Regulation of Interfacial Polarization and Local Electric Field Strength Achieved Highly Energy Storage Performance in Polyetherimide Nanocomposites at Elevated Temperature via 2D Hybrid Structure

Dielectric materials with excellent high-temperature energy storage performances are urgently demanded in advanced electronic market. However, the sharply reduced energy storage capabilities caused by conduction loss impede the applications of polymer-based nanocomposites at harsh environments. In this work, the 2D hybrid structure fillers of boron nitride nanosheets-titanium dioxide (BNNSs-TiO 2 ), where TiO 2 nanoparticles tightly wrap around the 2D BNNSs, are fused with polyetherimide (PEI) forming polymer nanocomposite films. The finite element simulation and experiment results indicate that the hybrid structure 2D BNNSs-TiO 2 can effectively regulate local electric field strength and interfacial polarization, facilitating the enhancement in energy storage properties. Accordingly, the composite film delivers a superior discharged energy density (≈4 J cm −3 ) and charging/discharging efficiency (≈90%) at 150 °C, better than recently discussed high-temperature pristine polymer and their composite films. This contribution offers a feasible idea to explore reliable dielectric capacitors at high temperature.