Facile synthesis of a graphene/nickel-cobalt hydroxide ternary hydrogel for high-performance supercapacitors.

In this paper, a graphene/nickel-cobalt hydroxide ternary hydrogel (G-Ni-Co) with superior electrochemical performances was prepared by a simple hydrothermal method using Ni(NO)·6HO, Co(NO)·6HO, and graphene oxide as the starting materials. The mass fraction and the pH value of the reaction system were optimized. The prepared G-Ni-Co was assembled into a symmetric supercapacitor and its electrochemical performance was estimated. In a symmetric supercapacitor, the specific capacitance of G-Ni-Co is 551.3 F g at the scan rate of 10 mV s and 646.1 F g at the current density of 0.5 A g, respectively. The specific capacitance still retains 70.8% after 5000 cycles at the scan rate of 100 mV s. The energy density reaches 108.6 W h kg at a power density of 550.0 W kg and remains 72.4 W h kg at 7600.0 W kg, respectively.