Study of the electro-oxidation of CoO and Co(OH)2 at 90 °C in alkaline medium

Frédéric Tronel (1) , Liliane Guerlou-Demourgues (1) , Lionel Goubault (2) , Patrick Bernard (2) , Claude Delmas (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 Direction de la recherche

Cobalt is usually post-added as CoO or Co(OH)2 to nickel hydroxide at the positive electrode (nickel oxide electrode) of alkaline batteries, to form a conductive network. In the present work, we focus on the transformation of CoO and Co(OH)2 phases when oxidized at 90 °C. The Co3O4 phase is the majority product of such a reaction, with CoOOH as a secondary product. It is shown that the Co3O4 phase results from the reaction of the CoOOH phase, formed by electrochemical oxidation of Co(OH)2, with Co2+ species in the electrolyte, which is made possible by temperature. This process requires a global migration of the cobalt phases towards the current collector.

Mots clés: Alkaline batteries; Cobalt oxide; Electro-oxidation

Domaines: Matériaux

Frédéric Tronel, Liliane Guerlou-Demourgues, Lionel Goubault, Patrick Bernard, Claude Delmas. Study of the electro-oxidation of CoO and Co(OH)2 at 90 °C in alkaline medium. Journal of Power Sources, 2008, 179 (2), pp.837-847. ⟨10.1016/j.jpowsour.2008.01.005⟩. ⟨hal-00270303⟩