Highly enhanced energy density induced by hetero-interface in sandwich-structured polymer nanocomposites

A novel sandwich-structured polymer-based nanocomposite with different dielectric fillers stacked together was fabricated employing a layer-by-layer casting process. In the sandwich-structured composite poly(vinylidene fluoride)-based film, the outer layer with TiO sub(2) nanoparticles increased the electric displacement while the central layer with paraelectric BaSrTO sub(3) nanofibers maintained the high breakdown strength. Compared with single layer films, the extractable energy density was greatly enhanced in the sandwich-structured film. Instead of solely being stored at the interface between the dielectrics and the electrodes as in a conventional capacitor, charges are also stored at the additional interfaces between the two heterofilm layers within the multilayer dielectric nanocomposite. A numerical simulation was performed to solve the electrostatic equilibrium equation and then to obtain the scenario of charge storage at the hetero interfaces inside the nanocomposite.