Multi-scale domain and microstructure engineering for the high-energy-storage BCZT based lead-free relaxor ferroelectric ceramics

Fulfilling the stringent demand of the miniature and eco-friendly pulsed power devices, development of high-energy-storage lead-free dielectric energy storage is critical. To achieve this goal, the mature strategy is to induce the formation of relaxor polar nano regions (PNRs) by means of constructing multiple solid solutions and element doping, which will inevitably lead to a significantly weakened polarization. How to better achieve the domain regulation is a challenge. Here, we reconsidered binary composite-induced domain evolution and designed a novel BT-based binary system with Na0.7Bi0.1NbO3 (NBN) modification. By adjusting the NBN content to retain the long-range ferroelectric domains and applying the hot-pressing (HP) method to modulate grain size, the coupling of multi-scale domain morphology and voltage allocation can be achieved, simultaneously contributing to the high polarization, the enhanced breakdown strength and the optimized polarization response. Accordingly, a 130% enhancement to 5.32 J/cm3 in energy storage density, a high energy storage efficiency of -90%, an ultrafast discharge period of -55 ns, and a giant power density of -369.9 MW/cm3 were realized in our HP ceramics, superior to the existing dielectric ceramics. Moreover, the energy storage properties also exhibited superior frequency and thermal stability. The proposed synergistic optimization strategy of the domain morphology regulation and the microstructure adjustment is valuable for further energy storage design, and the enhanced energy storage properties promote the applications for lead-free dielectrics in energy storage devices.