Enhancing Energy Storage Performance in Bi_0.5Na_0.5TiO₃-Based Ceramics via a Pyrochlore-Phase Composite Strategy

Enhancing the performance of energy storage dielectric materials is of great significance for addressing the developmental bottlenecks in energy and electronic devices. In this study, we introduced Bi_1/3TaO₃ into the Na_0.48Bi_0.48Ba_0.04TiO₃ ceramic to introduce disordered, distributed pyrochlore-phase grains into the perovskite matrix. The heterogeneous biphasic composite structure leads to enhanced dielectric breakdown strength and delayed polarization saturation; in addition to the formation of rhombohedral and tetragonal coexisting polar nanoregions with strong dielectric relaxation characteristics in the perovskite phase, the biphasic heterostructured ceramics exhibit outstanding energy storage performance with a recoverable energy density (W_rec) of 8.64 J/cm³ at an electric field strength of 500 kV/cm. Moreover, it demonstrated excellent thermal stability across a temperature range of room temperature to 140 °C and superior frequency stability between 0.5 and 140 Hz. Under an applied electric field of 350 kV/cm, the discharge time (t_0.9) is 3.4 μs, and the discharged energy density (W_D) is 4.38 J/cm³. The introduction of Bi_1/3TaO₃ into the Na_0.48Bi_0.48Ba_0.04TiO₃ ceramic to create a biphasic composite structure not only enhances the energy storage capabilities but also offers a direction for the development of high-performance energy storage ceramics.