Lead-free bulk ceramics have attracted increasing interest for electrical energy storage in pulsed power systems because of their superior mechanical properties, environment-friendliness, high power density and fast charge/discharge rate. Although considerable efforts have been made to design a large amount of lead-free bulk ceramics for energy storage applications, there is still a lack of scientific and feasible guidelines of how to explore new material systems with large recoverable energy density (W_rec), high energy storage efficiency (η) and excellent thermal stabilty, which are the three key parameters for energy storage applications. In this work, a strategy (coexistence of nanodomains and polar nanoregions via composition optimization) was proposed to achieve high comprehensive energy storage properties in lead-free bulk ceramics. NaNbO₃–Bi(Mg_0.5Zr_0.5)O₃ ceramics were selected as an example to verify the feasibility of this strategy. Encouragingly, both a high W_rec of 2.31 J cm⁻³ and a high η of 80.2% were achieved in 0.93NaNbO₃–0.07Bi(Mg_0.5Zr_0.5)O₃ (0.93NN–0.07BMZ) ceramics under 255 kV cm⁻¹, while keeping excellent thermal stability over 20 °C to 170 °C with the variation of W_rec < 10%, which is superior to other reported lead-free bulk ceramics. Compared with other lead-free bulk ceramics, the 0.93NN–0.07BMZ ceramic is a promising material for high-temperature pulsed power capacitors. Most importantly, this work provides a significant guideline for exploring a series of new high-performance lead-free dielectric ceramics for next generation advanced pulsed power capacitors in the future.

Inspired by the increasing demand for high energy-storage capacitors in electronic and electrical systems, the development of dielectrics with high energy-storage performance has attracted much attention recently. Here, a record-high recoverable energy-storage density of 11.18 J cm⁻³ and a high energy efficiency of 82.2% are realized in (Pb_0.98–xLa_0.02Sr_x)(Zr_0.9Sn_0.1)_0.995O₃ (PLSZS) antiferroelectric ceramics prepared using the tape-casting method. Sr²⁺-doping and the tape-casting method give rise to a colossal increase in breakdown strength and switching of the electric field between the antiferroelectric and ferroelectric phase, which are responsible for the excellent energy-storage properties. Furthermore, with respect to the discharge performance, the antiferroelectric PLSZS ceramics exhibit a high discharge energy density of 8.6 J cm⁻³, and fast discharge speed where 90% of the stored energy could be released in 185 ns. This study opens up a promising and feasible route for designing high energy-storage materials via an appropriate element doping and fabricating method, and more importantly, gives PLSZS antiferroelectric ceramics an unexpected role with potential for application in high-power pulsed capacitors.

1.8 -μm-(Pb_0.97La_0.02)(Zr_0.95−xSn_xTi_0.05)O₃ antiferroelectric thick films with orthorhombic (x = 0.05 and 0.25) and tetragonal (x = 0.40) structure were deposited on platinum-buffered silicon substrates by using a chemical solution way. All the films had a uniform microstructure with pure perovskite phase. With increasing x value, dielectric constant and critical electric breakdown field of the thick films were gradually increased, while their saturated polarizations were decreased. As a result, their maximum recoverable energy-storage density was increased for the thick films with larger x values. A huge recoverable energy-storage density of 56 J/cm³ was obtained in antiferroelectric thick films with x = 0.40. Moreover, a good temperature-dependent stability of the energy storage was obtained in the all films from 20 to 120 °C.