Multiscale modulation strategy for achieving superior energy storage performance in Ba_0.6Sr_0.4TiO₃ based relaxor ferroelectrics

Achieving high recoverable energy storage density (W_rec) and efficiency (η) in relaxor ferroelectric (RFE) ceramics with fatigue resistance and fast charge-discharge behavior remains a significant challenge. In this work, we report a novel lead-free RFE ceramic system, KTaO₃ (KT)-modified Ba_0.6Sr_0.4TiO₃ (BST), that exhibits excellent energy storage performance and fatigue-resistance (temperature, frequency, and cyclic poling) stability. The optimum composition, 0.92BST-0.08 KT, demonstrates a high W_rec of 3.91 J cm⁻³, an outstanding η of >87 %, an excellent power density (P_D) of 108.79 MW cm⁻³, and an ultra-fast discharge time (t_0.9) of 18.7 ns. The enhanced energy storage properties are attributed to the synergistic effects of the relaxor ferroelectric behavior, high breakdown strength, and optimized microstructure induced by KT doping. The multiscale modulation strategy employed in this work provides valuable insights into designing high-performance RFE ceramics for energy storage applications.