JPH0298914A - Electric double layer capacitor - Google Patents

Abstract

PURPOSE:To reduce an initial value of an equivalent series resistance(ESR) and a change with the passage of time of the resistance by a method wherein a sheet-like polarized electrode is formed in a hole or a recessed part and this polarized electrode is pasted on the inside of a metal case by using a conductive adhesive. CONSTITUTION:The following are provided: a sheet-like polarized electrode 1 where at least either a hole 2 or a recessed part has been made; a conductive adhesive 4 used to paste the polarized electrode 1 on the inside of a metal case 5. When the hole 2 is made in the polarized electrode 1 or the recessed part is formed on the surface, the conductive adhesive 4 enters the hole 2 or the recessed part; a contact area between the polarized electrode 1 and the conductive adhesive 4 is increased. Thereby, a contact resistance between the polarized electrode 1 and the conductive adhesive 4 is dropped; an ESR is dropped.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electric double layer capacitor.

(Prior technology) Electric double layer capacitors are made by, for example, impregnating polarizable electrodes with an electrolyte, separating them with a separator, storing them in a metal case, and bonding the polarizable electrodes to the inner surface of the metal case with a conductive adhesive. It has a structure in which multiple pieces are stacked and integrated as needed.

(Problem to be solved by the invention) However, polarizable electrodes are in the form of sheets cut to a predetermined size by kneading activated carbon powder or conductive carbon black with a binder, and the surface is smooth. #The contact area with the electrically conductive adhesive is small. Therefore, there is a drawback that the initial value of the equivalent series resistance (hereinafter referred to as ESR) and its change over time are large.

An object of the present invention is to improve the above-mentioned drawbacks and provide an electric double layer capacitor that can reduce ESR.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an electric double layer capacitor in which polarizable electrodes separated by a separator are housed in a metal case, in which at least either a hole or a recess is formed. The present invention provides an electric double layer capacitor characterized by having a sheet-like polarizable electrode provided on one side and a 4M adhesive that adheres the polarizable electrode to the inner surface of a metal case.

(Function) By providing holes in the polarizable electrode or forming recesses on the surface, the 39W adhesive enters the holes and the four parts, increasing the contact area between the polarizable electrode and the conductive adhesive. Therefore, the contact resistance between the polarizable electrode and the conductive adhesive is reduced, and the ESR is reduced. In particular, the lower the viscosity of the II conductive adhesive, the easier it is to enter holes and recesses.

(Example) Hereinafter, the present invention will be explained based on examples.

In Fig. 1, 1 is a polarizable electrode, which is made by pressing a mixture of activated carbon powder and conductive carbon black at a ratio of 1:1 and 10% of Teflon as a binder to a thickness of 0.3 to 2. It is in the form of a rhyme sheet and punched out to a predetermined size. Reference numeral 2 denotes holes with a diameter of about 0.05 to 1 MI formed in this sheet-like polarizable electrode 1, and are provided at a density of several tens per d. 3 is a separator that separates the polarizable electrode 1, and has a thickness of several tens of μm.
Use a non-woven fabric such as polypropylene. 4 is a conductive adhesive applied to the surface of the polarizable electrode 1, and is made of graphite, carbon black, polymer resin such as polyvinyl alcohol, polyvinyl butyral, polyvinyl acetate, fluorocarbon resin, silicone resin, urea resin, etc. Consists of carbon paint containing.

The metal case 5 is caulked with 0.25 mm thick stainless steel sandwiched between them. Moreover, in the separator 2, tetraethylammonium boron tetrafluoride iS! It is impregnated with an electrolytic solution containing 21 mol/1.

When the initial value of ESR and the value after the high temperature load test were measured for the above embodiment of the present invention and the conventional example, the results shown in the table were obtained.

In addition, in the example, a thickness of 500 μm and a hole diameter of 0°3fi were used.
, a polarizable electrode with a pore density of 20/cIK is used.

In the conventional example, except for using a polarizable electrode without holes,
Assume that it is the same as the example.

In addition, the high-temperature load test was conducted using direct FI in an atmosphere at a temperature of 85°C.
t71i A pressure of 2.4 V is applied and rlOOOHr is left standing.

As is clear from the table, according to the present invention, the initial value of ESR is 3/4 compared to the conventional example, and the value after the test is 215, which is an improvement.

In the embodiment shown in FIG. 1, the polarizable electrode is provided with holes, but as shown in FIG. 2, the polarizable electrode 7 may be provided with a recess 6. In this case as well, the conductive adhesive 8
Since the contact area is large, E and SR are improved.

(Effects of the Invention) As described above, according to the present invention, since the polarizable electrode is provided with holes and recesses, the contact area with the s'R adhesive increases, reducing the ESR and making the electric double layer capacitor more stable. is obtained.

[Brief explanation of the drawing]

FIG. 1 shows a front sectional view of an embodiment of the invention, and FIG. 2 shows a front sectional view of another embodiment of the invention. 1.7... Polarizable electrode, 2... Hole, 3... Separator, 4.8... Conductive adhesive, 5... Metal case, 6
...concavity. Patent applicant Hitachi Capacitor Co., Ltd.

Claims (1)

[Claims] (1) In an electric double layer capacitor in which polarizable electrodes are separated by a separator and housed in a metal case, a sheet-like polarizable electrode with holes or recesses and the polarizable electrode are pasted on the inner surface of the metal case. An electric double layer capacitor characterized by having a conductive adhesive.