Enhanced energy storage density in poly(vinylidene fluoride-hexafluoropropylene) nanocomposites by filling with core-shell structured BaTiO3@MgO nanoparticals

Abstract

Filling with high dielectric constant inorganic nanoparticles is an effective approach to enhance the energy storage performance of an organic dielectric. However, the dielectric mismatch between ceramic and polymer causes early breakdown, which limits the storage density of ceramic/polymer nanocomposites in the application of dielectric capacitors. Herein, we employed MgO as a buffer barrier to mitigate the mismatched dielectric characteristics among BaTiO3 (BT) nanoparticles and poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) substrate considering its high insulation and medium dielectric constant. The alien oxide was coated on the spherical BT by a simple chemical precipitation process, forming a BaTiO3@MgO (BT@MgO) core-shell nanostructure, which has been carefully examined by TEM and EDS. The BT-MgO heterogeneous interfacial region provides channels for carriers and promotes charge movement, and therefore the dielectric constant and potential shift have been significantly enhanced. The BT@MgO/P(VDF-HFP) nanocomposite with 1 vol% filling ratio delivered a maximum energy density Ud, and the value reaches up to 5.6 J/cm3 that is 40.0 % and 55.6 % greater than that of the host matrix and BT-filled counterpart with the same filler amount. The BT@MgO core-shell nanostructure demonstrates an alternative way to effectively heighten the energy storage performance of ceramic/polymer composite dielectrics.