Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
2000-06-20
2001-12-04
Bell, Bruce F. (Department: 1741)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S300000, C429S306000, C429S307000, C429S310000, C429S311000, C429S321000, C429S322000, C429S323000, C429S324000, C429S336000, C429S338000, C252S062200
Reexamination Certificate
active
06326105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to solid and semi-solid state polymer electrolyte composites which contain an inert electrically insulating non-woven glass fiber net, which is coated with an ion conductive solid or semi-solid state matrix.
DESCRIPTION OF THE PRIOR ART
In the prior art various polymers have been used as components of the electrolytes of solid state alkali metal, and alkaline earth metal batteries, and various other kinds of electrochemical devices.
Among the problems associated with the use of these polymers in electrolytes is that they have inherent relatively low ionic conductivity, and are not tough enough to prevent shorting during assembly or use.
Various solutions have been proposed such as described in the U.S. Pat. Nos. to Hope et al., 5,102,752; 5,328,558; Schwabet et al., 4,792,504; Ballard et al., 4,822,701; Bauer et al., 4,654,279; Lee et al., 4,830,939; Lee et al., 4,990,413, Kejha 5,521,023, and Taniuchi et al. 5,925,283.
Some of the prior art polymer containing electrolytes also have exhibited poor adherence to the electrodes, are not flexible and do not possess sufficient mechanical strength to prevent shorting under pressure, or punching through of dendrites and consequent shorting of the device.
While electrically insulating fibrous structures in solid ribbon or mesh form are used in composite electrolytes, and are satisfactory for their intended purpose, these prior art fibrous non-woven fabrics are thick, heavy, bulky, may absorb moisture, and may also cost more than is optimal. None of the prior art patents suggests, discloses or describes the composite electrolytes described herein.
The composite polymer electrolytes of the invention do not suffer from the prior art problems and provide many positive advantages.
SUMMARY OF THE INVENTION
It has now been found that, solid or semi-solid state electrolytes which are highly ion conductive,have low resistance, are shorting-proof, dendrite-proof, flexible yet mechanically strong, lightweight, and inert to component materials, can be made by using a composite construction, where an electrically insulating material, preferably a net of non-porous non-woven glass fibers, which includes a polyvinyl alcohol binder, and is coated with a liquid polymer material, which is solidified by cooling, or evaporation, or cross linking, or radiation to form a solid state matrix, which may be ionically conductive.
The principal object of the invention is to provide solid or semi-solid state composite polymer electrolytes for batteries, capacitors and other electrochemical devices, which include an electrically insulating net of non-porous non-woven glass fibers embedded in an ionically conductive matrix.
A further object of the invention is to provide composite electrolytes of the character aforesaid that are of low cost, and are inert to the component materials used in various electrochemical devices.
A further object of the invention is to provide composite electrolytes of the character aforesaid that have excellent adherence and low shrinkage properties, as well as contributing to greater cycle life and capacity retention of the devices.
A further object of the invention is to provide composite electrolytes of the character aforesaid, that are flexible, tough, easy to handle, and lend themselves to mass production.
A further object of the invention is to provide composite electrolytes of the character aforesaid that are lightweight, mechanically strong, and resist shorting under pressure.
A further object of the invention is to provide composite electrolytes of the character aforesaid that are non-reactive with the devices compositions, are highly stable at elevated temperatures, and allow rapid processing.
A further object of the invention is to provide composite electrolytes of the character aforesaid, wherein the electrically insulating component does not curl, resists shrinkage, and does not absorb moisture.
A further object of the invention is to provide composite electrolytes of the character aforesaid wherein the electrically insulating component can be dip coated, or coated by other means, or pressed under heat into a polymer electrolyte film.
Other objects and advantageous features of the invention will be apparent from the description and claims.
REFERENCES:
patent: 5521023 (1996-05-01), Kejha et al.
patent: 5529707 (1996-06-01), Kejha
patent: 5705084 (1998-01-01), Kejha
patent: 5750289 (1998-05-01), Kejha
patent: 5925283 (1999-07-01), Taniuchi et al.
patent: 5925483 (1999-07-01), Kejha et al.
Forlino Jay
Kejha Joseph B.
Kolla Santha
Bell Bruce F.
Drinker Biddle & Reath LLP
Lithium Technology Corporation
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