A novel porous coral-like Zn0.5Ni0.5Co2O4 as an anode material for lithium ion batteries with excellent rate performance

A novel porous coral-like Zn0.5Ni0.5Co2O4 (ZNCO) is prepared by a facile co-precipitation method using oxalic acid as complex agent, and the ZnCo2O4 (ZCO) nanospheres and NiCo2O4 (NCO) nanoflakes are also prepared for comparison. The obtained products are systematically characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the controlled metallic elements doping has significant effects on the nanostructure and electrochemical performance of the samples. Compared with the ZCO nanospheres and NCO nanoflakes, the coral-like ZNCO materials with enough free space as anodes in lithium ion batteries (LIBs) exhibit a high initial coulombic efficiency of 84%, a high specific capacity of ∼1445 mAh g−1 at a current rate of 100 mA g−1 after 50 cycles, and ∼730 mAh g−1 at a current rate of 1500 mA g−1 after 200 cycles, as well as an excellent rate capability at elevated current rates, such as, ∼1080 and ∼425 mAh g−1 at current rates of 500 and 6000 mA g−1, respectively. This work presents a meaningful way for the preparation of mixed metal oxides with porous nanostructure as superior anodes for lithium ion batteries.