Realization of superior thermal stability and high-power density in BNT-based ceramics with excellent energy storage performance

Herein, NaTaO3(NT) is introduced into 0.7Bi0.5Na0.5TiO3-0.3Sr0.7La0.2TiO3 (BNSLT) ceramic to increase the content of the highly stable P4bm phase, constructing a temperature-insensitive phase structure and permittivity over a wide temperature range (25–300 °C); thus, excellent thermal stability (Wrec = 4.68 ± 0.50 J/cm3, η = 89.0 ± 2.1%) over an ultra-wide temperature range (20–240 °C) is realized, superior to most lead-free ceramics. The co-substitution of heterovalent ions at both A and B sites in BNSLT leads to enhanced relaxor state and bandgap, delayed saturation polarization, reduced grain size and permittivity. Thereby, an excellent recoverable energy storage density (Wrec = 8.55 J/cm3), high efficiency (η = 89.5%), and extremely high power density (PD = 320 MW/cm3 at 280 kV/cm) are obtained in BNSLT-8%NT ceramics. This work offers a new paradigm for the development of ceramic capacitors with both excellent comprehensive energy storage performance and high-temperature working stability.