Facile Fabrication of Fe3O4@TiO2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries

Abstract

Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis, high specific capacity, and environmental-friendly. In this paper, Fe3O4@TiO2@C yolk–shell (Y–S) spheres, used as anode material for lithium ion batteries, were successfully fabricated by Stӧber method. XRD patterns reveal that Fe3O4@TiO2@C Y–S spheres possess a good crystallinity. But the diffraction peaks’ intensity of Fe3O4 crystals in the composites is much weaker than that of bare Fe3O4 spheres, indicating that the outer anatase TiO2@C layer can cover up the diffraction peaks of inner Fe3O4 spheres. The yolk–shell structure of Fe3O4@TiO2@C spheres is further characterized by TEM, HAADF-STEM, and EDS mapping. The yolk–shell structure is good for improving the cycling stability of the inner Fe3O4 spheres during lithium ions insertion–extraction processes. When tested at 200 mA/g, the Fe3O4@TiO2@C Y–S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles, which is much better than that of bare Fe3O4 spheres and TiO2@C spheres. Furthermore, cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe3O4 spheres.