Synergistic effect between ZnCo₂O₄ and Co₃O₄ induces superior electrochemical performance as anodes for lithium-ion batteries

The current work describes a facile synthesis of spinel-type ZnCo2O4 along with an additional phase, Co3O4, by simply maintaining a non-stoichiometric ratio of Zn and Co precursors. Pure ZnCo2O4 and Co3O4 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 ZnCo2O4/Co3O4 nanocomposite electrode exhibits a highly stable charge capacity of 1146.2 mA h g(-1) 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 ZnCo2O4 and Co3O4, increased active sites for Li+ ion diffusion, and higher electrical conductivity. Although the pure Co3O4 electrode displayed a much higher rate capability than the ZnCo2O4/Co3O4 nanocomposite electrode at all investigated current rates, the Co3O4 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.