Introducing of WO3@NiCo2O4/rGO ternary nanocomposites as active material for high-performance supercapacitor applications

Abstract

The combined materials with synergistic effects and integrate of properties of each component can be widely used for high capacity and high-power density storage devices. In this study, synthesis, energy storage ability and characterization of the novel ternary WO3@NiCo2O4/rGO nanocomposites (NWG) as active electrode materials are studied. NWG nanocomposites as high-efficiency supercapacitors material which is perfect transferring ions/electrons are constructed with multiple-step synthesis for supercapacitor application for the first time. For this purpose, at first, intertwined nanosheets of NiCo2O4 was synthesized through the hydrothermal process, afterwards, WO3 nanostructures were fabricated on the surface of NiCo2O4 via sonochemical method and finally, NWG nanocomposites were synthesized during the mild hydrothermal conditions. Towards the studying the physicochemical properties of as-fabricated NWG nanocomposites, the X-ray diffraction (XRD), Fourier transform infrared (FT-IR), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX) analysis were used. Also, the electrochemical behavior of innovative NWG nanocomposites as energetic electrode materials was investigated in two and three electrode configurations for high-performance supercapacitor application. Additionally, the synergetic effect between NiCo2O4, WO3 and rGO substrates in final product (NWG) was investigated based on cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic stability test. The well-designed NWG nanostructures with layered shape can acceleration the ion electrolyte diffusion and provided more redox active sites through energy storage process. The electrochemical results of the NWG nanocomposite electrodes represented a high specific capacity of 1211.75 F g−1 at a current density of 1.5 A g−1. Furthermore, the suggested electrode exhibited the great energy density of 11.92 Whkg−1, power density of 3000.8 Wkg−1 and excellent rate capability (91.51 % of capacity retention after 1000 cycles). Moreover, the specific capacitance of bare and binary nanocomposites i.e. NiCo2O4 and WO3@NiCo2O4 were investigated and compared with NWG at a current density of 2 A g−1. The results show that the specific capacitance of NWG ~1.5 times greater than NiCo2O4 and WO3@NiCo2O4 nanostructures [NiCo2O4 (498.33 F g−1), WO3@NiCo2O4 (580.33 F g−1) and NWG (917.67 F g−1)]. Remarkably, an asymmetric supercapacitor (ASC) assembled by newly-designed NWG electrode as a positive electrode and activated carbon (AC) as a negative electrode exhibited the good specific capacitance 37.2 mF g−1 at of 1.5 mA g−1. Also, the ASC device could provide energy density of 4.75 mWh kg−1 at the power density of 799.9 mWkg−1. This research recommends that NWG nanocomposites have an extraordinary potential for evolution of active electrode materials forthcoming supercapacitors in energy storage systems.