Spray Fluidized Bed Assisted Flexible Robust Lightweight Hollow Metallic Sphere Based Triboelectric Nanogenerator

Lightweight hollow metallic spheres are attracting significant interest for nanogenerator applications due to their exceptional combination of low density and high mechanical strength. This balance of structural integrity, reduced mass, and high specific strength is essential for ensuring the durability and long-term performance of nanogenerator devices optimized for efficient mechanical energy harvesting. In this work, we have fabricated lightweight and high-performance Fe-Cr-Ni alloy hollow metallic sphere (HMS) based triboelectric nanogenerators (TENGs) as robust energy-harvesting devices. The HMS was fabricated by using a method involving sacrificial expanded polystyrene (EPS) and a metal slurry to enhance the mechanical properties and energy conversion efficiency of the TENG device as compared to the uncoated EPS based device. Comprehensive characterization of the physical morphology, chemical composition, and microstructural properties of both HMS and EPS was conducted. The electronic properties of HMS, with a work function of 4.23 +/- 0.2 eV, were found to be superior to those of EPS, which exhibited a work function of 4.49 +/- 0.2 eV. This difference, highlighted by significant variances in potential observed in surface Kelvin probe force microscopy (SKPFM) measurements, indicates a higher efficiency in electron transfer and charge storage capabilities for HMS. Furthermore, the dielectric constant (kappa) of HMS was determined to be exceptionally high, measuring 1.6 x 10(7) at a low frequency of 10 kHz and reaching 3.7 x 10(7) at a frequency of 2 MHz. These properties are integral to the high-performance TENGs that incorporate HMS and EPS with a flexible ITO-coated PET substrate, demonstrating remarkable energy-harvesting capabilities. Notably, the HMS-based nanogenerator exhibits an energy output of 25 V even under minimal pressure, significantly outperforming the EPS-based nanogenerator. The findings confirm the potential of HMS-based TENGs as robust, lightweight solutions for effective mechanical energy scavenging, suggesting substantial applicability in current and emerging energy technologies.