A high-entropy strategy for enhancing energy storage performance and enabling ultrafast discharge in tungsten bronze ceramics

Dielectric ceramics, as core materials for energy storage capacitors, have been widely utilized across various fields owing to their high-power density and ultrafast charge-discharge characteristics. In this study, a synergistic strategy combining high-entropy and bandgap engineering was employed to successfully prepare lead-free high-entropy dielectric ceramics with a tungsten bronze structure, having the chemical composition Ba_2.38Sr_2.12Sm_0.5Gd_0.5Ti₁Zr₁Nb_8-<em>x</em>Ta<em>_x</em>O₃₀(Ta-<em>x</em>, <em>x </em>= 0, 0.5, 1 and 1.5). The long-range ferroelectric order is effectively disrupted through high-entropy design, which enhances cationic disorder and thereby promotes relaxor ferroelectric behavior. Meanwhile, the synergistic effects of grain refinement, increased activation energy for electrical conductivity, and an enlarged bandgap significantly enhance the material’s breakdown strength. Through the collective effects of these mechanisms, the energy storage performance of the ceramics is significantly enhanced, with a recoverable energy density of 7.93 J·cm^-3 and an energy efficiency of 94.25% achieved at <em>x</em> = 0.5. Furthermore, the material demonstrates a current density of approximately 971.34 A·cm^-2, a power density of 155.41 MW·cm^-3, an ultrafast discharge time of 1.56 µs, and a discharge energy density of 5.20 J·cm^-3. This study presents an effective approach for developing high-performance dielectric ceramic materials, highlighting their promising potential for application in advanced pulsed power systems.