Fantastic Energy Storage Performances and Excellent Stability in BiFeO₃–SrTiO₃-Based Relaxor Ferroelectric Ceramics

Dielectric energy storage capacitors play an increasingly great role in advanced electronic systems, while the difficulty in concurrently attaining high efficiency (η) and fantastic recoverable energy storage density (Wrec) has been long-term shortcoming for their practical applications. Here, an environment-friendly relaxor ferroelectric ceramic system (1 – x)(0.6BiFeO3–0.4SrTiO3)–xSr0.7Bi0.2TiO3 (BF-ST-xSBT) was designed and fabricated, where Sr0.7Bi0.2TiO3 was adopted as an additive for tailoring the energy storage performance (ESP) of the BiFeO3–SrTiO3 based lead-free relaxor ferroelectrics (RFEs). Profiting from the formation of polar nanoregions (PNRs) and the decrease in grain sizes (G), relaxation behavior and electric breakdown (Eb) of the BiFeO3–SrTiO3 ceramic were enhanced obviously after the introduction of SBT. Finally, a noteworthy Wrec (∼5.61 J/cm3) with excellent η (∼86.76%) was gained at 440 kV/cm at the same time. What is more, superior thermal stability, weak frequency dependence, and an amazing fatigue endurance after 105 cycles were also achieved. Furthermore, a superfast discharge speed (τ0.9 < 80 ns) and a giant current density (∼556.26 A/cm2), along with a great power density (∼55.63 MW/cm3), were also realized. All these impressive results make the BF-ST-xSBT ceramic system a hopeful candidate for energy storage applications.