JP2757573B2 - Electric double layer capacitor - Google Patents

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 having an improved lead terminal structure.

[0002]

2. Description of the Related Art The lead conductor portion of a conventional wound-type electric double layer capacitor has a structure in which a thin rod or a thin plate made of metal is joined to a current collector. The number of lead conductors is usually one for each current collector, and the number of lead conductors is several even for a long current collector for a large-capacity electric double layer capacitor.

[0003]

The electric double layer capacitor having such a structure has the following problems.

That is, in the above structure, the ratio of the sectional area of the lead conductor to the area of the electrode is small, and the distance from the electrode to the lead conductor is long. Therefore, when charging and discharging, electrons must travel a long distance and have a large resistance value. As a result, the internal resistance is increased, and when charging and discharging with a large current, a large amount of electrons flow through the thin lead conductor, so that the lead conductor generates heat and adversely affects the life of the capacitor. When the internal resistance is high, the voltage effectively applied to the capacitor becomes low due to the voltage drop due to the internal resistance, and there is also a disadvantage that the capacity as the capacitor becomes small.

In addition, since the lead conductor is joined to the current collector made of a thin metal foil, the strength of the current collector to which the lead wire is joined is reduced, and the reliability is reduced.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a highly efficient and reliable electric double layer capacitor which has a small resistance loss in a lead conductor and has no strength reduction due to the lead conductor bonding. The purpose is to:

[0007]

In order to achieve the above object, an electric double layer capacitor according to the present invention is provided on both sides thereof.
A pair of positive and negative current collectors on which an activated carbon layer serving as an electrode is formed;
Part where a pair of positive and negative activated carbon layers face each other
Alternately overlapped with the activated carbon layer to isolate
When configuring a capacitor element by winding a separator,
Each of the pair of current collectors has a different end side exposed.
An activated carbon layer is formed on each of the exposed portions, and the exposed portions of the current collector are used as lead terminals. Here, the extraction terminal
It is preferable that the exposed portion of the current collector is crushed.

[0008]

According to the above-mentioned means, by using the end of the current collector itself as a lead terminal, a wire is conventionally used as a lead conductor, whereas a large cross section of the current collector is used as a lead conductor. Therefore, the ratio of the cross-sectional area of the extraction conductor to the area of the electrode becomes very large, and the moving distance of the electrons when charging and discharging the capacitor is shortened. Is extremely small, and the capacitor capacity can be increased with the same electrode area.

Further, since the resistance value of the lead conductor is small, heat generation in the lead conductor is eliminated, and there is no physical junction between the current collector and the lead conductor, so that the strength of the lead conductor part is remarkably improved.

As a result, the loss is small and the high reliability is high.
Capacitive electric double layer capacitors can be made.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 shows an electrode configuration of an electric double layer capacitor. In FIG. 2, 1 is an electrode foil serving as a positive electrode, 2 is an electrode foil serving as a negative electrode, 3 is a current collector constituting the electrode foils 1 and 2, 4 is an activated carbon layer formed on the current collector 3, 5
Is a separator.

In this embodiment, an aluminum etching foil is used as the current collector 3. For example, the aluminum foil is cut into a length of 30 mm × 70 mm for the positive electrode 1 and a length of 30 mm × 60 mm for the negative electrode 2. To form a current collector 3. Electrodes of the activated carbon layer 4 were formed vertically 13 mm from one end of these current collectors to produce electrode foils. As the activated carbon electrode, powdered activated carbon (specific surface area 2500 mm ² / g,
Current collector 3 with an average particle size of 2 μm) mixed with a binder.
Was applied. The electrode foils manufactured in this manner are laminated from the bottom in the order of the separator 5, the positive electrode 1, the separator 5, and the negative electrode 2. At this time, the activated carbon layer 4 of the positive electrode 1 and the activated carbon layer 4 of the negative electrode 2 face each other with the separator 5 interposed therebetween, and the exposed portion of the current collector 3 of the positive electrode 1 and the exposed portion of the current collector 3 of the negative electrode 2 overlap. Arrange in the opposite direction so that they do not match. Thereafter, the electrode foils stacked on each other with the separator 5 interposed therebetween are wound from the lateral direction to obtain a rod-shaped capacitor element shown in FIG. In FIG. 3, reference numeral 5 denotes a separator which is sufficiently longer than the electrode foil so that the electrode portion of the activated carbon layer 4 does not appear on the surface of the rod-shaped capacitor element, and the separator 5 is formed on the surface of the rod-shaped capacitor element. It is exposed in a belt shape. The current collector 3 on which the activated carbon layer 4 is not formed is exposed on both sides of the strip-shaped exposed separator 5.

