Template-free and large-scale synthesis of hierarchical dandelion-like NiCo2O4 microspheres for high-performance supercapacitors

In this work, dandelion-like NiCo2O4 mesoporous microspheres were uniformly assembled from slim nanowires via a large-scale and templatefree method. The Brunauer-Emmett-Teller (BET) surface area of NiCo2O4 microspheres was determined to be about 35.2 m(2) g(-1) with dominant pore diameter of 10.9 nm and narrow size distribution of 8-20 urn. Furthermore, the electrochemical properties of NiCo2O4 microspheres were evaluated by cycle voltammetric (CV) and galvanostatic charge discharge (GCD) measurements. The results demonstrated that the NiCo2O4 microspheres exhibited high specific capacitance (372 F g(-1) at 1 Ag-1), good rate capability, and excellent cycling stability (88.3% retention after 2000 cycles). In principle, this synthetic approach could be extended for the fabrication of other microstructure materials for promising electrode candidates in energy storage devices. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.