Strongly polarizable nanodomains enable excellent energy storage performance at moderate electric fields in lead-free Bi _0.5 Na _0.5 TiO ₃ -based ceramics

Abstract The simultaneous achievement of high recoverable energy storage density (Wrec) and high efficiency (η) under moderate electric fields remains a critical challenge for dielectric ceramic capacitors in modern electronic systems, despite their ultrahigh power density and rapid charge-discharge capabilities. Here, we propose a strategy to construct strongly polarizable nanodomains, enabling excellent energy storage performance (ESP) under moderate electric fields in Bi0.5Na0.5TiO3 (BNT)-based ceramics. Compositional modulation by multiple cations, together with a regulative proportion of rhombohedral (R) and tetragonal (T) phases, enhances random fields, weakens interdomain interactions, forms strongly polarizable nanodomains, and elevates the breakdown strength (Eb) without sacrificing the intrinsic high polarity of the matrix. Consequently, the optimized 0.98(BNSB)0.985S0.01T–0.02CMN ceramic exhibits an ultrahigh maximum polarization (Pmax) of 65.8 μC/cm2, with slim polarization–electric (P–E) field loops. Owing to these features, the optimized bulk ceramic achieves a record Wrec of 6.11 J/cm3 and an impressive η of 86% at an Eb of 330 kV/cm. Moreover, this sample also presents outstanding temperature/frequency stability and charging–discharging performance. These findings suggest that the (BNSB)1–1.5ySyT–0.02CMN component has immense potential for advanced pulse power capacitors under a moderate applied electric field and further offers a valid avenue for exploring high-performance lead-free dielectric materials.