Superior Energy-Storage\nPerformances under a Moderate\nElectric Field Achieved in Antiferroelectric-like Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>‑Based Relaxor Ferroelectric\nCeramics by a Synergistic Optim

The progress of power systems and electronic devices\npromotes the\ndevelopment of lead-free dielectric energy-storage material. Particularly,\nNa<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-based ferroelectric\nceramics featuring large spontaneous polarization as well as wide\ndielectric adjustability and stability are highly recognized as promising\ncandidates. However, their large remanent polarization (<i>P</i><sub>r</sub>) and low electric breakdown strength (<i>E</i><sub>b</sub>) result in unsatisfactory recoverable energy density\n(<i>W</i><sub>rec</sub>) and/or energy conversion efficiency\n(η), severely restricting their energy-storage applications.\nHerein, an effective synergistic optimization strategy has been proposed\nto gain superior energy-storage performances. Interestingly, the antiferroelectric-like\n(AFE-like) (1 – <i>x</i>)(Na<sub>0.3</sub>Bi<sub>0.38</sub>Sr<sub>0.28</sub>TiO<sub>3</sub>)-<i>x</i>Bi(Mg<sub>0.5</sub>Zr<sub>0.5</sub>)O<sub>3</sub> (<i>x</i> = 0.00,\n0.05, 0.10, 0.15, and 0.20) relaxor ferroelectric (RFE) ceramics were\nconstructed via the phase structure, the polar structure, and the\ndefect dipole modulations. With Bi(Mg<sub>0.5</sub>Zr<sub>0.5</sub>)O<sub>3</sub> increasing, the slim and pinched polarization–electric\nfield hysteresis (<i>P–E</i>) loops become remarkably\nsimilar to the double-like <i>P–E</i> loops characterized\nby AFEs. Meanwhile, the strengthened <i>E</i><sub>b</sub> and delayed polarization saturation were also realized due to the\nenlarged band gap, refined grain size, and reduced free energy barrier.\nConsequently, superior energy-storage performances were achieved in\nthis work. Noticeably, a large <i>W</i><sub>rec</sub> of\n5.00 J/cm<sup>3</sup> and a high η of 90.09% were realized in\n0.85(Na<sub>0.3</sub>Bi<sub>0.38</sub>Sr<sub>0.28</sub>TiO<sub>3</sub>)-0.15Bi(Mg<sub>0.5</sub>Zr<sub>0.5</sub>)O<sub>3</sub> RFE ceramics\nat a moderate electric field of 340 kV/cm. Additionally, excellent\nenergy-storage and/or charge–discharge reliabilities in frequency\n(1–500 Hz), temperature (20–140 °C), and fatigue\ncycle (1–50,000) were confirmed. These satisfactory results\nnot only indicate the promising prospects of 0.85(Na<sub>0.3</sub>Bi<sub>0.38</sub>Sr<sub>0.28</sub>TiO<sub>3</sub>)-0.15Bi(Mg<sub>0.5</sub>Zr<sub>0.5</sub>)O<sub>3</sub> RFE ceramics in the dielectric\nenergy-storage field but also verify the effectiveness of the synergistic\noptimization strategy proposed in this work.