Reactive sputtering of vertically aligned vanadium oxide nanorods on an eco-friendly polymeric substrate for low-cost, flexible, and sustainable supercapacitors

As technology advances, there is a growing demand for flexible supercapacitors (FSCs) with high energy storage capabilities to facilitate seamless integration with wearable electronics. In particular, eco-friendly flexible supercapacitors (Eco-FSCs) are essential for advancing technologies within the Technology with Sustainability (TWS) framework. In this work, a one-step, binder-free, direct current (DC) magnetron sputtering technique was employed for the reactive fabrication of vertically aligned vanadium pentoxide (V2O5) nanorods at room temperature (RT) over a polyvinyl alcohol (PVA) substrate. The symmetric two-electrode mode electrochemical characterization in 1M Na2SO4 aqueous electrolyte revealed a specific capacitance of 160 F/g, a power density of 2 kW/kg, and an energy density of 3.6 Wh/kg. It demonstrated 100% capacitance retention for 2000 charging-discharging cycles, excellent mechanical flexibility, and rapid disposability. For the real-time application, four devices connected in series powered the different colored light-emitting diodes (LEDs) for over 60 s. Therefore, this work presents a facile strategy for fabricating eco-friendly FSCs with superior storage performance. The fabricated materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman spectroscopy, and energy dispersive X-ray spectroscopy (EDX).