Dielectric capacitors with high recoverable energy storage density (Wrec) are in urgent demand for clean energy technologies. However, their lower breakdown strength (Eb) strongly limits their energy storage performance. We, herein, propose a facile method to enhance Eb by enhancing mechanical strength via second phase modulation. The efficiency of this method is validated in the (1-x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xSr(Ta0.5Sb0.5)O3 ((BNT-BT)-xSTS, x = 0.1, 0.15, 0.2, 0.25, and 0.3) ceramics. The introduction of Sr(Ta0.5Sb0.5)O3 (STS) increases the relaxor degree, refines grain size, and most importantly, creates a second phase of BiSb2O7, which hinders dislocation movement and improves mechanical strength. Our results show that the breakdown strength strongly depends on the mechanical strength. The highest hardness of 7.42 GPa accompanied by the largest Eb of 620 kV/cm was obtained in (BNT-BT)-0.25STS sample. The sample exhibits the best energy storage properties of a large Wrec = 8.3 J/cm3, a high efficiency of 82.3 %, and excellent temperature/frequency stability. Furthermore, the sample also exhibits good charge/discharge stability and ultra-fast transient discharge time (62.26 ns). This work provides a theoretical guidance for developing lead-free dielectrics with superior energy-storage performance.

中文翻译：

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通过优化机电击穿，BNT-BT 无铅陶瓷具有出色的储能性能


清洁能源技术迫切需要具有高可恢复能量存储密度（Wrec）的介质电容器。然而，它们较低的击穿强度（Eb）严重限制了它们的储能性能。我们在此提出了一种通过第二相位调制增强机械强度来增强 Eb 的简便方法。该方法的效率在 (1-x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xSr(Ta0.5Sb0.5)O3 ((BNT-BT)-xSTS, x = 0.1, 0.15, 0.2、0.25 和 0.3) 陶瓷。 Sr(Ta0.5Sb0.5)O3 (STS)的引入增加了弛豫程度，细化了晶粒尺寸，最重要的是，产生了BiSb2O7第二相，它阻碍了位错运动并提高了机械强度。我们的结果表明，击穿强度很大程度上取决于机械强度。 (BNT-BT)-0.25STS 样品获得了最高硬度 7.42 GPa 和最大 Eb 620 kV/cm。该样品表现出最佳的储能特性，大Wrec = 8.3 J/cm3、82.3%的高效率以及优异的温度/频率稳定性。此外，该样品还表现出良好的充放电稳定性和超快瞬态放电时间（62.26 ns）。这项工作为开发具有优异储能性能的无铅电介质提供了理论指导。