Nanorod-assembled Co₃O₄ hexapods with enhanced electrochemical performance for lithium-ion batteries

Highly symmetric Co₃O₄ hexapods assembled by numerous porous nanorods were successfully grown on copper foil through a facile hydrothermal method followed by thermal treatment. The as-prepared Co ₃O₄ hexapods were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Directly configured as binder-free anodes for lithium-ion batteries, the as-grown Co₃O₄ hexapods on copper foil exhibited a very high reversible capacity of 800 mA h g^-1 at 100 mA g^-1 and 440 mA h g^-1 at 500 mA g^-1 even after 40 cycles. The good electrochemical performance is attributed to the unique porous structure of the Co₃O₄ hexapods and the good contact with Cu foil. The performance could be further improved by carbon coating, exhibiting an enhanced reversible capacity of 1001 mA h g^-1 after even 40 cycles. The synthetic strategy holds the potential for large scale production of other transition metal oxides as high performance anodes for lithium-ion batteries.