Excellent Energy Storage Capability in Sr0.6ba0.4nb2o6-Based Ceramics Via Incommensurate Modulation and Grain Boundary Reinforcement

Abstract

The energy storage performances for tungsten bronze ferroelectric ceramics have always been limited by the weak relaxor behavior and low breakdown strength. To boost the energy storage capability of the tungsten bronze ferroelectric ceramics, a synergistic two-step optimization strategy is proposed based on the Sr0.6Ba0.4Nb2O6 ceramic in this work, that is, enhance the relaxor behavior to generate slim hysteresis loops through introducing Bi0.5K0.5TiO3, and then optimize the microstructure to improve the breakdown strength by adding the sintering aid CuO. Ultimately, a remarkable comprehensive performance with a recoverable energy storage density (~6.31 J/cm3) and an efficiency (~91.8%) is realized under 600 kV/cm. In particular, a high-power density (~178 MW/cm3) and ultrafast discharge speed (<65 ns) are realized simultaneously, indicating an excellent capacitive performance. Moreover, it is revealed that the enhanced relaxor behavior is closely related to the incommensurate modulation structure in the ceramic, while the improved breakdown strength should be ascribed to the reinforced grain boundary, which collectively contribute to the superior energy storage performances.

Keywords: Tungsten bronze, Energy storage, Two-step optimization strategy, Incommensurate modulation, Reinforced grain boundary