Giant energy density and high efficiency achieved in silver niobate-based lead-free antiferroelectric ceramic capacitors via domain engineering

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Dielectric materials have drawn increasing attention due to their high power density and fast charge-discharge speed. Although satisfactory energy storage performance has been achieved in lead-based ceramics, the exploration of suitable lead-free substitutions is highly desired since the rising environmental concerns caused by lead-based compounds. Herein, we demonstrate that a giant recoverable energy density of 7.01 J cm−3 together with high energy efficiency under 476 kV cm−1, as well as impressive frequency stability (maximum variation of recoverable energy density < ±3% at 1 − 100 Hz) and thermal stability (maximum variation < ±10% over 25−120 °C) under 320 kV cm−1, can be obtained in Lanthanum (La)-modified AgNbO3 ceramics. It is revealed that the long-range antiferroelectric order in AgNbO3 is interrupted by the incorporation of La, resulting in the transformation of micron-scale antiferroelectric domains into antiferroelectric nanodomains with concurrently improved energy density and efficiency. Additionally, the introduction of La content greatly suppresses the ferrielectricity of AgNbO3 and enhances the dielectric breakdown strength up to 494 kV cm−1 versus 178 kV cm−1 for the pure AgNbO3 ceramics. These results not only reveal the high potential of La-modified AgNbO3 ceramics for energy storage applications but also open up a feasible approach of domain engineering to develop new lead-free energy-storage dielectric materials.