Lithium Ion Battery Anode of Mesocrystalline CoTiO<sub>3</sub>/TiO<sub>2</sub> Nanocomposite with Extremely Enhanced Capacity
Xing Wang, Weijie Cheng, Jiaqiao Hu, Ying Su, Xingang Kong, Shinobu Uemura, Takafumi Kusunose, Qi Feng
Abstract
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.