3D urchin-like of Zn-Ni-Co ternary oxide microspheres as high-performance electrodes for supercapacitors

Ternary transition metal oxides are attractive candidates for supercapacitor electrodes owing to the potential synergistic effects of multi metal species. However, their actual electrochemical performance is not satisfactory due to unsatisfied microstructures, morphologies or components. It is well known that electrode materials with appropriate morphology have a great influence on their electrochemical performance. In this work, a new urchin-like zinc-nickel-cobalt oxide (ZNCO) microsphere with a spinel cubic structure is prepared by simple hydrothermal method. Such an interesting structure is expected to offer larger surface areas, and the multi metal species can enhance the electrical conductivity, introduce extrinsic defects and improve its electrochemical performance. As expected, the specific capacity and rate performance of prepared ZNCO are 766 C/g at 1 A/g and 93.21% of capacity retention at 20 A/g, respectively. The study of charge storage mechanism of ZNCO shows that it includes both diffusion and capacitive-controlled processes. Moreover, the assembled device shows a high specific energy of 41.4 Wh/kg at a specific power of 850 W/kg and the cycling stability is nearly 90% after 20000 charge/discharge cycles. Impressively, the specific energy remains 21.6 Wh/kg at the specific power of 12.75 kW/kg. Therefore, the urchin-like ZNCO microsphere prepared in this work has a good prospect for supercapacitors electrode and this work provides guidance on designing ternary transition metal oxides for energy conversion and storage.