Significantly enhanced energy storage density and efficiency of BNT-based perovskite ceramics via A-site defect engineering

In recent years, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) -based relaxor ferroelectrics have attracted more and more attention for energy storage applications owing to their high power density, large saturated polarization (P-s)/maximum polarization (P-max) as well as meeting the needs of environment-friendly society. However, the recoverable energy storage density and energy storage efficiency (eta) of most BNT-based relaxor ferro- (W-rec) electric ceramics are lower than 3.5 J cm(-3) and/or 80%, respectively, in recently. In this work, the relaxor ferroelectric ceramics of 0.75Bi((0.5+x))Na((0.5-x))TiO(3)-0.25SrTiO(3) (BNST-x) were constructed via A-site defect engineering and prepared by tape-casting method. It is worth noting that an ultrahigh W-rec of 5.63 J cm(-3) together with outstanding eta of 94% can be achieved simultaneously at a relative high electric field of 535 kV cm(-1) with the composition of BNST-0.08, Meanwhile, for BNST-0.08 ceramic, the eta is higher than 90% and the variation of W - rec is less than +2% and +5% within the frequency range of 1-100 Hz and temperature range of 30-130 degrees C, respectively. The W rec is always higher than 3 J cm(-3) and did not deteriorate significantly after 10(4) fatigue cycles. In addition, the BNST-0.08 ceramic also possesses ultrafast discharge speed (t(0.9), less than 125 ns) and ultrahigh power density (P D , higher than 147 MW cm -3 ) within the temperature range of 30-130 degrees C at 300 kV cm(-1). Therefore, the BNST-0.08 ceramic is promising candidate environment-friendly materials for advanced pulsed power capacitor applications and the energy storage properties of BNT-based relaxor ferroelectrics can be enhanced significantly via A-site defect engineering.