High-performance supercapacitors based on conductive graphene combined with Ni(OH)2 nanoflakes

Abstract

A green and facile strategy is reported for the synthesis of a three-dimensional (3D) graphene nanosheets (GNS)/Ni(OH)₂ composite for use as a supercapacitor material. During this process, graphene oxide was reduced to graphene and Ni(OH)₂ was attached in it to form the GNS/Ni(OH)₂ composite via a chemical precipitation route without any complicated procedures. The product was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The analyses indicated that the Ni(OH)₂ sheets were well interwoven on the surfaces of the graphene nanosheets. Furthermore, the composite was electrochemically tested by cyclic voltammetry, galvanostatic charge/discharge, specific capacitance, and by assessing its cycle life. The GNS/Ni(OH)₂ composite exhibited a high specific supercapacitance of 2053 F g⁻¹ at a current density of 0.3 A g⁻¹ in 6 M KOH electrolyte and a long cycle life, along with 97% specific capacitance remaining after 1000 cycles. The GNS/Ni(OH)₂ composite had superb electrochemical performance compared to bare Ni(OH)₂, which could be attributed to its architecture. These results suggest that the GNS/Ni(OH)₂ composite could have potential application as a supercapacitor material.