Lead-free, high-current output piezoelectric nanogenerators using three-dimensional interdigitated electrodes

Harvesting mechanical energy based on piezoelectricity has attracted extensive attention, but achieving lead-free piezoelectric nanogenerators (PENGs) with high output current is still a big challenge, which severely limit their wide applications. Here, to address it, flexible composites with excellent piezoelectric capability are proposed and used to fabricate lead-free, high-current output PENGs using three-dimensional (3-D) interdigitated electrodes. By forming heterojunctions of Ag/(Ba,Ca)(Zr,Ti)O 3 (Ag/BCZT), polarization charges in BCZT nanowires unidirectionally transfer to Ag nanoparticles under external force, resulting in the enhanced piezoelectric outputs of Ag/BCZT nanowires embedded PVDF composites macroscopically. By creating multi-layered PENGs using 3-D interdigitated electrodes (IPNGs), the total amount of polarization charges increased, giving rise to the significantly improved output current. Optimally, the 4-unit IPNG can generate a proper voltage of 20 V and a considerable current of 15 μA (corresponding current density is 3.75 μA/cm 2 ), which is higher than the other lead-free piezoceramics based PENGs previously. The excellent outputs can also charge a 1 μF capacitor from 0 V to 5.3 V in 30 s (equivalent charge density is 272 μC/m 2 ). This work presents a brand-new paradigm for high-performance PENGs from the perspective of material and device design.