Synthesis and characterization of polyindole-NiO-graphene composite for supercapacitor electrode

In this study, indole was chemically polymerized (PIN) onto nickel oxide-graphene (NiO-GR) layers and attached to carbon cloth, forming a composite material (PIN-NiO-GR). The electrochemical performance and capacitive properties of this material were further investigated in alkaline medium using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP) techniques. The lifespan and stability of PIN-NiO-GR composite were evaluated through galvanostatic charge/discharge (GCD) measurements. Moreover, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were also employed to study the physical and chemical characteristics of the PIN-NiO-GR composite. Electrochemical study revealed that the PIN-NiO-GR electrode reaches specific capacitance at a current density of 427.3 F g-1 at 1.2 A g -1 with good cycling stability. It is able to retain 95.7% of initial capacitance after 2000 cycles at the same current density. The electrochemical results deduced from GCD curves and CV were complementary as they confirmed the promise of the PIN-NiO-GR nanocomposite electrode for use in flexible energy storage devices.