Shear stress-induced augmentation of electroactive phases of PVDF for high-power nanogenerator using supersonically sprayed Sr2SnO4 nanorods

초록

Supersonic spraying is a scalable, non-vacuum, rapid coating technique that uses a supersonic gas stream from a de Laval nozzle to deposit precursors under atmospheric conditions. In this study, the supersonic spraying of Sr2SnO4 nanorods (SSO-NRs) was found to increase the content of electroactive ,B-and gamma- phases in poly (vinylidene fluoride) (PVDF) by more than twofold. Specifically, shear stress between the PVDF and SSO-NRs, induced by supersonic blowing, amplified the ,B-and gamma-phases, which enhanced the energy-harvesting performance of a flexible piezoelectric nanogenerator (PENG). The swirling of the high-aspect-ratio SSO-NRs intensified the turbulence, thereby magnifying the influence of the shear stress. The supersonically driven shear stress caused multidirectional stretching, elongation, and twisting of PVDF and transformed a large amount of the alpha-phase into electroactive ,B-and gamma-phases, as evidenced by Xray diffractometry and infrared spectroscopy. The composite film with a minimal filler content of 2.5 wt.% exhibited a piezopotential of 41 V without additional poling. The optimal SSO/PVDF-based PENG delivered a high power density of 90 mu W cm-2 when subjected to a tapping force. Furthermore, the practical applicability of the PENG was demonstrated using air pressure, vibration, and human body movement. The fabricated PENG device was integrated with a supercapacitor electrode to exhibit a wide application range in wearable and portable electronics. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

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