Superior energy-storage density and ultrahigh efficiency in KNN-based ferroelectric ceramics via high-entropy design

The rapidly advancing energy storage performance of dielectric ceramics capacitors have garnered significant interest for applications in fast charge/discharge and high-power electronic techniques. Simultaneously improving the recoverable energy storage density W_rec and efficiency η becomes more prominent at the present time for their practical applications. Herein, a high-entropy concept is implemented on the (K_0·5Na_0.5)NbO₃ (KNN)-based ferroelectric ceramics to design the high-performance dielectric capacitors. First, the strong lattice distortion can absorb some electric energy during the electrical loading process and result in the delayed polarization saturation. Additionally, the large composition fluctuations induce the weak correlation between polar nanoregions and enhance the η. Finally, the high-entropy design and viscous polymer processing method reduce the grain size and improve the E_b. In consequence, excellent W_rec of 11.14 J/cm³ with high η of 87.1% are achieved under an electric field of 750 kV/cm in the high-entropy component. These results demonstrate that the high-entropy concept is a potential avenue to design the KNN-based high-performance dielectric energy storage capacitors.