Uniform urchin-like nickel cobaltite microspherical superstructures constructed by one-dimension nanowires and their application for electrochemical capacitors

A novel two-step synthetic strategy was proposed to synthesize urchin-like nickel cobaltite (NiCo2O4) microspherical hierarchical superstructures constructed by one-dimension nanowires: hydrothermal precipitating (Ni, Co) carbonate hydroxide followed by calcinating process. Electrochemical data reveals that the as-synthesized urchin-like NiCo2O4 superstructures can deliver a specific capacitance (SC) of 296 F/g at 1 A/g, and keep it as high as 215 F/g at 5 A/g in 6 M KOH aqueous solution. Such unique urchinlike hierarchical superstructures make each electroactive NiCo2O4 nanowire building block contacted easily by electrolyte ions and electrons at high rates, ensuring that sufficient Faradaic reactions take place at large current densities for energy storage. Moreover, no obvious SC degradation after 1000 continuous charge-discharge cycles at 2 A/g demonstrates good electrochemical stability of the urchin-like microspherical superstructures, promising their great potential application in electrochemical capacitors. (c) 2012 Elsevier Ltd. All rights reserved.