Comprehensively improved energy storage and DC-bias properties in Bi0.5Na0.5TiO3NaNbO3 based relaxor antiferroelectric

Dielectric pulse capacitors are of great concerns due to the fast charge/discharge rate and high-power density over traditional counterparts. However, energy-storage capacitor in power converters typically works at a large DC-biased voltage, where the energy-storge density (W_dis) and efficiency (η) will dramatically decay, thus fatally blocks its further applications. Herein, we proposed a synergistic strategy to achieve a comprehensively improved energy storage property in Bi_1–xNa_xTiO₃-NaNbO₃ based ceramics. Configuration of chemical composition optimization, A-site vacancy engineering, grain size refinement, and sample thickness reduction were designed in the ceramics. Finally, an optimum W_dis of 8.04 J/cm³ and an ultrahigh η of 85% was achieved for the 0.50 (0.95Bi_0.52Na_0.44TiO₃-0.05SrZrO₃)-0.50NaNbO₃ composite under a breakdown strength of 630 kV/cm, along with a stable DC-biased capacitance retention. Additionally, a superior performance stability was affirmed in a wide temperature/frequency range (25–150 °C and 1–100 Hz, respectively). It also exhibits an impressive ability in fatigue resistance after being subjected to up to 10⁶ cycles, which enable it to be a suitable candidate for high energy density storage devices.