A high breakdown strength (E_b) together with a large maximum polarization (P_m) is essential for achieving a high recoverable energy density (W_rec) in energy storage dielectric ceramics. However, meeting the urgent need for practical applications remains a challenge due to the intrinsic properties of bulk dielectric ceramics. Herein, a composition and structure optimization strategy combined with a two-step sintering (TSS) process is proposed to design and fabricate (1−x)Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃−xBi(Mg_1/2Sn_1/2)O₃ (BCZT-BMSx-TSS) lead-free ceramics. Highly dynamic locally polar nano-regions (PNRs) are formed via composition optimization, exhibiting a very high P_m and energy storage efficiency (η). Compared to the traditional one-step sintering (OSS) process, the TSS process results in a composition with finer grain size and higher density, dramatically increasing E_b. As a result, an ultrahigh energy storage performance with W_rec ∼ 10.53 J cm⁻³ and η ∼ 85.71% is achieved for the BCZT-BMSx-TSS (x = 0.08) ceramic which is attributed to a record high E_b ∼ 830 kV cm⁻¹ and a large P_m ∼ 44.66 μC cm⁻². Complex impedance spectroscopy revealed that the activation energies of the bulk and grain boundary counterparts significantly increased, suggesting an increase in insulation resistance and a decrease in oxygen vacancies, which is the main reason for the high E_b value. In addition, excellent thermal/frequency stability is achieved in both energy density and efficiency, along with good charge–discharge performance. These findings suggest that BCZT-based lead-free ceramics have the potential for practical use in the future.

中文翻译：

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卓越的储能性能，通过多种协同策略，在块状 Ba0.85Ca0.15Zr0.1Ti0.9O3 基无铅陶瓷中具有创纪录的高击穿强度


高击穿强度 （E_b） 和大最大极化 （P_m） 对于在储能介电陶瓷中实现高可恢复能量密度 （W_rec） 至关重要。然而，由于块状介电陶瓷的固有特性，满足实际应用的迫切需求仍然是一个挑战。在此，提出了一种成分和结构优化策略，结合两步烧结 （TSS） 工艺来设计和制造 （1−x）Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃−xBi（Mg_1/2Sn_1/2）O₃ （BCZT-BMSx-TSS） 无铅陶瓷。通过成分优化形成高动态局部极性纳米区域 （PNR），表现出非常高的 P_m 和储能效率 （η）。与传统的一步烧结 （OSS） 工艺相比，TSS 工艺产生的成分具有更细的晶粒尺寸和更高的密度，从而显著提高了 E_b。因此，BCZT-BMS x-TSS （x = 0.08） 陶瓷实现了 W_rec ∼ 10.53 J ^cm-3 和 η ∼ 85.71% 的超高储能性能，这归因于创纪录的高 E_b ∼ 830 kV ^cm-1 和大 P_m ∼ 44.66 μC ^cm-2。 复阻抗谱显示，体边界和晶界的活化能显著增加，表明绝缘电阻增加，氧空位减少，这是 E_b 值高的主要原因。此外，在能量密度和效率方面都实现了出色的热/频率稳定性，以及良好的充放电性能。这些发现表明，基于 BCZT 的无铅陶瓷在未来具有实际应用的潜力。