In-situ growth of ultrathin Ni 6MnO 8 nanosheets on nickel foam as a binder-free positive electrode for asymmetric supercapacitor: Effects of alkaline aqueous and redox additive electrolytes

摘要

AbstractIn this paper, the growth of ultrathin Ni6MnO8nanosheet arrays on nickel foam via a simple hydrothermal reaction and calcination process without the introduction of other nickel sources has reported. The reaction between nickel ions on the substrate and manganese ions in a solution developed a good contact between the active material and the substrate. To improve capacitance performance of the active material, two strategies including the use of redox active additive electrolyte (K3Fe(CN)6+KOH) together with different aqueous electrolytes (KOH, NaOH, LiOH) were followed. The electrode was characterized by X-ray diffraction technique (XRD), Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Reflection electron energy loss spectroscopy (REELS), Brunauer, Emmett, and Teller (BET), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The as-synthesized Ni6MnO8nanosheet in LiOH electrolyte exhibited a maximum specific capacitance of 824Fg?1, which is superior to that in KOH and NaOH at 1.0Ag?1. Afterward, the fabricated asymmetric device exhibited good electrochemical performance and cyclic stability of about 79% at 1.5mA after 1500charge/dischargecycles as well as a volumetric energy density of 54mWhcm?3at a volumetric power density of 0.41mWcm?3.展开▼