Ultrahigh energy-storage in lead-free ceramic capacitors via local structure design.

Zhang, Ji; Li, Zhiqing; Wang, Shuhao; Luo, Huajie; Zhang, Shujun; Wang, Yaojin · Nat Commun · 2026

basic_science · Level V

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Abstract

Dielectric capacitors are crucial energy-storage modules in pulsed- and high-power devices. However, the simultaneous enhancement in recoverable energy density (W<sub>rec</sub>) and efficiency (η) still remains challenge owing to the restrictive relationship between the maximum polarization (P<sub>max</sub>), remanent polarization (P<sub>r</sub>) and electric breakdown strength (E<sub>b</sub>). To address this, we propose a strategy of local polar structure design in BiFeO<sub>3</sub>-based ceramics. By incorporating NaNbO<sub>3</sub> to create embedded, persistent polar nanoregions within a weakly polar matrix, we achieve a giant polarization difference ΔP (56.4 μC cm<sup>-2</sup>), a low P<sub>r</sub> (3.6 μC cm<sup>-2</sup>) and a large E<sub>b</sub> (66 kV mm<sup>-1</sup>), endowing an ultrahigh W<sub>rec</sub> of 14.5 J cm<sup>-3</sup> and a high η of 88%. The local structure, directly visualized via the 2D/3D atomic displacement mapping, enables a high P<sub>max</sub> under an applied field and a low P<sub>r</sub> at zero field, a mechanism explicitly validated by phase-field simulation. Meanwhile, the optimized microstructure and enhanced insulating property contribute to a giant E<sub>b</sub>. This work provides insights to overcome the paradox between multiple parameters and paves a feasible route for the cutting-edge energy-storage applications.