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

Abstract 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 (PS)/maximum polarization (Pmax) as well as meeting the needs of environment-friendly society. However, the recoverable energy storage density (Wrec) and energy storage efficiency (η) of most BNT-based relaxor ferroelectric 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)TiO3-0.25SrTiO3 (BNST-x) were constructed via A-site defect engineering and prepared by tape-casting method. It is worth noting that an ultrahigh Wrec of 5.63 ​J ​cm−3 together with outstanding η 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 η is higher than 90% and the variation of Wrec is less than ±2% and ±5% within the frequency range of 1–100 ​Hz and temperature range of 30–130 ​°C, respectively. The Wrec is always higher than 3 ​J ​cm−3 and did not deteriorate significantly after 104 fatigue cycles. In addition, the BNST-0.08 ceramic also possesses ultrafast discharge speed (t0.9, less than 125 ​ns) and ultrahigh power density (PD, higher than 147 ​MW ​cm−3) within the temperature range of 30–130 ​°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.