Significant increase in comprehensive energy storage performance of potassium sodium niobate-based ceramics via synergistic optimization strategy

• An ultrahigh W Rec of 8.09 J·cm ?3 was achieved at the optimum composition x = 0.15 under electric field 870 kV·cm ?1 . Such high accompanied by a energy storage efficiency ( ? ) 88.5%, which is superior to that other KNN-based bulk ceramics and very important for practical applications. The findings in this work provide significant designing strategy exploring series new high-performance lead-free APPCs future. K 0.5 Na0 .5 NbO 3 (KNN)-based are considered as one most promising dielectric owing relatively breakdown strength (DBS) resulted from their unique submicron grains. Unfortunately, it has been difficult increase recoverable energy-storage density rec simultaneously present. Herein, we propose synergistic optimization strategy, namely, enhancing DBS tailoring grain size scale inducing temperature range between maximum permittivity T max Burns B room temperature, solving bottleneck. (1- )K Na - Bi(Ni Zr )O (KNN-BNZ) were chosen an example illustrate validity strategy. obtained , much higher than those reported ceramics. Most importantly, 88.46%, excellent comprehensive performance polar nanoregions, confirmed high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), piezo-force (PFM) first-order reversal curve (FORC) distributions. not only finds out novel with properties, but also provides remarkable properties applications