Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2002-11-14
2004-07-27
Ruthkosky, Mark (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S231200, C429S231950, C429S233000, C429S122000, C429S231700
Reexamination Certificate
active
06767670
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to the conversion of chemical energy to electrical energy and, more particularly, to an alkali metal electrochemical cell having a cathode current collector provided with a conductive coating to increase the electrode's conductivity. A preferred cathode includes a solid active material and a most preferred cathode active material is a metal oxide, such as silver vanadium oxide (SVO).
2. Prior Art
It is known to coat a cathode current collector screen before contacting the active material thereto. Carbonaceous materials are suitable for this purpose. For example, U.S. Pat. No. 6,451,483 to Probst et al., which is assigned to the assignee of the present invention and incorporated herein by reference, describes a prior art Li/CF
x
cell including a titanium cathode current collector screen coated with a thin layer of graphite/carbon paint. In addition to increasing the electrical conductivity between the CF
x
and the current collector, the graphite/carbon paint serves to prevent direct contact at their interface. A major problem with CF
x
active materials supported on titanium current collectors is that the fluorine reacts with titanium to form titanium fluoride. This by-product is corrosive and degrades cell discharge performance through current collector pitting.
For example, U.S. Pat. No. 6,261,722 to Dasgupta et al. disclose a lithium battery comprising a cathode current collector provided with a mixture of carbon fibres and fine carbon particles. The problem is that these coating materials are added to a fluorinated polymer and possibly a low boiling point solvent such as toluene, acetone, or n-methyl pyrrolidinine (NMP). The coating is brushed or dipped onto the current collector and then evaporated off before being contacted by the cathode active material. Dasgupta et al. list a host of suitable current collector materials including titanium. However, according o the present invention, the presence of fluorine ions in contact with the titanium current collector detracts from cell performance, especially as the cell approaches end-of-life (EOL).
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to coating a titanium substrate with a carbonaceous material. When the substrate is used as a current collector, this increases the electrical conductivity at the active material/substrate interface. Preferably, the carbonaceous material in an alcohol-based suspension is contacted to the substrate followed by a heating step to affect the bonding process. The thusly-processed substrates are useful as a cathode current collector in a lithium/solid cathode active material cell. Preferred cell chemistry is of a Li/SVO couple.
These and other objects of the present invention will become increasingly more apparent to those skilled in the art by reference to the following description and to the appended drawings.
REFERENCES:
patent: 4212933 (1980-07-01), Markin
patent: 4925752 (1990-05-01), Fauteux et al.
patent: 5011501 (1991-04-01), Shackle et al.
patent: 5041199 (1991-08-01), DiFranco
patent: 5326653 (1994-07-01), Chang
patent: 5443928 (1995-08-01), Takeuchi et al.
patent: 5518839 (1996-05-01), Olsen
patent: 5716728 (1998-02-01), Smesko et al.
patent: 5824120 (1998-10-01), Mitchell
patent: 5955218 (1999-09-01), Crespi et al.
patent: 6106978 (2000-08-01), Takeuchi
patent: 6130005 (2000-10-01), Crespi et al.
patent: 6150057 (2000-11-01), Takeuchi
patent: 6261722 (2001-07-01), Dasgupta
patent: 6296961 (2001-10-01), Moy et al.
patent: 6368738 (2002-04-01), Passaniti et al.
patent: 6414837 (2002-07-01), Sato et al.
patent: 6436571 (2002-08-01), Passaniti et al.
patent: 6451483 (2002-09-01), Probst et al.
patent: 2001/0001055 (2001-05-01), Takeuchi
patent: 2002/0015890 (2002-02-01), Nakura
patent: 2002/0025476 (2002-02-01), Takeuchi
patent: 1014460 (2000-06-01), None
patent: 1122804 (2001-08-01), None
patent: 53032332 (1978-03-01), None
patent: 80030666 (1980-08-01), None
Freitag Gary L.
Frustaci Dominick J.
Gan Hong
Paulot William M.
Roy Mark J.
Ruthkosky Mark
Scalise Michael F.
Wilson Greatbatch Technologies, Inc.
LandOfFree
Carbon-coated titanium current collectors for use in alkali... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Carbon-coated titanium current collectors for use in alkali..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carbon-coated titanium current collectors for use in alkali... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3221529