Studies of layered lithium metal oxide anodes in lithium cells

Numerous efforts have been made to use metal oxides as anode materials for lithium-ion batteries. In this study, we examined layered oxides of the type LiMO2 (M = Co, Ni) and Li2MO3 (M = Mn, Mo, Sn) in lithium cells and found them to be electrochemically active while possessing a high capacity. In general, LiMO2 electrodes provide higher reversible capacities than Li2MO3 electrodes. First-principles theoretical calculations were used as a guide to determine the most favorable reaction pathway from possible insertion (addition) reactions, decomposition reactions, and metal displacement reactions. For example, using in situ X-ray diffraction, LiCoO2 was found to discharge first to CoO and Li2O (decomposition reaction) and thereafter, upon further reduction, to Co metal and additional Li2O (displacement reaction). On charging to 3.0 V, only CoO was reformed; the electrode cycled with a reversible capacity of 575 mAh g−1; this reaction pathway is in good agreement with theoretical predictions.