Dielectric substances exhibit great potential for high-power capacitors due to their high stability and fast charge–discharge; however, a long-term challenge is to enhance energy density. Here, we propose a poly(vinylidene fluoride) (PVDF) composite utilizing BaTiO3 nanoparticle@TiO2 nanosheet (BT@TO ns) 2D nanohybrids as fillers, aiming at combining the interfacial strategy of using a core–shell filler and the electron scattering of a 2D filler to improve the energy density. With 4 wt% filler, the composite possesses the largest breakdown strength (Eb) of 561.2 MV m−1, which is significantly enhanced from the 407.6 MV m−1 of PVDF, and permittivity of 12.6 at 1 kHz, which is a 23% increase from that of PVDF. A superhigh energy density of 21.3 J cm−3 with an efficiency of 61% is obtained at 550 MV m−1. The 2D BT@TO ns-filled composite exhibits a higher energy density than composites filled with core–shell 1D BT@TO nws or non-core–shell 0D BT, 1D TO, or 2D TO particles. The Eb and energy density improvements are attributed to the buffer layer-based interface engineering and enhanced area scattering of electrons caused by the 2D hybrids, an effect similar to that of a ping-pong paddle to scatter electric field-induced charge migrations in composites. Thus, an effective hybrid strategy is presented for achieving high-performance polymer composites that can be used in energy storage devices.
This work presents a polymer-matrix composite filled with BaTiO3@TiO2 nanosheets for tailoring the energy density. Due to the fact that TiO2 possesses the intermediate dielectric constant between that of BaTiO3 and the polymer matrix thus it reduces the interface charges, and also, the large aspect ratio of nanosheets enhance the ping-pong-like electron area scattering, as a result, significantly enhanced breakdown strength and energy density are fulfilled in the composite, with high potentials in electrostatic energy storage capacitors.