High energy storage density over a broad temperature range in sodium bismuth titanate-based lead-free ceramics

A series of (1-x)Bi_0.48La_0.02Na_0.48Li_0.02Ti_0.98Zr_0.02O₃-xNa_0.73Bi_0.09NbO₃ ((1-x)LLBNTZ-xNBN) (x = 0-0.14) ceramics were designed and fabricated using the conventional solid-state sintering method. The phase structure, microstructure, dielectric, ferroelectric and energy storage properties of the ceramics were systematically investigated. The results indicate that the addition of Na_0.73Bi_0.09NbO₃ (NBN) could decrease the remnant polarization (P _r ) and improve the temperature stability of dielectric constant obviously. The working temperature range satisfying TCC _150 °C ≤±15% of this work spans over 400 °C with the compositions of x ≥ 0.06. The maximum energy storage density can be obtained for the sample with x = 0.10 at room temperature, with an energy storage density of 2.04 J/cm³ at 178 kV/cm. In addition, the (1-x)LLBNTZ-xNBN ceramics exhibit excellent energy storage properties over a wide temperature range from room temperature to 90 °C. The values of energy storage density and energy storage efficiency is 0.91 J/cm³ and 79.51%, respectively, for the 0.90LLBNTZ-0.10NBN ceramic at the condition of 100 kV/cm and 90 °C. It can be concluded that the (1-x)LLBNTZ-xNBN ceramics are promising lead-free candidate materials for energy storage devices over a broad temperature range.