Enhanced nickel hydroxide positive electrode materials for alkaline rechargeable electrochemical cells

摘要

A positive electrode material for use in electrochemical cells. This material comprises particles of positive electrode material including at least one electrochemically active hydroxide and a substantially continuous, uniform, encapsulant layer surrounding the particles of positive electrode material. The encapsulant layer is formed from a material which, upon oxidation during processing or during charging of the electrode, is convertible to a highly conductive form, and which, upon subsequent discharge of the electrode, does not revert to its previous form. Preferably, the electrochemically active hydroxide includes at least nickel hydroxide. The encapsulant layer is preferably formed from at least cobalt hydroxide or cobalt oxyhydroxide. This layer is formed on the particles of positive electrode material by precipitation from a cobalt salt solution, which can be a cobalt sulfate solution. Also disclosed are positive electrodes including the material and a precipitation method of forming the material.