Excellent Energy Storage Performance and Thermal Stability in Lead-Free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics

Dielectric energy storage capacitors have attracted considerable attention due to their excellent performance. Tungsten bronze-type ceramics have long been underestimated for energy storage applications owing to their relatively low breakdown strength and polarization. In this work, a lead-free relaxor ferroelectric ceramic, BaSrTiNb_2-<i>x</i>Ta_<i>x</i>O₉, was developed through Ta doping. Under an applied electric field, the material achieves a high recoverable energy density of 9.5 J/cm³ with an efficiency of 87.8%. Notably, it also exhibits excellent thermal stability and ultrafast discharge characteristics. The optimization strategy proposed in this study offers valuable guidance for the development of high-performance dielectric energy storage ceramics. It points to a direction for designing materials that combine superior energy storage properties with good temperature stability and provides an important reference for promoting technological innovation in advanced ceramic-based energy storage devices such as multilayer ceramic capacitors (MLCCs). It is expected to lead the development of the next generation of high-temperature stable dielectric materials.