Significantly improved energy storage density in Bi0.5Na0.5TiO3-based dielectric ceramics through in-situ heterogeneous composite strategy

Lead-free Bi 0.5 Na 0.5 TiO 3 -based dielectric ceramics are promising for high-power energy storage applications, but their energy storage performance remains constrained by a relatively low breakdown strength. To overcome this limitation, we proposed to introduce a linear dielectric material LaNbO 4 into the 0.7(Bi 0.5 Na 0.5 TiO 3 )-0.3(Ba 0.5 Sr 0.5 )TiO 3 matrix, aiming to simultaneously enhance lattice distortion and induce the in-situ precipitation of a secondary pyrochlore phase. Rietveld refinement of X-ray diffraction patterns and scanning electron microscopy observations clearly revealed the intensified lattice distortion and the formation of the Bi 2 Ti 2 O 7 pyrochlore phase upon LaNbO 4 modification. These phenomena effectively retarded polarization saturation and increased the breakdown electric field, thereby significantly improving the overall energy storage performance. As a result, the optimized composition 0.62Bi 0.5 Na 0.5 TiO 3 -0.3Ba 0.5 Sr 0.5 TiO 3 -0.08LaNbO 4 delivered an ultrahigh recoverable energy storage density of 10.6 J/cm 3 and an attractive efficiency as high as 88.2% at 680 kV/cm. This heterogeneous composite strategy provides a new and effective pathway for developing high-performance lead-free dielectric materials for advanced energy-storage systems.