High-performance energy storage in BNST-based lead-free ferroelectric ceramics achieved through high-entropy engineering

Abstract

The utilization of a high entropy approach for the design of high-performance perovskite dielectric capacitors has been gaining much attention for the development of next-generation pulse power capacitors. Despite this, there are still challenges to further enhance their energy storage density and efficiency. To address this, a high-entropy strategy is proposed to significantly improve the energy storage characteristics of ceramics by increasing the configurational entropy and delaying saturation polarization. This approach has resulted in an ultra-high recoverable energy storage density (Wrec) of 7.16 J/cm3 and a high efficiency (η) of 93.3 % for 0.8[0.65(Bi0.5Na0.5)TiO3-0.35SrTiO3)]-0.2[Ba(Zr0.2Ti0.2Sn0.2Hf0.2Nb0.2)O3] (abbreviated as 0.8BNST-0.2Ba(5 M)O) ceramic. The inclusion of Ba(5 M)O high entropy oxides has resulted in slender polarization–electric field hysteresis loops with delayed polarization saturation. The increase in atomic configuration entropy, degree of atomic disorder and lattice distortion due to the Ba(5 M)O high entropy oxides, has led to an increase in breakdown field, improved energy storage density and efficiency. Furthermore, excellent thermal stability (30–150 ℃), superior frequency stability (5–1000 Hz), and robust fatigue (100–105 cycles) endurance were achieved. The high entropy strategy has been demonstrated to be an effective method for the design of novel capacitors with superior energy storage performance.