Electrodeposited WO₃ on Stainless Steel as a High-Energy Supercapacitor Electrode

Tungsten oxide (WO₃) thin films were successfully deposited onto stainless steel (SS) substrates via an electrochemical deposition method. The structural and electrochemical characteristics of the resulting WO₃/SS electrode were systematically investigated using a three-electrode configuration in an aqueous electrolyte. Cyclic voltammetry (CV) measurements revealed that the electrode maintains a wide electrochemical stability window of approximately 1.2 V, indicative of its suitability for high-energy applications. At a scan rate of 10 mV s⁻¹, the WO₃/SS electrode delivered a high specific capacitance of 652.9 F g⁻¹, reflecting excellent charge storage capability. Galvanostatic charge-discharge (GCD) tests performed at a current density of 1 A g⁻¹ yielded an impressive energy density of 139.9 Wh kg⁻¹ and a corresponding power density of 7160.6 W kg⁻¹. Moreover, the electrode retained a high Coulombic efficiency of 98.2% after 10,000 continuous GCD cycles, highlighting its outstanding cycling stability. These results demonstrate that the WO₃/SS electrode is a promising candidate for next-generation supercapacitor devices, offering both high energy and power densities along with long-term durability.