High-performance underwater energy harvesting using flexible piezoelectric nanogenerator based on electrospun polyvinylidene fluoride-LiNbO3 fibers

Abstract

A piezoelectric nanogenerator based on PVDF/lithium niobate (NB) for water-energy harvesting is described in this paper. PVDF nanofibers with varying concentrations of NB (0, 0.5, 1, 1.5, and 2 wt%) were synthesised by electrospinning using DMF and acetone as solvents. NB microparticles were found to augment the β-phase concentration in PVDF. Optimizing the NB concentration is vital for superior piezoelectric properties, with 1.5 wt% NB in PVDF yielding the highest β-phase content and enhanced performance. The uniform dispersion of NB throughout the PVDF matrix enhances the formation of PVDF's β phase while decreasing the occurrence of the less desirable α phase structure. A PENG was fabricated with PVDF containing 1.5 wt% NB and tested under finger tapping, producing an output of 7 V. Underwater energy harvesting tests, conducted across water flow speeds of 0–2 m/s, revealed a maximum peak-to-peak voltage of 92.5 V and a short-circuit current of 48 µA at 2 m/s. The device produced 1.24 mW of power and a power density of 0.41 W/m² when connected to 10 kΩ load. This performance allowed for the illumination of 50 blue LEDs and facilitated the charging of a 10 µF capacitor to 17 V in just 20 seconds. The nanogenerator exhibited excellent anti-biofouling properties, resisting biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa, ensuring long-term efficiency under underwater conditions. These findings highlight the potential of the device to harvest water energy effectively, offering a sustainable alternative to conventional batteries and enabling the powering of submersible wireless sensor networks.