Hollow CoFe₂O₄ nanospheres as a high capacity anode material for lithium ion batteries.

Hollow structured CoFe₂O₄ nanospheres were synthesized by a hydrothermal method. The uniform hollow nanosphere architecture of the as-prepared CoFe₂O₄ has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis, which give an outer diameter of 200-300 nm and a wall thickness of about 100 nm. CoFe₂O₄ nanospheres exhibited a high reversible capacity of 1266 mA h g⁻¹ with an excellent capacity retention of 93.6% over 50 cycles and an improved rate capability. CoFe₂O₄ could be a promising high capacity anode material for lithium ion batteries.