Effects of phase transition on the dynamic discharge energy density of antiferroelectric ceramics

Antiferroelectrics (AFEs) are widely used for energy storage capacitors. At present, there are two methods to evaluate the energy density of AFE: the recoverable energy density Wre calculated by the low-frequency P-E loop and the dynamic discharge energy density Wdis calculated by the fast discharge current. It has been widely observed that the value of Wdis is lower than Wre but less attention was paid to how to increase Wdis. Compared with Wre, the value of Wdis is closer to the energy density of AFE pulse capacitors in practical applications. In this work, the effects of phase transition properties on the dynamic discharge energy density were studied from the aspect of domain switching mobility. Compositions with P-E loop varying from "square" to "slant" were fabricated. It was found that in AFEs with "square" P-E loops, the recoverable energy density Wre was remarkably higher than Wdis. By modifying the P-E loops to long slim, the value of Wdis tended to be close to Wre, resulting in higher dynamic discharge energy efficiency. This indicates that by adjusting the P-E loop, higher Wdis can be achieved in AFE with lower Wre. The AFEs with long slim P-E loops also have faster discharge speeds, leading to higher power density. The outstanding fast discharge performance of AFEs with long slim P-E loops originated from their faster domain mobility and less viscous force during domain switching. This work provides a new approach to designing the AFEs energy storage materials by tuning their dynamic phase-transition properties and domain mobility.