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

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.