Multilayered Piezoelectric Nanogenerator Based on Lead-Free Poly(vinylidene fluoride)-(0.67BiFeO₃-0.33BaTiO₃) Electrospun Nanofiber Mats for Fast Charging of Supercapacitors

Polymer-based piezoelectric nanogenerators (PENG) produce satisfactory voltage but low current outputs. Herein, a flexible, multilayered PENG with a high power density is demonstrated based on poly(vinylidene fluoride) (PVDF)-[0.67(BiFeO3)-0.33(BaTiO3)] (BF33BT) electrospun nanofiber mats. With a maximum β-phase and piezoresponse, the optimized composite with 30 wt % BF33BT was used to fabricate the multilayered PENG (MPENG). The MPENG, comprising three layers, shows an open-circuit voltage, short-circuit current, and instantaneous power density of 83 V, 1.62 μA, and 142 mW m–2, respectively, by applying a compressive force of 0.1 kgf at 3 Hz frequency. This power density is almost three times more than that of a single-layer composite-based PENG and 65 times more than that of a single-layer PENG of pristine PVDF. The exceptional piezoresponse is due to the combined effect of the piezoceramic and multilayered structures. The MPENG was used to charge a supercapacitor (0.047 F) up to 1.5 V in 660 s to power a calculator. The device showed no performance degradation for more than 5000 cycles, thus opening up promising avenues for sustainable energy harvesting applications.