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 ( W rec ) 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 NaNbO 3 -BiFeO 3 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 0.90NaNbO 3 –0.10BiFeO 3 ceramic demonstrates ultrahigh W rec 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 0.90NaNbO 3 –0.10BiFeO 3 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 NaNbO 3 -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.