Achieving High Energy Storage Performance under a Low Electric Field in KNbO3-Doped BNT-Based Ceramics

Ceramic capacitors have great potential for application in power systems due to their fantastic energy storage performance (ESP) and wide operating temperature range. In this study, the (1 - x)Bi_0.5Na_0.47Li_0.03Sn_0.01Ti_0.99O₃-xKNbO₃ (BNLST-xKN) energy storage ceramics were synthesized through the solid-phase reaction method. The addition of KN disrupts the long-range ferroelectric order of the BNLST ceramic, inducing the emergence of polar nanoregions (PNRs), which enhances the ESP of the ceramics. The BNLST-0.2KN ceramic demonstrates a high recovered energy density (W_rec ∼ 3.66 J/cm³) and efficiency (η ∼ 85.8%) under a low electric field of 210 kV/cm. Meantime, it exhibits a large current density (C_D ∼ 831.74 A/cm²), high power density (P_D ∼ 78.86 MW/cm³), and fast discharge rate (t_0.9 ∼ 0.1 μs), along with good temperature stability and excellent fatigue stability. These properties make the BNLST-0.2KN ceramic a promising candidate for energy storage applications in low electric fields.