An Fe3O4@(C-MnO2) core-double-shell composite as a high-performance anode material for lithium ion batteries

An Fe3O4@(C-MnO2) composite with a cube-like core-double-shell structure has been successfully designed and prepared by a combination of the hydrothermal method and a layer-by-layer (LBL) self-assembly technique. This novel hybrid composite was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy and electrochemical tests. It has been found that this material has a cube-like morphology with a core-double-shell structure. Compared with the bare alpha-Fe2O3 and Fe3O4-C materials, the as-prepared composite has a significantly enhanced electrochemical performance, with a high capacity, good rate capability, and excellent cycling stability as an anode material for lithium ion batteries (LIBs). At a current density of 100 mA g(-1), the as-obtained Fe3O4@(C-MnO2) composite electrode delivers a reversible capacity exceeding 1000 mA h g(-1) and retains 979 mA h g(-1) after 150 cycles. In contrast, the discharge capacities of the bare alpha-Fe2O3 and Fe3O4-C show only 111 mA h g(-1) and 282 mA h g(-1) at a current density of 100 mA g(-1) after 150 cycles, respectively. This improved electrochemical performance can be attributed to the high theoretical capacity and larger specific surface area of the MnO2 layer, as well as the high electrical conductivity of the carbon layer, which acts as both the linker and the stabilizer between Fe3O4 and MnO2.