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.