Influence of the alkaline electrolyte on the behavior of Na0.6CoO2 used as conductive additive in positive electrode of Ni-MH cells

Myriam Douin (1, 2) , 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

The influence of the electrolyte alkaline ions, potassium, lithium, and sodium, on the efficiency of the Na0.6CoO2 phase, as a conductive additive in the positive nickel oxide electrode, is analyzed in the present paper. Aging tests of the Na0.6CoO2 phase and of the gamma-Co phases, deriving from it, in the three electrolyte components, KOH, NaOH, and LiOH, have shown the presence of topotactic exchange/(de)intercalation reactions of the alkaline ions, occurring within the materials. Electrochemical tests, performed in the various electrolytes, underline an unfavorable effect of lithium ions. The formation of a semiconductive LixCoO2 phase has been identified as responsible for the loss of efficiency of the conductive material, when lithium ions are present in the electrolyte.

Mots clés: Inorganic compounds; Cells; Electrolyte; Alkaline ions; Nickel

Domaines: Matériaux

Myriam Douin, Liliane Guerlou-Demourgues, Lionel Goubault, Patrick Bernard, Claude Delmas. Influence of the alkaline electrolyte on the behavior of Na0.6CoO2 used as conductive additive in positive electrode of Ni-MH cells. Journal of The Electrochemical Society, 2008, 155 (12), pp.A945-A951. ⟨10.1149/1.2988095⟩. ⟨hal-00338337⟩