Facile preparation of a highly efficient coin cell supercapacitor based on WO3 nanorods

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Developing sustainable energy storage devices is challenging for the progress of energy storage applications. Here, nanotechnology represents a strategic route to reduce the amount of used critical materials, while continuing to take advantage of their properties, thanks to the high surface to volume ratio which characterizes nanostructures. WO3 nanostructures represent a promising active material for energy storage applications, thanks to their wide capability of small positive ions (H+ and Li+) intercalation and their high stability in acidic conditions. The coupling between WO3 nanorods and carbon black powder is studied to realize a highly efficient coin cell supercapacitor. The morphology of WO3 nanorods and carbon black is investigated by using a scanning electron microscope, and the energy storage performances were evaluated by performing cycling voltammetry and galvanostatic charge and discharge analysis, thus obtaining promising specific capacitance results (79 and 70 F/g at 5 mV/s and 0.5 A/g respectively). Moreover, the stability of the obtained coin cell was investigated, thus getting good capacity retention over 250 charge-discharge cycles. Energy and power densities were also calculated, obtaining the highest energy density of 39 Wh/kg at a power density of 500 W/kg. The WO3‑carbon black coin cells are used to power a red LED, so demonstrating the viability for practical applications.