Bi0.5Na0.5TiO3-based energy storage ceramics with excellent comprehensive performance by constructing dynamic nanoscale domains and high intrinsic breakdown strength.

Lead-free ceramic-based dielectric capacitors show huge potential in electrical energy storage in pulsed power systems due to their fast charge/discharge rate, ultrahigh power density and environmental friendliness. However, unsatisfied charge/discharge performance characterized by inferior recoverable energy storage density (W rec generally <5 J/cm³) has become a key bottleneck to restrict their applications in cutting-edge energy storage devices. In this paper, we focus on simultaneously realizing ultrahigh W rec and efficiency (ƞ) in eco-friendly Bi 0.5 Na 0.5 TiO 3 (BNT)-based dielectric ceramics via chemical doping. Interestingly, highly dynamic polar nanoregions (PNRs) and nanodomains are constructed by incorporating Sr 0.7 Nd 0.2 TiO 3 (SNT) into 0.94BNT-0.06BaTiO 3. Of great importance, the resulting relaxor ferroelectrics (RFEs) exhibit high bulk resistivity, submicron grain size and wide band gap due to high level of SNT doping accompanying with 1 at% Nb donor doping. Therefore, excellent energy storage properties with ultrahigh W rec ∼8.08 J/cm³ and ƞ ∼92.1% are achieved due to coexistence of large polarization difference (Δ P = P max − P r) and giant dielectric breakdown electric field (E b ∼540 kV/cm). Furthermore, excellent temperature / frequency/cycling stability characterized by Δ W rec < ±4% and Δ η < ±2% ensure the energy storage applications of the studied dielectric ceramics over an enormous range of scales. [Display omitted] • Energy storage performance of 0.96BNT-0.06BT ceramic is remarkably improved by SNT and Nb co-doping. • Ultrahigh W rec ∼8.08 J/cm3 and ƞ ∼92.1% are simultaneously realized due to existence of large Δ P and giant E b. • Excellent temperature/frequency/cycling stability are characterized by Δ W rec <+4% and Δ η <+2% • The present paper provides a strategy to design advanced high/pulsed power dielectric capacitors. [ABSTRACT FROM AUTHOR]