Synchronously enhancing energy storage density, efficiency and power density under low electric field in lead-free ferroelectric (1-x)(Bi0.5Na0.5)0.7Sr0.3TiO3-xSr1/2La1/3(Ti0.7Zr0.3)O3 ceramics

Lead-free ferroelectric ceramics with outstanding energy storage properties (ESP) are considered as the most prospective candidates applied in advanced pulsed power systems (APPS). Nevertheless, the recoverable energy storage density (Wrec) and energy storage efficiency (η) are still difficult to be satisfied simultaneously. In this work, the lead-free ceramics were fabricated by doping Sr1/2La1/3(Ti0.7Zr0.3)O3 into (Bi0.5Na0.5)0.7Sr0.3TiO3 matrix (BNST-SLTZ) to optimize the ESP. The introduction of SLTZ induces the generation of polar nano regions (PNRs) to increase the proportion of weakly polar phase and flatten the dielectric peak, resulting in an effective decline of the remnant polarization (Pr). Furthermore, apparent grain size refinement is observed with the doping of SLTZ which enhances the breakdown strength (BDS). Excellent energy storage performances (Wrec of 2.06 J/cm3, η of 90.6%) are achieved under a low electric field of 170 kV/cm in the 0.90BNST-0.10SLTZ ceramic accompanying with good temperature (25–150 °C) and frequency (10–90 Hz) stability. Furthermore, an outstanding current density (CD of 976.15 A/cm2) and an ultrahigh power density (PD of 78.09 MW/cm3) are gained at 160 kV/cm. Therefore, the strategies of constructing PNRs and reducing grain size provide an achievable approach to exploit lead-free ceramics applied in APPS and improve the ESP of environment-friendly ferroelectrics. [Display omitted] •Induce polar nanoregion to flatten dielectric peak and decline remnant polarization.•Apparent grain size refinement is achieved by ions substitution and donor doping.•Obtain high Wrec of 2.06 J/cm3 and η of 90.6% at low electric field of 170 kV/cm.•Achieve high CD (976.15 A/cm2) and ultrahigh PD (78.09 MW/cm3) at 160 kV/cm.