Strongly coupled nickel boride/graphene hybrid as a novel electrode material for supercapacitors.

Herein, we report the preparation of strongly coupled nickel boride/reduced graphene oxide (Ni 2 B/RGO) hybrid via simultaneous chemical reduction of nickel dichloride (NiCl 2 ·6H 2 O) and graphene oxide (GO) in one pot using NaBH 4 as reductant under nitrogen atmosphere. The Ni 2 B/RGO hybrid is demonstrated to be an excellent and novel electrode material for supercapacitors. The specific capacitance of Ni 2 B/RGO hybrid annealed at an optimized temperature of 200 °C (Ni 2 B/RGO-200) can reach 1073.4 F g −1 at a current density of 1 A g −1 in 6 M KOH solution. Meanwhile, the hybrid supercapacitor (HSC) device fabricated using Ni 2 B/RGO-200 as positive electrode and activated carbon (AC) as negative electrode delivers a high energy density of 22.1 Wh kg −1 at a power density of 724.9 W kg −1 . After 2500 charge-discharge cycles at a current density of 6 A g −1 , the HSC can still retain 72.4% of its initial performance. The excellent capacitor performance of Ni 2 B/RGO-200 hybrid should not only attribute to the adequate electrochemical reaction active sites of Ni 2 B particles, but also the enhanced electron transfer rate and superior electrochemical stability of graphene. [ABSTRACT FROM AUTHOR]