Synergistic effect between ZnCoO and CoO induces superior electrochemical performance as anodes for lithium-ion batteries.

The current work describes a facile synthesis of spinel-type ZnCoO along with an additional phase, CoO, by simply maintaining a non-stoichiometric ratio of Zn and Co precursors. Pure ZnCoO and CoO were also synthesized using the same method to compare results. The obtained morphologies of samples show that small-sized nanoparticles are interconnected and form a porous nanosheet-like structure. When used as anode materials for Li-ion batteries, the ZnCoO/CoO nanocomposite electrode exhibits a highly stable charge capacity of 1146.2 mA h g at 0.5C after 350 cycles, which is superior to those of other two pure electrodes, which can be attributed to its optimum porosity, synergistic effect of ZnCoO and CoO, increased active sites for Li ion diffusion, and higher electrical conductivity. Although the pure CoO electrode displayed a much higher rate capability than the ZnCoO/CoO nanocomposite electrode at all investigated current rates, the CoO morphology apparently could not withstand long-term cycling, and the electrode became pulverized due to the repeated volume expansion/contraction, resulting in a rapid decrease in the capacity.