Local Structure of Li-rich Layered Cathode Material Li[Ni0.17Li0.2Co0.07Mn0.56]O2

Abstract

The local structure of Li[Ni0.17Li0.2Co0.07Mn0.56]O2 was analyzed by high resolution scanning transmission electron microscopy (HR-STEM) and X-ray absorption spectroscopy (XAS). The HR-STEM images clearly showed a new type of stacking fault, as well as visual patterns of Li-ordering in the transition-metal (TM) layers. The XAS data showed that the valence states of the component TMs are Ni(II), Co(III) and Mn(IV), suggesting that some of the Li(I) in the TM layers of Li2MnO3 structure is replaced by Ni(II). Based on the results obtained, a detailed structural model for Li-rich solid-solution cathode materials was proposed.