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

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 (SrNaNbTaO) for the improvement of the dielectric breakdown strength and the polarization difference. As a result, the ceramic with = 1.5, that is, SrNaNbTaO, exhibited superior energy density (∼3.99 J/cm) 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 < 57 ns), a high discharge current density (925.8 A/cm) along with a high power density (78.7 MW/cm). The energy storage properties in combination with good stability achieved in this work indicate the powerful potential of SrNaNbTaO 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.