Fabrication and Characterization of Electrospun KNN / PVDF ‐Based Flexible Nanocomposite for Advanced Energy Harvesting Application

ABSTRACT Potassium sodium niobate (K, Na)NbO 3 (KNN) is a desirable lead‐free piezoelectric material that can replace lead zirconate titanate Pb(Zr, Ti)O 3 . In this work, KNN nanopowders were synthesized using the hydrothermal method. X‐ray diffraction analysis confirmed the formation of a monoclinic perovskite crystal structure, which is highly favorable for piezoelectric applications due to its lower structural symmetry that facilitates easier polarization rotation and electromechanical response. A high‐performance piezoelectric nanogenerator (PENG) based on the KNN/PVDF (Polyvinylidene fluoride) flexible nanocomposite films with different percentages of KNN ceramics powder (2, 4, 6, and 8 wt%) was prepared by an electrospinning process. The electrospinning process increases the β‐phase of PVDF, while the incorporated KNN nanoparticles act as effective nucleating agents, further enhancing β‐phase crystallization and piezoelectric properties through strong interfacial interactions between KNN and PVDF. Among these films, the 6 wt% KNN film exhibited the highest piezoelectric properties. When 10 N of pressure was applied to the surface of the fabricated piezoelectric nanogenerator, it produced a good open‐circuit output voltage of ~16 V and a short‐circuit current of ~0.80 μA. The device was tested using different biomechanical motions. Among those actions, wrist pressing yielded the highest output voltage, approximately 19.5 V, the highest short‐circuit current 0.98 μA, at a 20 MΩ load resistance. These values are quite high than the corresponding recent literature. We achieved the maximum Piezo performance by loading a very small amount of filler. Furthermore, the 6 wt% KNN/PVDF PENG exhibited excellent mechanical durability and stable electrical performance over 1000 cycles. These results demonstrate that the flexible PENG is a highly promising candidate for self‐powered, wearable, and implantable electronic applications.