Lithium Ion Battery Anode of Mesocrystalline CoTiO₃/TiO₂ Nanocomposite with Extremely Enhanced Capacity

Mesocrystalline materials consisting of nanocrystal subunit alignment with the same crystallographic orientation have a potential application as active materials for lithium ion battery (LIB) electrodes. In this study, a topochemical process was developed to synthesize mesocrystalline CoTiO3/TiO2 nanocomposites using a layered titanic acid H1.07Ti1.73O4 (HTO) precursor. The H2O2 treatment of HTO caused more Co2+ intercalation into the interlayer by the H+/Co2+ exchange reaction and the formation of a sandwich layered structure by stacking an HTO layer and a Co(OH)2–xx+ layer. This sandwich layered structure was topotactically transformed into a mesocrystalline CoTiO3/TiO2 nanocomposite by heat treatment at >600 °C. The selected area electron diffraction result suggests that the CoTiO3/TiO2 nanocomposite is constructed from [010]-oriented CoTiO3 nanocrystals and [110]-oriented rutile TiO2 nanocrystals. The electrochemical results indicate that the mesocrystalline CoTiO3/TiO2 nanocomposite exhibits an extremely enhanced anode capacity of about 400 mAh/g for LIB, which is 2 times higher than that of polycrystalline CoTiO3. The excellent anode performance can be ascribed to the high mobility of Li+ in the mesocrystalline nanocomposite and the synergistic effect of TiO2 nanocrystals in the nanocomposite by enhancing the cycling stability and electron conductivity.