High energy storage density and efficiency in aligned nanofiber filled nanocomposites with multilayer structure

Large dielectric loss and low energy storage efficiency are common problems of poly(vinylidene fluoride) (PVDF) and its copolymers based energy storage dielectrics which has limited their applications. To solve these problems, linear dielectric polymethyl methacrylate (PMMA) with low intrinsic dielectric loss was chosen as the interlayers of P(VDF-TrFE-CFE) (PVTC) to form the multilayer structure dielectric. A small amount of silicon dioxide-coated Ba_0.6Sr_0.4TiO₃ fibers (BST@SiO₂) were incorporated into the PVTC layer to compensate the polarization decreasing due to the introduction of PMMA. The results showed that the optimized multilayer structure can significantly improve the energy storage efficiency and has a positive impact on enhancing both breakdown strength and permittivity. An enhanced and acceptable efficiency (85%) with a high energy density (10 J/cm³) were achieved in the 0.5 vol% 9-layer aligned BST@SiO₂ PVTC/PMMA dielectric. This work can sever as a route to simultaneously obtain high energy storage density and efficiency in polymer based composites.