Realizing high energy density and efficiency simultaneously in (Bi0.5Na0.5)0.7Sr0.3TiO3-based ceramics via introducing linear dielectric CaTiO3

Abstract

Modern electronics and electrical power systems require a high energy storage density (W_rec) and a large efficiency (η) to deliver high performances. Although dielectric capacitors have been extensively explored owing to their numerous advantages, it is still a great challenge to develop dielectric materials with excellent comprehensive energy storage performances. Herein, we demonstrate that an ultrahigh W_rec of 7.0 J cm⁻³ and a large η of 90.9% are obtained simultaneously in 0.60(Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃-0.40CaTiO₃ ceramics by the synergistic contribution of delayed low-field polarization saturation and improved breakdown strength (E_b). The composition-driven fine domain size delays low-field polarization saturation and enhances η, which are confirmed by experimental characterization [high-resolution transmission electron microscopy (HR-TEM) and piezoresponse force microscopy (PFM)] and analysis using multiple models (V–F model, macroscopic and phenomenological model, and conceptual model based on the Landau–Devonshire theory). Phase-field simulations confirm that the fine grain size contributes to the enhancements of E_b. This contribution provides a feasible paradigm for designing dielectric materials exhibiting high energy storage performances and reveals fundamental insights into the origin of delayed polarization saturation and high E_b.