Improving energy storage efficiency through carbon doping of niobium oxide nanomaterials derived from areca husk in redox flow batteries and supercapacitors

Abstract

In this study, niobium oxide nanoparticles (NbO2) were synthesized using the hydrothermal technique and then composite with areca activated carbon (ACs) to produce activated carbon‑niobium oxide (ACs-NbO2) nanocomposite for use in energy storage devices. The surface morphology and properties were characterized using various techniques, such as FE-SEM, EDX, XRD, Raman spectroscopy, and BET. The composites were used to modify the electrode, and the electrochemical behavior was analyzed using various studies, including CV, CP, ESI, and Tafel methods. The results showed that the modified electrode improves the electrochemical performance, reversibility, faradaic redox reaction, and stability of the material compared to the untreated electrode. Additionally, the electrocatalytic activity of the composite material was tested for use in iron and vanadium redox flow batteries and its charge and discharge performance was studied using a 132 cm2 active surface area at different current densities. The results showed a significant improvement in the electrochemical performance of the VRFBs and IRFBs, with a columbic efficiency of 87 % and 89 % respectively. The electrode also displayed good life cycle stability in VRFBs and IRFBs, up to 100 cycles and 25 cycles respectively. Furthermore, the composite material was also tested for supercapacitor applications, showing a specific capacitance of 245 Fg−1 and a CE of 81 % with 77 % retention after 3000 cycles. This is a pioneering work in the field of energy storage devices as it utilizes low-cost and abundant areca husk to obtain the electrocatalyst, and the electrocatalytic activity is further improved by the NbO2 nanocomposite.