Electricity: electrical systems and devices – Electrolytic systems or devices – Double layer electrolytic capacitor
Reexamination Certificate
2003-11-26
2004-12-14
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Double layer electrolytic capacitor
C361S508000, C361S512000, C029S025030
Reexamination Certificate
active
06831826
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polarized electrode for an electric double-layer condenser and an electric double-layer condenser manufactured by using the polarized electrode and, more particularly, to a polarized electrode for an electric double-layer condenser, which can suppress the damage or separation of an electrode contained in the polarized electrode.
Further, the present invention relates to a polarized electrode for an electric double-layer condenser, a process for manufacturing the same, and an electric double-layer condenser manufacturing by using the polarized electrode and, more particularly, to a polarized electrode for an electric double-layer condenser, in which two end portions of the electrode are protected.
Still further, the present invention relates to a process for manufacturing an electrode sheet for an electric double-layer condenser, in which sheet-shaped electrodes are adhered to the surfaces of a conductive foil through an conductive adhesive, and a laminating apparatus suitable for executing the manufacturing process.
The electric double-layer condenser is also called as the “electric double-layer capacitor” and is provided with a polarized electrode and an electrolyte for storing electric charges by using the electric double-layer formed in the boundary between the polarized electrode and the electrolyte. Therefore, the electric double-layer condenser has a high farad-level capacity and is excellent in the charging/discharging cycle characteristics for quick-charging operations so that it is applied in recent years to various fields for a backup power source of an electronic device or a car-mounted battery.
The electric double-layer condenser of the prior art will be described with reference to FIG.
5
.
FIG. 5
is a sectional diagram schematically showing a construction of an electric double-layer condenser
101
of one example of the prior art. This electric double-layer condenser
101
is constructed such that a pair of polarized electrodes having collecting foils
104
and
104
adhered to carbon electrodes
105
and
105
are arranged in a container
102
through a separator
103
, and such that the container
102
is filled with an ion-conductive electrolyte.
When a voltage is applied to the electric double-layer condenser
101
of the prior art thus constructed, electric double layers, in which charges (as indicated by symbols + and −) are densely present at a distance as short as the molecular level, are formed at the interface between the solid polarized electrode (having the carbon electrodes
105
adhered to the collecting foils
104
) and the liquid electrolyte, so that the charges are stored in that electric double layers.
Here, the electrolyte to be used in that electric double-layer condenser
101
is coarsely divided into the “aqueous electrolyte” prepared by adding an electrolyte to a dilute sulfuric acid and the “organic solvent group electrolyte” prepared by adding an electrolyte to an organic solvent, which are properly used for the purpose. Specifically, the electric double-layer condenser using the aqueous electrolyte is relatively low in the internal resistance so that it is advantageous in the power density and relatively higher in the degree of freedom for setting the output voltage. On the other hand, the electric double-layer condenser using the organic solvent group electrolyte can have a relatively high electric strength per unit cell so that it is advantageous in the energy density and can use a relatively inexpensive and light metal foil of aluminum or the like.
(Polarized Electrode)
FIG.
3
A and
FIG. 3B
are diagrams schematically showing practical examples of such electric double-layer condenser.
FIG. 3A
is an exploded perspective view of a laminated type electric double-layer condenser, and
FIG. 3B
is a sectional view of a coin type electric double-layer condenser. Specifically, the laminated type electric double-layer condenser
1
is constructed such that a wound member
3
, which is prepared by spirally winding polarized electrodes
9
and
10
having electrodes
12
and
15
(
e
) adhered to collecting foils
11
and
14
through separators
17
and
18
, is housed in a container
2
, and such that the container
2
is filled with the aforementioned electrolyte.
On the other hand, a coin type electric double-layer condenser
1
′ shown in
FIG. 3B
is constructed such that a laminate, which is prepared by laminating polarized electrodes having electrodes
12
′ and
15
′ adhered to collecting foils
11
′ and
14
′ through a separator
17
′, is housed in a container
2
′, and such that the container
2
′ is filled with the aforementioned electrolyte. In
FIG. 3B
, reference numeral
21
designates a portion to be filled with the electrolyte, and reference numeral
22
designates a packing provided for preventing the leakage of the electrolyte to the outside. The winding type electric double-layer condenser shown in FIG.
3
A and the coin type electric double-layer condenser
1
′ shown in
FIG. 3B
are suitable for a backup power source of an electronic device or a car-mounted battery.
In this electric double-layer condenser, the polarized electrodes have to be provided with a porous structure for satisfying various characteristics demanded in the fields of the backup power source of the electronic device or the car-mounted battery. The additional demands are the durability for suppressing the cracking or damage and the strength for holding the shape properly while supposing the continuous use in various modes and under various conditions for a long time, and the proper coordinations between the flexibility cost suited for the shaping works at the manufacturing time.
A polarized electrode for an electric double-layer condenser, as satisfying those demands, is constructed such that electrodes, which are prepared by dispersing an active substance including mainly active carbon and a conductive filler through a binder and by forming them into a sheet shape, are adhered through an adhesive layer.
However, the electric double-layer condenser having such polarized electrode has an inherent problem that the electrode material such as carbon contained in the electrode partially falls due to the aging to invite deteriorations in performance such as the drop in the output voltage or the rise in the internal resistance. If the electrode material thus having fallen is floating in the electrolyte or is mixed into the separator, moreover, the desired output voltage is difficult to be stably kept for a long time.
As the method for preventing the falling of electrode forming granules or one of the electrode materials of the electric double-layer condenser, therefore, there is disclosed a method (as referred to Patent Publication) for manufacturing a polarized electrode for an electric double-layer condenser, by forming an intimate mixture of a material of an electrode such as fine carbon powder (or active carbon), a conductive filler and a binder, and a liquid lubricant into a sheet shape, subsequently by removing the lubricant, sequentially by stretching the formed sheet uniaxially or multi-axially.
In order to solve the aforementioned problem, alternatively, there is disclosed an electric double-layer condenser (as referred to Patent Publication 2), in which the tensile strength of a polarized electrode is regulated to 0.13 MPa or higher so as to prevent the falling of the carbon including the aforementioned electrode into the electrolyte.
[Patent Publication 1]
JP-B-7-105316
[Patent Publication 2]
JP-A-2001-267187
However, the polarized electrode for the electric double-layer condenser of the prior art can eliminate the falling of the granules contained therein to some extent. On the other hand, there is left unsolved a problem that the end portion is more susceptible to damage than the remaining portion at the step of packing that polarized electrode. If the end portion of the collecting foil is damaged,
Iwaida Manabu
Murakami Ken-ichi
Oyama Shigeki
Ozaki Kouki
Tsutsui Masanori
Arent & Fox PLLC
Dinkins Anthony
Honda Motor Co. Ltd.
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