Multistep synergistic modified NaNbO3-based ceramics for high-performance electrostatic capacitors

Abstract

NaNbO₃-based lead-free energy storage ceramics are highlighted as essential components for the next–generation pulsed power capacitors, especially in the realm of eco-friendly renewable energy sources. Nevertheless, their large electric hysteresis loss and low breakdown strength (E_b) lead to difficulties in simultaneously achieving high recoverable energy density (W_rec) and efficiency (η), severely hindering their further development. Herein, a multistep synergistic optimization strategy is proposed to balance W_rec and η in NaNbO₃-based ceramics. The addition of CaZrO₃ (CZ) and Bi_2/3HfO₃ (BH) into NaNbO₃ ceramic generates a stabilized antiferroelectric phase, highly dynamic polar nanoregions, refined grains, and increased band-gap, resulting in delayed polarization saturation and ultrahigh E_b. With the deliberate multistep synergistic route, the 0.85NNCZ–0.15BH ceramics attain an extraordinary W_rec of 9.2 J cm⁻³ and high η of 82.5% under 920 kV cm⁻¹, accompanied by superior stability of temperature, frequency, and fatigue resistance. The novel and easily applicable multistep synergistic optimization strategy presented in this work could be extended to other high-performance ceramic systems, paving a new and effective route for the development of high-performance capacitors.