Optimization of polarization behavior enabled by multiscale heterostructure design for excellent energy storage performance in Na0.5Bi0.5TiO3-based relaxor ferroelectric thin film

Abstract

Dielectric capacitors are promising candidates in the field of pulse power systems due to their ultrafast charge/discharge speed and high power density. A major challenge, however, is to improve the recoverable energy storage density (Wrec) and energy storage efficiency (η). In this work, Na0.5Bi0.5(Ti,Fe)O3 (NBFT)-based system is selected and the equivalent circuit of the corresponding capacitors is studied according to the Maxwell's displacement current hypothesis, providing a way of optimizing the polarization behavior by multiscale heterostructure design via adjusting the specific arrangement of layers and interface within the NBFT-based capacitors. By introducing heterogeneous components of (Ba,Sr)TiO3 (BST) and Na0.5Bi0.5(Ti,Zr)O3 (NBZT), abundant heterogeneous interfaces are obtained for NBFT/BSxT and NBFT/NBZT heterostructure thin films. Both the thin films possess superior breakdown strength (EBD) and polarization response (Pm–Pr) than that of NBFT, which is highly associated with the interfacial resistance, improvement of local component heterogeneity, changes in domain wall motion and Von Mises stress/strain distribution. Notably, the energy storage performance is modulated for NBFT/NBZT with enhanced relaxor ferroelectricity as the heterogeneous interface is increased with Wrec and η of 66.57 J/cm3 and 64.33%, respectively. These findings prove effective ways of optimizing NBT-based relaxor ferroelectric thin film for energy storage devices.