# US 7,407,520 B2 · Method of making a multi-electrode double layer capacitor having hermetic electrolyte seal

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- Number: US 7,407,520 B2
- Document ID: US7407520B2
- Status: Granted
- Kind: B2
- Application number: 11/503,322
- Filed: 2006-08-10
- Published: 2007-01-18
- Granted: 2008-08-05
- Earliest claimed: 1999-08-18
- Assignees: Maxwell Technologies, Inc.
- Inventors: C. Joseph Farahmandi; John M. Dispennette; Edward Blank; Robert W. Crawford; Chenniah Nanjundiah
- Web page: https://patentgrep.com/patent/US7407520B2

## CPC

- H01G 11/58: Liquid electrolytes
- H01G 11/72: specially adapted for integration in multiple or stacked hybrid or EDL capacitors
- H01G 11/78: Cases; Housings; Encapsulations; Mountings
- H01G 11/80: Gaskets; Sealings
- Y02E 60/13: Energy storage using capacitors
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A long life double layer capacitor and method of making the same including a case and a first terminal with an electrically insulating hermitic seal interposed between the first terminal and the case. A first current collector foil is electrically coupled to an interior portion of the first terminal and a first electrode comprising carbon which is juxtaposed against the first current collector foil. A porous separator is then juxtaposed against the first electrode comprising carbon and separating the first electrode from a second electrode comprising carbon. A second current collector foil is juxtaposed against a side of the second electrode and is electrically coupled to the second terminal. And an electrolyte solution saturates the first and second electrodes comprising carbon and is substantially contained by the case and the electrically insulating hermitic seal such that an influx of impurities into the electrolyte solution is substantially inhibited by the case and the electrically insulating hermetic seal.

## Claims

### Claim 1

A method of making a double layer capacitor comprising:
juxtaposing a respective side of each of a plurality of electrodes with one of a plurality of current collector foils wherein each of the plurality of electrodes comprises carbon;
interposing a porous separator between respective other sides of each of the plurality of electrodes;
saturating the plurality of electrodes with an electrolyte solution;
sealing hermetically the plurality of electrodes and the plurality of current collector foils within a case to substantially inhibit an influx of impurities into the electrolyte solution,
wherein said sealing comprises: interposing a glass-to-metal seal between an opening in said case and a first terminal, the glass-to-metal seal directly contacting said case and the first terminal; and electrically coupling the first terminal to one of said plurality of current collector foils.

### Claim 2 (depends on 1)

The method of claim 1 wherein said glass-to-metal seal can withstand exposure to temperatures of up to 250° C. for periods of up to 5 minutes.

### Claim 3 (depends on 1)

The method of claim 1 wherein said porous separator can withstand exposure to temperatures of up to 250° C. for periods of up to 5 minutes.

### Claim 4 (depends on 3)

The method of claim 3 wherein said porous separator comprises polytetrafluoroethylene (PTFE).

### Claim 5 (depends on 1)

The method of claim 1, further comprising selecting a material for said first terminal having a coefficient of thermal expansion substantially similar to a coefficient of thermal expansion of glass.

### Claim 6 (depends on 5)

The method of claim 5 wherein said selecting comprises selecting molybdenum.

### Claim 7 (depends on 5)

The method of claim 5 wherein said selecting comprises selecting platinum plated molybdenum.

### Claim 8

A method of making a double layer capacitor comprising:
coupling a first cuffent collector foil to an internal portion of a first terminal;
folding a first electrode over the current collector foil wherein the first electrode comprises carbon;
placing a porous separator against the first electrode;
juxtaposing a second electrode against the porous separator wherein the second electrode comprises carbon;
coupling electrically the second electrode to a case;
saturating the first electrode and the second electrode with an electrolyte solution; and
sealing hermetically the case, wherein the electrolyte is substantially contained within the case, and wherein influx of impurities into the electrolyte solution is substantially impaired,
wherein said sealing hermetically includes forming a glass-to-metal seal between another portion of said first terminal and said case, the glass-to-metal seal directly contacting said case and the first terminal.

### Claim 9 (depends on 8)

The method of claim 8 wherein said placing said porous separator comprises enveloping said first electrode with said porous separator.

### Claim 10 (depends on 9)

The method of claim 9 wherein said juxtaposing comprises juxtaposing said second electrode over said porous separator.

### Claim 11 (depends on 10)

The method of claim 10 wherein said coupling electrically comprises:
juxtaposing a second current collector foil over the second electrode; and
contacting the second current collector foil with the case.

### Claim 12 (depends on 8)

The method of claim 8 wherein said sealing hermetically further includes:
welding a header to a can, wherein the header includes the glass-to-metal seal.

### Claim 13 (depends on 8)

The method of claim 8 further comprising:
selecting material for said first terminal having a coefficient of thermal expansion substantially similar to a coefficient of thermal expansion of glass.

### Claim 14 (depends on 13)

The method of claim 13 wherein said selecting comprises selecting a plating material for said first terminal that is solderable.

### Claim 15 (depends on 8)

The method of claim 8, further comprising selecting a material for said porous separator that can withstand exposure to temperatures of up to 250° C. for periods of up to 5 minutes.

### Claim 16 (depends on 15)

The method of claim 15 wherein selecting said material for said porous separator comprises selecting said material comprising polytetrafluoroethylene (PTFE).

### Claim 17 (depends on 8)

The method of claim 8, further comprising selecting materials to make said double layer capacitor that can withstand exposure to temperatures of up to 250° C. for periods of up to 5 minutes.

### Claim 18 (depends on 8)

The method of claim 8, further comprising placing a constant pressure on said first and second electrodes, said first and second cuffent collector foils, and said porous separator.

### Claim 19 (depends on 18)

The method of claim 18 wherein said placing said constant pressure comprises forming crimps in said case.