Ultrahigh Energy Storage Performance in BiFeO₃-Based Lead-Free Ceramics via Tuning Structural Homogeneity and Domain Engineering Strategies

Lead-free ceramic-based dielectric capacitors are critical in electronics and environmental safety. Nevertheless, developing ideal lead-free ceramics with excellent energy storage properties remains a challenging task for practical applications. Herein, the enhanced relaxation behavior and increased breakdown electric field are utilized to realize the high energy storage behavior of (0.7-<i>x</i>)BiFeO₃-0.3BaTiO₃-<i>x</i>(Na_0.7Sm_0.1)NbO₃(BF-BT-<i>x</i>NSN) ceramics. The introduction of complex perovskite compound NSN facilitates the transition of domains to nanodomains and improves the homogeneity of the microstructure, which results in the enhancement of the relaxation properties and breakdown electric field. Hence, the BF-BT-0.2NSN ceramic can achieve an ultrahigh energy storage density of 13.1 J/cm³ under an electric field of 650 kV/cm. Moreover, the designed BF-BT-0.2NSN ceramic achieves remarkable thermal stability (20-100 °C), frequency stability (1-100 Hz), and excellent charge/discharge performance. This study develops an idea of dielectric capacitor design and reveals the remarkable potential of BiFeO₃-based dielectric ceramics within the realm of energy storage applications.