Synergistic Enhancement of Energy Storage Performance in NaNbO3‐Based Lead‐Free Relaxor Ferroelectrics via Weakly Coupled Relaxation Behavior

Advancements in pulsed electronic power systems depend significantly on high-performance dielectric energy storage ceramics. Lead-free NaNbO₃-based energy-storage ceramics are important materials for next-generation pulsed power capacitors owing to their large polarization and bandgaps. However, the high energy loss caused by the antiferroelectric-ferroelectric phase transition leads to low recoverable energy storage density and efficiency, which hinders its practical application. Herein, a weakly coupled relaxor ferroelectric is designed via chemical modification, which realises a high recoverable density of 12.7 J cm^{- 3} and a decent η of 85.7%. Compositionally induced domain-size refinement effectively delays low-field polarization saturation and elevates η. Experimental characterization and theoretical-model analysis confirm that the superior comprehensive energy-storage performance is attributed to the component-driven formation of polar nano-micro-regions with weak interactions, which suppresses the polarization hysteresis and improves the polarization difference. This study demonstrates that component-driven construction of weakly coupled relaxor ferroelectric materials is an effective strategy for achieving ultrahigh energy-storage characteristics.