Local defect structure design enhanced energy storage performance in lead-free antiferroelectric ceramics

•The local defect structure design is proposed to achieve high energy storage density in NN-based AFE ceramics.•The pinning effect of defect dipoles and the increased local structural disorder stabilize the AFE phase.•High energy storage characteristics (Wrec ∼ 9.7 J/cm3, η ∼ 88.75 %) with near-zero Pr.•Excellent charge–discharge performance (PD∼413.2 MW/cm3, WD∼4.47 J/cm3). Antiferroelectrics (AFEs) are ideal candidates in dielectric, electromechanical, and electrothermal applications. NaNbO3 (NN), as a lead-free antiferroelectric (AFE) material under extensive investigation, exhibits ferroelectric (FE)-like polarization–electric field (P-E) hysteresis loops, characterized by high remnant polarization and large hysteresis. Herein, the local defect structure design is proposed to achieve high energy storage (ES) density in NN-based AFE ceramics. The pinning effect of defect dipoles and the enhancement of local structural disorder stabilize the AFE phase and reduce hysteresis losses. Consequently, an excellent ES performance of large recoverable energy density (Wrec) of 9.70 J/cm3 and high efficiency (η) of 88.75 % is concurrently obtained in NN-based relaxor AFE ceramics, with outstanding charge–discharge performance (PD∼413.2 MW/cm3, WD∼4.47 J/cm3), which are significantly improved compared to other reported values in lead-free ES ceramics. This indicates that NN-based ceramics are candidates for advanced ES capacitors and provides a feasible modulation approach for the development of new lead-free high-performance dielectric materials.