Improved Capacitive Energy Storage in K0.5Na0.5NbO3-based High-entropy Ceramics with Order-disorder Polarization Configurations

Abstract

Advanced ceramic capacitors play an irreplaceable role in cutting-edge pulsed power facilities. Nevertheless, simultaneously obtaining ultra-high recoverable energy storage density (Wrec) with efficiency (η) remains a substantial challenge. In this work, a high-entropy design guided by the phase field simulation is adopted to construct local order-disorder polarization configurations, which results in the formation of polar nanoregions (PNRs) embedded in a disorder polar matrix and an ultra-high critical electric field accompanied by a delayed polarization saturation process. Ultimately, a giant Wrec of 10.6 J/cm3 is realized in the KNN-0.2 high-entropy ceramic alongside a high η ~92% at 890 kV/cm via a viscous polymer process. Furthermore, the ceramic also provides a giant discharge energy density of 5.81 J/cm3 and a high-power density of 551 MW/cm3 at 160 ℃ together with a variation rate below 7% during a quite wide temperature region (from 20 ℃ to 160 ℃), showing a significant advance in the lead-free bulk energy storage ceramics. This approach paves the new way for designing superior ceramic dielectrics for next-generation capacitors.