Significantly enhanced energy harvesting performance in lead-free piezoceramics via a synergistic design strategy.

With the rapid development of the Internet of Things, there exists an urgent necessity for high performance piezoelectric energy harvesters to facilitate the construction of more efficient wireless sensor systems. However, the development of piezoelectric energy harvesters with high power density remains a major challenge. In this study, we present a synergistic design strategy aimed at improving the output performance of piezoelectric energy harvesters. Micro-pores with low permittivity were introduced into the ceramics to improve the piezoelectric key parameters, including the piezoelectric voltage coefficient (g₃₃) and the piezoelectric energy harvesting figure of merit (FoM₃₃). The barium titanate (BTO) ceramics with 60% aligned pores obtained high g₃₃ and FoM₃₃, which were up to 24.8 × 10^-3 V m N^-1 and 3.3 × 10^-12 m² N^-1. By optimizing the aspect ratio of each ceramic unit, a higher effective stress level dispersed in the ceramic phase was achieved, and the open circuit voltage of the sensor was significantly improved (41.3%). The construction of high-output performance piezoelectric energy harvesters based on BTO ceramics with relatively low piezoelectric coefficients was successfully achieved via this synergistic design strategy. This high-performance energy harvester exhibits excellent open-circuit voltage (354.8 V), short-circuit current (710.1 μA) and power density (16.7 mW cm^-2), demonstrating the feasibility of this synergistic design strategy in developing high-output energy supply systems. The application of piezoelectric energy harvesters in powering micro-devices and monitoring train stability was demonstrated. This work is expected to provide new opportunities for the fabrication of future self-powered electronic devices.