Ultra-high energy harvester performance in KNN-based textured piezoceramics via multiscale reconfiguration design

The lower electromechanical performance of lead-free piezoelectric materials remains a critical bottleneck impeding their ability to replace lead-based materials in energy harvesting. To overcome this predicament, here, we propose a multiscale reconfiguration design to tailor the intricate coupling between structure and properties in (K,Na)NbO3-based piezoelectric materials. The constructed multiphase coexistence, local structural heterogeneity, enhanced crystal anisotropy, and acceptor doping yield (K,Na)NbO3-based ceramics with a harmonious balance between the piezoelectric coefficient and the dielectric constant. As a result, the (K,Na)NbO3-based textured ceramics demonstrate exceptional piezoelectric properties, including a piezoelectric charge coefficient (d33) of 551 pC N⁻¹ and a piezoelectric voltage coefficient (g33) of 54.2 mV m N-1. The energy harvesting devices exhibit an ultra-high instantaneous output power (Pout) of 4.85 mW and an instantaneous output power density (PD) of 70.2 μW mm-3. This work provides valuable insights into the design and development of high-performance lead-free piezoelectric ceramics, and significantly advances the potential of (K,Na)NbO3-based ceramics as viable replacements for Pb(Zr,Ti)O3-based ceramics in energy harvesting applications.