High recoverable energy density of Na0.5Bi0.5TiO3-based ceramics by multi-scale insulation regulation and relaxor optimization strategy

Dielectric ceramic capacitors (DCCs) are highly desired for advanced electronic and electrical power systems owing to their ultrahigh power densities and fast charge-discharge speed. However, the low recoverable energy density (Wrec) of dielectric ceramic resulting from the low Weibull breakdown strength (Eb) has been a long-standing challenge. Here, we fabricated 0.8Na0.5Bi0.5TiO3–0.2Sm1/3Sr1/2(Mg1/3Nb2/3)O3 (0.8NBT–0.2SSMN) relaxor ferroelectric (RFE) ceramics display a greatly improved Eb of 480 kV/cm and largely enhanced Wrec of 7.3 J/cm3, far outperforming pure NBT ceramic. We demonstrate that the proposed multi-scale insulation regulation strategy via introducing SSMN with optimal content can effectively reduce grain sizes, increase the bandgap, and create a highly insulating second phase, leading to a high Eb. Additionally, the introduction of Sm3+ and Mg2+–Nb5+ dopants on the A/B-sites of the Na0.5Bi0.5TiO3 lattice created disruptions in the long-range-ordered ferroelectric domains, leading to excellent RFE property. The high Eb and excellent RFE property led to the substantial improvement of Wrec. Else, an exceptional thermal stability of Wrec and efficiency (η) are obtained at 25–200 °C (Wrec ∼ (1.77 ± 0.08) J/cm3, η ∼ 82.9% ± 4.3%). This work offers a route for designing high energy storage performance relaxor ferroelectric ceramics for high-voltage dielectric ceramic capacitors.