High energy storage performance of (1-x) (0.96K0.48Na0.52NbO3-0.04BaZrO3)-xBi5/6In0.5Sn0.5O3 ceramics via a combined strategy of fine grains and multiphase regulation

Abstract

Dielectric ceramics have been the subject of considerable interest due to their high-power density. Nevertheless, the primary impediments to their practical implementation are the low energy storage density and efficiency. In this study, 0.96K0.48Na0.52NbO3-0.04BaZrO3(KNNBZ) ceramics doped with different ratios of Bi5/6In0.5Sn0.5O3(BIS) were prepared. The KNNBZ-0.15BIS ceramics exhibited superior energy storage performance, with a recoverable energy storage density of 4.16 J/cm3, a breakdown strength of 550 kV/cm, and an energy storage efficiency of 88.4 %. The substitution of ions with different radii and valence states for equivalent sites (A or B sites) in the ceramic results in the coexistence of rhombohedral phase, orthorhombic phase, tetragonal phase, and cubic phase, as well as the emergence of polyphase polar nanoregions. This lattice distortion and chemical disorder lead to the formation of small-sized polar nanoregions and an elongated P-E loop. Concurrently, the elevated resistivity and ultra-fine grain of the ceramics markedly enhance the breakdown strength. This study employs a strategy of multiphase regulation and grain refinement to demonstrate the potential of KNNBZ-xBIS ceramics as candidate materials for lead-free energy storage ceramics.