Self-poled piezoelectric charge generator–separator for a hybrid self-charging piezo-supercapacitor

On-demand, compact, self-powered electronics have attracted interest in hybrid piezoelectric–supercapacitors as alternatives to traditional batteries. However, their practical implementation is limited by the requirement of high-field external poling for the piezoelectric layer, the need for separate charge generation and storage layers, and poor self-charging stability. To address these challenges, we report a fully self-poled piezoelectric-supercapacitor hybrid device based on a cerium-doped porous β-PVDF composite film. The film simultaneously functions as mechanical energy harvester and an electrolyte-permeable separator enabling concurrent charge generation and storage within a single flexible structure. Cerium doping induces electroactive β-phase formation (∼89 %) through hydrogen bonding and dipole alignment, thereby eliminating the need for external electrical poling. Under biomechanical motion, the film generates a peak output voltage of 13.6 V and a short-circuit current of 0.5 μA, sufficient to power small electronic components. The hybrid device, assembled with MnO₂ nanowire electrodes and a PVA-H₃PO₄ gel electrolyte, self-charges up to 690 mV under biomechanical motion and delivers an areal capacitance of 10.51 mF/cm² and an energy density of 1.46 µWh/cm², with excellent cyclic stability. This self-poled, dual-functional PVDF-based piezoelectric separator offers a scalable and environmentally friendly route towards next-generation hybrid energy harvesting devices.