Synergistic effect between ZnCo 2 O 4 and Co 3 O 4 induces superior electrochemical performance as anodes for lithium-ion batteries.

The current work describes a facile synthesis of spinel-type ZnCo 2 O 4 along with an additional phase, Co 3 O 4 , by simply maintaining a non-stoichiometric ratio of Zn and Co precursors. Pure ZnCo 2 O 4 and Co 3 O 4 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 ZnCo 2 O 4 /Co 3 O 4 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 ZnCo 2 O 4 and Co 3 O 4 , increased active sites for Li + ion diffusion, and higher electrical conductivity. Although the pure Co 3 O 4 electrode displayed a much higher rate capability than the ZnCo 2 O 4 /Co 3 O 4 nanocomposite electrode at all investigated current rates, the Co 3 O 4 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.