UV Radiation-Assisted Chemically Grown Tin Oxide Nanoparticles with Multiwalled Carbon Nanotubes toward Large Area Solid-State Supercapacitors

A simple ultraviolet (UV) radiation-assisted chemical route has been successfully employed to grow tin oxide (SnO 2 ) nanoparticles onto MWCNTs to form SnO 2 -MWCNT nanocomposite. Structural, surface morphological, functional, and elemental techniques have been performed to analyze the nanocomposite. The synthesized nanocomposite has been employed not only as a supercapacitive electrode but also to configure a large area (10 cm × 4 cm) solid-state supercapacitor device. Electrochemical investigation of the electrodes yields a specific capacitance of 122.14 F/g (areal 103.8 mF/cm 2 ) at 5 mV/s with a stable voltage window of 1 V along with capacitive retention of 101% at 3000 cyclic voltammetry (CV) cycles. Interestingly, the solid-state symmetric device delivered a specific capacitance of 36.89 F/g (areal 31.3 mF/cm 2 ) at 5 mV/s with a superior capacitive retention of 90% at 3000 CV cycles with a wider voltage window of 2 V. Two devices in series and parallel combinations have been thoroughly assessed using CV, galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS), and phase angle analysis. Interestingly, the single solid-state device has been successfully employed to power three LED panels and a small fan, whereas two devices connected in series and parallel have been used to power an LED panel consisting of 1150 LEDs, along with a series device powering a large fan to showcase the prototype nature.