Topochemical synthesis of Mn2O3/TiO2 and MnTiO3/TiO2 nanocomposites as lithium-ion battery anodes with fast Li+ migration and giant pseudocapacitance via the mesocrystalline effect

摘要

Transition metal compounds are a promising substitute for graphite as lithium-ion battery (LIB) anodes. In this study, mesocrystalline Mn2O3/TiO2 and MnTiO3/TiO2 nanocomposites were synthesized using a layered titanic acid H1.07Ti1.73O4 (HTO) precursor. The β-MnOOH layer is intercalated into the interlayer of HTO by Mn2+-exchange treatment of H2O2-intercalated HTO, which includes ion-exchange of Mn2+ with H+ in the interlayer and oxidation of Mn2+ to the β-MnOOH layer by H2O2 in the interlayer space. Mesocrystalline Mn2O3/TiO2 and MnTiO3/TiO2 nanocomposites with a platelike morphology were obtained by heat treatment of a sandwich layered HTO/β-MnOOH under air and H2/Ar atmospheres, respectively. The electrochemical results suggest that the mesocrystalline Mn2O3/TiO2 and MnTiO3/TiO2 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 Mn2O3/TiO2 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−1 for the mesocrystalline Mn2O3/TiO2 nanocomposite. This work proposes a new concept to enhance the performance of anode materials for LIBs using mesocrystalline materials.