Entropy-driven synergistic enhancement of energy storage in relaxor ferroelectrics at medium-low electric fields

High-performance dielectric capacitors are essential due to their exceptionally high instantaneous power density and rapid charge-discharge rates. To date, lead-free ceramic capacitors still face the challenge of low energy storage density. In this study, an entropy-driven optimization strategy was employed to enhance energy storage performance. As a result, the manipulation of configurational entropy in 0.62Sr 0.7 Bi 0.2 TiO 3 –0.38K 0.5 Bi 0.5 TiO 3 compounds (KBT-SBT) is realized by adding different amounts of Re 2 O 3 (where Re = La, Nd, Sm). Entropy-driven effects inhibit grain growth and, at the same time, limit the development of ferroelectric domains. Accordingly, the refinement of ferroelectric domains not only increased the breakdown field strength but also improved the energy storage efficiency. Moreover, doping KBT-SBT with 1 % (La 2/3 Nd 2/3 Sm 2/3 )O 3 exhibits the optimal energy storage performance. Which the material demonstrates an impressive energy density of 4.07 J/cm 3 with the efficiency of 79.75 % when applying an electric field strength of 230 kV·cm −1 . Interestingly, at an electric field strength of 100 kV·cm −1 , it demonstrated exceptional stability across temperature, frequency, and fatigue tests. The outstanding performance of KBT-SBT based ceramics proves that our entropy-driven strategy opens a new way to understand and design dielectric energy storage materials.