Li-Storage via Heterogeneous Reaction in Selected Binary Metal Fluorides and Oxides

We report on electrochemical reactions of a variety of metal fluorides metal oxides (TiO, NbO, and TiN with lithium in nonaqueous lithium cells over a wide voltage range (0.02-4.3 V) at room temperature. In most cases, deep Li uptake occurs via heterogeneous reaction resulting in transformation of or O or S or N) into a nanocrystalline or amorphous composite from which Li can be extracted under restoration of the phase. Thermodynamic and kinetic aspects, especially overpotential and its possible origins for both Li uptake and Li extraction processes, are discussed. © 2004 The Electrochemical Society. All rights reserved.