of each ring will damage the separator and contact each other,
Although a short circuit may occur, if the rings fixed to the case and the cover are formed to have different diameters, the upper edges of the respective rings will not abut against each other via the separator. Therefore, such a short circuit can be prevented.

[0016]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

First, as shown in FIGS. 1 (a) and 1 (b),
A stainless ring 14 is fixed to the inner bottom surfaces of the flat container-shaped metal case 10 and cover 12. A flange 14a is formed inside the bottom of the ring 14,
The flange 14a is fixed to the case 10 and the cover 12 by spot welding at several places. In the present embodiment, each ring 14 has the same diameter, and the outer diameter thereof is set in accordance with the cover 12 having the inner diameter smaller than that of the case 10.

Next, as shown in FIG. 2, the preformed activated carbon electrode 16 is placed inside the ring 14 and placed on the lower die 18a of the press-molding die 18. This activated carbon electrode 1
No. 6 is composed of a mixture of activated carbon powder, acetylene black, and Teflon binder. By preforming, activated carbon powder and acetylene black are bound to each other via the binder. The diameter of the preformed pellet is slightly smaller than the inner diameter of the ring 14, and the thickness dimension thereof is thicker than the height of the ring 14. The pressing force required for the pre-molding is smaller than the pressing force for the subsequent main molding in the ring 14.

Next, a main forming process is carried out in which the punch 18b is lowered to pressurize the activated carbon electrode 16. The diameter of the punch 18b is set to be slightly larger than the inner diameter of the ring 14, and the size of the punch 18b is regulated by a mold so as not to crush the ring 14. Therefore, the activated carbon electrode 16 arranged in the ring 14 is compressed and filled in the space surrounded by the ring 14 in accordance with the pressing force caused by the lowering of the punch 18b, and as shown in FIG. The molding operation is completed with the bottom surface and the inner surface of the ring 14 in close contact with each other. Although not shown, the activated carbon electrode 16 is formed inside the ring 14 by the same operation for the cover 12.

After completion of the above molding operation, an electrolytic solution is poured into each activated carbon electrode 16 as in the conventional case. As the electrolytic solution, a solution obtained by dissolving (Et) ₄ NBF ₄ which is an electrolyte in propylene carbonate (PC) is used.

Then, as shown in FIG. 4, a separator 20 is arranged in the middle of both the activated carbon electrodes 16, and a cover 12 is fitted inside the case 10 with a sealing gasket 22 around the periphery, and an opening of the case 10 is formed. By crimping, the activated carbon electrodes 16 are insulated from each other, and an internally sealed coin type electric double layer capacitor is completed. As shown in FIG. 4, the outer diameter of the activated carbon electrode 16 is increased by 2D, which is twice the thickness of the die, as compared with the case of molding using a conventional die.

Next, the performance of the electric double layer capacitor obtained by the manufacturing method of the present invention and the performance of the electric double layer capacitor obtained by the conventional manufacturing method were compared and investigated.

A stainless ring having a wall thickness of 0.1 mm, a diameter of 20 mm and a height of 1.2 mm is spot-welded inside the case and cover of the electric double layer capacitor obtained by the manufacturing method of the present invention, and a pressure is applied to the ring. The activated carbon electrode pellets having a diameter of 19.6 mm and a thickness of 1.5 mm, which had been preformed at 25 kg / cm ² , were placed and pressure-formed at a pressure of 480 kg / cm ² . The diameter of the resulting activated carbon electrode is 20 mm,
The thickness was 1.25 mm.

The diameter of the activated carbon electrode formed in the case and cover having the same size as the product of the present invention by the conventional manufacturing method (see FIGS. 5 and 6) is 18.6 mm. It is the upper limit, and its height is also 1.25 mm
Is.

An electrolytic solution was poured into these molded activated carbon electrodes, and a case and a cover were integrated with each other through a separator and a sealing gasket, and the finished product was compared for capacitance and internal resistance. The capacitance of the product is 8.
2 farad, internal resistance was 2.3Ω, while
The capacitance of the product of the present invention was 10.1 farads and the internal resistance was 2.1Ω. It was confirmed that the capacitance increases and the internal resistance also decreases.

The reason why the internal resistance is reduced is that the ring 14 also has a function of a current collector, and the ring 14 is brought into close contact with the periphery of the activated carbon electrode to increase the contact area of the activated carbon electrode with the case 10 and the cover 12. it is conceivable that.

Furthermore, in this embodiment, the case 10 is used.
The diameter of the ring fixed to the cover 12 and the diameter of the ring fixed to the cover 12 are the same, but the ring diameter may be different for the case and the cover. (For example,
Set the diameter of the case ring to 20.4 mm and the diameter of the cover ring to 20.0 mm. )

[0028]

As described above in detail with reference to the embodiments, according to the method for manufacturing the coin-type electric double layer capacitor of the present invention, a flat container-like metal case constituting the positive and negative electrode current collectors and A metal ring is pre-fixed on the inner bottom surface of the cover, and a pellet-shaped activated carbon electrode made of a mixture of preformed activated carbon powder and a binder is arranged inside the ring, and then the activated carbon electrode is pressed. Therefore, the activated carbon electrode can be formed with an outer diameter according to the maximum inner diameter of the cover, and more activated carbon electrodes can be formed on the case and cover than the coin-type electric double layer capacitor manufactured using the conventional press molding die. It is possible to fill the inside and increase the capacitance even with the same external dimensions, and increase the contact area between the activated carbon electrode and the case and cover to reduce the internal resistance. It can be.

Further, if the rings fixed to the case and the cover are formed so as to have different diameters, the upper ends of the respective rings are pressed even when the cell composed of the case and the cover is pressed from above and below. Since the edges do not abut each other through the separator, damage to the separator and the resulting short circuit can be prevented, etc.
Has various excellent effects.

[Brief description of drawings]

1A is a sectional view of a case before assembly of an electric double layer capacitor to which the method of the present invention is applied, and FIG. 1B is a sectional view of the cover.

FIG. 2 is an explanatory view showing a state before a press molding process of an activated carbon electrode of an electric double layer capacitor to which the method of the present invention is applied.

FIG. 3 is an explanatory view showing a press forming process of an activated carbon electrode of an electric double layer capacitor to which the method of the present invention is applied.

FIG. 4 is a cross-sectional view showing a completed state of a coin type electric double layer capacitor to which the method of the present invention is applied.

FIG. 5 is an explanatory view showing a press forming process of an activated carbon electrode of an electric double layer capacitor by a conventional manufacturing method.

FIG. 6 is a sectional view showing a completed state of a coin type electric double layer capacitor manufactured by a conventional manufacturing method.

[Explanation of symbols]

 10 Case 12 Cover 14 Ring 16 Activated Carbon Electrode 18 Press Mold 18a Lower Mold 18b Punch 20 Separator 22 Sealing Gasket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Nakamura 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Inventor Kazuo Takada 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (2)

[Claims] 1. A metal ring is preliminarily fixed to the inner bottom surface of a flat container-shaped metal case and a cover constituting the positive and negative electrode current collectors, and a preformed activated carbon powder is bound to the inside of the ring. A pellet-shaped activated carbon electrode made of a mixture with an agent is arranged, and then the activated carbon electrode is pressed to perform molding in a state of being in close contact with the inner bottom surface of the case and the cover and the inner circumference of the ring. Method for manufacturing coin type electric double layer capacitor. 2. The method of manufacturing a coin-type electric double layer capacitor according to claim 1, wherein the metal rings fixed to the case and the cover are formed to have different diameters from each other. .