Microstructural Engineering of Poly(vinylidene fluoride) Nanofibers Enables Superior Piezoelectric Nanogenerators for Motion Monitoring

Piezoelectric nanogenerators (PENGs) are promising for efficient nanoenergy harvesting, yet their output is often limited by disruption of the active phase by nonpolar phases. Here, we introduce a postelectrospinning hot-stretching treatment after conjugated electrospinning to precisely regulate the microcrystalline morphology of a poly(vinylidene fluoride) (PVDF) nanofiber yarn (NY). This strategy increased the lamellar long period and lateral size of the resultant NY, yielding a highly regular crystalline structure with ∼60% crystallinity and ∼93% β-phase content. Consequently, the optimized PVDF NY achieved a fracture stress of 65 MPa, a 444% improvement over the pristine sample. The piezoelectric output also rose by 366.7%, from 0.3 to 1.4 V. These enhancements highlight hot stretching as an effective approach to simultaneously improving the mechanical and electrical properties of a PVDF NY. This work provides a new pathway for developing high-performance PENGs with significant potential in sustainable energy-harvesting applications.