Electrical double layer capacitor

Details Electrical double layer capacitor Electrical double layer capacitor

2001-09-07

2003-03-11

Dinkins, Anthony (Department: 2831)

Electricity: electrical systems and devices

Electrolytic systems or devices

Double layer electrolytic capacitor

C361S503000, C361S508000, C361S511000, C361S512000, C029S025030

Reexamination Certificate

active

06532144

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrical double layer capacitor, and more particularly to a large-capacitance electrical double layer capacitor using a solid polarized electrode.
2. Description of the Prior Art
An electrical double layer capacitor in a conventional example 1 will be described with reference to
FIGS. 1
to
3
.
Referring to
FIG. 1
, a cell laminate
171
of the electrical double layer capacitor has the structure of laminating two cells. Each cell
161
comprises a gasket
151
of a frame shape, a couple of polarized electrodes
110
deposited within the gasket
151
, a separator sandwiched between the polarized electrodes
110
and a current collectors
121
adhered to the upper surface of the gasket
151
. An electrolytic solution
130
is sealed in the cell
161
. The polarized electrodes
110
contact with the current collectors
121
. The upper and the lower surfaces of the gasket
151
are flat as shown in FIG.
2
.
The polarized electrodes
110
are made of solid activated carbon mainly containing activated carbon/polyacene material or the like as disclosed in Japanese Patent Application Laid-open No. Hei 4-288361. The current collector
121
is made of rubber or plastic, which contains electrically conductive carbon.
Because a withstand voltage of the electrical double layer capacitor is limited by the electrolysis voltage of the electrolytic solution
130
, cells
161
are connected in series in accordance with a required withstand voltage. Also, as shown in
FIG. 3
, both sides of the cell laminate
171
are sandwiched between pressure plates
190
to apply a pressure between the cells and between terminal electrodes
180
, thereby lessening a contact resistance between the current collector
121
and the polarized electrode
110
.
In recent years, the electrical double layer capacitor thus structured is made large in capacitance by using an improved polarized electrode, and new usage of the electrical double layer capacitor is found by lessening an equivalent series resistance (hereinafter referred to as “ESR”). As its examples, there are a usage of a power supply for driving a starter motor in an automobile in combination with a lead-acid battery, and an intended use of an auxiliary power supply in combination with a solar battery.
In the case where the electrical double layer capacitor is used for those intended uses, there is a high possibility that the electrical double layer capacitor is located under a high temperature environment, and the high reliability of the electrical double layer capacitor is required under such an environment. However, the above-described electrical double layer capacitor in the conventional example 1 has the following problems.
(1) In the cell laminate
171
, the electrolytic solution
130
within the cell
161
is sealed with the adhesion of the gaskets
151
and the current collectors
121
which are different in material from each other. At a high temperature, the electrolytic solution
130
is thermally expanded. Also, a gas is produced within the cell by the application of a large voltage or a high temperature. As shown in
FIG. 1
, the outer peripheral end surfaces of the current collectors
121
are exposed to the side surfaces of the cell laminate
171
. Because of this structure, there occurs a gap between the gaskets
151
and the current collectors
121
due to their separation caused by the thermal expansion of the electrolytic solution and the occurrence of a gas within the cell, thereby being liable to leak the electrolytic solution
130
within the cell to the exterior from that gap.
(2) In order to improve the electric contact of the polarized electrodes
110
and the current collectors
121
, the cell laminate
171
is so structured as to be pressurized from the outside at the outermost current collector
121
and nipped by high rigid metal plates which are hardly deformable (refer to the pressure plates
190
in FIG.
3
). Also, among the structural materials of the electrical double layer capacitor, there are many cases in which the polarized electrodes
110
are formed of hard and rigid members such as a sintered body of the activated carbon, and the gaskets
151
are made of a hard material such as ABS resin in order to enhance a precision in the dimensions of a product. Because the current collectors
121
are made of an electrically conductive rubber, which is thin and elastic, a positional displacement occurs when pressurizing the current collectors
121
. As a result, a strong force is locally exerted on the current collectors
121
, and a crack is liable to occur in the current collectors
121
.
A technique by which the above problems are solved is disclosed in Japanese Patent Application laid-open No. Hei 8-78291 (a conventional example 2), Japanese Utility Model laid-open No. Sho 61-117238 (a conventional example 3) and Japanese Patent Application Laid-open No. Hei 5-46026 (a conventional example 4).
In the electrical double layer capacitor of the conventional example 2, as shown in
FIG. 4
, the outer diameter of a current collector
122
within a cell
162
of a cell laminate
172
is smaller than the outer diameter of the current collector
121
at the outermost side. That is, the electrical double layer capacitor is structured such that the outer diameter of the current collector
122
within the cell is set to have an intermediate value between the inner diameter and the outer diameter of a gasket
152
, and the peripheral edge portion of the current collector
122
is received in a recess
153
of the inner peripheral surface of the gasket
152
, as shown in FIG.
5
.
In the electrical double layer capacitor of the conventional example 3, as shown in
FIG. 6
, step portions are formed on inner peripheral portions of both end surfaces of gasket
154
, as shown in
FIG. 6
, a current collector
123
is received in these step portions
58
, and a cell is composed in the electric double layer capacitor. Two or more cells are stacked and a cell laminate is formed in the conventional example 3.
Also, in the electrical double layer capacitor of the conventional example 4, as shown in
FIG. 7
, a concave is formed over each of the frame entire periphery on both of the upper and lower surfaces of gaskets
155
of a cell
163
of a cell laminate
173
. A projection is formed on a current collector
124
corresponding to the concave, and the projection engages with the concave.
FIG. 8
is a schematic view of the gasket
155
. A concave
156
is formed over the frame entire periphery on both of the upper and lower surfaces of gasket
155
.
In the electrical double layer capacitor of the conventional example 2 to the conventional example 4, there prevents the leakage of the electrolytic solution due to a crack or separation by enhancing the seal strength between the respective cells.
However, the capacitors of the conventional example 2 to the conventional example 4 suffer from the following problem in that it is difficult to improve the productivity and to ensure the reliability.
After the side edge portion of collector
122
in the cell is inserted in the concave portion of gasket
152
, gasket
152
is compressed in manufacturing the electric double layer capacitor of the conventional example 2. As a result, the bonding strength of collector
122
and gasket
152
is improved, and the sealing reliability in the electric double layer capacitor of the conventional example 2 is improved, compared with that in the above-mentioned capacitor of the conventional example 1.
However, both the upper and lower end surfaces of the gasket
152
are flat as shown in
FIG. 5 and a
portion of concave portion
153
of the gasket
152
in which the side edge portion of the current collector
122
is received is thick because the thickness of the current collector
122
exists, and a portion of the concave portion
153
into which the current collector
122
is not inserted is thin. Since a distortion occurs on a boundary with different thickness, the

Affiliated with

Also associated with

Rating

Electrical double layer capacitor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electrical double layer capacitor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical double layer capacitor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3074750