Core-sheath PVDF hollow porous fibers via coaxial wet spinning for energy harvesting

As a promising sustainable power source for intelligent electronics, flexible piezoelectric nanogenerators (PENGs) have gained significant attention for their potential applications in the Internet of Things. Here, the polyvinylidene fluoride (PVDF) fibers with a core-sheath hollow porous structure that consisting of the liquid metal (LM) as the inner electrode layer and the copper and silver nanoparticle (Cu@AgNP) as the external electrode layer are prepared via a coaxial wet spinning process to construct high-performance PVDF/LM/Cu@AgNP composite fibers. The PVDF fiber has stratified pore structure and the existence of arbitrarily deformable LM electrode, which significantly reduces the effective dielectric constant, thereby enhancing the piezoelectric properties. The results demonstrate that PVDF/LM/Cu@AgNP-PENG yields an optimal voltage output of 410 mV, providing a clear advantage over PENG by using alternative fibers. Moreover, the PVDF/LM/Cu@AgNP-PENG demonstrates an excellent charging capability for energy storage devices, being able to charge 1 µF capacitors to 10 V within 30 seconds and directly power commercial LEDs. This study demonstrates the significant potential for utilizing composite PVDF piezoelectric fibers in flexible wearable electronic devices.