Comparing the Effect of Oxygen Stoichiometry on the Behavior of Li_2MnO_3 in Pure Phase and Li-rich Forms

摘要

This work presents an investigation on the effect of oxygen stoichiometry on the behavior of Li_2MnO_3 and related cathode materials using a thin film deposition technique. It is shown that pure Li_2MnO_3 and Li_2MnO_3-based Li-rich cathodes behave very differently when prepared under similar oxygen partial pressure. Li-rich cathodes perform the best when deposited at low oxygen partial pressure while Li_2MnO_3 requires a moderate partial pressure for optimum capacity. This behavior is attributed to impurity formation in pure Li_2MnO_3 at low oxygen stoichiometry as well as stabilization of Li_2MnO_3 by the LiMO_2 (M= Ni, Co, Mn) matrix in the case of the Li-rich cathodes.