High Capacitive Performance Achieved in NaNbO3‐Based Ceramics via Grain Refinement and Relaxation Enhancement

Lead‐free antiferroelectric (AFE) energy storage material NaNbO 3 has received increasing attention because of the advantages of low density, low cost, and environmental friendliness. Nevertheless, square P – E hysteresis loops and low electric breakdown strength suppress the realistic energy storage applications of the pristine NaNbO 3 ceramic. Herein, the Ba 0.6 Sr 0.4 TiO 3 relaxor ferroelectric is introduced into the NaNbO 3 AFE ceramic, aiming to enhance energy storage performances. (1– x )NaNbO 3 – x Ba 0.6 Sr 0.4 TiO 3 ceramics with different doping levels are manufactured via the conventional solid‐state processing route. A remarkable recoverable energy storage density ( W rec ≈ 3.04 J cm −3 ) and a high efficiency ( η ≈ 88.83%) are achieved synchronously in the ceramic with x = 0.20, under an applied electric field of 320 kV cm −1 , benefiting from the enhanced relaxor behavior and reduced grain size caused by the introduction of Ba 0.6 Sr 0.4 TiO 3 . Furthermore, excellent frequency stability (5–1000 Hz) and temperature stability (20–150 °C) along with outstanding fatigue resistance (up to 2 × 10 5 cycles) are also achieved. Moreover, the ceramic displays outstanding charge–discharge capabilities such as big current density ( C D ≈ 1096.23 A cm −2 ), high power density ( P D ≈ 106.7 MV cm −3 ) and fast discharge speed ( t 0.9 ≈ 142 ns). These results demonstrate that the Ba 0.6 Sr 0.4 TiO 3 modified NaNbO 3 ‐based ceramics could be competitive candidates for high power systems.