Ruoxuan Che, Kaihua Yang, Wei You, Zhenyong Cen, Nengneng Luo
The Bi0.5Na0.5TiO3-based lead-free ceramics demonstrate significant potential as energy storage dielectric materials owing to their high polarization and satisfactory compatibility of multiple elements. In this study, multi-aliovalent B-site ions-doped (Na0.2Bi0.2Ba0.2Sr0.2Ca0.2)TiO3 (NBBSCT) high-entropy ceramics were prepared to enhance energy storage performance. The introduction of (Mg1/3Nb2/3)4+ (MN) dopants significantly increased configurational entropy, thereby promoting ionic disorder. Consequently, a high recoverable energy storage density (W rec) of 7.1 J/cm3 and an ultrahigh energy storage efficiency (η ) of 93% were simultaneously realized in 3% MN-modified NBBSCT ceramics under 610 kV/cm, accompanied by good charge-discharge performance. The enhanced performance was attributed to the improved relaxor feature enabled by the high-entropy strategy. Moreover, the ceramics exhibited outstanding frequency stability with a minimal variation of less than 3% over a broad range of 1 to 200 Hz and good temperature stability with a variation of less than 10% from room temperature to 120 °C in W rec. These results confirm that the high-entropy strategy combined with multi-aliovalent B-site doping provides an effective approach to achieving superior energy storage performance in Bi0.5Na0.5TiO3-based relaxor ferroelectrics.