Topochemical synthesis of MnO/TiO and MnTiO/TiO nanocomposites as lithium-ion battery anodes with fast Li migration and giant pseudocapacitance the mesocrystalline effect.

Transition metal compounds are a promising substitute for graphite as lithium-ion battery (LIB) anodes. In this study, mesocrystalline MnO/TiO and MnTiO/TiO nanocomposites were synthesized using a layered titanic acid HTiO (HTO) precursor. The β-MnOOH layer is intercalated into the interlayer of HTO by Mn-exchange treatment of HO-intercalated HTO, which includes ion-exchange of Mn with H in the interlayer and oxidation of Mn to the β-MnOOH layer by HO in the interlayer space. Mesocrystalline MnO/TiO and MnTiO/TiO nanocomposites with a platelike morphology were obtained by heat treatment of a sandwich layered HTO/β-MnOOH under air and H/Ar atmospheres, respectively. The electrochemical results suggest that the mesocrystalline MnO/TiO and MnTiO/TiO nanocomposites show a synergistic effect for enhanced cycling stability and a mesocrystalline effect for enhanced discharge-charge specific capacity by improving the Li mobility and enhancing the pseudocapacitance of the mesocrystalline nanocomposites as LIB anode materials. The discharge-charge specific capacity of the mesocrystalline MnO/TiO nanocomposite is twice as high as that of the polycrystalline one caused by the mesocrystalline effect. Furthermore, the synergistic and mesocrystalline effects led to a stable large discharge-charge specific capacity of 710 mA h g for the mesocrystalline MnO/TiO nanocomposite. This work proposes a new concept to enhance the performance of anode materials for LIBs using mesocrystalline materials.