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 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 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 0.90NaNbO₃–0.10BiFeO₃ 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.

介电电容器因其在未来高功率和/或脉冲电力电子系统中的广泛应用而受到越来越多的关注。然而，迄今为止，介电陶瓷的可恢复储能密度（W _rec）相对较低，这在很大程度上限制了其实际应用。在此，域工程被用来构建弛豫反铁电NaNbO ₃ -BiFeO ₃块状陶瓷，它结合了反铁电和弛豫的优点。结果表明，反铁电相从正交P相转变为R相，反铁电畴从微米级块体演变为纳米级团簇。特别重要的是 0.90NaNbO₃ –0.10BiFeO ₃陶瓷表现出18.5 J cm ^{-3 的}超高W _rec和99.5 kV mm ^{-1 的}巨大电击穿强度，优于最先进的体介电陶瓷。此外，0.90NaNbO ₃ –0.10BiFeO ₃陶瓷具有优异的频率、循环和热可靠性，以及可观的电流密度（2140.6 A cm ^-2）、超高功率密度（428.1 MW cm ^-3）和超快放电速率（ 14 纳秒）。这些结果不仅表明 NaNbO ₃基于弛豫的反铁电陶瓷是先进储能电容器的有希望的候选者，但也为开发新型无铅高性能介电材料提供了可行的领域工程策略。