The electrochemical displacement reaction of lithium with metal oxides

The electrochemical reaction of lithium with alpha -LiFeO2, beta -Li5FeO4, and CoO is studied by in situ X-ray diffraction and in situ Mossbauer measu rements. The results of the measurements show that these metal oxides are i mmediately decomposed during discharge to form lithia and the reduced metal . This reaction proceeds through a single intermediate or surface phase. Th e reaction products are nanometer-sized, but are not amorphous as was sugge sted previously. During charge the metal displaces the lithium in lithium o xide to form a metal oxide and lithium. In the case of CoO, the original li thium oxide oxygen lattice is preserved and the reaction resembles an ion e xchange process. This also appears to be the case for the iron oxides. Upon discharge, the reverse occurs and the lithium replaces the metal in the me tal oxide, once again forming lithium oxide and reduced metal on the bottom of discharge. Further cycling proceeds via oxidation/reduction of the meta l by these displacement reactions with lithium. (C) 2001 The Electrochemica l Society.