Ceramic capacitors have optimistic application prospects in the field of high power density energy storage. However, most of the investigations have sought to increase energy storage density (W), but ignore the importance of energy storage efficiency (η). In this work, the novel KNb_0.6Ta_0.4O₃-modified [(Bi_0.55Na_0.45)_0.94Ba_0.06]_0.98La_0.02TiO₃ ceramics were designed and prepared. Particularly, the long-range order of ferroelectricity for the ceramic is broken due to the addition of KNb_0.6Ta_0.4O₃ (KNT), which causes shoulder dielectric peak (T_s) to move towards low temperatures and increases the content of weakly polar phase. Therefore, the remanent polarization P_r is effectively decreased, but the large saturation polarization P_s is maintained, leading to simultaneously high η and large W. Moreover, the addition of KNT significantly reduces the grain size, causing an enhanced dielectric breakdown strength (DBS). As a result, ultra-high values for η of 92.9% and W_rec of 2.1 J/cm³ are realized in the ceramic with x = 0.10, which are superior to most of the reported ceramic capacitors under the similar electric field. More importantly, the ceramic exhibits excellent thermal (25 - 150 ^oC) and frequency stability (5 - 105 Hz). The present strategy of adjusting the T_s and weakly polar phase provides a promising approach to design novel Bi_0.5Na_0.5TiO₃-based materials with excellent energy storage performance.

陶瓷电容器在高功率密度储能领域具有广阔的应用前景。但是，大多数研究都试图提高储能密度（W），但却忽略了储能效率（η）的重要性。在这项工作中，设计并制备了新型的KNb _0.6 Ta _0.4 O ₃改性的[（Bi _0.55 Na _0.45）_0.94 Ba _0.06 ] _0.98 La _0.02 TiO ₃陶瓷。特别是，由于添加了KNb _0.6 Ta _0.4，打破了陶瓷的铁电长程分布O ₃（KNT）会导致肩部电介质峰（T _s）向低温移动，并增加弱极性相的含量。因此，有效地减小了剩余极化强度P _r，但是保持了较大的饱和极化强度P _s，从而同时导致了高η和大的W。此外，添加KNT大大减小了晶粒尺寸，从而提高了介电击穿强度（DBS ）。结果，在具有x的陶瓷中实现了η为92.9％和W _rec为2.1 J / cm ^3的超高值。= 0.10，在类似电场下优于大多数报道的陶瓷电容器。更重要的是，陶瓷具有出色的热稳定性（25-150 ^o C）和频率稳定性（5-105 Hz）。当前的调节T _s和弱极性相的策略为设计具有优异储能性能的新型Bi _0.5 Na _0.5 TiO ₃基材料提供了一种有前途的方法。