Lithium intercalation into copper ferrite and copper chromite: Redox extraction of copper

From Mössbauer measurements we have shown that during lithium intercalation into copper ferrite no reduction of iron occurs, which means that the electronic transfer concerns copper. Copper chromite behaves in a similar way: the intercalation-induced reduction of copper results in its extraction from the structure as Cu 0, which can then be removed from the powder by reaction with an iodine solution. Concomitantly a partial disintercalation of lithium occurs so that a compound with the formula Li 0.76Cu 0.07Cr 2O 4 was obtained. During the intercalation-disintercalation reactions, the spinel framework is preserved but, contary to the pristine spinel, the intercalated and disintercalated compounds are cubic due to the elimination of the Jahn-Teller ion, Cu II.