Synthesis of Li–Mn–O mesocrystals with controlled crystal phases through topotactic transformation of MnCO3

Abstract

Mesocrystals of Li–Mn–O compounds, such as LiMn₂O₄, Li₂MnO₃, and LiMnO₂–Li₂MnO₃, consisting of oriented nanoscale units were selectively produced under hydrothermal conditions from biomimetically prepared MnCO₃ mesocrystals. Topotactic transformation through the intermediate phase of Mn₅O₈ inheriting a hierarchical structure of the MnCO₃ precursor was essential for the formation of the mesocrystal compounds. The crystal phases were successfully controlled by varying the conditions for the hydrothermal reactions. The Li–Mn–O mesocrystals have considerable potential as cathodes of Li-ion batteries.