Enhanced dielectric constant and energy density in a BaTiO3/polymer-matrix composite sponge

Abstract

Abstract Polymer-matrix dielectric composites are promising for use in electrostatic energy storage devices due to the ultra-fast charge–discharge speed and the long service life. Here we report a strategy for designing BaTiO 3 sponge polymer composites for energy storage. BaTiO 3 sponges with tunable porosities are prepared from polymethyl methacrylate micro-sphere arrays. Liquid epoxy completely fills the pores in a BaTiO 3 sponge during vacuum de-foaming, forming a solid composite. The resulting composites possess a maximum dielectric constant of ε r ~332 and ε r / ε m ~85, compared to ε r ~38 in a sample filled with BaTiO 3 NPs, at 1 kHz. The composites also possess, at 100 kV cm −1 , a high discharge energy density of U d ~105 × 10 −3 J cm −3 and U d / U m ~51, and electric displacement of 3.2 μC cm −2 , compared with those utilizing traditional strategies at low electric fields. Finite element simulation reveals the enhanced energy density is due to a high local electric displacement in composites.