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 (W_rec) 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 W_rec of 10.6 J cm⁻³ is realized in the KNN-0.2 high-entropy ceramic alongside a high η ∼ 92% at 890 kV cm⁻¹ via a viscous polymer process. Furthermore, the ceramic also provides a giant discharge energy density of 5.81 J cm⁻³ and a high-power density of 551 MW cm⁻³ at 160 °C together with a variation rate below 7% in a quite wide temperature region (from 20 °C to 160 °C), showing a significant advance in the lead-free bulk energy storage ceramics. This approach paves a new way for designing superior ceramic dielectrics for next-generation capacitors.