High performance triboelectric nanogenerators based on phase-inversion piezoelectric membranes of poly(vinylidene fluoride)-zinc stannate (PVDF-ZnSnO₃) and polyamide-6 (PA6)

Vertical contact-separation mode triboelectric generator (TEG) based on lead-free perovskite, zinc stannate (ZnSnO₃)-polyvinylidene fluoride (PVDF) composite and polyamide-6 (PA6) membrane is demonstrated. For the 5 wt% PVDF-ZnSnO₃ nanocomposites, the facile phase-inversion method provides a simple route to achieve high crystallinity and β-phase with a piezoelectric coefficient d₃₃ of −65 pm V⁻¹, as compared to −44 pm V⁻¹ for pristine PVDF membranes. Consequently, at a cyclic excitation impact of 490 N/3 Hz, the PVDF-ZnSnO₃/PA6 based TEGs provide a significantly higher voltage of 520 V and a current density of 2.7 mA m⁻² (corresponding charge density of 62.0 µC m⁻²), as compared to the pristine PVDF-PA6 TEG which provides up to 300 V with a current density of 0.91 mA m⁻² (corresponding to a charge density of 55.0 µC m⁻²). This increase in the electrical output can be attributed to not only the enhanced polarisation of PVDF by ZnSnO₃ leading to an increase in the β-phase content, but also to the surface charge density increase by stress induced polarisation of ZnSnO₃, leading to the generation of stronger piezoelectric potential. The work thus introduces a novel method of enhancing the surface charge density via the addition of suitable high polarisation piezoelectric materials thus eliminating the need for prior charge injection for fluoropolymer membranes.