Fabrication and Transformation of K_0.5Na_0.5Nb_0.9Sb_0.1O₃ Nanostructures to Nanofibers in PVDF-HFP Matrix for Flexible Nanogenerator-Based Thermal Management in Heat Pipes

A new approach to process one-dimensional antimony-doped potassium sodium niobate nanostructures by a hydrothermal process and electrospinning to prepare KNNSb/PVDF-HFP composite nanofibers are investigated for fabricating a flexible nanogenerator. Crystal structure and morphology analyses of KNNSb nanostructures were carried out using XRD and SEM, respectively, and confirmed the formation of nanostructures having an orthorhombic structure of two symmetries configurations. Also, XRD and FT-IR analysis confirmed the in situ formation of the piezoelectric β-phase of PVDF-HFP and composite nanofibers during the electrospinning process. The dielectric constant of the composite nanofibers film increased significantly compared to pure PVDF-HFP nanofiber film. Developed composite nanofiber film was used for fabricating a flexible nanogenerator using poly­(dimethylsiloxane) as an encapsulating material. The 20 wt % KNNSb/PVDF-HFP composite nanofiber-based nanogenerator generates an open-circuit peak voltage of ∼4.9 V and a 0.25 μA current with a power of 0.78 μW when constant cyclic mechanical pressure is applied on NG using a sewing machine. Foremost, the feasibility study of a KNNSb/PVDF-HFP composite nanofiber-based nanogenerator was carried out by implementing a heat pipe for thermal management and exhibited an open-circuit voltage of ∼150 mV at a temperature of 104 °C.