Dielectric capacitors with high power density and fast charge-discharge speed play an essential role in the development of pulsed power systems. The increased demands for miniaturization and practicality of pulsed power equipment also necessitate the development of dielectric materials that possess high energy density while maintaining ultrahigh efficiency (η). In particular, ultrahigh efficiency signifies minimal energy loss, which is essential for practical applications but challenging to effectively mitigate. Here, we demonstrate a strategy of incorporating heterovalent elements into Ba(Zr_0·1Ti_0.9)O₃, which contributes to achieving relaxor ferroelectric ceramics and reducing lattice strain, thereby improving the comprehensive energy storage performance. Finally, optimal energy storage performance is attained in 0.85Ba(Zr_0·1Ti_0.9)O₃-0.15Bi(Zn_2/3Ta_1/3)O₃ (BZT-0.15BiZnTa), with an ultrahigh η of 97.37% at 440 kV/cm (an advanced level in the lead-free ceramics) and an excellent recoverable energy storage density (W_rec) of 3.74 J/cm³. Notably, the BZT-0.15BiZnTa ceramics also exhibit exceptional temperature stability, maintaining fluctuations in W_rec within ∼10% and η consistently exceeding 90% across the wide temperature range of −55 °C–160 °C, and under a high electric field of 250 kV/cm. All these features demonstrate that the relaxor and lattice strain engineering strategies have been successful in achieving high-performance lead-free ceramics, paving the way for designing high-efficiency dielectric capacitors with a wide temperature range.

具有高功率密度和快速充放电速度的介质电容器在脉冲功率系统的发展中发挥着至关重要的作用。对脉冲功率设备的小型化和实用性的日益增长的需求也需要开发具有高能量密度同时保持超高效率（η）的介电材料。特别是，超高效率意味着最小的能量损失，这对于实际应用至关重要，但有效缓解具有挑战性。_{在这里，我们提出了一种在Ba(Zr 0·1} Ti _0.9 )O ₃中掺入异价元素的策略，这有助于实现弛豫铁电陶瓷并减少晶格应变，从而提高综合储能性能。_{最终，0.85Ba(Zr 0·1} Ti _0.9 )O ₃ -0.15Bi(Zn _2/3 Ta _1/3 )O ₃ (BZT-0.15BiZnTa)获得了最佳的储能性能，其η高达97.37% 440 kV/cm（无铅陶瓷中的先进水平）和3.74 J/cm ^{3的优异可恢复储能密度（} W _rec ） 。值得注意的是，BZT-0.15BiZnTa陶瓷还表现出卓越的温度稳定性，在-55°C–160°C的宽温度范围内和高电场下，Wrec波动保持_在~10%以内，并且η始终超过90% 250 kV/cm。所有这些特征表明，弛豫和晶格应变工程策略已成功实现高性能无铅陶瓷，为设计宽温度范围的高效介电电容器铺平了道路。