Superb Energy Storage Capability for NaNbO3‐Based Ceramics Featuring Labyrinthine Submicro‐Domains with Clustered Lattice Distortions

Abstract Designing superb dielectric capacitors is valuable but challenging since achieving simultaneously large energy‐storage (ES) density and high efficiency is difficult. Herein, the synergistic effect of grain refining, bandgap widening, and domain engineering is proposed to boost comprehensive ES properties by incorporating CaTiO 3 into 0.92NaNbO 3 ‐0.08BiNi 0.67 Ta 0.33 O 3 matrix (as abbreviated NN‐BNT‐xCT). Apart from grain refining and bandgap widening, multiple local distortions embedded in labyrinthine submicro‐domains, as indicated by diffraction‐freckle splitting and ½‐type superlattices, produce slush‐like polar clusters for the NN‐BNT‐0.2CT ceramic, which should be ascribed to the coexisting P 4 bm , P 2 1 ma , and Pnma 2 phases. Consequently, a high recoverable ES density W rec of ≈ 7.1 J cm −3 and a high efficiency η of ≈ 90% at 646 kV cm −1 is achieved for the NN‐BNT‐0.2CT ceramic. Such hierarchically polar structure is favorable to superb comprehensive ES properties, which provide a strategy for developing high‐performance dielectric capacitors.