Superior Energy-Storage Performances under a Moderate Electric Field Achieved in Antiferroelectric-like Na0.5Bi0.5TiO3-Based Relaxor Ferroelectric Ceramics by a Synergistic Optimization Strategy

The progress of power systems and electronic devices promotes the development of lead-free dielectric energy-storage material. Particularly, Na0.5Bi0.5TiO3-based ferroelectric ceramics featuring large spontaneous polarization as well as wide dielectric adjustability and stability are highly recognized as promising candidates. However, their large remanent polarization (P-r) and low electric breakdown strength (E-b) result in unsatisfactory recoverable energy density (W-rec) and/or energy conversion efficiency (eta), severely restricting their energy-storage applications. Herein, an effective synergistic optimization strategy has been proposed to gain superior energy-storage performances. Interestingly, the antiferroelectric-like (AFE-like) (1 - x)(Na0.3Bi0.38Sr0.28TiO3)-xBi(Mg0.5Zr0.5)O-3 (x = 0.00, 0.05, 0.10, 0.15, and 0.20) relaxor ferroelectric (RFE) ceramics were constructed via the phase structure, the polar structure, and the defect dipole modulations. With Bi(Mg0.5Zr0.5)O-3 increasing, the slim and pinched polarization-electric field hysteresis (P-E) loops become remarkably similar to the double-like P-E loops characterized by AFEs. Meanwhile, the strengthened E-b and delayed polarization saturation were also realized due to the enlarged band gap, refined grain size, and reduced free energy barrier. Consequently, superior energy-storage performances were achieved in this work. Noticeably, a large W-rec of 5.00 J/cm(3) and a high eta of 90.09% were realized in 0.85(Na0.3Bi0.38Sr0.28TiO3)-0.15Bi(Mg0.5Zr0.5)O-3 RFE ceramics at a moderate electric field of 340 kV/cm. Additionally, excellent energy-storage and/or charge-discharge reliabilities in frequency (1-500 Hz), temperature (20-140 degrees C), and fatigue cycle (1-50,000) were confirmed. These satisfactory results not only indicate the promising prospects of 0.85(Na0.3Bi0.38Sr0.28TiO3)-0.15Bi(Mg0.5Zr0.5)O-3 RFE ceramics in the dielectric energy-storage field but also verify the effectiveness of the synergistic