Modulating energy storage properties in layered paraelectric/ferroelectric/paraelectric composites via thickness and strain engineering

Abstract

Ferroelectric capacitors hold great promise for energy storage applications due to their rapid charge/discharge rates and high breakdown strength. However, the relatively low density and efficiency of energy storage limit their practical application, and it is necessary to develop methods to improve their performance. In this study, we introduce a synergistic modulation of layer thickness and strain to enhance the energy storage density and efficiency of paraelectric/ferroelectric/paraelectric (SrTiO₃/PbTiO₃/SrTiO₃) composite multilayer structure. Phase field simulations reveal that the layered composites exhibit superior energy storage properties when the thickness of paraelectric (PE) layer exceeds that of ferroelectric (FE) layers in the studied range of thickness. Under different in-plane strains, larger tensile strains are found to enhance the energy storage performance by effectively reducing the remnant polarization. Furthermore, by carefully adjusting the layer thickness and applied strain, the layered composites exhibit tunable hysteresis loops of polarization versus electric field, including ferroelectric, antiferroelectric-like, and paraelectric-like characteristics. When the layer thickness and strain modulate synergistically, the sensitivity of the composite’s energy storage performance to strain becomes more pronounced as the thickness of the FE layer increases. Consequently, the optimal thicknesses of the FE and PE layers increase as the applied tensile strain increases. This modulation approach for the SrTiO₃/PbTiO₃/SrTiO₃ composite can also be extended to other layered PE/FE/PE systems, providing valuable guidance for optimizing the energy storage performance through either independent or synergistic adjustment of layer thickness and strain.