3D hierarchical mesoporous roselike NiO nanosheets for high-performance supercapacitor electrodes

In this paper, three-dimensional (3D) hierarchical mesoporous roselike NiO nanosheets were synthesized by a facile solvothermal method combining the calcination process. Nickel acetate and guanidine hydrochloride were used as nickel precursors and precipitant of weak base, respectively. The resultant NiO was characterized by Raman spectroscopy, X-ray diffraction, N2 adsorption and desorption and field emission scanning electron microscope. The electrochemical performances were evaluated by cyclic voltammetry (CV), charge–discharge and electrochemical impedance spectroscopy (EIS) in 6 M KOH solution. The hierarchical mesoporous roselike NiO nanosheets show an excellent electrochemical performance: a high specific capacitance of 1860 F g−1 at 1 A g−1, 897 F g−1 at high current density of 20 A g−1 and 92% capacity retention at a current density of 10 A g−1 in a testing range of 5000 cycles.