Superior Energy-Storage Properties in Bi0.5Na0.5TiO3-Based Lead-Free Ceramics via Simultaneously Manipulating Multiscale Structure and Field-Induced Structure Transition

Pratical applications have put forward great challenges to the comprehensive energy-storage performance of ceramic material. Here, a novel route of simultaneously manipulating multiscale structure and the field-induced structural transformation in (Bi_0.5Na_0.5)TiO₃-based ceramics is proposed to address the above concern. The multiscale structure of 0.88(Bi_0.5Na_0.5)TiO₃-0.12BaTiO₃ solid solutions such as grain and domain size, band gap, and phase structure can be adjusted by adding antiferroelectric NaNbO₃. Simultaneously, a field-induced P4bm relaxor antiferroelectric to P4mm ferroelectric phase transformation can be obtained by constructing a P4mm-P4bm phase boundary, which is expected to require a lower energy barrier compared with the field-induced P4bm relaxor antiferroelectric to R3c ferroelectric transformation in other (Bi_0.5Na_0.5)TiO₃-based ceramics. The optimized field-induced structural transformation behavior and the formation of nanodomains enables a minimized polarization hysteresis but an enhanced maximum polarization. Moreover, the decreased grain size together with increased band gap leads to a significantly improved breakdown strength. Accordingly, a giant energy density W_rec ∼ 8.0 J/cm³, a high efficiency η ∼ 86%, a short discharging time t_0.9 ∼ 41 ns, and a good temperature stability (W_rec = 1.32 ± 0.12 J/cm³, η = 88.5% ± 2.5% @ 25-200 °C) are simultaneously obtained in 0.63(Bi_0.5Na_0.5)TiO₃-0.12BaTiO₃-0.25NaNbO₃ relaxor antiferroelectric ceramics, demonstrating large potentials for the ceramic capacitor applications.