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

Lead-free antiferroelectric (AFE) energy storage material NaNbO3 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 NaNbO3 ceramic. Herein, the Ba0.6Sr0.4TiO3 relaxor ferroelectric is introduced into the NaNbO3 AFE ceramic, aiming to enhance energy storage performances. (1-x)NaNbO3-xBa(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) approximate to 3.04 J cm(-3)) and a high efficiency (eta approximate to 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 Ba0.6Sr0.4TiO3. Furthermore, excellent frequency stability (5-1000 Hz) and temperature stability (20-150 degrees C) along with outstanding fatigue resistance (up to 2 x 10(5)cycles) are also achieved. Moreover, the ceramic displays outstanding charge-discharge capabilities such as big current density (C (D) approximate to 1096.23 A cm(-2)), high power density (P (D) approximate to 106.7 MV cm(-3)) and fast discharge speed (t (0.9) approximate to 142 ns). These results demonstrate that the Ba0.6Sr0.4TiO3 modified NaNbO3-based ceramics could be competitive candidates for high power systems.