Synthesis of porous hollow Fe3O4 beads and their applications in lithium ion batteries

Porous hollow Fe3O4 beads constructed with rod-shaped Fe3O4 nanoparticles were synthesized via a facile solvothermal route. The formation mechanism of the obtained Fe3O4 beads was proposed on the basis of oriented assembly and Ostwald ripening. The as-prepared Fe3O4 beads had promising applications as lithium ion battery anodes, which showed a reversible specific capacity of 500 mAh g−1 after 50 cycles at 100 mA g−1. After being decorated with a carbon coating layer, the Fe3O4/C composite beads showed an enhanced capacity of 700 mAh g−1 after 50 cycles at 100 mA g−1. Such a satisfactory electrochemical performance was due to several factors of the Fe3O4/C composite beads including high theoretical capacity of Fe3O4, nanosized active Fe3O4 particles, hollow porous structure that mitigated the volume change problem, and carbon coating layer that enhanced both the electronic conductivity and structure integrity.