Ultrahigh energy storage density in lead-free relaxor antiferroelectric ceramics via domain engineering

Dielectric capacitors have drawn growing attention for their wide application in future high power and/or pulsed power electronic systems. However, the recoverable energy storage density (Wrec) for dielectric ceramics is relatively low up to now, which largely restricts their actual application. Herein, the domain engineering is employed to construct relaxor antiferroelectric NaNbO3-BiFeO3 bulk ceramics, which integrates the merits of antiferroelectrics and relaxors. It is revealed that the antiferroelectric phase transforms from orthorhombic P to R phase, and antiferroelectric domain evolves from micron-sized blocks to nanoscale clusters. Of particular importance is that the 0.90NaNbO3–0.10BiFeO3 ceramic demonstrates ultrahigh Wrec of 18.5 J cm−3 with giant electric breakdown strength of 99.5 kV mm−1, which is superior than state-of-the-art bulk dielectric ceramics. Moreover, the 0.90NaNbO3–0.10BiFeO3 ceramic exhibits superior frequency, cycling and thermal reliability, as well as the substantial current density (2140.6 A cm−2), ultrahigh power density (428.1 MW cm−3) and ultrafast discharge rate (14 ns). These results not only suggest that the NaNbO3-based relaxor antiferroelectric ceramics are promising candidates for advanced energy storage capacitors, but also provide feasible strategy of domain engineering to develop novel lead-free high-performance dielectric materials.