In the capacitor element thus manufactured, as shown in FIG. 1, the current collector 3 exposed next to both sides is flattened to form a lead terminal 6. In FIG. 1, reference numeral 7 denotes a metal or resin case of a capacitor, and a capacitor element having lead terminals 6 formed at both ends in a later step is impregnated with an electrolytic solution containing propylene carbonate as a main solvent,
Only the two lead terminals 6 are exposed and sealed in the case 7 to complete the electric double layer capacitor.

In this embodiment, a polypropylene film is used as a separator. (Example 2) The same structure as in Example 1 was used, except that fibrous activated carbon (specific surface area: 2000 mm ² / g, fiber diameter: 2 μm, fiber length: 5 μm) was used instead of powdered activated carbon.

Although powdered activated carbon is used in the first embodiment and fibrous one is used in the present embodiment (second embodiment), a chop-shaped one may be used.

(Example 3) The same structure as in Example 1 was used, and acetylene black was added to activated carbon as a conductivity-imparting agent.

Example 4 The same configuration as in Example 1 was used, except that an aluminum net foil was used as a current collector.

Although the aluminum foil is used as the current collector in the first embodiment and the aluminum net foil is used in the present embodiment (fourth embodiment), a metal plate or a punching metal may be used as the current collector. .

(Comparative Example) As a comparative example of the above four examples, a positive electrode of 13 mm long × 70 mm wide and a positive electrode of 13 mm long × 60 mm wide were used.
An activated carbon electrode is formed on a current collector in which a metal rod is joined to a negative electrode of mm as a lead conductor, and each electrode foil is wound up with a separator interposed therebetween, impregnated with an electrolytic solution containing propylene carbonate as a main solvent, and A multilayer capacitor was manufactured.

Table 1 shows a comparison between the characteristics and the performance of the electric double layer capacitor of this comparative example and the electric double layer capacitors of Examples 1 to 4.

[0022]

[Table 1]

According to Table 1, the electric double layer capacitors according to the four embodiments of the present invention have a larger capacitance with the same electrode foil area and an internal resistance value as compared with the electric double layer capacitor of the comparative example. It can be seen that the voltage holding time is significantly reduced and the voltage holding time is much longer.

[0024]

As is clear from the above description, according to the present invention, the capacitance can be increased with the same electrode foil area by using a part of the current collector as a direct lead terminal. Yes, as a result, the voltage holding time can be lengthened. In addition, since the internal resistance can be greatly reduced, it can withstand a large amount of charge and discharge. Furthermore, since the mounting strength of the lead terminal is dramatically improved, a high-performance and highly reliable electric double layer capacitor can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a shape before enclosing a case in an embodiment of an electric double layer capacitor of the present invention.

FIG. 2 is a perspective view showing a state of lamination of electrodes and separators in one embodiment of the electric double layer capacitor of the present invention.

FIG. 3 is a perspective view showing a capacitor element before processing of a lead terminal in an embodiment of the electric double layer capacitor of the present invention.

[Explanation of symbols]

 3 Current collector 4 Activated carbon layer 5 Separator 6 Outgoing terminal

Continuation of the front page (56) References JP-A-4-152616 (JP, A) JP-A-56-114314 (JP, A) JP-A-1-222428 (JP, A) Japanese Utility Model Application No. 54-181251 (JP, A) , U) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01G 9/016 H01G 9/155 H01G 9/008

Claims (1)

(57) [Claims] 1. A pair of positive and negative current collectors each having an activated carbon layer serving as an electrode formed on both surfaces thereof, and alternately overlapping with an activated carbon layer portion so as to isolate a portion where the pair of positive and negative activated carbon layers face each other. a capacitor element formed by winding a separator that is, an electric double layer capacitor configured with an electrolytic solution, wherein the pair of current collectors different ends side to form an activated carbon layer so as to expose each collector In front of the body
An electric double-layer capacitor in which the exposed parts are crushed to make each lead-out terminal .