Domain Engineered Lead-Free Ceramics with Large Energy Storage Density and Ultra-High Efficiency under Low Electric Fields

Dielectric energy storage materials are becoming increasingly popular due to their potential superiority, for example, excellent pulse performance as well as good fatigue resistance. Although numerous studies have focused on lead-free dielectric materials which possess outstanding energy storage characteristics, the results are still not satisfying in terms of achieving both large discharging energy density (W_d) and high discharging efficiency (η) under low electric fields, which is crucial to be conducted in miniatured electronic components. Here, we adopt the strategy of domain engineering to develop sodium bismuth titanate (Bi_0.5Na_0.5TiO₃)-based ceramics employed in the low-field situation. Remarkably, a large W_d of 2.86 J/cm³ and an ultrahigh η of 90.3% are concurrently obtained in 0.94­(Bi_0.5Na_0.5)_0.65(Ba_0.3Sr_0.7)_0.35TiO₃-0.06 Bi­(Zn_2/3Nb_1/3)­O₃ system when the electric field is as low as 180 kV/cm. Additionally, the ceramic shows brilliant thermal endurance (20–160 °C) and frequency stability (0.1–100 Hz) with high W_d (>1.48 J/cm³) together with an ultra-high η (>90%). What’s more, the ceramic displays a fast charge–discharge time (t_0.9 = 109.2 ns). The piezoresponse force microscopy (PFM) results reveal that the introduced Bi­(Zn_2/3Nb_1/3)­O₃ disrupts the microdomains of (Bi_0.5Na_0.5)_0.65(Ba_0.3Sr_0.7)_0.35TiO₃ ceramics and promotes the formation of nanodomains, leading to enhanced energy storage properties. The current work may arouse interest in developing low-field high-performing dielectric capacitors for energy storage application.