Novel Ni@Co₃O₄ Web-like Nanofiber Arrays as Highly Effective Cathodes for Rechargeable Li-O₂ Batteries

Novel vertically self-standing Ni@Co₃O₄ web-like nanofiber arrays (Ni@Co-WNFs) were synthesized via a facile hydrothermal method. The Co₃O₄ nanofibers were grown on a macroporous nickel foam skeleton and intertwined together as a special web structure containing both micropores and mesopores. This self-standing and carbon free binder bifunctional electrocatalyst was directly used as a cathode for rechargeable Li-O₂ batteries. These Li-O₂ batteries containing Ni@Co-WNFs cathode exhibited enormously enhanced performance in that a rare high specific capacity of 17118 mAh g⁻¹ at a current of 0.1 mA cm⁻² was demonstrated. Furthermore, this was shown over 128 and 61 stable cycles with the capacity limited to 500 and 1000 mAh g⁻¹. The enhanced electrochemical performance is believed to be related to the extraordinary structure and outstanding catalytic activity of the Ni@Co-WNFs cathode, indicating that it is a promising electrode material for Li-O₂ batteries.