Hollow CoFe <inf>2</inf>O <inf>4</inf> nanospheres as a high capacity anode material for lithium ion batteries

Hollow structured CoFe 2O 4 nanospheres were synthesized by a hydrothermal method. The uniform hollow nanosphere architecture of the as-prepared CoFe 2O 4 has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis, which give an outer diameter of 200300nm and a wall thickness of about 100nm. CoFe 2O 4 nanospheres exhibited a high reversible capacity of 1266mAhg 1 with an excellent capacity retention of 93.6% over 50 cycles and an improved rate capability. CoFe 2O 4 could be a promising high capacity anode material for lithium ion batteries. © 2012 IOP Publishing Ltd