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

There are imperious demands for developing eco-benign energy storage materials with high-performance in the sustainable society. In this paper, we introduce Sr0.85Bi0.1 0.05TiO3 (SBT) and NaNbO3 (NN) into Bi0.5Na0.5TiO3 (BNT) ceramics through compositional design. The introduction of Sr2+ and vacancies at A-sites construct the relaxor ferroelectrics according to order-disorder theory. The introduction of Nb5+ at B-sites is confirmed to possess two major implications. For one thing, it boosts higher induced polarization profited from its intrinsic larger polarizability and overall stronger diffuseness degree. For another, it contributes to forming core-shell microstructure proved by TEM, 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 (Wrec ~3.08 J cm-3) and efficiency (81.4%). Furthermore, the ceramics possess excellent discharge energy density (Wd=0.854 J cm-3) and rapid discharge speed (t0.9 ~100 ns) in a wide temperature range, proving high application potential. Our results break through the bottleneck of BNT-based ferroelectrics with a general recoverable energy storage density lower than 3 J cm-3, making the BNT-SBT-4NN ceramic a powerful candidate material in energy storage applications.