Coaxial-cable hierarchical tubular MnO2@Fe3O4@C heterostructures as advanced anodes for lithium-ion batteries

Nanostructured manganese oxides have been regarded as promising anodes for lithium-ion batteries (LIBs) due to their high specific capacity, environmental friendliness and low cost. However, as conversion-type electrodes, their scalable utilization is hindered by intrinsically low reaction kinetics, large volume variation and high polarization. Herein, a coaxial-cable tubular heterostructure composed of a hollow carbon skeleton, Fe3O4 nanoparticles and ultrathin MnO2 nanosheets from inside out, donated as MnO2@Fe3O4@C, is synthesized via a facile two-step hydrothermal process. The unique design integrates conductive carbon and nanostructured MnO2 and Fe3O4 into a one-dimensional (1D) hierarchically open architecture, which provides abundant electrode-electrolyte contact areas, favorable heterointerfaces and ultrafast electron/ion pathways. Benefiting from these features, the MnO2@Fe3O4@C anode exhibits a high reversible capacity of 946 mAh g-1 at 200 mA g-1 after 160 cycles, and excellent cyclability with a specific capacity of 845 mAh g-1 at 500 mA g-1 after 600 cycles. This work might provide an insightful guideline for the design of novel electrode materials.