Enhanced Energy-Storage Performance in BF-BT Ceramics through Multiscale Structural Modulation and Regulatory Mechanism Analysis

Pb-free relaxor ferroelectric materials, owing to the integration of superior high-power density ( P D ) alongside ultrafast discharge kinetics, serve as optimal candidates for contemporary pulsed-power applications. Nevertheless, the pursuit of ultrahigh recoverable energy density ( W rec ) together with high efficiency ( η ) is still a difficulty because enhancing polarization often results in increased hysteresis loss. To tackle this challenge, we present a multiscale composition regulation approach by introducing Sm(Mg 2/3 Nb 1/3 )O 3 into the BiFeO 3 -BaTiO 3 (BF-BT) matrix. By employing this strategy, we successfully achieve a transformation from R -phase to T -phase, grain refinement, polar nanocluster formation, accompanied by higher bandgap ( E g ), and relaxor behavior. The synergistic effect of these structural changes contributes to the comprehensive improvement of energy-storage properties in the doped ceramics. Eventually, a W rec of 10.53 J/cm 3 and an η of 80.2% were achieved under 610 kV/cm. Furthermore, the optimized ceramics demonstrated remarkable stability under varying temperature, frequency, and cycling conditions, as well as exceptional pulse charge−discharge capability. This work demonstrates a viable strategy for designing materials for superior energy storage.