Tailoring ferroelectric polarization and relaxation of BNT-based lead-free relaxors for superior energy storage properties

Dielectric energy storage materials have attracted much attention because of their wide applications in the electronics industry. However, low energy storage density and poor thermostability limit their application. In this work, a strategy was proposed to prepare lead-free relaxor ferroelectric ceramics with ultra-high energy storage properties and superior temperature stability by precisely adjusting the relaxation and ferroelectricity states and increasing the electric field intensity. An ultra-high recoverable energy storage density (W_r) of 4.97 J/cm³ and an efficiency (η) of 84.4% are simultaneously obtained for the 0.95(0.9Bi_0.5Na_0.5TiO₃-0.1Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃)-0.05BaSnO₃ ceramic. Moreover, a high W_r of 2.73 J/cm³ with brilliant η of 80.6% are obtained in the ceramic at 140 ℃ and there is almost no thermal degradation of energy storage properties from 25 ℃ to 140 ℃. The W_r and η have decreased by 2.2% and 1.9% after 10⁵ cycles under 200 kV/cm, respectively, which demonstrates the good cycle stability of the sample. A discharge power density of up to 99.0 MW/cm³ is obtained in the 0.95(0.9Bi_0.5Na_0.5TiO₃-0.1Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃)-0.05BaSnO₃ ceramic and the good charge and discharge performance of this sample is important for practical applications.