One-pot synthesis of ultrafine ZnFe₂O₄ nanocrystals anchored on graphene for high-performance Li and Li-ion batteries

A ZnFe₂O₄-nanocrystals/graphene-nanosheets (ZnFe ₂O₄/G) nanohybrid has been prepared by a facile in situ hydrothermal route using Zn(NO₃)₂·6H₂O, Fe(NO₃)₃·6H₂O and graphite oxide (GO) as the precursors. Ultrafine ZnFe₂O₄ nanocrystals (below 10 nm) are confined by the few-layer graphene sheets reduced from GO, forming a unique sheet-like hybrid. In this structure, the direct restacking of the hydrophobic graphene sheets is refrained by loading ZnFe₂O ₄ nanocrystals as the spacers and the aggregation of ZnFe ₂O₄ nanocrystals is inhibited by the dispersing and confining effects of the graphene sheets. ZnFe₂O₄/G shows excellent rate capability and high-rate cycling stability for lithium storage. It also shows a high capacity when used as an anode for a ZnFe₂O ₄/G-LiFePO₄/C full cell.