Etude par desintercalation electrochimique des systemes NaxCrO2 et NaxNiO2

NaxCrO2 and NaxNiO2 phases have been obtained for the first time by electrochemical desintercalation from NaCrO2 and NaNiO2. Structures of non-stoechiometric phases can be related to the starting material by sheet shifting. Their strong oxidizing power (3.5V vs Na for x ⋍ 0.85) emphasizes the unstability of tetravalent chromium and nickel.