Ultra-stable dielectric properties and enhanced energy storage density of BNT-NN-based ceramics via precise core-shell structure controlling

Abstract

High discharge-energy-storage-density (W_dis) at low electric field is in high demand for advanced ceramics. In this work, a core-shell structure is well constructed and meticulously adjusted to enhance the energy storage properties. The meticulous control of the coating layer can effectively improve the breakdown strength (E_b), ensure a high polarization, and achieve a significant optimization of temperature stability, simultaneously. Compared with 0.78Bi_0.5Na_0.5TiO₃-0.22NaNbO₃ (BNTNN) ceramics without coating layer, the BNTNN@0.8 wt%SiO₂ ceramics achieve an inspiring improvement of 50% in E_b, which is benefit from the finer grains and the enhanced band gap. Notbaly, the BNTNN@0.8 wt%SiO₂ ceramics obtain a superior W_dis of 6.17 J/cm³ at 330 kV/cm. Importantly, BNTNN@0.8 wt%SiO₂ ceramics display an ultra-stable temperature stability with a high dielectric of 1350±2.5% over a wide temperature range from 35 to over 400 °C. The meticulous control of core-shell structure is expected to be a general and effective way to improve the energy-storage performance of diverse dielectric ceramics.