Probing the influence of morphological transformation on the electrochemical properties of hydrated tungsten oxide (WO _{3− <i>x</i>} ·H ₂ O) for a high-rate aqueous asymmetric supercapacitor

The present study aims to probe morphological tuning of hydrated tungsten oxide (WO_3-<i>x</i>·H₂O) nanostructures and investigate their electrochemical performance for energy storage in supercapacitors. The WO_3-<i>x</i>·H₂O nanostructures have been prepared <i>via</i> a single-step wet chemical method. Furthermore, a morphological transition of WO_3-<i>x</i>·H₂O nanostructures from nanosheet-assembled nanoflowers (W1) to nanoribbons (W2) as a result of regulating the reaction time has been achieved without disturbing the orthorhombic crystal structure. The morphological transformation from W1 to W2 exhibited a decrease in crystallinity and other physical properties, significantly affecting electrochemical behavior. Electrochemical investigations revealed that W1 has a higher specific capacitance (70 F g^-1) than W2 (37 F g^-1) at a current density of 1 A g^-1. Moreover, an aqueous asymmetric supercapacitor (AASC) device was fabricated using WO_3-<i>x</i>·H₂O as the negative electrode. The device exhibited a specific capacitance of 40 F g^-1 at 0.5 A g^-1 with an energy density of 12.5 W h kg^-1 and a power density of 3784 W kg^-1. Additionally, it demonstrated excellent cycling stability with 97% capacitance retention over 5000 cycles. These findings highlight the potential of morphology-controlled WO_3-<i>x</i>·H₂O nanostructures for advanced energy storage applications.