Hierarchical NiFe2O4/Fe2O3 nanotubes derived from metal organic frameworks for superior lithium ion battery anodes

Abstract

A simple method for the synthesis of NiFe₂O₄/Fe₂O₃ nanotubes by annealing core–shell Fe₂Ni MIL-88/Fe MIL-88 metal organic frameworks (MOFs) has been developed. The crystalline phase, morphology and specific surface area (BET) of the resulting sample have been systematically characterized. The results indicate that the NiFe₂O₄/Fe₂O₃ nanotubes, which have diameters of 78 nm and lengths of around 1 μm, are composed of nano-sized primary particles. The electrochemical performance of the NiFe₂O₄/Fe₂O₃ nanotubes when used as an anode material for lithium ion batteries has also been tested. A reversible specific capacity of 936.9 mA h g⁻¹ was achieved at a current density of 100 mA g⁻¹ up to 100 cycles. Even at 2000 mA g⁻¹, the discharge capacity of the composite anode could still reach 423.6 mA h g⁻¹. The enhanced electrochemical performance of the NiFe₂O₄/Fe₂O₃ nanotube anode can be ascribed to the rational design of the hierarchical porous hollow structures and the synergetic effect of different functional components.