Tailoring Nb2O5@α-Fe2O3 NanocompositeHeterostructures for a WearableQuasi-Solid-State Asymmetric Supercapacitor

Abstract The orthorhombic Nb2O5 and α-Fe2O3 composite exhibits strong intercomponent synergy, making it a promising candidate for high-performance supercapacitor applications. In the present study, orthorhombic Nb2O5 and α-Fe2O3 composites were synthesized at the ratios 1:1, 1:2, and 2:1 (NFO11, NFO12, and NFO21). The as-prepared samples were subjected to various physicochemical characterization to confirm their structure, surface morphology, and surface chemical environment. The NFO12 electrode exhibits the highest specific capacitance of 220 F g–1 at a current density of 1 A g–1, surpassing all other electrode materials. NFO12 and activated carbon (AC) materials on a graphite sheet were sandwiched to fabricate an asymmetric supercapacitor (NFO12// AC), which delivers specific energy and specific power of 15 Wh kg–1 and 916 W kg–1, respectively. The fabricated devices were tested by glowing the different voltage LED bulbs. Additionally, a flexible asymmetric supercapacitor (FASC) device was fabricated using carbon cloth as the substrate, which exhibits specific energy and specific power of 20 Wh kg–1 and 900 W kg–1, respectively. Furthermore, excellent cyclic stability, with 94% Coulombic efficiency and 93% capacitance retention, was achieved at a zero-degree (nonbending) angle even after 10,000 cycles. Similarly, the FASC device at a 180-degree bending angle shows 93% Coulombic efficiency and 92% capacitance retention even after 10,000 cycles. FASC devices were examined under various stressed conditions to substantiate the flexibility behavior.