Significant\nEnhancement of Energy Storage Performances\nby Regulating the Dielectric Contrast between Adjacent Layers in the\nHeterostructural Composites

Polymer-based\ncomposites with high discharged energy density and\nenergy efficiency are tremendously desired for modern electronic systems.\nIn this study, a bilayer heterostructural composite (named as THV/xBT) with excellent energy storage performances was constructed\nby one layer of a BaTiO3 nanoparticles (BT nps)-filled\nP­(VDF-HFP) composite and another layer of a pure poly­(tetrafluoroethylene-vinylidene\nfluoride-hexafluoropropylene) (THV) polymer with a moderate dielectric\nconstant and high breakdown strength. The experimental and finite\nelement simulation results indicate that the space charges could accumulate\nat the interfaces between THV/P­(VDF-HFP) and BT nps/P­(VDF-HFP) by\nregulating the dielectric contrast between these two adjacent layers.\nIt improves not only the interfacial polarization but also the breakdown\nstrength and limits the leakage current density of THV/xBT composites. As a result, the THV/5BT composite delivers the best\nenergy storage performance with the discharged energy density of 22.7\nJ/cm3, and an energy efficiency of 79.0% is achieved. This\nwork might open up a way for structural design of polymer-based composites\nwith remarkable energy storage performances.