High pseudocapacitance material prepared via in situ growth of Ni(OH)2 nanoflakes on reduced graphene oxide

Abstract

We report a two step approach to fabricate reduced graphene oxide/nickel oxide (RGO/Ni(OH)₂) nanocomposites by combining the reduction of graphene oxide (GO) with the help of PVP and the subsequent hydrolysis of Ni(Ac)₂ on RGO. The nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectra, X-ray power diffraction (XRD) and thermogravimetry (TG). The results show that Ni(OH)₂ nanoflakes with lateral sizes of tens of nm and thicknesses of several nm were homogeneously attached on the surface of RGO. Cyclic voltammetry (CV) and galvanostatic charge and discharge tests were conducted to study the performance of RGO/Ni(OH)₂. The RGO/Ni(OH)₂ composites demonstrate much better capacitance performance and rate performance compared with pure Ni(OH)₂ due to synergetic effects. The hybrid material with 84.5 wt% Ni(OH)₂ presents an extremely high specific capacitance of 1828 F g⁻¹ at 1 A g⁻¹ and an energy density of 63.5 Wh kg⁻¹ at a power density of 250 W kg⁻¹. The corresponding values at 10 A g⁻¹ are 780 F g⁻¹, 27.1 Wh kg⁻¹ and 2500 W kg⁻¹. The specific capacitance can maintain at a high value of 840 F g⁻¹ after 1000 charge and discharge cycles at 6 A g⁻¹.