Enhancing High-Temperature Energy Density through Al2O3 Nanoplates with Charge Barrier Effect in Polyetherimide-Based Composites

Polymer-based dielectric composites have a wide range of applications in modern electronics and power systems owing to their incomparable reliability, but remain a challenge to energy density at high temperatures. In this work, polyetherimide (PEI)-based nanocomposites with a small amount of aluminium oxide (Al2O3) nanoplates are prepared and obtain excellent energy density at elevated temperatures. The high-temperature energy density of the nanocomposites is significantly improved and reaches to 5.2 J cm(-3) at 550 kV mm(-1) and 150 degrees C after adding 0.6 wt% Al2O3 nanoplates. The enhanced energy density is attributed to the wide band gap and flaky morphology of Al2O3 nanoplates that can induce charge barrier effect and thus reduce the leakage current density within the nanocomposites. Furthermore, finite element simulations further reveal the mechanism of Al2O3 nanoplates acting as charge barrier to capture the charges transmitted from PEI matrix at the interface. This work offers a promising pathway to high-energy density polymer dielectrics capable of operating under high temperatures.