Performance enhancing additive material for the nickel hydroxide positive electrode in rechargeable alkaline cells

Abstract

A conductive additive for the positive nickel electrode for electrochemical cells which provides increased performance by suppressing an oxygen evolution reaction occurring parallel to the oxidation of nickel hydroxide, increasing conductivity of the electrode and / or consuming oxygen produced as a result of the oxygen evolution reaction.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present invention is a continuation of, and is entitled to the benefit of the earlier filing date and priority of, co-pending U.S. patent application Ser. No. 10 / 428,547, to Ovshinsky et al., which is assigned to the same assignee as the current application, entitled “PERFORMANCE ENHANCING ADDITIVE MATERIAL FOR THE NICKEL HYDROXIDE POSITIVE ELECTRODE IN RECHARGEABLE ELECTROCHEMICAL CELLS”, filed May 2, 2003, the disclosure of which is hereby incorporated by reference. The present invention is a continuation-in-part of, and is entitled to the benefit of the earlier filing date and priority of, co-pending U.S. patent application Ser. No. 10 / 378,586, to Ovshinsky et al., which is assigned to the same assignee as the current application, entitled “PERFORMANCE ENHANCING ADDITIVE MATERIAL FOR THE NICKEL HYDROXIDE POSITIVE ELECTRODE IN RECHARGEABLE ELECTROCHEMICAL CELLS”, filed Mar. 3, 2003, the disclosure of which is hereby incorporated b...

AI Technical Summary

Benefits of technology

[0013] Preferably, the metal oxide includes cerium and / or titanium. Cerium oxide, as an additive to the positive electrode, may be further doped with a divalent oxide, a trivalent oxide, a tetravalent oxide, or combinations thereof to improve the overall electrode performance. The titanium oxide may also be comprised of two or more sub-oxides having the formula TiOx, wherein x may range from 0.65 to 1.25.

Problems solved by technology

However, there are limitations on the amount of pressure used to increase packing density.

Application of too much pressure causes expansion of electrode plates and compresses the separators placed between the positive and negative electrodes.

The overcompression of the cells limit the wettability as well as the amount of electrolyte in separators by squeezing out the absorbed electrolyte, which in turn deteriorates the performance of these cells.

The oxygen evolution reaction (4) is not desirable and contributes to lower utilization rates upon charging, can cause a pressure build-up within the electrochemical cell, and can upon further oxidation change the nickel oxyhydroxide into its less conductive forms.

Images