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

Abstract

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 α-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 α-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.