Significant Enhancement of Energy Storage Performances by Regulating the Dielectric Contrast between Adjacent Layers in the Heterostructural Composites
Yang Liu, Yafei Hou, Ji Qian, Shixin Wei, Peng Du, Laihui Luo, Weiping Li
Abstract
Polymer-based composites with high discharged energy density and energy efficiency are tremendously desired for modern electronic systems. In this study, a bilayer heterostructural composite (named as THV/xBT) with excellent energy storage performances was constructed by one layer of a BaTiO3 nanoparticles (BT nps)-filled P(VDF-HFP) composite and another layer of a pure poly(tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene) (THV) polymer with a moderate dielectric constant and high breakdown strength. The experimental and finite element simulation results indicate that the space charges could accumulate at the interfaces between THV/P(VDF-HFP) and BT nps/P(VDF-HFP) by regulating the dielectric contrast between these two adjacent layers. It improves not only the interfacial polarization but also the breakdown strength and limits the leakage current density of THV/xBT composites. As a result, the THV/5BT composite delivers the best energy storage performance with the discharged energy density of 22.7 J/cm3, and an energy efficiency of 79.0% is achieved. This work might open up a way for structural design of polymer-based composites with remarkable energy storage performances.