Uniform hollow Fe3O4 spheres prepared by template-free solvothermal method as anode material for lithium-ion batteries

Unique hollow Fe3O4 spheres are prepared by a simple template-free solvothermal reaction. In the reaction, ethylene glycol (EG) and polyvinylpyrrolidone (PVP) serve as the reducing agent and surface stabilizer, respectively. NH4Ac plays the role of the structure-directing agent, which combines with the Ostwald ripening process, resulting in the favored formation of hollow structures. The morphologies and structures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hollow Fe3O4 spheres exhibit excellent cycling and rate performance as anode material for lithium-ion batteries, delivering reversible specific capacities of 870 mA h g−1 even after 50 cycles at 100 mA g−1 and 836 mA h g−1 at 500 mA g−1. The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability.

Graphical abstractUnique hollow Fe3O4 spheres assembled by Fe3O4 nanoparticles prepared by a simple template-free solvothermal reaction are tested as anode material for lithium-ion batteries. The results show that the material delivers reversible specific capacities of 870 mA h g−1 even after 50 cycles at 100 mA g−1 and 836 mA h g−1 at 500 mA g−1. The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Uniform hollow Fe3O4 spheres were prepared by a template-free solvothermal method. ► The hollow Fe3O4 spheres have the capacity of 870 mA h g−1 at 50th cycle. ► The specific capacity can be well maintained at a large current density. ► The hollow Fe3O4 spheres exhibit enhanced rate capability. ► Electrochemical performance of hollow Fe3O4 spheres is better than Fe3O4 powders.