High output power density of a shear-mode piezoelectric energy harvester based on Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ single crystals

Wireless sensing is widely adopted in internet of things (IoT) systems, but battery replacement is a critical issue for these devices. Triboelectricity, solar, heat, and vibration can be potential energy sources. Piezoelectric energy harvesters that can obtain energy from ambient vibrations are thought to be a promising approach to this problem. However, state-of-the-art energy harvesters made from cantilever-structured piezoelectric ceramics exhibit low output power densities. In this paper, we propose a bridge-type shear-mode piezoelectric energy harvester based on Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) single crystals. Owing to the large figure-of-merit d₁₅×g₁₅ (1.296 ×10⁻¹⁰C V m N⁻²) of the crystal and the higher electromechanical transfer efficiency of the flex-tensional structure when compared to a ceramic cantilever structure, the newly designed shear-mode energy harvester exhibits a power density of up to 1.378×10⁴ W m⁻³. This is much higher than the power densities provided by conventional cantilever energy harvesters based on piezoelectric ceramics (~10² W m⁻³). The output voltage and maximum output current are 21.6 V_pp and 6×10⁻⁴ A_pp, respectively under an inertial force of 0.25 N. This output current and power density are 5.5 times and 3.0 times, respectively, higher than those of the same structured energy harvester made from soft piezoelectric ceramics. A sample wireless sensing and data transmission system is successfully powered by the newly designed energy harvester. This work may help to address the issue of sustainable energy supplies for IoT systems.