Simultaneously achieving high energy storage performance and remarkable thermal stability in Bi0.5K0.5TiO3-based ceramics

A (1-x)(0.75Bi0.5K0.5TiO3-0.25BiFeO3)-xCaTiO3 (BKT-BF-xCT) ceramic energy storage system is fabricated in this work using multiple optimization strategies, including domain engineering, grain size, and bandgap optimization. A high recoverable energy storage density (Wrec ∼ 6.34 J/cm3) and a favorable efficiency (ƞ ∼ 93.32%) are realized in the BKT-BF-0.5CT ceramic due to the enhanced relaxation behavior and improved breakdown strength induced by CaTiO3 modification. Moreover, the BKT-BF-0.5CT ceramic also shows exceptional discharging performance, including an ultra-short discharge rate (τ0.9 < 50 ns) and a high power density (PD = 97.07 MW/cm3). Impressively, the ceramic exhibits great thermal stability, with Wrec and η variation below 7% and PD variation below 6% over the temperature range of room temperature (RT) to 160 °C. This is ascribed to the existence of polar nanoregions (PNRs) in a broad temperature range. These results demonstrate the great potential of the BKT-BF-0.5CT ceramic for pulsed power capacitor applications with remarkable energy storage performance across a wide range of operational temperatures.