Controlled synthesis of Fe3O4@C@manganese oxides (MnO2, Mn3O4 and MnO) hierarchical hollow nanospheres and their superior lithium storage properties

Abstract

We develop a facile approach to controlled-synthesize Fe3O4@C@MnOX (MnO2, Mn3O4 and MnO) hierarchical hollow nanospheres by using Fe3O4@C hollow nanospheres as the template. By simply adjusting the calcination temperature and time, three kinds of Fe3O4@C@MnOX (MnO2, Mn3O4 and MnO) hierarchical hollow nanospheres with different phase states of manganese oxides external layer are tailored. In virtue of the synergistic effect of Fe3O4 hollow nanostructures as supporters, the conductive carbon layer and MnOX external layer, the three hollow nanocomposites exhibit excellent lithium storage properties. At 0.1Ag-1, Fe3O4@C@MnO2, Fe3O4@C@Mn3O4 and Fe3O4@C@MnO hierarchical hollow nanospheres still have specific capacities of 708, 833 and 670mAhg−1 after 150 cycles, respectively. Even at 0.5Ag-1, the reversible capacity of the three hollow nanocomposites remains 609, 780 and 523mAhg−1 after 500 cycles, respectively. Interestingly, Fe3O4@C@Mn3O4 hierarchical hollow nanospheres possess more outstanding Li storage properties than Fe3O4@C@MnO2 and Fe3O4@C@MnO hierarchical hollow nanospheres because the former have more stable Mn3O4 external layer during intensive cycles. The rational design of the phase state for Fe3O4@C@MnOX (MnO2, Mn3O4 and MnO) hierarchical hollow nanospheres can provide a novel synthetic strategy for energy storage nanomaterials with optimized performances.