Simultaneous achievement of ultrahigh energy storage density and high efficiency in BiFeO3-based relaxor ferroelectric ceramics via a highly disordered multicomponent design

Ceramic-based dielectric capacitors have attracted ever-increasing interest owing to their wide applications in high-power and pulsed-power electronic systems. Nevertheless, synchronously achieving ultrahigh recoverable energy storage density (W-rec) and high efficiency (eta) in dielectric ceramics is still a great challenge. Herein, when lead-free Bi0.9La0.1FeO3-Ba0.7Sr0.3TiO3-K0.5Na0.5NbO3 ceramics with a high disorder degree at the atomic scale was systematically explored, it exhibited an ultrahigh W-rec of 13.9 J cm(-3) and high eta of 89.6% due to the synergistic contribution of high maximum polarization P-max, small remanent polarization P-r and large breakdown strength E-b. The high P-max is generated because of the genes of BiFeO3, while the small P-r originates from the significantly enhanced relaxor behavior. In particular, the large E-b stems from multiple intrinsic and extrinsic factors, such as the decreased average grain size at the submicron scale and promoted electrical microstructure. Moreover, the ceramics displayed exceptional reliability and giant power density. These results not only demonstrate the great potential of BiFeO3-based dielectric ceramics in energy storage applications but also pave a feasible way to develop novel lead-free dielectric capacitors with extraordinary energy storage properties.