Engineering nanohaired 3D cobalt hydroxide wheels in electrospun carbon nanofibers for high-performance supercapacitors

Abstract

Engineering nanostructures in the desired design and suitable size is one of the key issues for persuading high-performance supercapacitors (SCs). In this work, we report a successful synthesis of a new type of nanohaired three-dimensional cobalt hydroxide wheels/carbon nanofibers (3D Co(OH)2/CNFs) composite by a cost-effective electrospinning cum hydrothermal method. The 3D Co(OH)2 wheels are composed of many partially-fused, nanohaired and serrated sheet-like nanoleaflets furnishing abundant active sites. This novel architecture is quite significant for the stability of the composite since the wheels encircle one or more conductive CNFs firmly rather than the simple attachment on the surface of substrate. The growth process of 3D Co(OH)2 wheels on CNFs has been studied by synthesizing other two novel Co(OH)2/CNFs composites. The as-prepared material exhibits a specific capacitance of 1186 F g−1 at a current density of 1 A g−1 with excellent cyclic stability which is the highest reported value for Co(OH)2/CNFs composites. The asymmetric supercapacitor (ASC) device assembled using 3D Co(OH)2/CNFs as a positive electrode and nitrogen doped graphene hydrogel (NGH) as a negative electrode exhibits a high energy density of 60.31 W h kg−1 at power density of 740.8 W kg−1 which still remains 37 W h kg−1 even at a higher power density of 7500 W kg−1 with remarkable cycle life. Therefore, the composite stands as a promising candidate for SCs electrode material. This unique nanoengineering gives an insight into the synthesis of other stable nanocomposites for diverse applications like sensors, catalysis, etc.