Silk-regulated hierarchical hollow magnetite/carbon nanocomposite spheroids for lithium-ion battery anodes

Hierarchical olive-like structured carbon-Fe_3O4 nanocomposite particles composed of a hollow interior and a carbon coated surface are prepared by a facile, silk protein-assisted hydrothermal method. Silk nanofibers as templates and carbon precursors first regulate the formation of hollow Fe_2O3 microspheres and then they are converted into carbon by a reduction process into Fe_3O4. This process significantly simplifies the fabrication and carbon coating processes to form complex hollow structures. When tested as anode materials for lithium-ion batteries, these hollow carbon-coated particles exhibit high capacity (900 mAh g^-1), excellent cycle stability (180 cycles) and rate performance due to their unique hierarchical hollow structure and carbon coating.