Simultaneously enhanced energy storage density and efficiency in novel BiFeO3-based lead-free ceramic capacitors

In this work, a series of novel lead-free (1-x)Bi0.83Sm0.17Fe0.95Sc0.05O3-x(0.85BaTiO3-0.15Bi(Mg0.5Zr0.5)O3) [(1-x)BSFS-x(BT-BMZ), x = 0.45−0.85] relaxor ceramics were prepared by solid phase sintering, and their dielectric properties and energy storage performances were explored. It was revealed that all the samples have a dense structure with pure pseudo-cubic phase. With the increase of x, the ferroelectric hysteresis loop is gradually slimmed accompanied by a decreasing polarization, indicating an enhanced relaxor behavior. Moreover, the electric breakdown strength increases linearly with x due to the fine grain size and enhanced relative density. Interestingly, a large recoverable energy density (∼3.2 J/cm3) with an outstanding efficiency (∼92 %) is achieved under an electric field ∼206 kV/cm for the optimized component x = 0.75, which is superior to other reported lead-free ceramic systems. Moreover, the optimized ceramics of 0.25BSFS-0.75(BT-BMZ) show good thermal stability (25−100 °C) and excellent fatigue endurance (cycle number: > 105) in energy storage performances. This work opens up a new route to tailor lead-free dielectric ceramics with high energy storage properties.