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

Abstract

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.