High energy storage efficiency in lead-free perovskite (1-x)(0.3Ba0.85Ca0.15Zr0.1Ti0.9O3-0.7SrTiO3)-xBiMg1/2Ti1/2O3 ceramics with superparaelectric design

Abstract

Dielectric capacitors, possessing ultrafast charge–discharge speed and high-power density, have captured increasing attention and extensive research due to their potential applications in pulse power techniques. However, the limited energy density and efficiency hinder their applications in capacitive energy storage. Here, superparaelectric state, which exhibits a high polarization and a nearly nonhysteretic response to an external electric field, was designed by constructing (1-x)(0.3Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃-0.7SrTiO₃)-xBiMg_0.5Ti_0.5O₃ ternary system to establish a superior comprehensive energy storage system, considering the recoverable energy storage density (W_rec) and efficiency (η), working temperature range and fatigue resistance. A high efficiency of 94.2%, a large W_rec of 4.43 J/cm³ , and thus a superior overall energy storage performance U_F of 76.4 were realized in the ceramic with x = 0.3 at 460 kV/cm due to its suitable superparaelectric temperature range (24–126 °C) and the concomitant dynamic disordered polymorphic polar nanoregions. Benefiting from these features, remarkable long-term working and temperature stabilities, high power density of about 143.5 MW/cm³ and fast discharging speed (t_0.9 = 58 ns) were also obtained. This work provided an effective strategy in improving the comprehensive energy storage performance of dielectric capacitors especially for realizing high efficiency.