Synthesis of Hierarchical Hollow-Structured Single-Crystalline Magnetite (Fe3O4) Microspheres: The Highly Powerful Storage versus Lithium as an Anode for Lithium Ion Batteries

Hierarchical hollow Fe 3 O 4 (H–Fe 3 O 4 ) microspheres are prepared by the controlled thermal decomposition of an iron alkoxide precursor, which is obtained via an ethylene glycol (EG) mediated solvothermal reaction of ferric chloride hexahydrate (FeCl 3 ·6H 2 O), sodium acetate (NaAc), and polyvinylpyrrolidone (PVP). The microspheres are characterized by the assembly of highly oriented primary nanoparticles and have a single-crystal feature. As the anode materials for the lithium-ion batteries, the resultant H–Fe 3 O 4 microspheres show high specific capacity and good cycle stability (851.9 mAh g –1 at 1 C and 750.1 mAh g –1 at 3 C up to 50 cycles), as well as enhanced rate capability. The excellent electrochemical performance can be attributed to the high interfacial contact area between the microspheres and electrolyte, and good accommodation of volume change arising from the synergetic effect of the hierarchical hollow structure. It is suggested that the H–Fe 3 O 4 microsphere synthesized by this method is a promising anode material for high energy-density lithium-ion batteries.