Optimized NiCo 2 O 4 /rGO hybrid nanostructures on carbon fiber as an electrode for asymmetric supercapacitors.

The NiCo 2 O 4 nanowires and reduced graphene oxide (rGO) hybrid nanostructure has been constructed on carbon fibers (NiCo 2 O 4 /rGO/CF) via a hydrothermal method. The effects of graphene oxide (GO) concentration on the structure and performance of the NiCo 2 O 4 /rGO/CF were investigated in detail to obtain the optimized electrode. When the GO concentration was 0.4 mg ml -1 , the rGO/NiCo 2 O 4 /CF composite exhibited a maximum specific capacitance of 931.7 F g -1 at 1 A g -1 , while that of NiCo 2 O 4 /CF was 704.9 F g -1 . Furthermore, the NiCo 2 O 4 /rGO/CF//AC asymmetric supercapacitor with a maximum specific capacitance of 61.2 F g -1 at 1 A g -1 was fabricated, which delivered a maximum energy density (24.6 W h kg -1 ) and a maximum power density (8477.7 W kg -1 ). Results suggested that the NiCo 2 O 4 /rGO/CF composite would be a desirable electrode for flexible supercapacitors.