Fabrication of hollow N-doped carbon supported ultrathin NiO nanosheets for high-performance supercapacitor

The polydopamine-assisted hierarchical composites of ultrathin NiO nanosheets uniformly coating on the surface of hollow nitrogen-doped carbon spheres (HNCS-NiO) were successfully fabricated via a facile synthesis method. The hierarchical HNCS-NiO composites as electrode materials for supercapacitors exhibit high capacitance of 550.4 F g− 1 (880.6 mF cm− 2) at the current density of 0.5 A g− 1 (0.8 mA cm− 2), and present a good rate capability. The composites display excellent improved electrochemical properties not only because their hierarchical hollow nanostructures can provide enough space to buffer the volume expansion during the reversible intercalation/deintercalation processes, but also because their larger specific surface areas can provide adequate active sites for the redox electrochemical reaction.