Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1998-12-21
2001-05-08
Weiner, Laura (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S220000, C429S231200, C429S231500, C429S231950, C429S215000, C429S245000, C429S212000, C029S623100
Reexamination Certificate
active
06228534
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 positive electrode comprising a mixed metal oxide. Preferred mixed metal oxides include silver vanadium oxide, copper vanadium oxide and copper silver vanadium oxide. According to the present invention, electrode plates of mixed metal oxide active material are thermally treated to reduce polarization resistance of cells incorporating the treated plates.
2. Prior Art
It is known in the prior art to heat both anode and cathode electrodes to increase and enhance the bond between the electrode active material and the current collector. Examples of this include U.S. Pat. No. 5,429,894 to Leap et al. which is directed to dehydrating a silver oxide paste contacted to a current collector. Heating takes place under nitrogen at a temperature of about 50° C. to 70° C. The heating protocol serves to enhance the bond between the active material and current collector without reducing the silver oxide to elemental silver.
U.S. Pat. No. 5,532,086 to Thibault et al. teaches increasing the bond between a silver foil current collector layer and a zinc metal anodic layer. Bonding is accomplished by pressing the current collector and the anodic layer between a plate heated to a temperature of about 650° F. (334° C.) to 750° F. (398° C.) and under an anvil pressure of about 1,500 to 5,000 psi.
SUMMARY OF THE INVENTION
The present invention is directed to transition metal oxide active materials that are heated subsequent to contact with a current collector. Electrodes fabricated in this manner are useful in both multiplate and jellyroll cell designs to decrease the electrical resistivity of the completed electrode assemblies. In turn, the discharge efficiency of the cell is increased. Also, heat dissipation of the present invention cells is improved in comparison to untreated cells of a similar electrode chemistry. Reduced heat dissipation is related to the reactivity of the cathode with the electrolyte. Reduced reactivity consequently benefits improved discharge efficiency.
These and other aspects of the present invention will become more apparent to those skilled in the art by reference to the following description and to the appended drawings.
REFERENCES:
patent: 3847674 (1974-11-01), Kegelman
patent: 4792505 (1988-12-01), Moyes
patent: 5429894 (1995-07-01), Leap et al.
patent: 5532086 (1996-07-01), Thibault et al.
patent: 5543249 (1996-08-01), Takeuchi et al.
patent: 5580683 (1996-12-01), Takeuchi et al.
patent: 5639577 (1997-06-01), Takeuchi et al.
Takeuchi Esther S.
Thiebolt, III William C.
Hodgson & Russ LLP
Weiner Laura
Wilson Greatbatch Ltd.
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