Simultaneously Realizing Superior Energy Storage Properties and Outstanding Charge–Discharge Performances in Tungsten Bronze-Based Ceramic for Capacitor Applications

Abstract

The development of lead-free ceramics with appropriate energy storage properties is essential for the successful practical application of advanced electronic devices. In this study, a site engineering strategy was proposed to concurrently decrease grain size, increase the band-gap, and enhance the relaxor nature in Ta-doped tungsten bronze ceramics (Sr₂NaNb_5-<i>x</i>Ta_<i>x</i>O₁₅) for the improvement of the dielectric breakdown strength and the polarization difference. As a result, the ceramic with <i>x</i> = 1.5, that is, Sr₂NaNb_3.5Ta_1.5O₁₅, exhibited superior energy density (∼3.99 J/cm³) and outstanding energy efficiency (∼91.7%) (@380 kV/cm) as well as good thermal stability and remarkable fatigue endurance. In addition, the ceramic demonstrated an ultrashort discharge time (τ_0.9 < 57 ns), a high discharge current density (925.8 A/cm²) along with a high power density (78.7 MW/cm³). The energy storage properties in combination with good stability achieved in this work indicate the powerful potential of Sr₂NaNb_5-<i>x</i>Ta_<i>x</i>O₁₅ tungsten bronze ceramics for high-performance capacitor applications. This material can be considered as a complement to the widely studied perovskite-based relaxor ceramics and should be further investigated in the future.