Dielectric ceramics with outstanding energy storage performance are urgently expected for energy storage capacitors. In this work, high energy storage density were achieved by deliberately designing a (1-x)Bi_0.5Na_0.5TiO₃-xAgNb_0.5Ta_0.5O₃ (100xANT) relaxor antiferroelectrics, associating with defect engineering. Both relaxor behaviour and evident antiferroelectric characteristic were successfully realized through phase structure engineering to an antiferroelectric tetragonal (T) dominant structure. Furthermore, defect engineering was also adopted by sintering in a flowing oxygen atmosphere to eliminate various defects (such as metal silver and oxygen vacancies), which significantly improved the breakdown strength and reduced the hysteresis loss. As a consequence, ultrahigh recoverable energy storage density of 6.6 J/cm³ and good efficiency of 72% were achieved in O₂-sintered 15ANT ceramics, accompanying with excellent frequency stabilities and outstanding low field performance. This work not only provides a promising dielectric material for energy storage applications, but also proves that phase structure and defect engineering are effective ways for designing new high-performance Bi_0.5Na_0.5TiO₃-based dielectric material.

储能电容器迫切需要具有优异储能性能的介电陶瓷。在这项工作中，通过特意设计 (1- x )Bi _0.5 Na _0.5 TiO ₃ - x AgNb _0.5 Ta _0.5 O ₃ (100 xANT) 弛豫反铁电体，与缺陷工程相关。通过反铁电四方（T）主导结构的相结构工程，成功地实现了弛豫行为和明显的反铁电特性。此外，还采用了缺陷工程，在流动的氧气氛中烧结，消除了各种缺陷（如金属银和氧空位），显着提高了击穿强度，降低了磁滞损耗。_{因此，在 O 2中实现了 6.6 J/cm} ³的超高可回收储能密度和 72% 的良好效率。-烧结15ANT陶瓷，具有出色的频率稳定性和出色的低场性能。该工作不仅为储能应用提供了一种很有前景的介电材料，而且证明相结构和缺陷工程是设计新型高性能Bi _0.5 Na _0.5 TiO ₃基介电材料的有效途径。