Collaboratively improved energy density and efficiency in NaNbO3-based lead-free relaxor ferroelectrics via enhancing antiferrodistortion

Abstract

High-performance relaxor ferroelectrics for energy-storage capacitors have attracted enormous attention, but the difficulty in simultaneously enhancing energy density (W_rec) and efficiency (η) largely hinders their development. Herein, we introduce an effective strategy to collaboratively improve W_rec and η values in NaNbO₃-based lead-free relaxor ferroelectric (FE) ceramics through enhancing the antiferrodistortion of the FE superlattice, realizing an excellent comprehensive energy-storage performance of W_rec ∼ 8.5 J cm⁻³ and η ∼ 90%. Both the local FE orthorhombic supercells with a significantly enhanced antiferrodistortive degree and the formation of highly concentrated stripe-like polar nanodomains should be responsible for the markedly delayed polarization saturation, the suppressed polarization hysteresis and the maintained maximum polarization. These structural features also ensure outstanding temperature-insensitive charge–discharge properties of high-power density ∼343 ± 6% MW cm⁻³, high discharge energy density ∼4.3 ± 10% J cm⁻³ and ultra-short discharge time <30 ns at 0–150 °C, demonstrating great application potential in next-generation advanced pulse power capacitors. As a result, enhancing antiferrodistortion should be a valuable way to develop novel high-performance relaxor ferroelectric capacitors.