Development of Co0.5Ho0.5Fe2O4/graphene hybrid nanocomposites electrodes for all-solid-state printable micro-supercapacitor on flexible substrates

Abstract

Herein, we report the synthesis of Co0.5Ho0.5Fe2O4/graphene hybrid nanocomposite electrodes for all-solid-state printable supercapacitor on flexible substrate using a one-step laser scribe approach. The structure, morphology, oxidation state, and elemental composition characteristics were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area of electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) measurements. The results revealed that the laser scribe can not only used to print the films on the flexible substrate but also has high capability to convert the graphene oxide and the cobalt, holmium and iron salts to Co0.5Ho0.5Fe2O4/graphene hybrid nanocomposite during printing this suspension on a flexible substrate. The cyclic voltammetry and the galvanostatic charge/discharge measurements revealed that the decoration of the surface of graphene with Co0.5Ho0.5Fe2O4 nanocrystals increases the operational voltage window to 1.5 V. The combination of the developed polyethylene glycol/silica/lithium triflates (48:37:15) ionic gel with the Co0.5Ho0.5Fe2O4/graphene hybrid electrodes exhibits a capacitance of 590 F.g−1 (204 mF.cm−2). Furthermore, the printed supercapacitor on the flexible substrate exhibited an energy density of 161.3 Whkg−1 and a maximum power density of 211kWkg−1. The developed Co0.5Ho0.5Fe2O4/LSG hybrid nanocomposite supercapacitor showed outstanding capacitive performance under harsh mechanical conditions.