Dry-particle based adhesive and dry film and methods of making same

Abstract

Dry process based energy storage device structures and methods for using a dry adhesive therein are disclosed.

Description

RELATED APPLICATIONS [0001] The present Application is a Continuation-In-Part of and claims priority from commonly assigned copending U.S. patent application Ser. No. 11 / 116,882, filed Apr. 27, 2005, Attorney Docket M109US-GENIII-v.3; which is a Continuation-In-Part of U.S. patent application Ser. No. 10 / 817,702, filed Apr. 2, 2004, Attorney Docket Number M109US-GEN.5.FIELD OF THE INVENTION [0002] The present invention relates generally to the field energy storage devices. More particularly, the present invention relates to structures and methods for making dry particle based adhesives and films for capacitor products. BACKGROUND INFORMATION [0003] Energy storage devices are used throughout modern society to provide energy. Inclusive of such energy storage devices are batteries, fuel cells, and capacitors. With each type of device are associated positive and negative characteristics. Based on these characteristics, decisions are made as to which device is more suitable for use in a ...

AI Technical Summary

Benefits of technology

[0016] The present invention provides a high yield method for making durable, highly reliable, and inexpensive structures. The present invention eliminates or substantially reduces use of water, additives, and solvents, and eliminates or substantially reduces impurities, and associated drying steps and apparatus. The invention utilizes a dry fibrillization technique, where a matrix formed thereby is used to support or hold one or more types of particles for use in further processing steps.

Problems solved by technology

Overall cost of an energy storage device is an important characteristic that can make or break a decision as to whether a particular type of energy storage device is used.

Although, double-layer capacitors can theoretically be operated at voltages as high as 4.0 volts, and possibly higher, current double-layer capacitor manufacturing technologies limit nominal operating voltages of double-layer capacitors to about 2.5 to 2.7 volts.

Higher operating voltages are possible, but at such voltages undesirable destructive breakdown begins to occur, which in part may be due to interactions with impurities and residues that can be introduced into and / or attach themselves to electrodes during manufacture.

For example, undesirable destructive breakdown of double-layer capacitors is seen to appear at voltages between about 2.7 to 3.0 volts.

When such additives are utilized in the manufacture of a capacitor product, the operating lifetime, as well maximum operating voltage, of a final capacitor product may become reduced, typically because of undesirable chemical interactions that can occur between residues of the additive(s) and a subsequently used capacitor electrolyte.

With prior art coating based processes, as layer thickness is increased above a certain thickness or decreased below a certain thickness, it becomes increasingly more difficult to achieve an even homogeneous layer, for example, wherein a uniform above 25 micron thick coating of an adhesive / binder layer is desired, or a coating of less than 5 microns is desired.

The process of coating also entails high-cost and complicated processes.

Furthermore, coating processes require large capital investments, as well as high quality control to achieve a desired thickness, uniformity, top to bottom registration, and the like.

However, with such short drying times, sufficient removal of additive and impurity is difficult to achieve.

Long dwell times limit production throughput and increase production and process equipment costs.

During prior art extrusion and / or coating and / or subsequent calendering stages, although fibrillization is known to occur, such processes also cause a large number of the fibrillized binder particles to re / coalesce and be formed into agglomerates.

The large number of such re / coalesced binder particles results in a reduced final film integrity and performance.

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