Polyvinylidene Fluoride Energy Harvester with Boosting Piezoelectric Performance through 3D Printed Biomimetic Bone Structures

As an effective way of power-to-electricity conversion, piezoelectric energy harvesters have received extensive attention in the past decade. However, the relationship between output performance and the topological structure of piezoelectric devices is still unknown. In this study, a simple and fast in-situ chemical foaming assisted fused deposited modeling (FDM) method was developed, and complex three-dimensional (3D) bioinspired bone structures of polyvinylidene fluoride (PVDF) were successfully fabricated. The hierarchical porous structure couples advantages of arbitrary shape design by 3D printing and abundant inner pores inside the printed piezoelectric parts that amplify the stress–strain effect and improve the output capacity. Moreover, with the assistance of ionic liquid, high β-phase content (86.72%) PVDF was achieved, producing an output of ∼13 V and a maximum current density of ∼0.27 μA/cm2, which outperforms most of the PVDF piezoelectric energy harvesters reported so far. Impressively, the as-prepared PVDF device can directly light up eight green LED bulbs and charge a 1 μF commercial capacitor to 3.65 V within 300 s. This work highlights a new 3D printing strategy integrated with a 3D biomimetic structural design for high-performance piezoelectric energy harvesting.