Energy storage performance of K0.5Na0.5NbO3-based ceramics modified by Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3

The damage of lead-based ceramics to our environment and health completely hindered their industrial applications. K0.5Na0.5NbO3 (KNN) ceramic material is considered as a good substitute for lead-free ceramics because of its high dielectric constant, excellent piezoelectric properties, high Curie temperature and sustainability. However, it is challenging to achieve their high energy-storage performances because of their large energy loss density (Wloss) under an applied electric field. Thus, this work proposes a combinatorial optimization strategy of inducing polar nano-regions and improving breakdown strength (BDS) to enhance the energy-storage performances of the KNN-based ceramics. As a result, we obtained a record high recoverable energy-storage density (Wrec) value of 7.4 J·cm−3 for the Bi(Zn2/3(Nb0.85Ta0.15)1/3)O3 (BZNT)-modified KNN ceramic mainly due to its enhanced BDS. Furthermore, remarkable temperature stability was obtained for the 0.90KNN-0.10BZNT ceramic over a wide temperature range (20–180 °C). Remarkably, the first-order reversal curve (FORC) confirmed the excellent energy-storage performances of the 0.90KNN-0.10BZNT ceramic, which we ascribed to its enhanced relaxation behavior. Additionally, 0.90KNN-0.10BZNT material exhibited excellent pulsed charge/discharge properties of the high power density (184.84 MW·cm−3) and fast discharge time (46.3 ns). Our results demonstrated a novel strategy for improving the energy-storage performances of dielectric ceramics. This strategy could be used to design other or similar materials for various applications.