Superior energy storage properties and excellent stability of novel NaNbO3-based lead-free ceramics with A-site vacancy obtained via a Bi2O3 substitution strategy

Abstract

This study presents an innovative strategy to improve the energy storage properties of NaNbO₃ lead-free ceramics by the addition of Bi₂O₃. The introduction of Bi₂O₃ can effectively increase the breakdown strength and decrease the remnant polarization of NaNbO₃ ceramics. Meanwhile, hybridization between the O²⁻ 2p and Bi³⁺ 6p orbitals can enhance the polarization. The novel NaNbO₃-based (Na_0.7Bi_0.1NbO₃) ceramics demonstrate ultrahigh energy storage efficiency of 85.4% and remarkably high energy storage density (4.03 J cm⁻³) at 250 kV cm⁻¹ simultaneously, which are superior to the results of almost all recently reported lead-free alternatives. The outstanding stability of energy storage characteristics in terms of frequency (1–1000 Hz), temperature (20–120 °C) and fatigue (cycle number: 10⁵) is also observed in Na_0.7Bi_0.1NbO₃ ceramics. Furthermore, additional pulsed charge–discharge measurements for Na_0.7Bi_0.1NbO₃ ceramics are also carried out to evaluate actual operation performance. The Na_0.7Bi_0.1NbO₃ ceramics exhibit extremely high power density (62.5 MW cm⁻³) and current density (1250 A cm⁻²) and release all stored energy rapidly (∼155 ns) under various electric fields and temperatures. These properties qualify these environment-friendly Na_0.7Bi_0.1NbO₃ ceramics as innovative and most promising alternatives for energy storage applications, especially for high power and pulsed power system applications.