Enhanced energy harvesting ability of bismuth sodium titanate/polyvinylidene fluoride composite film-based piezoelectric nanogenerators for mechanical energy scavenging and safety-walker applications

Herein, we proposed a piezoelectric Bi_0.5Na_0.5TiO₃ (BNT)/polyvinylidene fluoride (PVDF) flexible composite film-based peizoelectric nanogenerator (PNG) device as a highly efficient mechanical energy harvester. Initially, the BNT nanoparticles (NPs) with high dielectric constant were synthesized and loaded into a PVDF polymer matrix. The effect of BNT loading on the chemical property, dielectric property, and β phase of PVDF-based composite films was analyzed in depth. The various PNG devices based on the PVDF piezoelectric films with different concentrations of BNT NPs and aluminum electrodes were fabricated. The external force was applied to all the PNGs and their electrical output was systematically investigated to find the optimal concentration of BNT NPs inside the PVDF. The optimized 0.5 wt% BNT loaded PVDF composite film-based PNG device produced a highly efficient electrical output of about 19 V, 1.2 μA, and 3.5 mW/m². The fabricated PNG device was robust and could generate highly stable electrical output over a long period. A highly efficient external electrical circuit was developed to effectively store the generated electricity from the PNG into various energy storage devices. Furthermore, the generated electrical energy was utilized to charge various energy storage capacitors and to power small electronics. Additionally, the flexible PNG device was demonstrated as a biomechanical energy harvester to convert various human movements into electricity successfully. Owing to the high flexibility, robustness, and energy conversion efficiency of the fabricated PNG device, it is expected to be utilized to harvest various mechanical movements available in daily life through large-scale technology. The unique PNG-powered self-illuminating bracelet-based safety walker system was proposed, which can be utilized in daily life to avoid accidents on roads and for many other applications.