3D spirally coiled piezoelectric nanogenerator for large impact energy harvesting

Piezoelectric nanogenerator is an emerging technology that can convert irregular discrete mechanical energy in the environment into electricity, which provides a long-term continuous power supply solution for mobile distributed electronics. However, it is still difficult to effectively harvest the large impact mechanical energy. Here, we developed a new kind of three-dimensional spirally coiled piezoelectric nanogenerator (SC-PENG), which can effectively convert irregular axial impact forces into uniform radial pressures, and achieve large-scale impact mechanical energy harvesting (corresponding pressures range from 80 kPa to 6.32 MPa). Especially, under a large impact pressure of 3.05 MPa, the output current, voltage and the equivalent transfer charge density of SC-PENG is up to 196 mu A, 36 V and 2550 mu C m(-2) respectively, which break the record of PENG among previous studies. The volume of the piezoelectric film and the corresponding volume charge density are 0.224 cm(-3) and 580 nC cm(-3), respectively. Moreover, factors such as particle connectivity and modulus of the piezoelectric film are explored in detail, which can further improve the electromechanical conversion capability of PENG. This work not only achieves high electrical output of PENG, but also paves an efficient strategy for large impact mechanical energy harvesting towards practical application.