High-Entropy Relaxor State towards Ultra-high Capacitive Energy Storage in BiFeO3-based Ceramics

Lead-free relaxor ferroelectric ceramics show promise as materials for advanced pulsed power systems, owing to their exceptional power density and ultrafast charge-discharge capabilities. However, a strategic challenge persists in simultaneously achieving high recoverable energy density ( W rec ) and high efficiency ( η ), as efforts to enhance polarization typically lead to an increase in hysteresis dissipation. In view of this, a high-entropy strategy in BiFeO 3 -based ceramics was proposed to form high-dynamic polymorphic polar nanoregions (PPNs). Atom-scale structure characterization revealed that the nano-sized PPNs (2-5 nm) with robust polar magnitude (20.3 pm) endows to reduce the energy barrier for domain switching, thereby decreasing the polarization hysteresis while maintaining high polarization. Consequently, an excellent energy storage capability, including a high W rec of 11 J/cm 3 and a high η of 92%, was achieved. This approach validates the high-entropy strategy for designing high-performance dielectrics, paving the way for next-generation energy-storage capacitors.