Scalable, flexible BaTiO₃/PVDF piezocomposites prepared via supersonic spraying for use in energy harvesting and integrated energy storage devices

Flexible piezoelectric nanogenerators (PENGs) are emerging as sustainable power sources for self-charging wearable electronic devices owing to their ability to harvest ambient mechanical energy. The use of piezopolymer polyvinylidene fluoride (PVDF) and piezoceramic barium titanate (BaTiO₃) as flexible composite materials for PENGs deposited using the supersonic cold-spraying technique was investigated in this study. The PENG with an optimized concentration of BaTiO₃ to PVDF generated a piezoelectric voltage of 11.5 V when subjected to a tapping force of 5 N for 15,000 cycles. Scanning electron microscopy images captured after cycling confirm the robustness of the BaTiO₃ and PVDF composite films. A maximum power of 28.7 μW was achieved at an impedance-matching resistance of 0.7 MΩ. A flexible-PENG bending test of 3000 cycles with a bending radius of 0.8 cm confirmed the durability when an optimal PVDF matrix accommodated well-dispersed BaTiO₃ particles. Furthermore, the ferroelectric characteristics of BaTiO₃ and PVDF were activated by electrical poling for 14 h, thereby increasing an open circuit voltage to 37.5 V, indicating the possibility of a 3.3-times enhancement after poling.