Enhanced energy storage properties in sodium bismuth titanate-based ceramics for dielectric capacitor applications

Abstract

There are imperious demands for developing eco-benign energy storage materials with high-performance in a sustainable society. In this paper, we introduce Sr_0.85Bi_0.1□0.05TiO₃ (SBT) and NaNbO₃ (NN) into Bi_0.5Na_0.5TiO₃ (BNT) ceramics through compositional design. The introduction of Sr²⁺ ions and vacancies at the A-sites constructs relaxor ferroelectrics according to order–disorder theory. The introduction of Nb⁵⁺ ions at the B-sites is confirmed to have two major implications. In one way, it boosts a higher induced polarization due to its intrinsic larger polarizability and overall stronger degree of diffuseness. In another, it contributes to forming a core–shell microstructure, as proven using transmission electron microscopy, promoting the breakdown strength (BDS) to a higher level. With the above strategies, our BNT–SBT–4NN ceramics demonstrate excellent energy storage performances with simultaneously ultrahigh energy storage density (W ∼ 3.78 J cm⁻³), recoverable energy storage density (W_rec ∼ 3.08 J cm⁻³) and efficiency (81.4%). Furthermore, the ceramics possess excellent discharge energy density (W_d = 0.854 J cm⁻³) and rapid discharge speed (t_0.9 ∼ 100 ns) in a wide temperature range, proving their high application potential. Our results break through the bottleneck of BNT-based ferroelectrics with a general recoverable energy storage density of lower than 3 J cm⁻³, making the BNT–SBT–4NN ceramic a powerful candidate material for use in energy storage applications.