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

Abstract

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 (η) in dielectric ceramics is still a great challenge. Herein, when lead-free Bi_0.9La_0.1FeO₃–Ba_0.7Sr_0.3TiO₃–K_0.5Na_0.5NbO₃ 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 η 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.