Ultrahigh energy harvesting properties in textured lead-free piezoelectric composites

Piezoelectric energy harvesters have gained significant attention in recent years due to the strong demand of sustainable power sources for wireless sensor networks and portable/wearable electronics. However, the relatively low figure of merit (d × g) induced by thermodynamic constraints seriously hinders the enhancement of power generation capability in lead-free piezoelectrics. In this work, crystallographic texture and composite design strategies were integrated to develop novel 0-3 type (Ba, Ca)(Ti, Sn)O ₃ /BaTiO ₃ (BCTS/BT) composites with highly [001] _c -oriented and "core-shell" structured grains to resolve this challenge. Increasing texture degree F ₀₀₁ above 86% enabled rapid enhancements of piezoelectric charge/strain coefficients d ₃₃ and . Meanwhile, the inclusion of low-ϵ _r BT microcrystals inside the oriented BCTS grains effectively suppressed the dielectric permittivity ϵ _r of the composites, thus remarkably improving the piezoelectric voltage coefficient g ₃₃ . Especially, the 98%-textured 0-3 composites demonstrated as high as ∼405% improvement in d ₃₃ × g ₃₃ value (17.0 × 10 ^-12 m ² N ^-1 ), attributed to the strong piezoelectric anisotropy, the formation of much finer domains and the elastoelectric composite effect. The cantilever energy harvesters based on such composites possessed ∼560% enhancement in power density (4.5 μW mm ^-3 ) at 1 g acceleration relative to the non-textured counterpart, which significantly outperformed many previously reported lead-free piezoelectrics. This work provides a new important paradigm for developing high-performance viable green energy harvesters, which can largely expand the application fields of lead-free piezoelectrics.