Outstanding comprehensive energy storage performance in BNT-based lead-free ceramics via synergistic optimization strategy

Lead-free ceramic dielectric capacitors have attracted substantial attention for application in pulsed power systems, thanks to their high power density, outstanding thermal stability, fast charge/discharge rates, and eco-friendly properties recently. However, their practical applications have been constrained by relatively low recoverable energy storage density (W-rec < 6 J/cm(3)) and/or energy storage efficiency (eta < 90 %). To address this limitation, this study focused on optimizing both the W-rec and eta of lead-free ceramics through the development of Bi0.5Na0.5TiO3-Sr0.85Bi0.1TiO3-SrHfO3 compositions, employing a synergistic optimization strategy. This approach involved decreasing porosity, enhancing bandgap, inducing smaller domains and linear-like behavior to minimize remnant polarization while maintaining high maximum polarization and increasing breakdown strength. As a result, an impressive energy storage performance was attained, featuring a high W-rec of 7.07 J/cm(3) and an almost ideal eta of 94 % under an electric field of 550 kV/cm. Moreover, the energy storage properties demonstrated remarkable stability across a wide temperature range (25-150 degrees C), frequency range (1-200 Hz), and up to 4.5 x 10(4) cycles. Thus, the Bi0.5Na0.5TiO3-Sr0.85Bi0.1TiO3-SrHfO3 lead-free ceramics developed in this study show great promise for pulsed power applications, providing a viable method for improving the energy storage performance of lead-free dielectric capacitors.