Superior Energy-Storage Performance in Sandwich-Structured AgNbO₃-Based Ceramics

Antiferroelectric (AFE) ceramics with typical double polarization-electric field loops hold exceptional potential for high capacitance density capacitors. However, the inherent contradiction between polarization and breakdown strength limits the energy storage performance in AFE ceramics. Herein, the polarization and breakdown strength are improved simultaneously via optimizing the sandwich structure with alternate large polarization (Ag_0.82Bi_0.06)NbO₃ layer and high breakdown strength (Ag_0.70Bi_0.10)NbO₃ layer. A recoverable energy storage density W_rec of 16.8 J cm^-3 with energy efficiency η of 81.3% is realized in (Ag_0.70Bi_0.10)NbO₃/(Ag_0.82Bi_0.06)NbO₃/(Ag_0.70Bi_0.10)NbO₃ ceramic, attaining the peak value of AgNbO₃-based AFE ceramics. Moreover, the sandwich-structured ceramic shows good stabilities with variations of less than 7.0% over a temperature range of 30-150 °C, frequency range of 1-500 Hz, and 10⁵ cycling in W_rec, and a discharge energy density W_d of 6.2 J cm^-3 along with a fast discharge time t_0.9 of 120 ns. This research provides an effective strategy for enhancing the energy storage performance of lead-free AFE ceramics, highlighting their potential for practical applications in pulse power systems.