Preparation and capacitive properties of the core-shell structure carbon aerogel microbeads- nanowhisker-like NiO composites

In current study, nanowhisker-like NiO/carbon aerogel microbead (NiO/CAMB) composites with chestnut-like core-shell structure are prepared by in situ encapsulating method. The structure and morphology of NiO/CAMB are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results indicate that the appearance of composite becomes chestnut-like morphology with core-shell structure when NiO is coated. Electrochemical performances of the NiO/CAMB composites with different NiO contents are evaluated by using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). Results show that the supercapacitive behaviors of NiO/CAMB composites are largely improved due to the combination of electrical double-layer capacitance of CAMB and pseudo-capacitance based on the redox reaction of NiO. Especially, the 15%-NiO/CAMB composite exhibits the best capacitive properties, its specific capacitance is up to 356.2 F g(-1). Besides, the symmetric supercapacitor using 15%-NiO/CAMB composite as the electrode active material shows stable cycling performance. (C) 2012 Elsevier B.V. All rights reserved.