Electrospinning of porous polyvinylidene fluoride microspheres alloyed fibrous membrane with enlarged strain for efficient piezoelectric energy harvesting

Piezoelectric energy harvesters (PEHs) developed from electrospun polyvinylidene fluoride (PVDF) fibers offer flexibility and superior piezoelectric output, making them promising for self-powered systems and sensors. Nonetheless, the electromechanical conversion efficiency of conventional electrospun PVDF fibers is impeded by their limited pressure-strain range. Herein, elastic porous PVDF microspheres are introduced in-situ via electrospinning to craft a piezoelectric membrane with higher compressive strain. The PVDF microspheres are uniformly embedded between the fibers in a sandwich fashion, and their dimension is easily tunable by varying spinning solution's concentration. Moreover, the micropores on the PVDF microspheres created by removing pre-mixed SiO₂ template not only elevates the β crystal content of PVDF to 82.19%, but also improves the compressibility, significantly boosting the piezoelectric output. The microsphere alloyed PVDF PEH delivers a piezoelectric output of 33.0 V and a power density of 8 μW/cm², over 5.8 times that of conventional electrospun PVDF membrane, and can consistently charge lithium-ion batteries. Our research unveils a novel strategic path to modify fiber structured PEHs, advancing their applications in self-powered systems.