Preeminent energy storage properties and superior stability of (Ba(1–)Bi )(Ti(1–)Mg2/3Ta/3)O3 relaxor ferroelectric ceramics via elongated rod-shaped grains and domain structural regulation

(Ba(1–x)Bix)(Ti(1–x)Mg2x/3Tax/3)O3 (BBTMT-x, x = 0.075, 0.1, 0.125, and 0.15) ceramics were manufactured via a solid-phase reaction method. The pseudo-cubic BaTiO3 (BT) as the primary phase and Ba4MgTi11O27 as the secondary phase were detected in BBTMT-x ceramics. The elongated rod-shaped grains therein became numerous as x increased. The introduction of Bi/Mg/Ta (BMT) elements transformed BT ceramics from ferroelectrics to relaxor ferroelectrics and induced the formation of short-range order polar nanoregions (PNRs), which were beneficial for the preeminent energy storage properties (ESPs). The highest ESPs (a giant recoverable energy-storage density Wrec of 5.97 J cm–3 with a high-efficiency η of 87.4%) were achieved in BBTMT-0.1 ceramics at 710 kV cm–1. BBTMT-0.1 ceramics also possessed excellent frequency (1–500 Hz), temperature (30–150°C), and fatigue (cycle number of 1–100000) stabilities. Finite element simulations (FES) demonstrated that elongated rod-shaped grains had stronger obstacles to the development of electrical branches, which was beneficial to improving the comprehensive ESPs.