Inhibition conduction loss for distinct improvement of energy storage density over a broad temperature range in polyetherimide-based composite films

The exploration of high-energy-density polymer dielectrics that can operate stably under high temperatures is of great significance in order to meet the growing needs for modern high-power electronics. However, the drasti-cally deteriorated capacitive performances brought by the inevitable conduction loss at elevated temperature grievously hinder their application in extreme circumstances. Herein, a class of sandwich-structured dielectric nanocomposites capitalizing on binary wide-bandgap nanofillers is reported. The synergy of wide bandgap Al2O3 nanoparticles and hydroxyl-modified BNNSs can build higher interfacial barrier to efficiently depress the thermionic charge injection and carrier transport in dielectrics, yielding a substantially inhibited electrical conduction of the composites under elevated temperature. Indeed, the resulting sandwich-structured polymer composites deliver first-class-level discharged energy density (Ud) of-2.23 J/cm3 with efficiency (eta) > 90% even under the ultra-high temperature of 200 degrees C, which is by far the current free-standing high-temperature dielectric polymer and polymer-based composites reported to date. Together with remarkable dielectric stability over a wide temperature and frequency range and outstanding cyclability, this contribution puts forward an efficient approach to groping for scalable high-temperature dielectric polymer nanocomposites for advanced electrical energy storage.