Achieving ultra-high energy storage performance in (Bi0.5Na0.5)0.7Sr0.3TiO3-based relaxor ferroelectrics

Abstract

For (Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃ energy storage materials, two critical factors, the low breakdown electric field and premature polarization saturation, are the main reasons for the limited energy storage performance, significantly hindering the development of these ceramic capacitors toward lightweight and miniaturized applications. Herein, Sm(Mg_2/3Nb_1/3)O₃ (SMN) doped into (Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃ (BNST) was used to refine grain size, improve breakdown strength, enhance the activity of polar nanoregions, and increase the recoverable energy storage density (W_rec) and energy storage efficiency (η). The Vogel–Fulcher model analysis confirms that the incorporation of appropriate SMN facilitates the formation of additional weakly coupled polar nanoregions (PNRs), thereby enhancing the polarization response of the system. As a result, an ultra-high W_rec of 12.09 J cm⁻³ and a high η of 88.90% are obtained in 0.88BNST-0.12SMN under an electric field of 890 kV cm⁻¹. In addition, the change rate of energy storage density is less than 10% at 5–150 Hz and 40–140 °C, demonstrating good frequency stability and temperature stability. These results indicate that the ceramic is expected to be a potential candidate material for high energy storage capacitor device components.