Hexadecyl trimethyl ammonium bromide assisted growth of NiCo2O4@reduced graphene oxide/ nickel foam nanoneedle arrays with enhanced performance for supercapacitor electrodes

NiCo2O4@reduced graphene oxide (rGO)/nickel foam (NF) composites were prepared via a hydrothermal method followed by annealing assisted by hexadecyl trimethyl ammonium bromide (CTAB). NiCo2O4@rGO/NF nanoneedle arrays grew directly on Ni foam (NF) without using a binder. The effect of graphene oxide (GO) concentration on the electrochemical properties of the composite was studied. When the GO concentration was 5 mg L−1, the as-prepared NiCo2O4@rGO/NF reaches the highest specific capacitance of 1644 F g−1 at a current density of 1 A g−1. Even at 15 A g−1, the specific capacitance is still 1167 F g−1 and the capacitance retention rate is 89% after 10 000 cycles at 10 A g−1. Furthermore, a NiCo2O4@rGO/NF//graphene hydrogel (GH) asymmetric supercapacitor cell (ASC) device was assembled and exhibits a high specific capacitance of 84.13 F g−1 at 1 A g−1 and excellent cycle stability (113% capacitance retention) after 10 000 charge/discharge cycles at 10 A g−1. This provides potential for application in the field of supercapacitors due to the outstanding specific capacitance, rate performance and cycle stability of NiCo2O4@rGO/NF.