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

Abstract

Herein, we report the preparation of strongly coupled nickel boride/reduced graphene oxide (Ni2B/RGO) hybrid via simultaneous chemical reduction of nickel dichloride (NiCl2·6H2O) and graphene oxide (GO) in one pot using NaBH4 as reductant under nitrogen atmosphere. The Ni2B/RGO hybrid is demonstrated to be an excellent and novel electrode material for supercapacitors. The specific capacitance of Ni2B/RGO hybrid annealed at an optimized temperature of 200°C (Ni2B/RGO-200) can reach 1073.4Fg−1 at a current density of 1Ag−1 in 6M KOH solution. Meanwhile, the hybrid supercapacitor (HSC) device fabricated using Ni2B/RGO-200 as positive electrode and activated carbon (AC) as negative electrode delivers a high energy density of 22.1Whkg−1 at a power density of 724.9Wkg−1. After 2500 charge-discharge cycles at a current density of 6Ag−1, the HSC can still retain 72.4% of its initial performance. The excellent capacitor performance of Ni2B/RGO-200 hybrid should not only attribute to the adequate electrochemical reaction active sites of Ni2B particles, but also the enhanced electron transfer rate and superior electrochemical stability of graphene.