Excellent energy storage properties in lead-free ferroelectric ceramics via heterogeneous structure design

Dielectric capacitors with ultrahigh power density have emerged as promising candidates for essential energy storage components in electronic and electrical systems. They enable enhanced integration, miniaturization, and lightweight design. However, the development of dielectric materials for cutting-edge energy storage applications has been significantly limited by their low recoverable energy storage density (W_rec) and energy efficiency (η), especially at moderate electric fields. In this study, we fabricated 0.85K_0.5Na_0.5NbO₃-0.15Sr_0.7Nd_0.2ZrO₃ ceramics with an outstanding energy storage performance (W_rec ~ 7 J cm^-3, η ~ 92% at 500 kV cm^-1; W_rec ~ 14 J cm^-3, η ~ 89% at 760 kV cm^-1). The exceptional energy storage performance can be primarily attributed to the heterogeneous structure, where orthorhombic and tetragonal polar nanoregions are embedded in a cubic matrix. This work provides a good paradigm for designing dielectric materials with ultrahigh energy storage density and excellent energy efficiency at a moderate applied electric field, aligning with the stringent demands for advanced energy storage applications.