Electricity: electrical systems and devices – Electrolytic systems or devices – Liquid electrolytic capacitor
Reexamination Certificate
2000-03-09
2001-08-14
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Liquid electrolytic capacitor
C361S520000, C361S530000, C361S538000, C361S540000
Reexamination Certificate
active
06275372
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an energy storage device and a method for producing such a device.
The invention has been developed primarily for use with carbon double layer capacitors and will be described hereinafter with reference to that application. However, it will be appreciated that the invention is not limited to that particular field and is also suited to other double layer capacitors, dielectric capacitors, electrochemical cells and other energy storage devices.
BACKGROUND OF THE INVENTION
It is known to construct both dielectric and double layer capacitors in accordance with the following general steps. Initially, a pair of foil electrodes, with an appropriate intermediate dielectric or separator, as the case may be, are overlapped and wound together into a spiral configuration to define a cylindrical body. The nature of the overlap is such that the electrodes protrude from respective opposed axial ends of the body. For dielectric capacitors it is known from U.S. Pat. No. 1,479,315 to form a metallised layer on the two ends of the body and from U.S. Pat. No. 3,256,472 to subsequently solder lead wires, or terminals, to those layers. Insofar as double layer capacitors and other electrochemical cells are concerned the use of metallisation layers and soldering has not been effective due to corrosion problems arising from the use of an electrolyte within such cells.
Accordingly, for double layer capacitors the terminals are usually connected to the respective electrodes by “stakinge” or spot welding. While these operations have the advantage of simplicity and low cost they are also known to distort the shape of the electrodes and thereby compromise the quality and longevity of the capacitor. Additionally, the resultant electrical connection between the terminals and electrodes often have a high electrical resistance, thereby increasing the overall series resistance of the capacitor.
An alternative approach for double layer capacitors is to utilise a non-porous metallisation layer. In practical terms, however, this is unworkable, as the ingress of the electrolyte into the capacitor is slowed prohibitively.
The prior art also suffers from the limitations of forming a metallisation layer. More particularly, during metallisation it is known that some of the particles being applied will enter between the spaced apart portions of the electrode. If the number of such particles is sufficient they short circuit the two electrodes and either reduce the overall capacitance or render the capacitor defective. A partial solution to this problem is to reducing the overlap of the sheets so that the particles will have to travel further before contacting the other electrode. This, however, reduces the capacitance and increases the bulk of the resultant capacitor.
DISCLOSURE OF THE INVENTION
It is an object of the invention, at least in the preferred embodiments, to overcome or substantially ameliorate one or more of the disadvantages of the prior art.
According to a first aspect of the invention there is provided an energy storage device including:
a plurality of first electrode members each extending between a first end and a second end;
a plurality of second electrode members each extending between a third end and a fourth end wherein, in use, the second members are interleaved with the first members such that the third ends are located intermediate the fist and second ends of the adjacent first members;
an insulator disposed between the adjacent first and second members to prevent electrical contact therebetween; and
first contact means extending from at least one of the first ends and being electrically connected to all the first members, said means providing:
(a) a site for the metallisation of particles thereupon such that said particles form a connection layer for an electrical terminal for the first members; and
(b) a barrier against the ingress of said particles beyond said first ends.
Preferably, the second ends of the first members are located intermediate the third and fourth ends of the adjacent second members and the device includes second contact means extending from at least one of the fourth ends and being electrically connected to all the second members, said second means providing:
(a) a site for the metallisation of particles thereupon such that said particles form a connection layer for an electrical terminal for the second members; and
(b) a barrier against the ingress of said particles beyond said fourth ends.
Preferably also, the first members are integrally formed from a first conductive sheet and the second members are integrally formed from a second conductive sheet, the first and second sheets being adjacent each other and wound in a spiral.
In a preferred form, the contact means includes a flange extending away from the first end of each first member, each flange overlapping with at least one adjacent flange.
Preferably, the connection layer is porous to allow passage therethrough of an electrolyte. More preferably, the connection layer extends over less than all of the contact means.
In some embodiments the porosity is provided by macroscopic discontinuities in the connection layer. For example, the connection layer can include a plurality of spaced apart discontinuities such as apertures. In other embodiments the porosity is provided by microscopic discontinuities in the connection layer.
Preferably also the terminal is welded to the connection layer.
According to a second aspect of the invention there is provided a method for producing an energy storage device of the type including a plurality of first electrode members each extending between a first end and a second end and a plurality of second electrode members each extending between a third end and a fourth end, the method including the steps of:
interleaving the second members with the first members such that the third ends are located intermediate the first and second ends of the adjacent first members;
disposing an insulator between the adjacent first and second members to prevent electrical contact therebetween; and
providing first contact means which extend from at least one of the first ends and which is electrically connected to all the first members, said means providing a first site for metallisation of particles thereupon and a barrier against the ingress of said particles beyond said first ends; and
directing a stream of said particles toward said site such that said particles metallise to form a connection layer for an electrical terminal for the first members.
Preferably, the method includes the further steps of:
locating the second ends of the first members intermediate the third and fourth ends of the adjacent second members;
providing second contact means which extend from at least one of the fourth ends and which is electrically connected to all the second members, said second means providing a second site for metallisation of particles thereupon and a barrier against the ingress of said particles beyond said fourth ends; and
directing a stream of said particles toward said second site such that said particles metallise to form a connection layer for an electrical terminal for the first members.
Preferably also, the method includes the steps of:
integrally forming the first members from a first conductive sheet and integrally forming the second members from a second conductive sheet;
disposing the first and second sheets adjacent to each other and separated by the insulator; and
winding the sheets and the insulator in a spiral.
In a preferred form, the contact means is provided by a flange extending away from the first end of each first member, and the method includes the step of overlapping each flange with at least one adjacent flange during the winding.
Preferably, the connection layer is porous and said method includes the further step of passing an electrolyte through said metallisation and between said interleaved members.
Preferably also, the method includes the step of providing at least a portion of the connection layer with a substantially planar exterior
Keshishian Sarkis Minas
Vassallo Anthony Michael
Dinkins Anthony
Energy Storage Systems Pty. Ltd.
Kenyon & Kenyon
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