Enhanced capacitive energy storage of NaNbO3-based relaxor via modulating the phase structure strategy for high power energy storage

Abstract

In modern advanced pulse power devices, developing dielectric electrostatic capacitors with high energy storage density and outstanding thermal stability is crucial for their practical applications. Herein, a novel 0.9NaNbO₃–0.1La(Mg_0.5Zr_0.5)O₃ lead-free ceramic was designed to improve the energy storage properties by modulating the phase structure strategy. The introduction of suitable La(Mg_0.5Zr_0.5)O₃ into the NaNbO₃ matrix effectively modulates the phase structure of the ceramic, refines the domain size, improves the relaxation properties, and reduces the energy loss during the discharge process. As a result, a high recoverable energy density (W_rec) of 7.0 J cm⁻³ and a high efficiency (η) of 85.9% are simultaneously achieved at a high breakdown field of 575 kV cm⁻¹. The ceramic also exhibits excellent high-temperature and outstanding fatigue energy storage stability, achieving a high η of 88.9% at 160 °C and 1–10⁵ cycle number. In addition, an exceptionally high-power density (P_D) of 80.0 MW cm⁻³ and a nanosecond discharge time close to 13.0 ns are achieved, thereby indicating huge potential for high-temperature and high-power capacitors. This work synergistically optimizes both W_rec and η, providing new insights into the design of high-performance energy storage materials.