High energy storage density and temperature stable dielectric properties of (1-x)Bi_0.5(Na_0.82K_0.18)_0.5Ti_0.99(Y_0.5Nb_0.5)_0.01O₃-xNaNbO₃ ceramics

The development of lead-free ceramics with high energy storage density is critical due to the human health and environmental hazards of lead and the demand to miniaturize and integrate electronic devices. Nevertheless, the high applied electric field limits their use in integrated circuits. In this work, (1-x) Bi_0.5(Na_0.82K_0.18)_0.5Ti_0.99(Y_0.5Nb_0.5)_0.01O₃-xNaNbO₃ (BNKTYN-100xNN) ceramics were prepared, and excellent energy storage properties were obtained. It has revealed that NaNbO₃ dopant reduces remanent polarization and increases relaxor degree. BNKTYN-9NN ceramics has high energy storage density (W_rec =1.6 J/cm³) and responsivity (ξ = W_rec/E = 145.5 J/(kV•m²)) under 110 kV/cm. Meanwhile, good temperature stability (20–120 °C) and fatigue resistance (10⁵ cycles) were also obtained in BNKTYN-9NN ceramics. In addition, doping NaNbO₃ suppresses the dielectric anomaly peak, and BNKTYN-9NN ceramics has excellent temperature-stable dielectric permittivity from 53° to 447°C. These results suggest that BNKTYN-100xNN ceramics are promising for energy storage equipment.