Fast development of electrostatic capacitors requires dielectric materials to perform large energy storage densities with high efficiency over a wide temperature range. Although antiferroelectric materials hold great potentials for achieving superior energy storage effect due to the field-induced antiferroelectric-ferroelectric transition, the strongly first-order transition is inevitably accompanied with a low energy storage efficiency and inferior thermal stability. Here, we found that a high polarization change and low hysteresis can be simultaneously achieved in a crossover composition between antiferroelectric and relaxor antiferroelectric states. As a result, a large recoverable energy storage density (W_rec ∼ 8.6 J/cm³) with high efficiency (η ∼ 85%) is obtained in lead-free Ag_1-3xLa_xNb_0.9Ta_0.1O₃ (x=0.03) ceramics under 460 kV/cm. The x=0.03 ceramics also exhibit excellent energy storage properties (W_rec > 6.8 J/cm³ with ultrahigh η ∼ 90%) in the temperature range of 20-120°C. This promising energy storage effect of the antiferroelectric crossover composition arises from the coexistence of micro- and nano-antiferroelectric domains, which can persist over a wide temperature range. Our work may push forward the development of high-performance lead-free antiferroelectric dielectrics for energy storage devices.

静电电容器的快速发展需要介电材料在宽温度范围内以高效率执行大能量存储密度。尽管反铁电材料由于场致反铁电-铁电转变而具有实现优异储能效果的巨大潜力，但强一级跃迁不可避免地伴随着低储能效率和较差的热稳定性。在这里，我们发现在反铁电态和弛豫反铁电态之间的交叉组合中可以同时实现高极化变化和低滞后。结果，大的可恢复储能密度（W _rec ∼ 8.6 J/cm ³）和高效率（η∼ 85%) 是在 460 kV/cm 下在无铅 Ag _{1-3 x} La _x Nb _0.9 Ta _0.1 O ₃ ( x =0.03) 陶瓷中获得的。x =0.03 的陶瓷还表现出优异的储能特性 ( W _{rec >} 6.8 J/cm ³具有超高η∼ 90%) 在 20-120°C 的温度范围内。反铁电交叉组合物的这种有前途的储能效果源于微米和纳米反铁电畴的共存，它可以在很宽的温度范围内持续存在。我们的工作可能会推动用于储能设备的高性能无铅反铁电介质的发展。