Hollow (Co0.62Fe1.38)FeO4/NiCo2O4 nanoboxes with porous shell synthesized via chemical precipitation: A novel form as a high performance lithium ion battery anode

Transition metal oxides containing different metal cations, also called as mixed metal oxides (MMOs), have confirmed improved electrochemical activities in comparison with single metal oxides (SMOs, containing single metal cations). In this study, for the first time, we have synthesized the hollow (Co0.62Fe1.38)FeO4/NiCo2O4 nanoboxes by simple and cost effective chemical precipitation method and investigated its lithium storage property. The uniqueness of this composite material is the hollow nano-structure with a very thin porous shell, which has rarely reported previously. The observed surface area of nanoboxes is 21.8 m2 g−1 with average pore size of 4 nm. As a results, the (Co0.62Fe1.38)FeO4/NiCo2O4 nanoboxes manifests a high reversible capacity of around 835.5 and 676.2 mAh g−1 over 350 cycles at a current densities of 200 and 500 mA g−1, respectively. The nano-dimention with hollow structure not only benefited electron and Li-ion transportation, it also provided large electrode–electrolyte contact area. Furthermore, the high reversible capacity in (Co0.62Fe1.38)FeO4/NiCo2O4 nanoboxes electrodes is most likely attributed to the synergistic electrochemical activity of both the phases, (Co0.62Fe1.38)FeO4 and NiCo2O4. Hence, based on high reversible capacity as well as an outstanding rate performance, the (Co0.62Fe1.38)FeO4/NiCo2O4 nanoboxes electrode sheds light on commercial applications as an alternative lithium-ion battery anode material.