LiTaO₃-Based Flexible Piezoelectric Nanogenerators for Mechanical Energy Harvesting

Mechanical energy is one of the freely available green energy sources that could be harvested to meet the small-scale energy demand. Piezoelectric nanogenerators can be used to harvest the biomechanical energy that is available in everyday human life and power various portable electronics. Herein, a ferroelectric material, i.e., lithium tantalate (LiTaO₃), was synthesized and used to fabricate a flexible piezoelectric nanogenerator (FPNG). Generally, ferroelectric materials display a strong electrostatic dipole moment and high piezoelectric coefficient, thus resulting in enhanced electrical performance. First, LiTaO₃ nanoparticles were synthesized and loaded into poly(vinylidene difluoride) (PVDF) to form a piezoelectric film and then, the piezoelectric composite film was sandwiched between two aluminum electrodes to fabricate an FPNG. The effect of the electrical performance of FPNG as a function of the concentration of LiTaO₃ loaded into PVDF was systematically investigated and optimized. The 2.5 wt % FPNG exhibited open-circuit voltage, short-circuit current, and power density values of ∼18 V, ∼1.2 μA, and ∼25 mW/m², respectively. Furthermore, the FPNG revealed good electrical stability and mechanical durability. Finally, the FPNG was employed as a weight sensor to harvest various biomechanical energies and operate low-power- electronics.